JPH02234102A - Antireflection film - Google Patents

Abstract

PURPOSE:To obtain the antireflection films which are fewer in the number of film layers and have excellent antireflection characteristics by laminating and forming two layers; a 1st antireflection film layer consisting of a specific mixture and a specific 2nd antireflection layer film layer. CONSTITUTION:A mixture composed of Al2O3 and ZrO2 is deposited by using a vacuum vapor deposition method, etc., on the surface of optical parts 1 consisting of a transparent material to form the 1st antireflection film layer 2 having, for example, 0.25lambda0 (lambda0=780nm) film thickness. MgF2 is then deposited by evaporation on this 1st antireflection film layer 2 at 0.25lambda0 film thickness to laminate and form the 2nd antireflection film layer 3, by which the antireflection films having the two-layered constitution are formed. The antireflection films which are fewer in the number of the layers and are excellent in optical characteristics are obtd. at a low cost in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antireflection coating for optical components used in office automation equipment, cameras, optical communications, optical information processing, and the like.

[Conventional technology]

Conventionally, in order to prevent surface reflection of optical parts such as lenses, an anti-reflection film has been provided on the surface of the optical parts. In particular, in order to reduce the cost of optical parts for use with laser beams, as shown in FIG. An antireflection film having a single-layer film structure is generally used.

[Problem to be solved by the invention]

By the way, in the case of BK7, which is commonly used as an optical glass material, the reflectance of the conventional antireflection film consisting of a single layer of MgF2 is approximately Since 1.3% remains, it does not have sufficient properties for preventing reflection in optical components. In particular, depending on the structure of the optical system and the number of components, it is necessary to reduce harmful reflected light as much as possible, so an antireflection film consisting of a single layer of MgF has poor antireflection properties and is not practical. Therefore, in order to reduce reflected light, a technology has been proposed in which the antireflection film has a multilayer structure. However, if a multilayer film with three or more layers is used, the reflectance curve will ripple due to interference effects. A phenomenon occurs? A problem arises in that the optical characteristics deteriorate, and in addition, from the viewpoint of productivity due to the multilayer film, there is also a problem in that the production cost increases when a multilayer film having a structure of three or more layers is used. The present invention was made in view of the above circumstances, and it is an object of the present invention to provide an antireflection film that has a small number of coatings and has excellent antireflection properties. [Means for Solving the Problems] In order to achieve the above object, in the antireflection film according to the present invention, a first reflection film made of a mixture of AM, O, and ZrO is applied from the surface side of an optical component made of a transparent material. A preventive film layer, M
It is characterized by being formed by laminating two layers of the second antireflection film reservoir made of gF■. [Function] In the present invention, AQ, 03 and Z
Deposit a mixture with rO■, 0.25λ.

(λ.=780 nm), and then, on this first anti-reflection film layer, MgF
2 to 0.25λ. Since a two-layer antireflection film is formed by laminating the second antireflection film layer by vapor deposition to a film thickness of , an antireflection film with excellent optical properties can be obtained at low cost. [Examples] Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of an optical component on which an antireflection film according to the present invention is formed. In the figure, an optical component 1 made of BK7 optical glass is placed in a predetermined jig after precision cleaning. Place the set into a vacuum evaporation tank and add about 2
Heating to 80℃, the degree of vacuum is about IXIO-' Tor
A mixture of AM,03 and ZrO (refractive index 1.67) was heated to 0.25λ using an electron beam under conditions of r. (λ
, =780 nm) to form the first antireflection film layer 2. Next, MgFz (refractive index 1.38) was heated to 0.25λ by a resistance heating method. (λ.=780 stops) to form the second antireflection film layer 3, thereby forming an antireflection film composed of two layers.

The spectral reflectance of the antireflection film thus formed is shown in FIG. As is clear from FIG. 2, the anti-reflection film in this example has a reflectance of 0.1% or less at a center wave length of 780 mm, and has better reflective properties than the conventional anti-reflection film. Obtainable. Next, another embodiment of the present invention will be shown. First, in the same manner as in the first embodiment described above, A'
Q, O, and ZrO. (7) Mixture (refractive index 1.67
) is 0.25λ. (λ = 780 nm) to form the first anti-reflection film layer 2. Next, MgF'
y (refractive index 1.38) to 0.251 by resistance heating method.
．． (λ.=780 nm) to form the second antireflection film layer 3, thereby forming an antireflection film composed of two layers. Figure 3 shows the spectral reflectance of the antireflection film formed in this way. As is clear from FIG. 3, the antireflection film in this example has a center wavelength (780 nm).
m) and the reflectance is 0.1% or less. Furthermore, Fig. 4 shows the spectral reflectance of a conventional MgF single-layer antireflection coating formed on the surface of an optical component made of quartz optical glass (refractive index 1.45) similar to that described above. In this case, the reflectance was approximately 1.8% at the center wavelength (stopping at 780), and it can be seen that the antireflection film according to the present invention is significantly superior to the conventional one.

〔Effect of the invention〕

As explained above, the antireflection film according to the present invention is made of Al
Since it has a structure in which two layers are laminated: the first anti-reflection film layer made of a mixture of l, ○, and zro2, and the second anti-reflection film layer made of MgF, the number of layers is small and productivity is low. Can be manufactured easily and at low cost.

Therefore, according to the present invention, a practically advantageous antireflection film with excellent spectral reflectance characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a configuration example of an optical component on which an anti-reflection film according to the present invention is formed, FIG. 2 is a diagram showing spectral reflectance of an anti-reflection film according to the present invention, and FIG. FIGS. 4 and 6 are diagrams showing the spectral reflectance of the anti-reflection film of the example, respectively, and FIG. 5 is a diagram showing the spectral reflectance of the conventional single-layer anti-reflection film. FIG. 2 is a diagram showing an example of the configuration of an optical component. DESCRIPTION OF SYMBOLS 1... Transparent optical component, 2... 1st antireflection film layer, 3... 1st antireflection film layer. Saiinu Z Zuzawa & (Le Town ■ Miyako Sai ＼

Claims (1)

[Claims] An anti-reflection film coated on the surface of an optical component made of a transparent material, from the surface side of the optical component, Al_2
An antireflection film characterized by being formed by laminating two layers: a first antireflection film layer made of a mixture of O_3 and ZrO_2 and a second antireflection film layer made of MgF_2.