JPH09245367A - Manufacturing method of light guide member - Google Patents

Abstract

(57) Abstract: When a guide bar is manufactured by cutting a third substrate block, it is possible to prevent the third substrate block from bending and to accurately cut the third substrate block. To aim. A third substrate block 230 including a plurality of optical element groups serving as light guide members 5 and 41 is cut along a cut surface 226.
After being cut by, the filler 229 is injected into the void formed when the third substrate block 230 is cut at the time of cutting, and the filler 229 is cured, and then cut non-parallel to the cut surface 226. A manufacturing method of cutting the third substrate block 230 at the surface 227 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup, which records or reproduces information on an optical element, an optical disc or the like, and a method of manufacturing an optical guide member used for an optical pickup for a phase change optical disc.

[0002]

2. Description of the Related Art In recent years, an integrated optical pickup device has been developed with the aim of miniaturizing an optical pickup, and is going to be put to practical use.

An important point of an integrated optical pickup is to integrate a light guide member that guides light to a medium and guides light reflected from the medium to a light receiving element or the like.

As a known example, there is a method of manufacturing a polarization splitting prism as described in Japanese Patent Application Laid-Open No. 5-66303.

[0005]

However, in the above-mentioned conventional structure, there is a problem that the production efficiency is very poor because there are a plurality of lapping steps between the cutting steps.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for efficiently manufacturing a light guide member by using a lapping step as one step.

[0007]

In order to achieve this object, a substrate block including a plurality of optical element groups serving as a light guide member is cut on a first plane and then the substrate block is cut on the first plane. A manufacturing method is used in which a filler is injected into the void formed when the substrate is cut, the filler is cured, and then the substrate block is cut along a second plane that is not parallel to the first plane.

[0008]

The invention according to claim 1 has a plurality of substrates inclined with respect to the incident direction of the light emitted from the light source, and guides the light from the light source to the medium and reflects the light from the medium. A method of manufacturing a light guide member for guiding light to a predetermined position, comprising: cutting a substrate block including a plurality of optical element groups serving as the light guide member in a first plane, and then cutting the substrate block in the first plane. By processing the substrate block after injecting a filler into the void formed when the substrate block is cut, it is possible to prevent processing accuracy from being deteriorated due to distortion or bending during processing. it can.

The invention according to claim 2 has a plurality of substrates inclined with respect to the incident direction of the light emitted from the light source,
A method of manufacturing a light guide member, which guides light from a light source to a medium and guides light reflected from the medium to a predetermined position, wherein a first substrate block includes a plurality of optical element groups to be the light guide member. After cutting along the plane, a filler is injected into the void formed when the substrate block is cut along the first plane, and after the filler is cured, the filler is non-parallel to the first plane. By cutting the substrate block along the second plane, it is possible to prevent the second substrate block from bending when the second substrate block is cut along the second plane.

[0010] According to a third aspect of the present invention, there are provided a plurality of substrates inclined with respect to the incident direction of light emitted from the light source,
A method of manufacturing a light guide member, which guides light from a light source to a medium and guides light reflected from the medium to a predetermined position, wherein a first substrate block includes a plurality of optical element groups to be the light guide member. After cutting along the plane, the filler is injected into the void formed when the substrate block is cut along the first plane, and after the filling is hardened, the first plane perpendicular to the first plane is cut. By cutting the substrate block along the second plane, it is possible to prevent the second substrate block from being bent when the second substrate block is cut along the second plane, and the rectangular parallelepiped light is used. The guide member can be easily manufactured.

According to a fourth aspect of the present invention, there is provided a plurality of substrates inclined with respect to the incident direction of the light emitted from the light source,
A method for manufacturing a light guide member that guides light from a light source to a medium and guides light reflected from the medium to a predetermined position, the first substrate block including a plurality of optical element groups to be the light guide member. A void portion formed when a plurality of second substrate blocks are stacked to form the second substrate block, the second substrate block is cut on the first plane, and then the second substrate block is cut on the first plane. A plurality of light guide members for a short time by injecting a filler into the substrate, and after the filler is cured, cutting the second substrate block along a second plane perpendicular to the first plane. Can be manufactured in large quantities.

According to the fifth aspect of the present invention, since the water-soluble photo-curing bonding material is used as the filling material, the void portion can be easily and reliably held in a short time.
The processing accuracy of the light guide member can be improved, and at the same time, the manufacturing cost can be reduced.

The packaging of the optical pickup according to the embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are sectional views showing the packaging structure of an optical pickup according to an embodiment of the present invention.

Reference numeral 1 denotes a light source. As the light source 1, various lasers such as a semiconductor laser and a gas laser such as He-Ne can be considered. Here, it is preferable to use a semiconductor laser which is the smallest among these, can reduce the size of the entire device, and has an output of several mW to several tens mW which is inexpensive. Semiconductor lasers made of AlGaAs, InGaAsP, I
nGaAlP, ZnSe, GaN, and the like are conceivable. Here, AlGaAs, which is most commonly used and is inexpensive, is used. Furthermore, when performing high-density recording, the spot diameter on the recording medium can be made smaller, and
It is preferable to use a semiconductor laser such as InGaAlP or ZnSe having a shorter wavelength than s.

Reference numeral 2 denotes a submount, and the submount 2 has a rectangular parallelepiped shape or a plate shape, and the light source 1 is attached to the upper surface thereof. This submount 2 is a light source 1
And has the function of releasing the heat generated by the light source 1. In consideration of the thermal conductivity and the like, the bonding between the submount 2 and the light source 1 is made of Au-Sn, Sn-Ag, Sn-
It is preferable to use a method in which a solder foil (thickness of several μm to several tens of μm) such as Sb is pressure-bonded at a high temperature. In addition, if the light source 1 and the submount 2 are not mounted substantially horizontally, aberrations in the optical system and a decrease in coupling efficiency may be caused. Therefore, at the time of joining, it is preferable that the light source 1 be mounted on the submount 2 at a predetermined position at a predetermined height and substantially horizontally. Further, an electrode surface 2a is provided on the upper surface of the submount 2 so as to make electrical contact with the lower surface of the light source 1. The electrode surface 2a is for supplying power to the light source 1, and it is preferable to use a thin Au film in consideration of conductivity and corrosion resistance as a metal film constituting the electrode surface 2a. Further, the submount 2 has a high thermal conductivity and a linear expansion coefficient of that of the light source 1 (approximately 6.5 × 10 ⁻⁶ /) due to heat generated from the light source 1 and problems such as attachment to the light source 1.
C) are preferred. Specifically, the coefficient of linear expansion is 3
A substance having a thermal conductivity of 100 w / mK or more at -10 × 10 ⁻⁶ / ° C., for example, AlN, SiC, T-cBN, Cu
/ W, Cu / Mo, Si, and the like, and particularly, when a high-output laser is used, it is preferable to use diamond or the like when the thermal conductivity must be extremely large. When the linear expansion coefficients of the light source 1 and the submount 2 are set to be equal or close to each other, the occurrence of distortion between the light source 1 and the submount 2 can be suppressed. It is possible to prevent inconveniences such as detachment of the attachment portion and cracking of the light source 1. However, if the distance is out of this range, a large distortion is generated between the light source 1 and the submount 2, and there is a possibility that the attachment portion between the light source 1 and the submount 2 is detached, and a crack or the like occurs in the light source 1. Get higher. Further, by making the thermal conductivity of the submount 2 as large as possible, the heat generated in the light source 1 can be efficiently released to the outside. However, when the thermal conductivity is equal to or less than this limit, the heat generated by the light source 1 is difficult to escape to the outside, so that the temperature of the light source 1 increases, the output of the light source 1 decreases, and the life of the light source 1 is shortened. In the worst case, the light source 1 is likely to be broken. In the present embodiment, AlN which is relatively inexpensive and has excellent both of these two characteristics is used. Further, it is preferable to form a thin film on the upper surface of the submount 2 in order of Ti, Pt, and Au from the submount 2 toward the light source 1 in order to improve the bonding property with the light source 1. When Si is used for the submount 2, T
It is preferable that an oxide film such as Al ₂ O ₃ or an insulating film formed by surface oxidation is formed before i.

Reference numeral 3 denotes a block. The block 3 is basically rectangular parallelepiped and has a large protrusion 3a on its side surface, and the submount 2 is attached to the upper surface thereof. Like the submount 2, the block 3 also has a high thermal conductivity and a material having a linear expansion coefficient close to that of the submount 2, for example, due to heat generated from the light source 1 and problems such as attachment to the submount 2. It is preferable to use Mo, Cu, Fe, Kovar, 42 alloy or the like other than those shown in the material examples of the submount 2. However, the requirements for these characteristic values are not so strict as compared with the submount 2, so that it is preferable to select them with emphasis on cost. Here, the block 3 is formed of a material such as Cu or Mo which is very inexpensive as compared with AlN and has relatively excellent characteristics. In consideration of the thermal conductivity and the like, the joining between the block 3 and the submount 2 is somewhat expensive, but also Au-Sn, Sn-Ag, S, similarly to the case of the submount 2 and the light source 1.
It is preferable to press-bond a solder foil (thickness of several μm to several tens μm) of n-Sb, Sn-Pb, Sn-Pb-In or the like at a high temperature.

Reference numeral 4 denotes a heat radiating plate. The heat radiating plate 4 has a function of releasing heat generated by the light source 1 and transmitted through the submount 2 and the block 3 to the outside.
Various members forming the optical pickup are mounted thereon, and serve as a packaging substrate. The heat radiating plate 4 is provided with a hole 4a for adjustment. Block 3 is brazed,
It is fixed to the upper surface of the heat sink 4 by solder foil or the like. Heat sink 4
Cu, Al, Fe, etc., which have high thermal conductivity, can be considered as the material of the.

The submount 2 and the block 3 are used here.
Are formed separately, but when the output of the light source 1 is high and a higher thermal conductivity is required for these members, these members are integrally formed in order to improve the thermal conductivity. Is preferred. In this case, it is preferable to use those having extremely high thermal conductivity such as AlN.

It is desirable that the block 3 is larger than the submount 2 to have a large contact area with the heat sink 4.

Since the light source 1 is required to have high accuracy with respect to the optical axis, the upper surface of the submount 2 is preferably horizontal with high accuracy. Therefore, it is preferable to pay close attention to the mounting of the submount 2, the block 3, and the heat sink 4.

Reference numeral 5 denotes a light guide member. The light guide member 5 has a rectangular parallelepiped shape, has a plurality of slopes and various films formed on the slopes therein, and is emitted from a light source. It has a function of emitting the emitted light and guiding the returned light to a predetermined position. The light guide member 5 is adhered on its side surface to the end surface 3b of the projection 3a of the block 3. The bonding material used for this purpose must have conditions such as high adhesive strength, workability that can be fixed at any moment, small changes in volume due to changes in volume before and after curing and changes in temperature and humidity, that is, low shrinkage. It is required, and by satisfying these, workability and stability of the joint surface can be improved. Here, a UV adhesive which is instantly cured by irradiating ultraviolet rays is used as such a bonding material. Further, a moisture-absorbing and curing instant adhesive may be used. It is preferable that the contact area (S) between the block 3 and the light guide member 5 is S> 1 mm ² in order to have a sufficient mounting strength.

Reference numeral 13 denotes a light receiving element, and the light receiving element 13 is composed of various electric circuits formed on a plate-shaped semiconductor wafer, and is attached to the bottom surface of the light guide member 5. At the time of attachment, the position is adjusted using the holes 4 a provided in the heat sink 4. Regarding the attachment of the light receiving element 13 and the light guide member 5, a large adhesive strength, workability that can be fixed at any moment, change in volume before and after curing, temperature and
Conditions such as a small change in volume due to humidity, that is, a low shrinkage ratio are required. By satisfying these conditions, workability and stability of the joint surface are improved. As such a bonding material, a UV adhesive having particularly good workability was used because it is instantaneously cured by irradiating ultraviolet rays. Note that a moisture-absorbing-curing instant adhesive may be used. The light receiving element 13 has a plurality of light receiving portions for receiving the light signal emitted from the light source 1 and reflected by the light guide member 5 and the recording medium and returned. The light signal detected by the light receiving unit is converted into an electric signal according to the light amount. This electric signal has the magnitude of the current value at the beginning of the conversion. However, this current has the disadvantages that it is very weak and that noise is easily picked up.
For this reason, it is preferable here to use, as the light receiving element 13, an element formed with an IV amplifier having a function of converting a current value to a correlated voltage value and amplifying it. However, it is required that the response of the output voltage be good with respect to the incident frequency of light. Further, on the surface of the light receiving element 13, there are provided a plurality of electrodes 13a made of a thin film of Al or the like for extracting the received information as a signal.

14 is a package, and the package 14 is
On the upper surface of the heat radiating plate 4, the above-described block 3 and the light guide member 5,
It is provided so as to surround the light receiving element 13 and the like, and a lead frame 14a used for extracting an electric signal from the light receiving element 13, supplying power to the light source 1, and the like is molded therein. The shape of the package 14 is a rectangular parallelepiped shape with a hollow central portion.
The step 14 is formed on the inner surface of the package 14 on the side where the mold 4a is molded so as to expose the legs 14b of the lead frame.
c is provided. Note that the shape of the package 14 may be a cylindrical shape or the like. Then, the legs 14b of the lead frame exposed on the steps 14c provided on the package 14 for extracting an electric signal from the light receiving element 13
And a plurality of electrodes 13 provided on the surface of the light receiving element 13
a is connected by wire bonding with a wire 14d made of Au, Al, or the like. In order to supply power to the light source 1, the upper surface of the light source 1 and the leg 14 b of the lead frame exposed on the step 14 c provided on the package 14 are bonded by wires 14 d, and
The electrode surface 2a provided on the upper surface of the light source 1 so as to be in electrical contact with the lower surface of the light source 1 and the leg 14b of the lead frame exposed on the step 14c provided on the package 14 are also wire-bonded with the wire 14d. By connecting. The material of the package 14 is required to be excellent in low water absorption, low outgassing, and the like. Here, a thermosetting resin such as an epoxy resin, which is the most common, is used as the IC mold. As the material of the lead frame 14a, a metal such as Cu, 42 alloy or Fe plated with Ag or Au is often used. Here, Cu plated with Ni and Au plated thereon was used. Further, for attachment between the package 14 and the heat radiating plate 4, a bonding material having properties such as high adhesive strength, low water absorption, and high airtightness (low leak characteristics) is used. As a result, the stability of the bonding surface and bonding position can be improved, and impurities can be prevented from entering the inside of the packaging of the optical pickup. Here, an inexpensive epoxy adhesive excellent in these characteristics was used.

Reference numeral 15 denotes a shell, and the shell 15 also has an outer shape like a rectangular parallelepiped hollowed out like the package 14, and its horizontal cross section is substantially the same as that of the package 14. . The material is required to have characteristics such as low water absorption and low outgassing in order to prevent impurities from being mixed into the interior of the packaging. Here, polybutylene terephthalate (hereinafter referred to as PBT) having excellent properties is used. However, in particular, when characteristics excellent in strength, dimensional accuracy, and the like are required, an LCP that is more expensive than PBT but has these characteristics may be used. And the adhesion between the shell 15 and the package 14 is
An epoxy adhesive was used for the same reason as the attachment of the package 14 and the heat sink 4 described above. This shell 1
Instead of using 5, the height of the side wall portion of the package 14 may be made higher than that of the light guide member 5 for substitution.

Reference numeral 16 is a cover member, which is used to prevent dust and dirt from adhering to the light guide member 5 and the light receiving element 13, and is attached to the upper surface of the shell 15 by an epoxy adhesive. ing. Further, as the material of the cover member 16, it is preferable to use glass such as BK-7, FK-1, and K-3, or resin having high light transmittance such as urethane, polycarbonate, and acrylic.
Further, it is preferable to form anti-reflection films 16a on both upper and lower surfaces of the cover member 16 to prevent reflection. This antireflection film 16a is preferably formed of a material such as MgF ₂ .

As for the positional relationship between the cover member 16 and the light guide member 5, it is considered that the cover member 16 and the light guide member 5 are brought into contact with each other or a space is provided between them. When the two are brought into contact, the light guide member 5 is attached to the bottom of the cover member 16 with an epoxy-based adhesive or a UV adhesive. At this time, the thickness (t1) of the cover member 16 is set to 0.3 ≦ t1 ≦ 3.0 (m
m) is preferable. The reason for this is that if the lower limit is made thinner than this, the cover member 16 may not be able to withstand the weight of the light guide member 5 or the like attached thereto or the tension when the adhesive is hardened, and may be damaged. Regarding the upper limit, since the cover member 16 has a larger refractive index than air, a converging action is generated on the light and the light does not spread. As a result, the cover member 16 and the collimator lens (in the case of an infinite optical system) or the objective lens (In the case of a finite optical system), you have to increase the distance from
This is because it is disadvantageous in downsizing the pickup unit. By using such a configuration, the height of the optical pickup can be further reduced, and the pickup unit can be downsized while maintaining sufficient mounting strength.

On the other hand, when a space is provided between the two, the thickness (t2) of the cover member 16 is set to 0.1≤t2≤.
3.0 (mm), and the distance (d) between the cover member 16 and the light guide member 5 is also preferably 0.1 ≦ d ≦ 3.0 (mm). The reason for this is that the lower limit of t2 is different from the previous example in that the light guide member 5 is not attached, and it is only necessary to withstand external factors such as vibration. Also, as for d, the smaller the better, the better. However, there is a possibility that the accuracy error during assembly cannot be reduced to 0.1 mm or less. In this case, the cover member 16 comes into contact with the light guide member 5 during assembly and breaks. There is a risk that it will. By using such a configuration, the block 3 or the submount 2 is brought into thermal contact with another member while improving the relative positional accuracy between the light guide member 5 and the light source 1, the submount 2, and the block 3. Therefore, the heat generated in the light source 1 can be easily released to the outside.

Inside the optical pickup, the light source 1 and the light receiving element 13 are prevented from being oxidized and the light guide member 5 and the cover member 1 are provided.
6, gas such as N ₂ or Ar, N
It is preferable to fill an inert gas such as e or He. In this case, the gap 17 existing between the heat radiating plate 4 and the light receiving element 13 is filled with a bonding material having characteristics such as a small shrinkage ratio, low water absorption, and high airtightness (excellent leak characteristics), for example, an epoxy potting agent. It is necessary to fill with solder or solder. Thereby, the inside airtightness can be improved.

By using the configuration shown above,
The heat generated by the light source 1 can be easily released to the outside, and the antioxidant gas can be easily sealed by providing a total of two openings on both end surfaces of the packaging. Further, in the optical system, the relative positional relationship between the light source 1, the light guide member 5, and the light receiving element 13 can be correctly and firmly maintained. do not do.

The thermal resistance of the entire packaging of this optical pickup is preferably 35 ° C./w or less because heat can be more efficiently released to the outside of the package. Next, the operation of the optical pickup according to one embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a conceptual diagram of the operation of the optical pickup according to the embodiment of the present invention, and FIG. 4 is a perspective view showing the assembly of the optical guide member according to the embodiment of the present invention.

3 and 4, the laser light emitted horizontally from the light source 1 mounted horizontally on the heat sink 4 via the submount 2 and the block 3 has a plurality of parallel inclined surfaces. 5 is incident on the light guide member 5 from the surface 5f and is formed on the second slope 5b of the light guide member 5 and converts the diffusion angle of the emitted light with respect to the diffusion angle of the incident light (hereinafter NA is converted. Then, the reflection type diffusion angle conversion hologram 7 having a function is reached. The light whose NA has been converted and reflected by the diffusion angle conversion hologram 7 is reflected by the reflection type diffraction grating 6 formed on the first slope 5a as a 0th-order diffracted light (hereinafter referred to as a main beam) and ± 1st-order diffracted light (hereinafter referred to as a side beam). ). The main beam and side beam generated by the diffraction grating 6 are incident on a first polarization-selective beam splitter film 9 (hereinafter simply referred to as a first beam splitter film). The first beam splitter film 9 is a light having a vibration component parallel to the incident surface (hereinafter simply referred to as a P-polarized component).
And has a constant reflectance with respect to a vertical vibration component (hereinafter simply referred to as S-polarized component). Of the light that enters the first beam splitter film 9, the light that passes through the first beam splitter film 9 is used as the monitor light of the light emitted from the light source 1. Further, the main beam and side beam linearly polarized into the S-polarized light component reflected by the first beam splitter film 9 are:
The light passes through the surface 5 e of the light guide member 5 and the cover member 16, enters the objective lens 26, and is focused on the recording medium surface 27 a of the recording medium 27 by the light condensing action of the objective lens 26. At this time, the beam spots 29a and 29c of the two side beams are imaged on the recording medium surface 27a at positions substantially symmetric about the beam spot 29b of the main beam. Beam spots 29b, 29a, and 29c of the main beam and side beams with respect to the recording medium surface 27a
To read out information recording or reproduction signals and tracking and focusing so-called servo signals.

The diffusion angle conversion hologram 7 is a diffusion angle conversion hologram 7 with respect to a diffusion angle of a light beam of the light emitted from the light source 1 which can enter the diffusion angle conversion hologram 7.
The angle of diffusion of the light reflected from the object is converted. Further, the light can be converted into parallel light having no diffusion angle by the diffusion angle conversion hologram 7. Also, the same diffusion angle conversion hologram 7
Thus, as shown in FIG. 3, the light flux emitted from the light guide member 5 becomes an ideal spherical wave 30 from which the wavefront aberration accumulated in the midway path is removed. Therefore, the light incident on the objective lens 26 becomes an ideal spherical wave 30, and the beam spot on the recording medium 27 by the objective lens 26 is narrowed down to almost the diffraction limit to have an ideal size, so that information can be easily recorded or reproduced. Can be.

The return light of the main beam and the side beam reflected by the information recording surface 27a of the recording medium 27 passes through the objective lens 26 and the surface 5e of the light guide member 5 again,
The light enters the first beam splitter film 9 formed on the second inclined surface 5b of the light guide member.

Of the return light from the recording medium 27, the light transmitted from the first beam splitter film 9 is the light guide member 5.
The second polarization-selective beam splitter film 11 formed on the third slope 5c parallel to the first slope 5a of FIG.
(Hereinafter simply referred to as a second beam splitter film). The second beam splitter film 11 is similar to the first beam splitter film 9 in that the P beam component is almost 10
It has a transmittance of 0% and a constant reflectance for the S-polarized light component.

Here, the transmitted light 117 of the light flux incident on the second beam splitter film 11 will be described. The transmitted light 117 enters the polarization plane conversion substrate 31 laminated on the third inclined surface 5c.

FIG. 5 is a perspective view of a polarization plane conversion substrate according to one embodiment of the present invention, and FIG. 6 is a diagram showing a light receiving portion arrangement and signal processing of an optical pickup according to one embodiment of the present invention. The polarization plane conversion substrate 31 is the first other inclined surface 31.
a (hereinafter simply referred to as the first other slope) and the first other slope 31
The second other inclined surface 31b substantially parallel to a (hereinafter simply referred to as the second
(Referred to as another slope), and the reflection film 1 is provided on the first other slope 31a.
26, the polarization separation film 12 is formed on the second other inclined surface 31b. The transmitted light 117 enters the polarization splitting film 12 formed on the second other slope 31b. Second other slope 31b
Is formed such that the angle formed by the polarization plane 117a of the transmitted light 117 and the incident surface 128 is approximately 45 × (2n + 1) °: (n is an integer). As a result, the P-polarized light component 117P and the S-polarized light component 117S of the transmitted light 117 have an intensity ratio of about 1: 1. The P polarization component 117P having a polarization component parallel to the incident surface 128 is almost 100% transmitted by the polarization separation film 12, while the S polarization component 117S having a polarization component perpendicular to the incidence surface 128 is on the second other slope 31b. Approximately 100% is reflected by the polarization separation film 12 and the first other slope 31
The light enters the a-plane, is reflected by the reflection film 126, and is guided to the light receiving element 13. The P deflection component 117P guided to the light receiving element 13 reaches the light receiving portion 170, and the S deflection component 117 reaches the light receiving portion 171, and creates an RF signal.

Next, the reflected light 123 of the light beam incident on the second beam splitter film 11 shown in FIG. 3 will be described. The reflected light 123 is incident on the astigmatism generating hologram 10 formed by a reflection type hologram on the second inclined surface 5b. The reflected light 123 generates astigmatism by the astigmatism generation hologram 10 and is further reflected by the reflecting films 124 and 125, and the return light of the main beam is transmitted to the light receiving section 172 on the light receiving element 13 to the side beam. The returning light of the above reaches the light receiving portions 176 and 177 on the light receiving element 13.

Next, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a configuration of an optical pickup particularly supporting a phase-change optical disk will be described. Phase-change optical discs record information by irradiating light to change the crystal structure in the recording medium, and require more light than conventional optical recording / reproducing devices to change the crystal structure. Therefore, a more efficient optical system is required. FIG. 7 is a configuration diagram of an optical pickup corresponding to a phase change optical disk according to an embodiment of the present invention. Note that members having the same numbers as those shown in FIGS. 1, 2 and 3 have the same functions and configurations, and thus description thereof will be omitted.

The laser light emitted from the light source 1 enters the light guide member 41 from the surface 41f of the light guide member 41 having a plurality of parallel inclined surfaces, and the diffusion angle conversion hologram 7, the diffraction grating 6 and the polarization selective light. A certain beam splitter film 3
5 (hereinafter, referred to as a beam splitter film), and is emitted from the surface 41 e of the light guide member 41. Here, unlike the case of one embodiment, the beam splitter film 35 has an S-polarized component reflectance of 95% or more and a P-polarized component reflectance of about 1%. Among the light incident on the beam splitter film 35, the light transmitted through the beam splitter film 35 (about several percent of the total light amount in the P-polarized light component) is the light source 1
It is used as the monitor light of the light emitted from. The light emitted from the surface 41 e of the light guide member 41 is
Is transmitted through the λ / 4 plate 33 provided in the. FIG. 8 is a schematic view of the λ / 4 plate 33 according to the embodiment of the present invention. λ
The / 4 plate 33 is installed so that its extraordinary optical axis is π / 4 · (2m−1); (where m is a natural number: the same below) with respect to the plane of polarization of the incident light from the light guide member 41. , The phase difference between the extraordinary component of the incident light and the ordinary component is π / 2 · (2m-
It has the function of generating only 1). Generally, a uniaxial crystal material is used as a material forming the λ / 4 plate 33.
Among them, it is preferable to use quartz which is low in cost and excellent in light transmittance. In uniaxial crystals have abnormal optical axis 616 and ordinary light axis 617, and has a different refractive index, called extraordinary refractive index n _e and ordinary index n _o for each of the optical axes. Since the optical distances of extraordinary light and ordinary light are different, λ /
Assuming that the substrate thickness of the four plate 33 is QD and the incident light wavelength is λ, a phase difference Δ determined by the following relational expression occurs. The thickness QD of the λ / 4 plate 33 is determined so that the phase difference Δ is π / 2 · (2m−1).

Δ = 2π · (n _e −n _o ) · QD / λ In this embodiment, wavelength λ = 790 nm, extraordinary light refractive index ne = 1.5477, and ordinary light refractive index no = 1.5388.
(However, the refractive index differs depending on the cutting angle of the substrate. In this case, the cutting is performed in parallel with a plane including both the extraordinary optical axis and the ordinary optical axis.) The substrate thickness of the λ / 4 plate 33 is 21. It becomes 9 · (2m−1) μm. By setting such conditions, it is possible to convert linearly polarized light that is incident at an incident angle of 0 degree into circularly polarized light. That is, the linearly polarized light including only the S-polarized component emitted from the light source 1 can be converted into circularly polarized light. Although the crystal of 21.9 μm is provided on the cover member 16 as the λ / 4 plate 33 here, it may be provided on the surface 41e of the light guide member or the objective lens 26.

The light which has been circularly polarized after passing through the λ / 4 plate 33 enters the objective lens 26 and is focused on the recording medium surface 27a of the recording medium 27 by the condensing action of the objective lens 26.
Is reflected. The rotation direction of the circularly polarized light reflected by the recording medium surface 27a is reversed, so that when the return light passes through the objective lens 26 and again through the λ / 4 plate 33, P
It is converted into linearly polarized light containing only the polarized component. The return light converted in this way again passes through the surface 41e of the light guide member 41 and again enters the beam splitter film 35 formed on the second inclined surface 41b of the light guide member. As described above, the beam splitter film 35 has approximately 1 for the P-polarized component.
It has a transmittance of 00% and is almost 10 for S-polarized light components.
It has a reflectance of 0%. Therefore, the return light having only the P-polarized component almost passes through the beam splitter film 35.

Then, the return light is incident on the half mirror 34 formed on the third surface 41c parallel to the first slope 41a of the light guide member 41. The half mirror 34 has a function of reflecting a predetermined amount of the incident light and transmitting the rest.

Among the light fluxes that have entered the half mirror 34, the transmitted light 117 is guided to the light receiving section 37 provided on the light receiving element 36.

Next, the reflected light 123 of the light beam incident on the half mirror 34 shown in FIG. 3 will be described. FIG. 9 is a layout diagram of a light receiving portion provided in a light receiving element of an optical pickup for a phase change optical disc according to an embodiment of the present invention. The reflected light 123 is incident on the astigmatism generating hologram 10 formed of a reflection type hologram on the second inclined surface 41b. The reflected light 123 is the astigmatism generating hologram 10
While astigmatism is generated by the reflection film 124,
The light reflected by the reflection film 125 returns the main beam to the light receiving section 38 on the light receiving element 36, and returns the side beam to the light receiving sections 39 and 40 on the light receiving element 36.

In the optical pickup having the above structure, the λ / 4 plate is used as the beam splitter film 35 and the recording medium 2.
7, and converts the output light, which is linearly polarized light of the S-polarized light component, into circularly polarized light, and then converts the circularly polarized light reflected by the recording medium 27, whose rotation direction is reversed, to the P-polarized light component only. Beam splitter film 35 by converting into linearly polarized light having
, The light reflected by the recording medium 27 can be guided almost 100% onto the light receiving element 36.
The reflectance of the S-polarized light component of the beam splitter film 35 can be greatly increased, and therefore, the amount of light applied to the recording medium 27 can be increased. That is, limited light source 1
Can be efficiently irradiated to the recording medium 27, and the reflected light from the recording medium 27 can be efficiently guided to the light receiving element 36.

Next, the manufacturing process of the light guide members 5 and 41 will be described. The light guide members 5, 41 are basically composed of a plurality of substrates.

First, the first substrate of the plurality of substrates will be described with reference to the drawings. FIG. 10 to FIG. 17 are diagrams showing a manufacturing process of the first substrate in one embodiment of the present invention.

First, as shown in FIG. 10, BK-7
Used for positioning at the time of bonding to the first surface 200a of the first substrate 200 formed of optical glass or the like.
The marker 201 is formed. As a material of the first marker 201, a metal material such as Ti, Cr, Cu, Au, Ag, Ta, or Al or an alloy containing them can be used. Among them, a material that can be wet-etched is used. Is preferable in terms of cost and man-hour. Here, a Ti film most suitable for such a condition is used.

Here, the procedure for forming the first marker 201 will be briefly described. First, a Ti film as a marker material is formed on the first surface 200a to a predetermined thickness by a method such as vacuum evaporation. Then, after forming a marker pattern at a marker forming position thereon by photolithography technology, the Ti film in the portion where the marker pattern is not formed is removed by wet etching by spray etching, and finally the marker pattern is removed to remove the first marker. The formation of 201 is completed.

Next, as shown in FIG. 11, the second marker 202 is formed on the second surface 200b of the first substrate 200. The second marker 202 is also formed in the same manner as the first marker 201. When forming the second marker 202, it is preferable to provide a protective film on the first marker 201 because damage or peeling of the first marker 201 from the etching liquid or the like can be prevented.

Although wet etching has been mainly described as a method for forming the marker, a process method using a dry etching technique such as ion milling etching or reactive etching, which causes less side etching, may be used. Also, a lift-off method may be used for pattern formation.

Next, as shown in FIG. 12, the diffraction grating 6 is formed at a predetermined position on the first surface 200a of the first substrate 200.
At the time of formation, the pattern of the diffraction grating 6 is formed at a predetermined position using the first marker 201 by using a photolithography technique. Then, a portion where the pattern is not formed is etched to a predetermined depth from the pattern using reactive ion etching or ion milling. After the etching is completed, the pattern is removed using an oxygen plasma asher or an organic solvent.

Next, as shown in FIG. 13, the diffusion angle conversion hologram 7 is formed on the second surface 200b of the first substrate 200.
The cross-sectional shape of the diffusion angle conversion hologram 7 is most preferably in the shape of a sawtooth wave. However, since it is difficult to process the cross-sectional shape, a 4-step step hologram was formed here. By using such a step-like hologram as the diffusion angle conversion hologram 7 and appropriately controlling the pitch and depth thereof, the diffusion angle conversion hologram 7 can be easily formed and the diffusion angle conversion hologram 7 can be formed.
Is preferable because the diffraction efficiency can be increased.

Here, a method of forming a four-step step type hologram used for the diffusion angle conversion hologram 7 will be described. FIG. 18 is a front view of a four-step step hologram according to an embodiment of the present invention, and FIG. 19 is a sectional view taken along line XX ′ of the embodiment of the present invention. A hologram pattern is formed twice and a hologram pattern is etched twice in order to form a four-step shape with reference to the second marker 202 to form the diffusion angle conversion hologram 7. FIG.
Reference numeral 0 shows a process diagram of forming a four-step hologram in one embodiment of the present invention. As the first pattern formation, the first step hologram pattern 261 having a duty ratio of 50/50 is formed with respect to the four-step step hologram pitch P. The first etching etches approximately 2 / 3d of the final etching amount d. The etching is performed using the same means as that of the reflection type diffraction grating 6. After the etching, the first step hologram pattern 261 is removed by an oxygen plasma asher or an organic solvent to form a first step hologram 262. Subsequently, a second step hologram pattern 263 is formed on the first step hologram 262 formed as the second pattern formation. The second step hologram pattern 263 is a pattern in which the first step hologram line portion 264 and the first step hologram space portion 265 of the first step hologram 262 have a duty ratio of 50/50, respectively. The second etching is approximately 1 / 3d of the final etching amount d.
Etch minutes. The etching is performed using the same means as that of the reflection type diffraction grating 6. After the etching is completed, the second step hologram 263 is formed by removing the second step hologram pattern 263 with an oxygen plasma asher or an organic solvent.

The formation of the second step hologram 266 is completed.
After that, the reflection film 267 is formed thereon as shown in FIG.
To form The reflection film 267 is formed by a lift-off method.
It is preferable to use such as. The putter of the reflection film 267
Is a reverse tapered putter for easy lift-off.
Use a negative photoresist or
Negatives such as Hoechst's AZ-5218E
Performs pattern formation using positive reversal type photoresist
It is preferable to apply. Here, AZ-5 from Hoechst
The pattern of the reflection film 267 was formed using 218E.
After pattern formation, the reflective film 267 is
Form a film. Here, it was formed by a vacuum deposition method. Reflection
As a material for forming the film, a material such as Ag, Al, Cu, or Au may be used.
The use of a metal material with reflectivity is an
This is preferable because efficiency can be improved. Especially Ag is
Excellent in strike surface, high reflectivity material, and design center wavelength
λ ₀(790 nm) has an absorption coefficient of about 5.1
High reflectivity with extremely thin film thickness
And easy lift-off in the lift-off process
And can achieve the required performance at low cost.
New After forming the reflective film, organic solvent or remover solvent
Lift-off, and the reflection type
The diffusion angle conversion hologram 7 is formed.

Although the reflection film 267 was formed by the lift-off process, the first marker 201 was formed.
Similarly to the above, a forming method by wet etching by pattern formation and spray etching may be used. As for the etching method, a formation method using dry etching may be used.

Further, in the present embodiment, the number of steps of the hologram is four, but if the number of steps is more than four, the diffraction efficiency is usually improved. However, in consideration of the number of manufacturing steps, it is preferable to use 2 ⁿ stages (where n is a natural number).

Next, as shown in FIG. 15, the first substrate 200
The first beam splitter film 9 is formed on the second surface 200b. The first beam splitter film 9 in the present embodiment is an S-polarized light incident type, and is approximately 100
%, A constant transmittance for S-polarized light, and a relative phase difference between S-polarized light and P-polarized light of transmitted light of approximately 0.
Must. In order to realize such a property, generally, a beam splitter film having polarization selectivity is often formed of a dielectric multilayer film. The material of the dielectric multilayer film is composed of a material in which the internal stress generated during film formation of each material shows tensile stress and compressive stress, and is a combination that cancels each other's internal stress during multilayer film formation. Desirably, the coefficient is in the middle of the expansion coefficient of the combination material. By adopting such a configuration, it is possible to prevent peeling during multilayer film formation, deterioration of substrate surface accuracy, and occurrence of cracks, leading to improvement in reliability of the optical pickup and extremely high yield during production. can do. Examples of material combinations satisfying such characteristics include TiO ₂ / SiO ₂ and Ta ₂ O ₅ / S
There are iO ₂ , Al ₂ O ₃ / SiO ₂ , ZnS / MgF _{2 and the} like. In any case, each combination is determined by the design refractive index value in the beam splitter film design. In particular, in the case of this embodiment, when the incident angle is 45 ° and the material forming the substrate is BK-7, the refractive index _ng on the incident light beam side
Can satisfy the Brewster condition by the combination of Al ₂ O ₃ / SiO ₂ , so that the reflection for P-polarized light can be made substantially zero and a transmittance of about 100% can be obtained, which is preferable.

The Brewster conditional expression is shown below. ( _Ng ) ² = 2 × (n _h ) ² × (n _l ) ² / ((n _h ) ² + (n _l ) ² ) ·· (4) _ng = 1.511, Al ₂ O ₃ Refractive index n _h = 1.580,
Equation (4) can be satisfied with the refractive index of SiO ₂ , n _l = 1.450. On the other hand, the optical film thickness is determined so as to satisfy the following equation with respect to the design center wavelength λ ₀ .

N _{H, L} × d = λ ₀ / (4 × cos θ _t ) θ _t represents the refraction angle to each thin film. The refraction angle can be determined by the following equation according to Snell's law.

[0062] _{n g × sinθ 0 = n H} , L × sinθ t θ 0 denotes an angle of incidence. However, the determination of these film thicknesses changes according to the reflectance specification of the S-polarized light, and is further adjusted to make the relative phase difference between the S-polarized light and the P-polarized light substantially zero. According to these combinations, a beam splitter film can be formed without causing P-polarized light reflection due to film thickness accuracy at the film forming stage. However, it is also possible to design the combination of the constituent materials described above. In particular, there is a Thelen method or the like as a design technique that enables such design. Further, according to the configuration of the present embodiment, the incident light velocity is the finite light velocity converted by the reflection-type diffusion angle conversion hologram 7 and is incident on the second beam splitter film 9. The design was made so that the spectral characteristics of ## EQU1 ## and the generated phase difference became the smallest. The method of forming the second beam splitter film 9 uses a lift-off process,
₂ O ₃ and SiO ₂ are alternately laminated in a predetermined thickness.

Although the first beam splitter film 9 is formed only at a predetermined position on the first substrate 200 in this embodiment, it may be formed on the entire second surface 200b of the first substrate 200. . In this case, since it is not necessary to form a lift-off pattern, man-hours can be reduced and manufacturing costs can be reduced.

Next, as shown in FIG. 16, a resist 204 is formed on almost the entire second surface 200b. This resist 2
Reference numeral 04 has a function of protecting various optical elements of the second surface 200b, which have already been formed, from damage that may occur in the subsequent steps.

Finally, as shown in FIG. 17, the reflection film 203 is formed on the diffraction grating 6 by the lift-off method or the like. The pattern of the reflection film is formed by using a negative type photoresist so as to be a reverse tapered pattern so that lift-off can be easily performed, or by using a negative-positive inversion type photoresist such as AZ-5218E of Hoechst. It is preferred to carry out the formation. Here, the pattern of the reflection film was formed using AZ-5218E manufactured by Hoechst. After pattern formation, a reflective film of the reflective diffraction grating 6 is formed by a vacuum film forming apparatus. Here, it was formed by a vacuum deposition method. Ag, A is used as a material for forming the reflection film.
It is preferable to use a metal material having a high reflectance such as l, Cu, or Au, or an alloy containing these, since the efficiency of the reflection type diffraction grating 6 can be improved. In particular, Ag is a high-reflectance material that is also highly cost-effective and has an absorption coefficient of about 5.1 with respect to the design center wavelength λ ₀ (790 nm), so that high reflectance can be achieved with an extremely thin film thickness. This is preferable because the lift-off process can be easily performed and the predetermined performance can be realized at low cost. After forming the reflective film, lift-off is performed with an organic solvent or a remover solvent to form a reflective diffraction grating 6
Is completed.

Although the reflective film is formed by the lift-off process in the pattern formation, it may be formed by pattern formation and wet etching by spray etching as in the case of the first marker 201. As for the etching method, a formation method using dry etching may be used.

Next, of the plurality of substrates, the second substrate 205 will be described with reference to the drawings. First, FIG.
As shown in FIG. 2, similarly to the case of the first substrate 200, a third marker 206 is formed at an end of the first surface 205a of the second substrate 205, and the second substrate 205 is
The fourth marker 207 is formed on the second surface 205b. The method of forming these markers is the same as the method of forming the first marker 201 and the second marker 202 on the first substrate 200.

Next, as shown in FIG. 23, the astigmatism generation hologram 10 is formed at a predetermined position on the first surface 205a with the third marker 206 as a reference. This astigmatism generating hologram 10 has a curved shape unlike the diffusion angle conversion hologram 7 in appearance, but has a four-step shape like the diffusion angle conversion hologram 7 in cross section. It is a reflection type hologram. The manufacturing method is the same as that of the hologram 7 for converting the diffusion angle.

Next, as shown in FIG. 24, the second surface 205b
Half mirror at a predetermined position based on the fourth marker 207
-208 is formed. The half mirror 208 is
Formed of a dielectric multilayer film in the same manner as the beam splitter film 9.
Often. Here, Al _TwoO_Three・ SiO_TwoCombine
It is formed. However, in general, the dielectric of a half mirror
The number of stacked layers is smaller than that of the beam splitter film.
Yes. Also in the present embodiment, the first beam splitter
Compared with the case where the film 9 is formed by stacking 11 layers,
The half mirror 208 has only seven layers.

Although not shown in FIG. 3, the half mirror 208 is for generating monitor light for monitoring the amount of light emitted from the light source 1 and guiding it to a predetermined position.

Next, as shown in FIG. 25, the reflection film 124 is formed at a predetermined position on the second surface 205b. Regarding the method of forming the reflection film 124, the reflection film 2 of the diffusion angle conversion hologram 7 is used.
67 and the like.

Next, as shown in FIG. 26, the second beam splitter film 11 is formed at a predetermined position on the second surface 205b. The forming material and the forming method of the second beam splitter film 11 are the same as the forming material and the forming method of the first beam splitter film 9 described above. At this time, it is preferable that the reflective film 124 described above is formed so as to be covered by the second beam splitter 11. This is because the reflective film 12 is formed of a metal material having a relatively weak bonding force to the substrate.
This is because, by covering 4, the reflection film 124 can be prevented from peeling off from the substrate, and the deterioration of the optical characteristics caused by this can be prevented.

Next, as shown in FIG. 27, a resist 209 is formed on almost the entire second surface 205b. This resist 2
Reference numeral 09 has a function of protecting various optical elements of the second surface 205b which have already been formed.

Finally, as shown in FIG. 28, a reflection film is formed on the astigmatism generation hologram 10 in the same manner as the reflection film of the diffraction grating 6 and the reflection angle conversion hologram 7. Thereafter, the resist 209 is removed from the second surface 205b, and the formation of the second substrate 205 is completed.

As described above, various optical elements having a predetermined shape are formed at predetermined positions on the first substrate 200 and the second substrate 205, so that various kinds of light are provided at predetermined positions of the light guide members 5 and 41. Since the optical element can be positioned, various optical members do not block the optical path of light passing through the inside of the light guide members 5 and 41. Therefore, the predetermined light can be guided to the predetermined position without deteriorating or deteriorating the characteristics of the light transmitted through the light guide members 5 and 41. Therefore, such a manufacturing method of the light guide members 5 and 41 is very preferable.

In this embodiment, one set of optical element groups is formed on one substrate, but in an actual process, a plurality of sets of optical element groups are formed on one substrate, It is preferable that a plurality of substrates for the light guide member can be formed from one substrate from the viewpoint of reduction of manufacturing cost and manufacturing time.

Hereinafter, the first substrate 200 and the second substrate 20 will be described.
5 will be described. FIG. 29 is a diagram showing an assembling process of the first substrate block in one embodiment of the present invention.

As shown in FIG. 29, first, in the first step, the first substrate 200 and the 0th substrate 211, which have the predetermined optical elements formed at the predetermined positions by the above-mentioned process steps, are bonded. At the time of bonding, the first substrate 200 and the zeroth substrate 211
The first substrate group 212 is formed by applying a bonding material to at least one of the substrates, roughly performing alignment, and bonding the two. As the bonding material used at this time, it is preferable to use an epoxy resin, a glass bonding material, a light-curing bonding material, or the like.

In this embodiment, no optical element is provided on the 0th substrate 211, but a predetermined optical element may be provided if necessary.

Then, in the second step shown in FIG. 29, the first substrate group 212 formed in the first step.
And the second substrate 205 are joined to form a second substrate group 213. In forming the second substrate group 213, unlike the case of the first substrate group 212, the first substrate 200 and the second substrate 2
Since it is necessary to adjust and position the mutual positional relationship of the plurality of optical elements provided at 05 with extremely high accuracy,
When forming the second substrate group 213, very strict alignment is required.

Next, the procedure of bonding will be described with reference to the drawings. FIG. 32 is a sectional view showing an alignment apparatus according to one embodiment of the present invention. In FIG. 32, the second substrate 205 is fixed to the fixing table 300,
The first substrate group 212 placed on the movable stage 301 is arranged in a predetermined positional relationship. Then, a predetermined amount of a bonding material is applied to the upper surface of the substrate group 212, and the movable stage 301 is moved in the z direction so that the second substrate 205 and the first substrate group 212 are brought into contact, and the bonding material spreads over the entire space between the substrates. Pressurize as follows. Since the bonding material spreads evenly between the substrates by applying the pressure as described above, the bonding surface is not peeled due to the shortage of the bonding material at the time of cutting, and a thickness difference is not generated, and a phase difference is not generated in the transmitted light. Therefore, a high-performance optical pickup with a high yield can be provided.
Then, before the bonding material is cured, the first marker 201 or the second marker 202 provided on the first substrate 200 by the observation means 302 and the third marker 206 or the fourth marker 207 provided on the second substrate 205. The movable stage 301 is moved in the x and y directions while monitoring the position between the positions to adjust the positions of these markers so as to be accurately in a predetermined relationship.

Second substrate group 2 formed as described above
13 is cut at a predetermined position as shown in step 3 of FIG. When cutting, using a machine tool whose cutting surface such as a wire saw is relatively smooth and the time required for cutting is short can reduce the time required for subsequent lapping work of the cut surface and the like, and furthermore, the manufacturing time The cost can be reduced by shortening the cost.

In this way, a plurality of first substrate blocks 210 can be obtained from the substrate group 213. At this time, the number of first substrate blocks 210 obtained from one second substrate group 213 can be adjusted by the number of sets of optical elements provided on the first substrate 200 and the second substrate 205. The larger the number of sets of the optical elements, the greater the number of pieces to be taken from one substrate, which is preferable because the manufacturing cost can be reduced.

Further, various optical elements are mounted on the first substrate block 2
10 is sandwiched between the substrates 200, 205 and 211 so as not to be exposed on the surface of
Damage or peeling of the optical element that occurs when the substrate block 210 is cut can be suppressed. Therefore, the incidence of defective products in the light guide members 5, 41 can be greatly reduced, and the light guide members 5, 4 having extremely high reliability can be obtained.
1 can be obtained.

Next, the manufacturing process of the second substrate block 214 including the polarization plane conversion substrate 31 will be described with reference to the drawings. FIG. 30 is a diagram showing a manufacturing process of the second substrate block in the embodiment of the present invention, and FIG. 31 is a sectional view showing a manufacturing process of the same laminated block.

First, the end surface 215a of the third substrate 215 is first formed.
Then, the polarization separation film 12 is formed. The position to be formed is a predetermined position
The end surface 215a of the substrate 215 may be entirely placed.
It may be formed on the surface. The bias formed in the present embodiment
The light separation film 12 has a design center wavelength λ₀About 1 for S-polarized light
It has a reflectance of 00% and is almost 100% for P-polarized light.
Has transmittance. Therefore, it is generally formed of a dielectric multilayer film.
It is. Similar to the case of forming the first beam splitter film 9.
The constituent material was decided for the reason. The bias in the present embodiment
The angle of incidence on the light separation film 12 is approximately 53 °, and the structure of the film is
TiO as a material_Two/ SiO_TwoUsing a combination of
You. Polarization separation film 1 for transmitting approximately 100% of P-polarized light
The optical admittance Yep of 2 is the optical admittance of the incident light beam medium.
Must be the same as the mittens Y0. Designed for this
The Thelen method was used for this. Here to the Thelen method
A brief explanation will be given. The Thelen method is a long wavelength transmission filter.
Multilayer optics of the following formula, which is the basic film configuration of the Luther design
Admittance Ym is another basic structure
Optical admittance of whole multilayer film by mittance Yn
(Here, the optical admittance of the polarization separation film 12 Yep
Equal to the optical admittance Y0 of the incident light beam medium
The configuration is as follows. ) (0.5H × L × 0.5H)^m (5) H and L indicate the optical film thickness of the high and low refractive index materials, and m is
Indicates the number of repetitions. Formula (5) shows a multilayer optical add
Mitance Ym is Y0 and design center wavelength λ₀Will be equal
As described above, an adjustment layer represented by the following equation (6) is provided. Basic membrane configuration
(H ', L') ⁿOf the incident light velocity medium
And the transmittance of the P-polarized light is approximately 10
The thicknesses of H, L, H ', L' are determined so as to be 0%.
You.

(0.5H ′ × L ′ × 0.5H ′) ⁿ × (0.5H × L × 0.5H) ^m × (0.5H ′ × L ′ × 0.5H ′) ⁿ ... (6) Regarding the method for forming the polarization separation film 12, the same method as the method for forming the first beam splitter film 9 is performed.

Next, the end surface 216a of the fourth substrate 216
Then, a reflection film 126 is formed. The constituent material and the forming method of the reflection film 126 are the same as those of the reflection film of the diffraction grating 6 provided on the first substrate 200.

Next, as shown in FIG. 30, the third substrate 215 on which the polarization separation film 12 is formed and the fourth substrate 216 on which the reflection film 126 is formed are formed by using an epoxy resin or a photocurable resin. The substrate group 217 is formed by bonding. Then, the substrate groups 217 are stacked in a substantially stair-like shape and joined to form a stacked block 218. Also in this case, it is preferable to use an epoxy resin or a photocurable resin as the bonding material, since sufficient bonding strength can be obtained, and thus occurrence of peeling of the substrate or the like can be suppressed in a subsequent cutting step. . Further, it is preferable to use a bonding material having a refractive index almost the same as that of the third substrate 215 and the fourth substrate 216 because a phase difference does not occur in transmitted light.

Next, as shown in FIG.
8 is cut along a predetermined cut surface 218a to form a polarization plane block 219 having a predetermined shape. In that case, the cutting surface 21
8a and the end faces 215a, 216a are formed using a machine tool such as a wire saw or an inner peripheral tooth / outer peripheral tooth cutting machine so that an angle formed by the end surface 215a and the end surface 216a becomes a predetermined angle.

By manufacturing the polarization plane wafer 219 by such a method, a large amount of polarization plane wafers 2 can be obtained in one step.
Since 19 can be cut, the number of steps can be significantly reduced, and the cost can be reduced.

Both sides of the polarization plane wafer 219 manufactured as described above are polished to a predetermined thickness and then bonded to the fifth substrate 220 to complete the formation of the second substrate block 214. The bonding material used here is the third substrate 2 described above.
This is the same as that used for bonding the first substrate 15 and the fourth substrate 216.

Next, the first substrate block 210 and the second substrate block 214 described above are joined in a predetermined positional relationship to manufacture the third substrate block 230. As for the bonding material used here, it is also possible to obtain sufficient bonding strength by using an epoxy resin or a photocurable resin as the bonding material at this time. It is preferable because occurrence of peeling or the like can be suppressed. Further, it is preferable to use a bonding material whose refractive index is almost the same as the refractive index of each substrate because a phase difference does not occur in transmitted light.

In the present embodiment, the bonding is performed by accurately bonding the fourth marker 207 provided on the first substrate block 210 and the end of the polarization plane wafer, but the positioning is accurately performed. Any method may be used as long as it can be performed.

The third substrate block 2 described above
FIG. 33 is a top view and a side view of FIG.
FIG. 33 is a light guide surface 230a indicating the outer peripheral surface of the light guide members 5 and 41 in the third substrate block 230. A method of cutting out the light guide members 5 and 41 from the third substrate block 230 along the light guide surface 230a will be described.

First, the cutting position of the third substrate block 230 is cut with a multi-wire saw as shown in FIG. When the wire is cut out, the wire entrance surface 230b may be cut with a slicer and flattened so as to prevent the wire from entering smoothly and causing a misalignment.
This is preferable because the cutout accuracy of 41 is improved. Further, in the present embodiment, the side surface portions 230c and 230d perpendicular to the wire entry surface 230b of the third substrate block 230 are the abutment reference surfaces at the time of cutting, so that the abutment position is determined accurately. Entry surface 230b
It is preferable to take the same means as described above.

Then, with reference to the alignment marker 221 shown in FIG. 34, the upper surface 2 of the third substrate block 230
The cutting position 222 is determined at 30e. Regarding the method of determining the cutting position 222, first, the second surface 200 of the first substrate 200 on which the alignment marker 221 is formed from the upper surface 230e of the third substrate block 230
The thickness (t) up to b is measured. Then, an intersection 230f between the straight line passing through the alignment marker 221 and perpendicularly intersecting with the upper surface 230e and the upper surface 230e is determined.
T from the intersection 230f in the direction of a shown in FIG.
Marking is performed using the point advanced by only as a cutting position 222. As a marking method, a method using a laser, a groove using a grindstone, or the like can be considered.

Next, the third substrate block 230 is fixed in a predetermined direction on a cutting means (here, a multi-wire saw, an outer peripheral tooth cutting machine or the like is used). At the time of fixing, the third substrate block 230 was pressed against a plurality of positioning pins, wall surfaces, and the like, and was fixed with wax. It is preferable to arrange as many third substrate blocks 230 as possible on the cutting means in a predetermined positional relationship, since it is possible to increase production efficiency.

The cutting is performed at an angle of θ3 with respect to the upper surface 230e of the third substrate block 230 while adjusting the cutting position by the cutting means with reference to the cutting position 222. In the present embodiment, θ3 is set to 45 °.

Even when a large number of substrates are cut at once, once the cutting position 222 is determined, the cutting start position can be specified by setting the interval between the wire saws to a predetermined value.

A method of cutting the third substrate block 230 will be described with reference to FIG.

First, as a first step, a jig 2 having a plane 224a having an angle of 45 ° with respect to the reference plane 223
Prepare 24. The third substrate block 230 is fixed on the plane 224a of the jig 224 by the method described above. In addition to this, as the fixing means, fixing with a bonding material or the like may be used. Then, after aligning the cutting portion of the cutting means 225 with the cutting position 222 provided on the third substrate block 230, the cutting means 225 is moved from the front side to the back side of the paper surface of FIG. 35 (or vice versa). Alternatively, the jig 224 is moved to form the cut surface 226 as shown in the second step of FIG. As a cutting means, it is preferable to use a cutting tool such as a multi-wire saw or an outer peripheral tooth cutting machine that can cut at a plurality of positions at one time from the viewpoint of cost reduction because it improves production efficiency.

Next, as a third step, a filler 229 is injected into the cut surface 226 which is cut to form a space and is hardened. The filler 229 has a function of preventing the guide bar 228 obtained in the next cutting step from being separated during cutting and also of preventing the third substrate block 230 from being bent at the cutting surface 226 during cutting. There is. Therefore, it is possible to prevent the guide bar 228 from being damaged and to suppress the cutting error of the guide bar 228 due to the bending of the substrate which occurs in the cutting, so that the product yield can be improved. As the material of the filler 229, it is possible to easily remove the filler 229 by using a water-soluble photo-curable bonding material or a low melting point epoxy resin. Therefore, the filler 229 is injected. Since the guide bar 228 can be easily taken out from the 3 substrate block 230,
It is a preferable material from the viewpoint of shortening the manufacturing time. Among these, it is possible to more surely hold the cut surface 226 by using a water-soluble photo-curing bonding material that is hardened in a short time by light having a relatively short wavelength and high energy such as ultraviolet rays and visible light, and therefore, it is possible to cut. Sometimes, the guide bar 228 hardly bends, which is preferable from the viewpoint of improving the processing accuracy of the light guide member.

The removal of the filling material 229 will be described below particularly when a water-soluble photo-curing bonding material is used. In this case, since the filler 229 is water-soluble, it will peel off naturally when immersed in water. The temperature of the water used at this time is 60 ° C to 100 ° C.
It is preferable to use one having a temperature of 0 ° C., because the time required for peeling can be shortened without causing distortion or warpage of the guide bar 228 and the manufacturing cost can be reduced by shortening the manufacturing time. Further, in order to promote the above-mentioned peeling, it is preferable to use a solution in which water and ethyl alcohol are mixed at a temperature of 50 ° C to 80 ° C, preferably about 60 ° C. Under such conditions, the filling material 229
By melting the resin, the filler can be peeled off in a shorter time, so that the manufacturing time can be shortened, the cost can be reduced, and the highly accurate optical guide member can be easily prepared.

Next, the jig 224 is rotated 90 ° to the left in the drawing so that the surface B becomes the bottom surface as shown in the fourth step of FIG. Then, similarly to the first step, the cutting means 225 is moved and cut to form the cut surface 227, and the guide bar 22 shown in the fifth step of FIG.
Cut out 8. After that, the periphery of the cut out guide bar 228 is lapped by a predetermined amount as shown in the sixth step of FIG.

Finally, as shown in the seventh step of FIG. 35, the light guide members 5 and 41 are cut out from the guide bar 228.

[0107]

As described above, according to the present invention,
After cutting a substrate block including a plurality of optical element groups serving as a light guide member on a first plane, a filler is injected into a void portion formed when the substrate block is cut on the first plane, and the filling is performed. After the material hardens, by cutting the substrate block in a second plane that is non-parallel to the first plane,
It is possible to prevent the processing accuracy from being deteriorated due to distortion or bending during processing. Therefore, it is possible to prevent damage to the substrate block and the like and to suppress the occurrence of cutting error at the cutting site due to the bending of the substrate that occurs during cutting, so that the yield of products can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the optical pickup packaging according to the embodiment of the present invention;

FIG. 3 is a conceptual diagram of an operation of the optical pickup according to the embodiment of the present invention;

FIG. 4 is a perspective view of a light guide member according to one embodiment of the present invention.

FIG. 5 is a perspective view of a polarization plane conversion substrate according to an embodiment of the present invention.

FIG. 6 is a diagram showing a light receiving unit arrangement and signal processing of the optical pickup according to one embodiment of the present invention;

FIG. 7 is a configuration diagram of an optical pickup for a phase-change optical disc according to an embodiment of the present invention.

FIG. 8 is a schematic view of a λ / 4 plate according to an embodiment of the present invention.

FIG. 9 is a layout diagram of a light receiving section provided in a light receiving element of an optical pickup for a phase change optical disk according to an embodiment of the present invention.

FIG. 10 is a diagram showing a manufacturing process of a first substrate according to one embodiment of the present invention.

FIG. 11 is a view showing a manufacturing process of a first substrate in one embodiment of the present invention.

FIG. 12 is a diagram showing a manufacturing process of a first substrate in one embodiment of the present invention.

FIG. 13 is a view showing a manufacturing process of the first substrate in one embodiment of the present invention.

FIG. 14 is a view showing a manufacturing process of a first substrate in one embodiment of the present invention.

FIG. 15 is a view showing a manufacturing process of the first substrate in one embodiment of the present invention.

FIG. 16 is a view showing a manufacturing process of the first substrate in one embodiment of the present invention.

FIG. 17 is a view showing a manufacturing process of the first substrate in one embodiment of the present invention.

FIG. 18 is a front view of a four-step step hologram according to an embodiment of the present invention.

FIG. 19 is a cross-sectional view taken along line XX ′ in one embodiment of the present invention.

FIG. 20 is a process diagram of forming a four-step hologram in one embodiment of the present invention.

FIG. 21 is a diagram showing a manufacturing process of a second substrate in one embodiment of the present invention.

FIG. 22 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 23 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 24 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 25 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 26 is a view showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 27 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 28 is a diagram showing a manufacturing process of the second substrate in one embodiment of the present invention.

FIG. 29 is a view showing an assembling step of the first substrate block according to the embodiment of the present invention;

FIG. 30 is a diagram showing a manufacturing process of the second substrate block in one embodiment of the present invention.

FIG. 31 is a sectional view showing a manufacturing step of the laminated block in one embodiment of the present invention.

FIG. 32 is a sectional view showing an alignment device according to an embodiment of the present invention.

FIG. 33 is a top view and a side view of a third substrate block in one embodiment of the present invention.

FIG. 34 is a sectional view of a third substrate block in one embodiment of the present invention.

FIG. 35 is a view showing a step of cutting a third substrate block in one embodiment of the present invention.

FIG. 36 is a diagram showing a reference plane cut of a third substrate block in one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 light source 2 submount 2a electrode surface 3 block 3a protrusion 3b end surface 4 heat sink 4a hole 5 light guide member 5a first slope 5b second slope 5c third slope 5e surface 5f surface 6 diffraction grating 7 diffusion angle Conversion hologram 9 First beam splitter film 9a Protective film 10 Astigmatism generation hologram 11 Second beam splitter film 12 Polarization separation film 13 Light receiving element 13a Electrode 14 Package 14a Lead frame 14b Lead frame foot 14c Step 14d Wire 15 Shell 16 cover member 16a antireflection film 17 gap 26 objective lens 27 recording medium 27a recording medium surface 28 second beam splitter film 29a, 29b, 29c beam spot 30 ideal spherical wave 31 polarization plane conversion substrate 31a first other slope 31b second Other slope 31c One surface 31d Second surface 33 λ / 4 plate 34 Half mirror 35 Beam splitter film 36 Light receiving element 37, 38, 39, 40 Light receiving part 41 Light guide member 41a First slope 41b Second slope 41c Third slope 41e 41f surface 117 transmitted light 117a polarizing surface 117S S-polarized component 117P P-polarized component 123 reflected light 124 reflective film 125 reflective film 126 reflective film 128 incident surface 170, 171, 172, 172a, 172b, 172
c, 172d, 176, 177 Light receiving portion 200 First substrate 200a First surface 200b Second surface 201 First marker 202 Second marker 203 Reflective film 204 Resist 205 Second substrate 205a First surface 205b Second surface 206 Third marker 207 4th marker 208 Half mirror 209 Resist 210 1st substrate block 211 0th substrate 212 1st substrate group 213 2nd substrate group 214 2nd substrate block 215 3rd substrate 215a End face 216 4th substrate 216a End face 217 Substrate group 218 Lamination Block 218a Cutting surface 219 Polarizing surface wafer 220 Fifth substrate 221 Alignment marker 222 Cutting position 223 Reference surface 224 Jig 224a Flat surface 225 Cutting means 226 Cutting surface 227 Cutting surface 228 Guide bar 228a OL surface 22 a sensor surface 228a incident surface 228a incident rear surface 229 filler 230 third substrate block 230a light guide surface 230b wire entry surface 230c, 230d side surface 230e upper surface 230f intersection 261 first step hologram pattern 262 first step hologram 263 second step hologram Pattern 264 First step hologram line portion 265 First step hologram space portion 266 Second step hologram 267 Reflective film 300 Fixed table 301 Movable stage 302 Observing means 616 Extraordinary optical axis 617 Normal optical axis

Claims (5)

[Claims] 1. A light guide member having a plurality of substrates inclined with respect to an incident direction of light emitted from a light source, and guiding light from the light source to a medium and guiding light reflected from the medium to a predetermined position. A method for manufacturing the same according to claim 1, wherein after a substrate block including a plurality of optical element groups serving as the light guide member is cut on a first plane, a void portion formed when the substrate block is cut on the first plane. A method of manufacturing a light guide member, comprising injecting a filler into the substrate and processing the substrate block. 2. A light guide member having a plurality of substrates inclined with respect to an incident direction of light emitted from a light source and guiding light from the light source to a medium and guiding light reflected from the medium to a predetermined position. A method for manufacturing the same according to claim 1, wherein after a substrate block including a plurality of optical element groups serving as the light guide member is cut on a first plane, a void portion formed when the substrate block is cut on the first plane. A method for manufacturing a light guide member, comprising: injecting a filler into the substrate, curing the filler, and then cutting the substrate block along a second plane that is not parallel to the first plane. 3. A light guide member having a plurality of substrates inclined with respect to an incident direction of light emitted from a light source and guiding light from the light source to a medium and guiding light reflected from the medium to a predetermined position. A method for manufacturing the same according to claim 1, wherein after a substrate block including a plurality of optical element groups serving as the light guide member is cut on a first plane, a void portion formed when the substrate block is cut on the first plane. A method of manufacturing a light guide member, comprising: injecting a filler into a substrate; and curing the filler, and then cutting the substrate block along a second plane perpendicular to the first plane. 4. A light guide member having a plurality of substrates inclined with respect to an incident direction of light emitted from a light source and guiding light from the light source to a medium and guiding light reflected from the medium to a predetermined position. The manufacturing method of the above, wherein a plurality of first substrate blocks including a plurality of optical element groups serving as the light guide member are laminated to form a second substrate block, and the second substrate block is formed into a first plane. After cutting with, the filler is injected into the void formed when the second substrate block is cut with the first plane, and after the filler is cured, it is perpendicular to the first plane. A method for manufacturing a light guide member, characterized in that the second substrate block is cut along a second plane. 5. The method for manufacturing an optical guide member according to claim 1, wherein a water-soluble photo-curable bonding material is used as the filling material.