KR960013791B1 - Optical device - Google Patents

Abstract

The film comprises a first layer having the thickness of 0.25=F0.01 O( O; definite wave length of visible ray), second layer 0.53=F0.01 O, third layer 0.53=F0.01 O and fourth layer 0.25=F0.01 O, wherein the first, second, third and fourth layer each comprises, in series, SiO2, CeF3, ZrO3, SiO2 and formed on a lens of synthetic resin, the multi-coating is performed less than 74 deg.C, and the synthetic lens comprises polystylene or PMMA.

Description

Multilayer Anti-reflection Film of Optical Components

1 is a cross-sectional view showing the configuration of a multilayer antireflection film of an optical component according to the present invention.

2 is a characteristic view showing the relationship between the wavelength and reflectance according to the multilayer anti-reflection film of the present invention.

3 is a cross-sectional view showing an internal structure of a coater for forming a multilayer anti-reflection film according to the present invention.

Industrial use

The present invention relates to a multilayer anti-reflection film of an optical component, and in particular, in the form of an anti-reflection film composed of a laminated film of a four-layer coating film composition, the plastics can not only improve the transmittance of the optical device but also increase the film strength. Synthetic resin).

In general, the antireflection film of an optical component can be roughly classified into a single layer antireflection film and a multilayer antireflection film.

In recent years, as high performance of optical devices has been pursued, when the structure of the optical system is complicated and the number of lenses increases, sufficient transmittance cannot be obtained with a single layer antireflection film, so that defects of the single layer antireflection film, such as a low reflection wavelength region, are narrow and residual reflectance is high. Many multilayer antireflection films have been used which have improved the above-mentioned shortcomings.

One of the basic types of the multilayer antireflection film is that the film thickness of the first layer film (λ °: set wavelength) having an optical film thickness of λ ° / 4 from the glass substrate side of the optical component, the second layer film having λ ° / 2, and A three-layer antireflection film is proposed as a third layer film of 4/4.

As the dielectric material of each layer, the first layer film is CeF3, LaF3, SiO, etc., which are intermediate refractive materials, and the second layer film is ZrO ₂ , TiO ₂ , TaSO ₅ , ZnS, etc., which are high refractive index materials, and the third layer film is a low refractive index material. MgF 2, SiO 2, etc. may be used.

As a conventional three-layer antireflection film having the above structure, for example, the constituent material is composed of CeF ₃ (λ ° / 4) -ZrO 2 (λ ° / 2) -MgF ₂ (λ ° / 4). The disadvantage is low degrees.

On the other hand, when AlO ₃ is used instead of CeF ₃ as the one-layer film, it is known that the film strength is increased and the above defect is improved.

However, in the case of depositing ZrO ₂ on an oxide such as Al ₂ O ₃ , the step of heating the bottom temperature to a certain temperature for the purpose of increasing the strength, the refractive index is gradually lowered as the thickness of ZrO ₂ increases, so the thickness direction is It became a non-uniform film, and there existed a fault which the peak reflection value of the design wavelength (lambda) (degree) of a 3-layer antireflection film becomes large.

As a solution to this drawback, Japanese Patent Application Laid-Open No. 52-31204, which is already disclosed, contains a very thin low refractive index MgF 2 layer in the middle of ZrO ₂ . Japanese Patent Nos. 51-33750 and 51-33751 have made equivalent films equivalent to ZrO ₂ (λ ° / 2) homogeneous in plural sides containing MgF _{2 and} CeO ₂ . However, all of these conventional materials have a large difference in the refractive index of the constituent material from the refractive index of ZrO ₂ (ZrO ₂ : 2.05, MgF ₂ : 1.39, CeO ₂ : 2.15). If present, there was a problem that it is difficult to obtain a stable high yield because it greatly affects the reflective properties of the product after deposition.

According to the invention as described above, by coating the multilayer antireflection film of the four-layer structure in the above-described configuration in the state where the maximum temperature of the lens is 74 ℃ or less, it is possible to prevent the reflection of light, so that the entire visible light region (particularly, 420-680 It is possible to improve the antireflection film characteristic of the light in nm), thereby improving the spectral transmittance in the region. In addition, by stacking the coating film at low temperature (relative), it is possible to manufacture optical parts that withstand the temperature change, which is a weak point of synthetic resin, at low cost. .

Accordingly, the present invention has been made in view of the above-mentioned point, and not only has good transmittance characteristics in the entire region of visible light (especially in the region of 420-680 nm), but also multilayer reflection of an optical component that can remove the cracking of the film due to temperature change. The purpose is to provide a protective film.

Composition of the Invention

Multi-layered anti-reflection film of the present invention for achieving the above object is the first layer film, 0.25 ± ± ± 1 ± 1, the optical film thickness of 0.25 ± 0.01 λ ° on the surface of the synthetic resin lens as an optical component is deposited form The second layer film formed at 0.01λ °, the third layer film formed at 0.53 ± 0.01λ °, and the fourth layer film formed at 0.25 ± 0.01λ ° are sequentially laminated so that the material of the first layer film is SiO2. The material of the second layer film is CeF3, the material of the third layer film is ZrO ₂ , and the material of the fourth layer film is SiO ₂ (lambda °: set wavelength of visible light).

Action

According to the above-described configuration, the present invention provides visible light by changing the deposition materials of the first layer, the second layer, the third layer, and the fourth layer formed on the surface of the synthetic resin lens, which is an optical component, and the refractive index and film thickness of the deposition material. It is possible to obtain a multilayer antireflection film having excellent spectral transmittance characteristics in the region.

Example

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a multilayer antireflection film structure of an optical component according to the present invention. The basic structure is that an antireflection film having a four-layer structure is laminated on the surface of a synthetic resin lens 1, and the refractive index of each layer film and The film thickness is characterized by being in the following range.

First layer 1.45≤N ₁ ≤1.48, 0.24λ ° ≤N ₁ D ₁ ≤0.26λ °

Second layer 1.62≤N ₂ ≤1.65, 0.24λ ° ≤N ₂ D ₁ ≤0.26λ °

Third layer 1.85≤N ₃ ≤2.25, 0.52λ ° ≤N ₃ D ₃ ≤0.54λ °

Fourth layer 1.45≤N ₄ ≤1.48, 0.24λ ° ≤N ₄ D ₄ ≤0.26λ °

Here, N1, N2, N3, and N4 represent refractive indices of materials constituting each layer film, and λ ° represents a set wavelength of visible light, and has a value of 503-515 nm in the present invention. Subsequently, N ₁ D ₁ , N ₂ D ₂ , N ₃ D ₃ , and N ₄ D ₄ represent a value obtained by multiplying the refractive index of the material constituting each layer film by the physical thickness, that is, the optical film thickness.

In each layer film dielectric material is a first layer film (3) in a SiO ₂ and the second layer film CeF _3, the third-layer film (7) as ZrO2, a fourth same SiO ₂ material and a layer film first layer film (9) The lens 1, to which the multilayer anti-reflection film is to be formed, may use optical materials such as polystyrene (P-Stulen) or PUMA, which have the most poor physical properties among synthetic resin lens materials. At this time, the multilayer coating film deposited on the fraudulent lens 1 is coated at the peak temperature of the lens below 74 ° C., thereby preventing cracks, and thus it is easy to use as a synthetic resin optical part. It has the advantage that it can be provided.

The coating method of the multilayer anti-reflection film having the structure as described above can be formed by the coater shown in FIG.

3 is a partial perspective view schematically showing the internal structure of the coating machine. Briefly explaining the process, the lens 19 is first inserted into the coating lens holder, and then the lens 19 is inserted (dome). 17) Insert three measuring glasses (25) on the top, middle and bottom. In this case, the material of the measuring glass 25 is set to BK-7 having a refractive index value of 1.52, and the height of the measuring glass 25 and the coating fez 19 is formed to be the same. The reason why the measurement glass 25 is placed on the lens dome 17 is that the lens has a curved surface, and thus, when the light is incident, all of the measurement glass 25 is transmitted so that the overall transmittance and reflectance cannot be checked. In this case, the measuring glass 25 is polished only on one surface and diffused on one surface, and then inserted into the upper, middle, and lower polished surfaces of the dome 17, respectively.

As shown in FIG. 3A of the sample crucible, SiO ₂ is placed in the crucible No. 1, CeF ₃ in the crucible No. ₂ , ZrO ₂ in the crucible No. ₃ , and SiO ₂ in the crucible No. 4 is separately arranged for each sample. 17) Insert three monitor glasses 21 with a refractive index of 1.49 of BK-4 material. That is, one of SiO ₂ and CeF ₃ is used as a common solution, and one of ZrO ₂ and SiO ₂ is used. In this case, the monitor glass 21 serves as an optical sensor for checking the reflectance when the multilayer antireflection film is coated to open and close the shutter 11.

Subsequently, a vacuum is performed, in which the vacuum degree is related to the film strength of each layer film to be coated, so it is necessary to accurately maintain 2 × 10 ⁻⁵ Torr. This means that the average free stroke distance up to 5 m 2, where the molecule can rise upwards towards the resin lens, indicates that the coating film strength can be improved.

Thereafter, using the samples arranged in the sample crucible (A) at a set wavelength of 503-510 nm, each of the laminated films, which are antireflective films, is formed, based on an experimental value selected from a specific range of the refractive index and the film thickness presented in this embodiment. It will be described for each of the erythrocyte forming process.

For example, consider a case where the set wavelength of visible light is 510 nm. First, the SiO ₂ sample, which is the first layer film material, is put into the sample crucible 1 and the shutter 11 is closed. Thereafter, the sample is centered on the electron beam 13, preheated, and when melted normally, the shutter 11 is opened and burned by 0.25λ. This causes the molecules to jump by the degree of vacuum formed inside the coater 23 so that SiO ₂ material is deposited on one surface of the measuring glass 25, the lens 19, and the monitor glass 21. Subsequently, CeF ₃ and ZrO 2 were added to sample crucible Nos. 2 and 3 in the same manner as above, and after preheating and melting, the shutter was opened and burned by 0.25λ ° and 0.53λ ° respectively to coat the laminated film. At this time, the peak temperature on the surface of the lens 19 to be coated on the lens dome 17 to be coated so that the laminated film is a low temperature 74 ℃ or less. If the temperature exceeds the above range, care should be taken because film cracking occurs. The fourth crucible was further coated with a layer of SiO 2, which is a fourth layer material, at a thickness of 0.25λ, thereby completing a multilayer anti-reflection film having a four-layer structure.

The film composition conditions of the optical component thus implemented are shown in table 1 as shown.

On the other hand, Figure 2 is a characteristic diagram showing the relationship between the wavelength and reflectance according to an embodiment of the present invention is a graph of the reflectance characteristics using the experimental data.

As shown in the figure, when the film thickness and refractive index were as described above, the actual reflectance in the 420-680 nm wavelength region was measured to be 0.5% or less, and the spectral transmittance in the wavelength region was also measured, 420 nm and 680 nm. The highest transmittances of 95.5% and 98% were measured, respectively (in this case, the measurement glass is made of BK-7).

Claims (3)

The first layer film having an optical film thickness of 0.25 ± 0.01λ °, the second layer film formed of 0.25 ± 0.01λ °, the third layer film formed of 0.53 ± 0.01λ ° and 0.25 ± 0.01λ ° on the synthetic resin lens surface, which is an optical component. The fourth layer film formed of the first layer film is SiO ₂ , the material of the second layer film is CeF ₃ and the material of the third layer film is ZrO ₂ . And the material of the fourth layer film is SiO ₂ , wherein a single layer anti-reflection film of an optical component (wherein λ ° is a visible light wavelength). The multilayer anti-reflection film of an optical component according to claim 1, wherein the multilayer anti-reflection film is multi-coated at a peak temperature of 74 ° C. or less on the lens surface on which the laminated film is to be formed. The multilayer anti-reflection film of an optical component according to claim 1, wherein the synthetic resin lens is made of one selected from polystyrene and PMMA optical materials.