JPH0552927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light source device for a laser recording device or a reading device having a semiconductor laser beam.

[Conventional technology]

A light beam generated by a laser generator such as a semiconductor laser device passes through an optical system such as a collimator lens, and then is scanned and irradiated onto a recording medium or a document surface.

Figure 6 shows an example of a conventional light source device published in Japanese Unexamined Patent Application Publication No. 1983.
-There is one shown in Publication No. 15206.

In the figure, a semiconductor laser package 1 containing a semiconductor laser element SL is fixed on a temperature control device 2, and this temperature control device 2 is fixed on a heat sink 3. A collimator lens 4 for collimating the laser beam is held by a support member 5, and is further fixed to a support member 6 mounted on the heat sink 3 with a double nut or the like.

[Problem that the invention seeks to solve]

The light beam emitted by the semiconductor laser element SL is required to be a light beam with extremely stable optical characteristics such as a light beam diameter, a light beam liquid level, a light beam traveling direction, and a traveling position. Furthermore, these characteristics must maintain stable accuracy within the allowable range of use even if the operating environment temperature fluctuates significantly. In other words, the positional spacing, optical axis, etc. between the semiconductor laser element SL and the optical system must be determined extremely accurately, and if the positional accuracy deviates due to the influence of heat, the optical system may not function as intended. There is a risk that you will not be able to fully demonstrate your abilities.

However, the temperature change in the environment in which such a laser light source device is installed ranges from about 0° C. to 45° C., and the heat generation of the laser element SL also has an effect, causing a problem of positional deviation due to temperature change.

However, in the light source device as shown in FIG. 6, the semiconductor laser element SL is fixed on the temperature control device 2;
The collimator lens 4 located on the same optical axis as the SL is held by support members 5 and 6, and each is independently fixed on the heat sink 3. Therefore, it is extremely difficult to maintain the relative position between the laser element SL and the collimator lens 4 with high accuracy due to the effects of the above-mentioned temperature changes, external vibrations, shocks, and the like.

[Means for solving problems]

The present invention eliminates the above-mentioned problems, and the relative position of the laser generator and the optical system is
It is an object of the present invention to provide a light source device that can maintain high accuracy without shifting even if the temperature or the like changes.

A light source device of the present invention that achieves this object is a light source device that includes a semiconductor laser element and a collimator lens section that collimates a light beam generated from the semiconductor laser element. A first holding member with good thermal conductivity that has a thermal conductivity of 50 W m ^-1 K ^-1 or more, and a thermal conductivity of 2 W m ^-1 that fits into the first holding member.・Second insulation property with K ^-1 or less
A holding member that fits into the second holding member and has a collimator lens portion has a linear expansion coefficient of 20×10 ^-6 °C.
^-1 or less, the third holding member has a low expansion property such that the package and the central axes of the fitting portions of the first, second, and third holding members are substantially coaxial. It is characterized by the fact that it is placed

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of a light source device according to the present invention, with FIG. 1A being a side sectional view and FIG. 1B being a front view. FIG. 2 is a partially cutaway side view of a laser generator built into the light source device of the present invention. In these figures, the same reference numerals are given to the same structural parts as in FIG. 6.

In FIG. 2, a laser generator 10 includes a semiconductor laser element SL, a chip stand 11 that supports and fixes the laser element SL, a package 12 that houses the laser element 10, and a package that transmits the light beam emitted from the laser element SL. Glass plate 13, laser element SL
The laser oscillator is electrically connected to a lead wire 14 for connection to an external laser oscillator.

When a voltage is applied to the laser element SL, a current flows, and a light beam is emitted and extracted to the outside through the glass plate 13.

The laser generator 10 is inserted into the central opening of the plate 21, as shown in FIG.
That is, the package 12, which is the exterior body of the laser generator 10, is positioned and fitted into the stepped opening of the plate 21 by the outer diameter of the flange and the shoulder. Furthermore, the bottom of the package 12 is backed up and axially positioned by a plate 22. Said plates 21 and 22
After inserting the package 12 between the
22 is integrated. This combined plate 21, 22 will be hereinafter referred to as a first holding member. In this state, the central axis (beam optical axis) of the package 12
is fixed substantially in line with the central axis of the first holding member.

Here, the first holding member, that is, the plate 21,
As the material for No. 22, a material with high thermal conductivity is preferable, and copper (403W·m ^-1 ·K ^-1 ) and aluminum (236W·m ^-1 ·K ^-1 ) are the most desirable. this is,
This is because the semiconductor laser element SL generates heat when emitting a light beam, so it is necessary to efficiently guide this heat to the outside (around the light source device).

A temperature detecting element 23 such as a thermistor is built into the plate 22, and an electronic cooling element such as a Peltier element 24 is closely attached to the back surface of the plate 22. Further, a heat radiator 25 such as a heat sink is attached to the other surface of the Peltier element 24. (However, lead wires, etc. are omitted.) The heat generated by the semiconductor laser element SL is thermally conducted to the plates 21 and 22 forming the first holding member, where it is detected by the temperature detection element 23 in the plate 22. The temperature is measured, and the current flowing through the Peltier element 24 having the Peltier effect is controlled using the signal. When this current is controlled to flow through the Peltier element 24, the conductive heat of the plate 22 is absorbed by the Peltier effect, and is further dissipated by the heat radiator 25. The temperature within the package 12 is thus maintained constant. FIG. 3 shows an electrical block diagram for controlling the temperature and driving the light source device.

The first holding member is fitted and held so that the central axes of the first holding member 26 and the second holding member 26 having heat insulating properties coincide with each other. As the material for the second holding member, a material having appropriate rigidity, low thermal conductivity, and good workability is used, such as polyacetal resin, polyamide resin, polycarbonate resin, phenol resin, etc. The reason for this is that even if the ambient temperature of the light source device fluctuates significantly, the amount of heat flowing into and out of the laser generator 10 and the first holding member (plates 21, 22) is reduced to maintain the heat insulation effect. This is because the temperature of the laser generator can be maintained constant.

The second holding member 26 is further fitted and held in a third holding member 27 such that their respective central axes coincide. The third holding member 27 is preferably made of a material with a small coefficient of linear expansion.
For example, Invar (Fe63%, Ni36%, Mn0.5%)
The linear expansion coefficient of is 1×10 ^-6 ℃ ^-1 , Super Invar (Fe63~65%, Ni30~32%, Co5%, trace amount of Mn)
is 0.5×10 ⁻⁶ °C ⁻¹ , which is particularly suitable. Generally, if a material with a coefficient of linear expansion of 20×10 ⁻⁶ ° C. ⁻¹ is used, it is possible to reduce relative position fluctuations of the optical system due to temperature fluctuations.

The third holding member 27 is fixed to the radiator 25 with screws 28. In addition, 27A is a mounting surface which made a part of the outer peripheral surface of the 3rd holding member 27 flat, and 27B is a mounting reference hole.

On the other hand, the collimator lens CL that collimates the light beam emitted from the laser generator 10 is
It is held within the lens holder 30 and the lens presser 31
Fixed by The lens holder 30 is
It is threadedly fitted to the mount member 32 and fixed with a lock nut 33 or the like. To focus the collimator lens CL, use the lens holder 3 above.
This is done by rotating and slightly moving the 0. Here, the collimator lens CL, the lens holder 30 for holding the collimator lens CL, the mount member 32, etc. are referred to as a collimator lens section.

The mount member 32 is the third holding member 2
It is fixed to the end face of 7 with a screw 34. The mounting member 32 is also made of a material with a low coefficient of linear expansion, similar to the third holding member 27.

Next, the reason why a material with a low expansion rate is required as the material for the third holding member 27 will be explained below.
FIG. 4 shows an optical functional diagram of a laser beam scanning optical system using the above light source device. Further, FIG. 5 is a perspective view showing the optical system of the laser beam scanning recording device.

In these figures, O ₁ is the semiconductor laser element
This is the light exit surface from SL, and the light beam generated from the semiconductor laser element is passed through the collimator lens CL.
The parallel light flux collimated by and emitted passes through an fΘ lens F (for example, f ₂ = 500 mm),
A beam spot is imaged onto the final scan plane _O2 .
At this time, the horizontal magnification α and vertical magnification β of the optical system are given by the following equations.

α≡(dy ₂ /dy ₁ )=f ₂ /f ₁ =50 β≡(dz ₂ /dz ₁ )=α ² =2500 This means that the light emission point of the laser element SL is in the y ₁ direction (due to rotational symmetry, If the beam spot moves by 1 μm due to thermal expansion (from _{the 1} −y ₁ plane), this means that the beam spot will move 50 times 50 μm in the y ₂ direction on the scanning plane O ₂ . Also, the laser element SL
If the light emission point of is moved by 1 μm in the _Z1 direction, the beam imaging position will be 2500 μm (2.5
mm) Z This means that the beam spot is in a defocus state by moving in _{the 2} direction.

In general, a precision laser beam recording device or reading device needs to be able to scan the beam spot accurately without any trouble even if the environmental temperature difference in which it is used changes by 40 to 50°C. a third holding member 27 that holds the laser element SL and forms an outer shell as described above;
By using materials with low coefficients of linear expansion for the mount member 32 constituting the outer shell of the collimator lens CL, it is possible to reduce optical system position fluctuations due to temperature fluctuations.

Also, a package 12 for sealing the semiconductor laser element SL, a first holding member (plates 21, 2
2), second holding member 26, third holding member 27
By forming a fitting structure and a rotationally symmetrical coaxial structure, the package 12, the first holding member, and the second holding member 26 are
Even if the third holding member 27 tries to expand, the third holding member 27 functions as the outermost fitting member to maintain low expansion.
Moreover, since it has a rotationally symmetrical structure, positional fluctuation (displacement) components only occur in directions parallel to the axial direction. This means that the displacement component of the lateral magnification of the optical system is suppressed.

Further, as shown in FIG. 1, the axial displacement component is sandwiched between the third holding member 27 and the radiator 25, and is made of a resin material having lower rigidity than the other holding members 21, 22, and 27. Second holding member 26
Since thermal expansion energy is accumulated as internal stress of the package 12 and the first holding member 2,
1, 22, and the displacement component of the second holding member 26 does not appear. This means that the displacement component of the vertical magnification system of the optical system is suppressed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the fluctuation in the relative position of the laser element and the optical system due to temperature changes, so that the desired beam flux can be stably obtained, and each of the constituent holding members This makes manufacturing, assembly, and adjustment easier.

[Brief explanation of drawings]

1A and 1B are a side sectional view and a front view of a light source device according to the present invention, FIG. 2 is a partially cutaway side view of a laser generator built in the light source device of the present invention, and FIG. 3 is a side view of the light source device according to the present invention. FIG. 4 is a functional diagram of the optical system of a laser beam scanning optical system using the above light source device, and FIG. 5 is a perspective view showing the optical system of the laser beam scanning recording apparatus. 6th
The figure is a sectional view showing an example of a conventional light source device. 1, 12... Package cage, 4, CL... Collimator lens, 10... Laser generator, 21, 2
2...Plate (first holding member), 23...Temperature detection element, 24...Peltier element, 25...Radiator, 26...Second holding member, 27...Third holding member, 30 ...Lens holder, 32...Mount member, SL...Semiconductor laser element.

Claims (1)

[Scope of Claims] 1. A light source device including a semiconductor laser element and a collimator lens section that collimates a light beam generated from the semiconductor laser element, comprising: a heat conduction device that fits into a package containing the semiconductor laser element; A first holding member with good thermal conductivity having a coefficient of 50 W・m ⁻¹・K ⁻¹ or more, and a member that fits into the first holding member has a thermal conductivity of 2W・m ⁻¹・K ⁻¹ or less and a low-expansion second holding member that fits into the second holding member and has a linear expansion coefficient of 20 × 10 ^-6 °C ^-1 or less and has a collimator lens portion. A light source characterized in that the holding member No. 3 is arranged so that the central axis of the fitting portion of the package and each of the first, second, and third holding members are substantially coaxial. Device.