JPH03252602A - Antireflection film - Google Patents

Abstract

PURPOSE:To provide an excellent antireflection effect over a wide wavelength region and to obtain sufficient durability by laminating a 1st layer consisting of CeO2, a 2nd layer consisting of the composite of TiO2 and HfO2 or the TiO2 and a 3rd layer consisting of SiO2 on an optical member made of a synthetic resin successively from the front surface side thereof. CONSTITUTION:The planar optical part (a) molded of an acrylic resin having a special alicyclic group is subjected to precise washing and drying and the 1st layer (b) is formed thereon by using a target consisting of the CeO2 and executing vapor deposition by electron beam heating with a vacuum vapor deposition device. The 2nd layer (c) is formed on this 1st layer (b) by using a target consisting of the TiO2 and executing the vapor deposition in the same manner. Further, the 3rd layer (d) is formed on the 2nd layer (c) by using a target consisting of the SiO2 and executing the vapor deposition in the same manner, by which the antireflection films of the 3-layered constitution are obtd. The antireflection film which maintains a low reflectivity over the range of a wide wavelength region and has excellent durability is obtd. in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applied to optical components made of synthetic resin used in the fields of OA equipment, optical communication, optical information processing, optical equipment such as cameras, etc. Regarding anti-reflection film.

[Conventional technology]

Conventionally, optical parts such as lenses and prisms used in laser application equipment such as laser printers, optical disk devices, laser processing equipment and measuring equipment, optical information processing equipment, and electronic imaging equipment such as video cameras and video projectors have been used. Therefore, an antireflection layer is provided to reduce harmful surface reflections.

In addition, in recent years, in order to increase productivity, reduce costs, and make optical components lighter and more compact, optical components have been developed using newly developed and improved transparent synthetic resin materials such as acrylic resin, polycarbonate resin, PS resin, and other materials. are being manufactured more and more. Anti-reflection treatment for such synthetic resin optical components is performed by vacuum evaporation or sputtering on an undercoat film formed by dip-coating or spin-coating and curing organic silane-based or acrylic-based paint. There is a method of forming an antireflection film using, for example, a vacuum evaporation method, and a method of forming an antireflection film consisting of a single layer or multiple layers of dielectric material is also known.

[Problems to be Solved by the Invention] The method of undercoating the surface of synthetic resin optical components as described above increases the number of steps and costs, and it is difficult to apply uniformly depending on the surface shape of the optical component. Therefore, there is a problem that it is not suitable for precision optical parts that require high precision.

On the other hand, when performing antireflection treatment directly on the surface of synthetic resin optical components by vacuum evaporation, etc., MP, F
In the case of a single layer film such as , or Sin, the anti-reflection effect is not sufficient, and the adhesion and durability of the film are also poor. Although it is possible to form a film with a low cost of 1- and to reduce the reflectance in the central wavelength range, it is difficult to reduce the reflectance to 0.5% or less in wavelength ranges far away from this. However, it was not always satisfactory as an antireflection film for optical components.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an antireflection film for synthetic resin optical components that has excellent antireflection effects over a wide wavelength range and has sufficient durability. It is something.

[Means for Solving the Problems] The object of the present invention is to provide a first layer made of CeO
This is achieved by an anti-reflection coating for an optical component made by sequentially laminating a second layer made of a composite of iO□ and HfO□ or TiO7 and a third layer made of SiO2 from the surface side of a synthetic resin optical component. be able to.

To form the antireflection film of the present invention on the surface of a synthetic resin optical component, a thin film forming technique such as a vacuum evaporation method or an ion blating method can be used. The anti-reflection film formed in this way is shown in Figure 1.
A first layer b, a second layer C, and a third layer d are laminated in this order on the optical component a. The first layer, second layer, and third layer as described above each have a wavelength of 0 with respect to the design wavelength λ of the applied light.
It is preferable to form it so that it has a thickness of about 25λ.

[For production]

The antireflection film of the present invention formed as described above has good adhesion to the synthetic resin optical component substrate, and has stable optical properties and excellent durability over a wide wavelength range. .

(Example 1) Acrylic resin having a special alicyclic group (Hitachi Chemical 0Z-1
After precision cleaning, a plate-shaped optical component molded with a refractive index of 1.49) was thoroughly dried, placed in a vacuum evaporator, and heated to about 70'C to form CeO□( Using a target with a refractive index of 1.95), the degree of vacuum is 1×10
The first layer was deposited to a thickness of 195 nm by electron beam heating under -5 Torr conditions.

Next, using a target of TiO□ (refractive index: 2.2), a film with a thickness of 195 nm was formed on this first layer in the same manner.
A second layer was formed by vapor deposition.

Furthermore, using a target of SiO□ (refractive index: 1.45), a third layer was similarly deposited on top of this second layer to a thickness of 195 nm, resulting in a three-layer structure. An antireflection film was obtained.

The film thickness of each of these layers corresponds to 0.25λ for light having a wavelength λ of 780 nm.

The results of measuring the spectral reflectance of the antireflection film thus obtained are shown in FIG. 1, and the reflectance was 0.3% or less over the wavelength range of 700 to 900 nm.

[Example 2] On the surface of a plate-shaped optical component molded from polycarbonate resin (Yodai Kasei AD-5503, refractive index: 1.57),
Example 3 was prepared in the same manner as in Example 1, except that a composite of TiOz and HfO□ (Nippon Metal TiO□ ・S6, refractive index: 2.25) was vapor-deposited to a thickness of 195 nm as the second layer. An antireflection film having a layered structure was obtained.

The results of measuring the spectral reflectance of the antireflection film thus obtained are shown in FIG. 2, and the reflectance was 0.4% or less over the wavelength range from '700 to 90 Onm.

[Comparative Example 1] MgI2.
A single-layer antireflection film with a refractive index of , 1.37 was formed.

The results of measuring the spectral reflectance of this antireflection film are shown in FIG. 3, and the reflectance was 1.5% or more.

[Comparative Example 2] Laz (L) having a film thickness of 195 nm was coated on the surface of the same plate-shaped optical component as in Example 1 by the same method as in Example 1.
+ (refractive index: 1.8) first layer and film thickness 195 nm
A laminated antireflection film was formed with a second layer of SiO□.

FIG. 4 shows the results of measuring the spectral reflectance of this antifouling film. In this case, the reflectance at the center wavelength of 780 nm is 0.1% or less, but as the wavelength moves away from the center, the reflectance reaches 1% or more.

[Test Example] The durability of an antireflection film provided on the surface of an optical component was evaluated by the following method.

Adhesion test: The adhesion of the film was examined by adhering a cellophane adhesive tape to the surface of the membrane and then peeling it off in the vertical direction.
No peeling was observed in any of the films of Comparative Example 2 and Comparative Example 1.2.

Humidity test: The film was left in a constant temperature and humidity chamber at a temperature of 45° C. and a relative humidity of 95% for 24 hours, dried, and changes in the state of the film were observed. No abnormalities were observed in the films of Example 1.2 and Comparative Example 2, but clouding occurred in the film of Comparative Example 1.

Further, in the adhesion test after the moisture resistance test, peeling occurred in the film of Comparative Example 1.

Thermal shock test: After repeating 10 times of leaving the product in an environment of 30°C and 70°C for 30 minutes each, the product was returned to room temperature and the surface condition was observed. No changes were observed in the films of Example 1.2 and Comparative Example 2, but the film of Comparative Example 1 had cracks and haze.

Further, in the adhesion test after the thermal shock test, peeling occurred in the film of Comparative Example 1.

Figures 2 and 3 are spectral reflection characteristic diagrams of antireflection films of Example 1 and Example 2 of the present invention, respectively, and Figures 4 and 5 are Comparative Example 1 and Comparative Example 2, respectively.
FIG. 2 is a spectral reflection characteristic diagram of an antireflection film.

a... Optical component, b... First layer, C... Second layer,
d...Third layer.

〔Effect of the invention〕

The antireflection film of the present invention is composed of a film material with high chemical and thermal stability, has good adhesion to the synthetic resin base material, and maintains low reflectance over a wide wavelength range. It has the feature of excellent durability.

Claims (1)

[Claims] A first layer consisting of CeO_2, TiO_2 and HfO_2
or a second layer consisting of TiO_2 and a composite of SiO
An antireflection film for an optical component, which is formed by sequentially laminating a third layer consisting of _2 from the surface side of a synthetic resin optical component.