JPH05346502A - High-reflection mirror of resin optical parts - Google Patents

Abstract

(57) [Summary] [Purpose] To maintain high surface accuracy as a high-reflection mirror even in high temperature and high humidity environments. A base layer 3 made of a metal film having good adhesion and moisture resistance to a replica layer 2 made of a resin having a three-stage lattice shape and sequentially arranged at a predetermined pitch on one surface of a substrate 1. , Metal reflective film layer 4 having high reflectance, metal reflective film layer 4
A protective film layer 5 for protecting the is laminated. In order to reduce the complicated change and curvature of the lattice shape of the replica layer 2, the underlayer 3 has a coefficient of thermal expansion of 6% or more when the coefficient of thermal expansion of the replica layer 2 is 100% in the range of room temperature to 100 ° C. A metal film having a coefficient of thermal expansion is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reflective mirror of a resin optical component capable of maintaining surface accuracy with high accuracy.

[0002]

2. Description of the Related Art Conventionally, for a highly reflective mirror of a resin optical component, a resin replica layer made of a thermosetting resin, a thermoplastic resin, an ultraviolet curable resin or the like is laminated on a substrate made of optical glass or the like. On the surface of the replica layer, a base layer made of an oxide film such as SiO having good adhesion and moisture resistance and a metal reflection film made of Cu, Al, Au or the like for reflecting light are sequentially formed. Second layer, SiO ₂ and Al ₂ O for preventing corrosion and surface roughening of the second layer by water vapor in the atmosphere
A third layer comprising a protective film such as ₃ is formed by laminating.

Further, in place of the third layer, the metal reflection film of the second layer in the previous term is protected and S is added with a function of increasing reflection.
There is a film in which two or more layers made of iO ₂ , Al ₂ O ₃ , TiO ₂ or the like are laminated.

[0004]

In the above conventional technique, when the coefficient of thermal expansion of the replica layer is 100% in the range of room temperature to 100 ° C., the coefficient of thermal expansion of the underlayer is 5% or less. ..

Therefore, when a leaving test in a high temperature and high humidity environment is carried out as a quality acceleration test, the surface shape of the replica layer is distorted due to the difference in the coefficient of thermal expansion, and as a result, as a high reflection mirror of a resin optical component. Surface accuracy is deteriorated. In particular, in a resin optical component for a phase grating in which a large number of minute concave and convex grooves are provided on the surface of the replica layer, the reflectivity decreases by 5% or more because the grating shape of each step is complicatedly changed and curved. The peak wavelength of the rate is 1 toward the short wavelength side
This shifts by 0 nm or more, and the original optical function of the reflection type color separation diffraction grating is significantly impaired.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and it is possible to maintain the surface accuracy as a high reflection mirror with high accuracy even in a high temperature and high humidity environment. It is an object of the present invention to realize a high-reflection mirror of a resin optical component that can be manufactured.

[0007]

In order to achieve the above-mentioned object, a high reflection mirror of a resin optical component of the present invention comprises a resin replica layer having a staircase type lattice shape, and a reflection film on the replica layer. A diffraction grating for color separation in which layers are stacked, wherein the diffraction grating has a coefficient of thermal expansion of 100% between the replica layer and the reflective film layer in a range of room temperature to 100 ° C. It is characterized in that an underlayer having a coefficient of thermal expansion of 6% or more is laminated.

Further, it is preferable that the underlayer is a simple substance of tantalum, chromium, titanium or copper or an alloy composed of two or more of these. Further, the underlayer may be an alternate layer in which a metal film layer made of tantalum, chromium, titanium, or copper alone or an alloy of two or more of these and a dielectric film layer are adjacent to each other.

Further, the thickness of the underlayer can be 500 angstroms or less.

[0010]

Since the difference in the coefficient of thermal expansion between the replica layer and the underlying layer laminated between the replica layer and the reflection film is small, the lattice shape of the surface of the replica layer can be prevented from being complicatedly changed or curved. .. Therefore, the peak wavelength of the reflectance does not shift to the short wavelength side.

[0011]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing a high reflection mirror of a resin optical component of the present invention.

The substrate 1 is made of optical glass or the like, and one surface of the substrate 1 is a resin replica layer having a three-step lattice pattern in which a replica layer made of a resin having a step lattice pattern is sequentially arranged at a predetermined pitch. Corrosion of the replica layer 2, the underlayer 3 made of a metal film having good adhesion and moisture resistance to the replica layer 2, the metal reflection film layer 4 having a high reflectance, and the metal reflection film layer 4 due to water vapor in the atmosphere. A protective film layer 5 for preventing roughening due to abrasion and the like is laminated.

In order to reduce the complicated change and curvature of the lattice shape of the replica layer 2, the underlayer 3 has a coefficient of 6 when the coefficient of thermal expansion of the replica layer 2 is 100% in the range of room temperature to 100 ° C. The metal film has a coefficient of thermal expansion of not less than percent. The replica layer 2 is made of an ultraviolet curable resin.

Therefore, the metal film forming the underlayer 3 is preferably tantalum, chromium, titanium, or copper alone or an alloy composed of two or more of these.

Further, since the replica layer 2 has water absorbency, the thickness of the metal film of the underlayer 3 is the minimum necessary thickness capable of preventing the corrosion from the replica layer 2 to the metal reflection film layer 4. Need to be formed. Therefore, the lower limit value of the underlayer 3 needs to be set to several tens of angstroms. Also,
The upper limit of the film thickness of the underlayer 3 is, for example, when an ultraviolet curable resin material is used, molding conditions of the replica layer 2 such as the type, irradiation energy and irradiation time, and the material of the metal reflection film layer 4. And the film thickness and the material and film thickness of the protective film layer 5, and if the thickness is 500 angstroms or less, good results can be obtained. However, substrate 1
In consideration of the reproducibility of the processing conditions, the productivity and the use environment when forming the high reflection mirror including the underlayer 3, the metal reflection film layer 4 and the protective film layer 5 on the resin optical component including the replica layer 2, The preferable thickness of the underlayer 3 is 50 to 150 angstrom.

The diffraction grating for color separation thus constructed has a reflective film structure (lower surface) so that the surface accuracy of each grating step satisfies a deformation amount of ± 30 nm or less in the range of room temperature to 100 ° C. Underlayer 3, metal reflective film layer 4, protective film layer 5)
Is provided.

Further, the diffraction grating for color separation thus constructed is used in a color image reading device known from Japanese Patent Laid-Open No. 214370/1990.

Next, each embodiment of the present invention will be described together with the manufacturing process.

Example 1 First, a so-called replica in which a replica layer 2 having a three-step lattice shape is laminated on one surface of a substrate 1 made of optical glass is manufactured by a known replica method, and contaminants attached to the surface are washed. And so on.

Here, the lattice shape formed on the surface of the replica layer 2 on the side opposite to the substrate may be formed in the following shape.

The recesses of the lattice have a pitch P of 90 to 190 μm, and each recess has three steps of different depths formed stepwise. The width of the deepest first step groove and the width of the fourth step on the surface of the replica layer serving as the reference surface are P × 0.19 μm, and the width of the second step groove of the second depth is 3 × The width of the third groove at the th depth is P × 0.31 micron.

The steps of each step are 580 to 580 which are the first step between the first step and the second step and the third step between the third step and the fourth step.
At 740 nanometers, the second step between the second and third steps is 590-780 nanometers.

Furthermore, the amount of change in the width of the groove in each step is set to ± 2 microns or less, and the amount of change in the step between each step is set to ± 30 nanometers or less.

Next, the above replica is set in a known vacuum vapor deposition apparatus, vacuum exhaust is performed, and 3 × 10 ^-5 Torr is set.
With the above high vacuum, the coefficient of thermal expansion is 9.4% when the coefficient of thermal expansion of the replica layer 2 is 100% in the range of room temperature to 100 ° C. by the resistance heating evaporation source or the electron beam evaporation source. Metal chromium was evaporated and vapor-deposited on the surface of the replica layer 2 to form the base layer 3.

After that, metal aluminum is vaporized by a resistance heating vapor deposition source or an electron beam vapor deposition source and vapor-deposited on the underlayer 3 so that the thickness of the metal aluminum film is 1000 angstrom, and the metal reflection film is formed. Layer 4
Formed.

Then, silicon dioxide was evaporated by an electron beam vapor deposition source and vapor-deposited so that the film thickness of silicon dioxide became 100 angstroms to form a protective film layer 5.

After that, the pressure of the vacuum vapor deposition apparatus is increased to atmospheric pressure, and the high reflection mirror 6 which is a resin optical component is taken out.

Regarding the high-reflection mirror of the resin optical component of Example 1 manufactured as described above, the room temperature to 100 ° C.
Table 1 shows the coefficient of thermal expansion of each layer and the film thickness of each layer in the above range.

[0030]

[Table 1]

In this embodiment, the film thickness is set to 1 in consideration of controllability, film quality reproducibility, and use environment when depositing a metal chromium film.
00 angstrom.

The high reflection mirror of the resin optical component of this embodiment is placed in a high temperature / high humidity tank at 70 ° C. and 85% RH for about 25 minutes.
After an accelerated test of standing for 0 hour, the surface accuracy, film adhesion, reflectance, appearance, etc. were evaluated, and as a result, no significant change was observed. In particular, when the surface accuracy was evaluated by interference fringes, Example 1 was compared with the case where an oxide made of SiO or the like having a thermal expansion coefficient of less than 6% was used for the underlayer 3 for the underlayer 3. Was extremely good, and high accuracy could be maintained.

The results of evaluation and comparison of the surface accuracy by interference fringes are shown in FIGS.

FIG. 2 is a view schematically showing a photograph in which the lattice plane shape of a resin optical component composed of the substrate 1 and the resin replica layer 2 is evaluated by interference fringes.

The lattices are arranged stepwise in the vertical direction of the figure,
Interference fringes are misaligned where there are steps on each step. This Figure 2
Then, the remarkable interference fringes are almost straight, and the interference fringes at the boundary between adjacent steps are sharp, so it can be seen that the surface shape of each step of this grating is extremely smooth.

FIG. 3 shows a case where a SiO film having a coefficient of thermal expansion of 0.7% is used in place of the Cr film for the underlayer 3 of FIG. That is, FIG.
On the lattice surface of the resin optical component (substrate 1 and replica layer 2), an SiO film having a film thickness of 100 angstroms as an underlayer 3, an Al film having a film thickness of 1000 angstroms as a metal reflection layer 4, and a SiO ₂ film as a surface protection film layer 5 are formed. Is formed by a vacuum vapor deposition method, and is an evaluation result after an acceleration test after leaving it for 250 hours in a high temperature and high humidity tank at 70 ° C.-85% RH.

FIG. 4 shows the evaluation results after the acceleration test, which uses the Cr film as the underlayer 3 and has the structure described in Table 1 above.

As is clear from the evaluation and comparison results of FIGS. 2 to 4, the underlayer 3 has a coefficient of thermal expansion of 6%.
When the SiO film composed of less than the percentage is used, the interference fringes after the acceleration test are largely deformed / curved at each stage. Especially, the deformation at the boundary between adjacent steps is remarkable. On the other hand, when a Cr film having a coefficient of thermal expansion of 9.4% was used as the underlayer 3 in FIG. 4, the deformation and curvature of the interference fringes after acceleration test were small. There is.

The reflectance and the peak wavelength before and after the acceleration test by high temperature and high humidity were measured on the sample using the Cr film as the underlayer 3, and as a result, the change was small, and the reflectance was 2% or less and the peak. In terms of wavelength, the wavelength was improved to a shift of 3 nm or less toward the short wavelength side, and there was an effect that the function as a reflection type color separation diffraction grating was sufficiently satisfied.

Example 2 As the underlayer 3, a metal titanium film having a coefficient of thermal expansion of 85 × 10 ⁻⁷ / ° C. and a film thickness of 300 Å was used as the underlayer 3 and an Ag film was formed as the metal reflection film layer 4. Same as Example 1 except that the thickness is 1500 angstrom.

Table 2 shows the coefficient of thermal expansion and the film thickness of each layer in this example.
Shown in.

[0042]

[Table 2]

In Example 2 as well, after the same acceleration test as in Example 1 was conducted, the surface accuracy, film adhesion, reflectance,
As a result of evaluating the appearance and the like, good results were obtained. Especially in terms of surface accuracy, high surface accuracy could be maintained.

Example 3 A Ni—Cu alloy film having a coefficient of thermal expansion of 160 × 10 ⁻⁷ / ° C. in the range of room temperature to 100 ° C. is formed as the underlayer 3, and an Al film is formed as the metal reflection film layer 4. Thickness 1
Same as Example 1 except that the thickness was set to 000 angstrom.

Table 3 shows the film thickness and the coefficient of thermal expansion of each layer in the examples.

[0046]

[Table 3]

After carrying out the same accelerated test as in Example 1 on Example 3, the surface accuracy, the film adhesion, the reflectance, the appearance and the like were evaluated. As a result, good results were obtained. Especially in terms of surface accuracy, high surface accuracy could be maintained.

Example 4 FIG. 5 is a schematic partial sectional view showing a high-reflection mirror of a resin optical component according to Example 4 of the present invention.

The substrate 1 is made of optical glass or the like. On one surface of the substrate 1, a resin replica layer 2 having a three-step lattice shape, which is a resin replica layer having a staircase lattice shape and arranged at a predetermined pitch, is sequentially provided. The underlayer 3 having good adhesion and moisture resistance to the replica layer 2 is composed of alternating layers of the metal film layer 7 and the dielectric film layer 8 adjacent to the metal film layer 7. Reference numeral 4 is a metal reflective film layer having a high reflectance, and 5 is a protective film layer for preventing the metal reflective film layer 4 from being corroded by water vapor or the like in the atmosphere and being roughened by abrasion. 6
Is a high reflection mirror of a resin optical component including an optical glass 1, a replica layer 2, a base layer 3 (metal film layer 7, dielectric film layer 8), a metal reflection film layer 4, and a protection film layer 5.

In order to reduce the complicated change and curvature of the lattice shape of the replica layer 2, the underlayer 3 has a coefficient of 6 when the coefficient of thermal expansion of the replica layer 2 is 100% in the range of room temperature to 100 ° C. It is composed of a metal film layer 7 having a coefficient of thermal expansion of not less than percent and a dielectric film layer 8 adjacent to the metal film layer 7.

The replica layer 2 is made of an ultraviolet curable resin.

Therefore, the metal film layer 7 forming the underlayer 3
As the material, tantalum, chromium, titanium, or copper may be used alone or an alloy composed of two or more thereof.

Further, the dielectric film layer 8 is preferably made of aluminum oxide alone or a dielectric material containing aluminum oxide as a main component.

Further, since the replica layer 2 has water absorbency, the thickness of the metal film of the underlayer 3 is the minimum necessary thickness capable of preventing corrosion from the replica layer 2 to the metal reflection film layer 4. Need to be formed. For this reason, the lower limit of the underlayer 3 needs to be several tens of angstroms for the metal film layer 7 and the dielectric film layer 8 forming the underlayer 3. The upper limit of the film thickness of the underlayer 3 is, for example, when an ultraviolet curable resin material is used, the molding conditions of the replica layer 2 such as its type, irradiation energy and irradiation time, and the metal reflection film layer 4. It is related to the material and the film thickness of the above and the material and the film thickness of the protective film layer 5, and when the thickness is 500 angstroms or less, good results can be obtained.

However, the reproducibility and productivity of the processing conditions when forming the high reflection mirror including the underlayer 3, the metal reflection film layer 4 and the protective film layer 5 on the resin optical component including the substrate 1 and the replica layer 2 are described. Considering the usage environment, the preferable thickness of the underlayer 3 is 150 to 400 angstroms. Among them, the preferable thickness of the metal film layer 7 is 40 to 100 angstroms, and the preferable thickness of the dielectric layer 8 is 110 to 300 angstroms.

The diffraction grating for color separation constructed as described above has a reflective film structure (lower surface) so that the surface accuracy of each grating step satisfies a deformation amount of ± 30 nm or less in the range of room temperature to 100 ° C. Formation 3 (metal film layer 7, dielectric film layer 8),
A metal reflective film layer 4 and a protective film layer 5) are provided.

The diffraction grating for color separation constructed as described above is used in a color image reading apparatus known from Japanese Patent Laid-Open No. 214370/1990.

Next, the fourth embodiment will be described together with the manufacturing process.

First, in the same manner as in Example 1, a replica is manufactured by laminating a replica layer 2 having a three-step lattice shape having the above dimensions on one surface of a substrate 1 made of optical glass.

The above replica is set in a known vacuum vapor deposition apparatus, and vacuum evacuation is performed to obtain a high vacuum of 3 × 10 ⁻⁵ Torr or more, using a resistance heating vapor deposition source or an electron beam vapor deposition source.
In the range of room temperature to 100 ° C., metal chromium having a coefficient of thermal expansion of 9.4% when the coefficient of thermal expansion of the replica layer 2 is 100% is evaporated and vapor-deposited on the surface of the replica layer 2 to form a metal film layer. Formed 7.

Then, the coefficient of thermal expansion is set to a replica layer 2 in the range of room temperature to 100 ° C. by an electron beam evaporation source.
Aluminum oxide having a coefficient of thermal expansion of 9.7% was evaporated to form a dielectric film layer 8 adjacently on the metal film layer 7 to form the underlayer 3.

After that, metal aluminum is vaporized by a resistance heating vapor deposition source or an electron beam vapor deposition source and vapor-deposited so that the thickness of the metal aluminum film is 1000 angstrom on the underlayer 3, and the metal reflection film is formed. Layer 4
Formed.

Then, using an electron beam evaporation source, Al ₂
Silicon dioxide containing about 3% of O ₃ was evaporated and vapor-deposited so that the film thickness of silicon dioxide was 130 Å to form protective film layer 5.

After that, the pressure of the vacuum vapor deposition apparatus is increased to the atmospheric pressure, and the high reflection mirror 6 which is a resin optical component is taken out.

Table 4 shows the film thickness and the coefficient of thermal expansion of each layer in the range of room temperature to 100 ° C. for the high reflection mirror of the resin optical component of Example 4 manufactured as described above.

[0066]

[Table 4]

In Example 4, the metallic Cr film and the dielectric Al were used.
Considering the controllability, the reproducibility of the film quality, and the usage environment when depositing the ₂ O ₃ film, the film thickness of each film is 60 Å, 150 Å.
Angstrom.

In Example 4, the same acceleration test as in Example 1 was conducted, and then the surface accuracy, the film adhesion, the reflectance, the appearance and the like were evaluated. As a result, good results were obtained. Especially in terms of surface accuracy, high surface accuracy could be maintained.

Example 5 The metal film layer 7 of the underlayer 3 has a coefficient of thermal expansion of room temperature to 10.
In the range of 0 ° C., a metal chromium film of 66 × 10 ⁻⁷ / ° C. has a film thickness of 60 Å, and as the dielectric film layer 8 adjacent to the metal film layer 7, the coefficient of thermal expansion is from room temperature to 100 ° C.
The titanium oxide film of 1 × 10 ⁻⁷ / ° C. has a film thickness of 120 Å, the metal reflection film layer 4 has an Al film thickness of 1000 Å, and the protective film layer 5 has Al ₂ O ₃ of about 3%.
Example 4 is the same as Example 4 except that the contained SiO ₂ film has a film thickness of 100 Å.

Table 5 shows the coefficient of thermal expansion and the film thickness of each layer of Example 5.

[0071]

[Table 5]

In Example 5, the same accelerated test as in Example 1 was conducted, and then the surface accuracy, the film adhesion, the reflectance, the appearance and the like were evaluated. As a result, good results were obtained. Especially in terms of surface accuracy, high surface accuracy could be maintained.

[0073]

Since the present invention is configured as described above, it has the following effects.

Since the surface accuracy of the grating shape formed on the resin optical component is maintained high even in a high temperature and high humidity environment, the reflectance is reduced and the shift of the peak wavelength is reduced. The optical function as the diffraction grating for reflective color separation can be exhibited.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of a high reflection mirror of a resin optical component of the present invention.

FIG. 2 is a diagram in which the surface accuracy of a resin optical component is evaluated by interference fringes.

FIG. 3 is a diagram in which the surface accuracy of a resin optical component is evaluated by interference fringes.

FIG. 4 is a diagram in which the surface accuracy of the resin optical component of the present invention is evaluated by interference fringes.

FIG. 5 is a schematic cross-sectional view of another embodiment of the high reflection mirror of the resin optical component of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Replica layer 3 Underlayer 4 Metal reflective film layer 5 Protective film layer 6 High reflection mirror of resin optical parts

Claims (4)

[Claims] 1. A color-separating diffraction grating in which a resin-made replica layer having a step-like grating shape and a reflective film layer are laminated on the replica layer, wherein the diffraction grating includes the replica layer and the replica layer. An underlayer having a coefficient of thermal expansion of 6% or more, when the coefficient of thermal expansion of the replica layer is 100%, is laminated between the reflective film layer and the reflective film layer in the range of room temperature to 100 ° C. High-reflection mirror for optical components. 2. The high reflection mirror for a resin optical component according to claim 1, wherein the underlayer is made of a single substance of tantalum, chromium, titanium or copper or an alloy of two or more of these. 3. The high reflection mirror for a resin optical component according to claim 1, wherein the underlayer has a thickness of 500 angstroms or less. 4. A metal film layer made of tantalum, chromium, titanium, or copper alone or an alloy of two or more of these, and a dielectric film layer are adjacent alternating layers. Item 1. A highly reflective mirror of the resin optical component according to Item 1.