JPH04204906A - Multilayer thin film optical element - Google Patents

Abstract

PURPOSE:To prevent degradation in characteristics even when a UV-ray setting type adhesive is used for joining by using a specified mixture material for one of two layers which are formed on a carrier optical element and are the nearest to the surface of a joining optical member. CONSTITUTION:On a carrier glass prism, one of Ti oxide, Zn sulfide, Zr oxide, Ce oxide is used as a material of high refractive index, and one of Al oxide, Y oxide Mg oxide, Ca fluoride is used as a material of low refractive index to deposit a multilayered film by vacuum vapor deposition. These prisms are joined with a UV-ray setting type adhesive. One of two layers nearest to the surface of the joining optical member is formed of a mixture material containing Pr oxide and Ti oxide by 0.5-5 Pr/Ti/ ratio, and preferably 2-3. Further, metal or compd. of Zr, Ta, Y, La, etc., can be incorporated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a beam splitter having various prism shapes used in optical memory heads, color copying machines, and TV projection devices.

[Prior art]

A beam splitter called a "gichroic filter" is used in TV projection devices and color copying machines to extract desired colored light from a light source. In addition, the reading optical system of optical memory devices, which has been attracting attention in recent years,
Many beam splitters are also used in writing optical systems. These beam splitters are made by laminating a plurality of dielectric thin films on the surface of a prism processed into a predetermined shape as a carrier optical member (hereinafter sometimes referred to as a carrier glass prism, a carrier prism, or simply a prism). It is often manufactured by bonding another prism to the prism surface. There are two types of bonding agents used to bond two prisms: a thermosetting type and an ultraviolet curing type. Comparing these two types of adhesives in terms of workability and production efficiency, the thermosetting adhesive is: 1) The thermosetting adhesive sandwiched between the two prisms is pressurized and heated. As a result, the viscosity of the adhesive becomes low and it flows between the prism and the adhesive jig, causing the prism and the adhesive jig to be glued together, making it difficult to remove and even damaging the prism. ) Since the two prisms are heated while aligned using a jig, thermal stress and thermal expansion occur in the jig, which tends to cause the prisms to become misaligned. 3) If air bubbles occur during adhesion, regeneration may occur. 4) Although it differs somewhat depending on the type of adhesive, it has the disadvantage of - Numerically, it requires a longer curing time than the ultraviolet curing type.

In contrast, UV-curable adhesives have the following advantages.

1) Since the polarizing beam splitter is removed from the adhesive jig while temporarily fixed (UV irradiation for several seconds to several seconds), removal is easy and damage to the prism is less likely.

2) Since there is no need to heat the adhesive jig, misalignment of the prisms is less likely to occur.

It is possible to inspect the occurrence of misalignment or bubbles while temporarily fixed, and even if misalignment or bubbles occur, it can be easily regenerated.

3) Since the adhesive jig is used only for temporary fixing, the rotation efficiency of the jig is high.

As mentioned above, from the perspective of mass production, UV-curable adhesives are overwhelmingly advantageous. However, when bonding is performed using ultraviolet light, there is a drawback that the properties of the laminated film change significantly.

This is particularly noticeable when titanium oxide is used as the vapor deposition material.

[Purpose of the invention]

An object of the present invention is to provide a laminated optical film whose properties are not impaired even by a bonding method using an ultraviolet curable adhesive that is excellent in workability and efficiency in mass production.

[Structure of the invention]

The object of the present invention is to laminate and support a high refractive index layer and a low refractive index layer on the optical member surface of a carrier, sandwich the formed laminated film, and bond the optical member surface with an ultraviolet curable adhesive. In the bonded multilayer thin film optical element, at least one of the two layers closest to the surface of the bonded optical member is a layer of a hybrid material containing praseodymium oxide and titanium oxide. achieved by

The number of laminated layers can be arbitrarily determined according to need, but in the present invention, it is sufficient if one of the two layers closest to the bonded optical member surface is the above hybrid layer, but it is preferable to use as many hybrid layers as possible. is preferred.

Further, the praseodymium/titanium ratio in the hybrid layer is 0.5 to 5, preferably 2 to 3.

Furthermore, metals such as Zr, Ta, Y, La, etc. and/or oxides thereof may be contained within a range that does not impair the properties.

The layer of the laminated optical film facing the surface of the bonded optical member through only the adhesive layer may be a high refractive index layer or a low refractive index layer depending on the number of laminated layers.

Further, various vapor phase deposition methods such as vacuum deposition, sputtering, physical vapor deposition such as ion beam deposition, or CVD method while controlling a reaction gas can be used as desired to form the laminated optical film.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples.

First, before explaining this example, a comparative example will be described next.

I made a blue reflection gichroic filter with 30° incidence. TiO* is used as the vapor deposition material for the high refractive index layer, and ^1!0. is used as the vapor deposition material for the low refractive index layer. was used. Each material was deposited under the deposition conditions shown in Table 1 to form a layer structure as shown in FIG. 2 and Table 2.

Table 1 Table 2 Note) Materials T = Tilt A = AItO + After the vapor deposition, the prism was taken out into the atmosphere and another prism that had not been vapor deposited was attached as shown in Figure 1. An ultraviolet curing adhesive was used to bond the prisms together, and the bonding conditions were as shown in Table 3.

FIG. 3 shows the spectral transmittance after temporary fixation (curve a) and after main curing (curve b). It is clearly seen from FIG. 3 that the transmittance decreases after main curing.

[Example 1] A mixture containing praseodymium oxide and titanium oxide as main components (for example, [!, product name “Substance 2” manufactured by Merck Company, referred to as a mixture of two or less)] was used as a high refractive index substance, A
Thirty-three layers of lxOs as a low refractive index substance were alternately stacked on a carrier glass prism (material: BK7) as a carrier optical member by vacuum deposition. The vacuum level at the start of evaporation is I
The 10-'Torr substrate heating temperature was 350°C. According to the vapor deposition conditions shown in Table 1 above, the prism was taken out into the atmosphere and bonded as shown in Table 3 above using a bonded glass prism (material: BK7) and an ultraviolet curing adhesive. Depending on the conditions, bonding was carried out as shown in FIGS. 4 and 5.

The spectral transmittance i of this prism after temporary fixing and after main curing is shown in FIG. 6, and no difference was observed between the two. (Example 2) The same material as in Example 1 was laminated on a carrier glass prism (material: BK7) as shown in Figs. A reflective gichroic filter was prepared.The vapor deposition conditions and bonding conditions were the same as in Example 1, and the laminated film consisted of 19 layers with the configuration shown in FIG. 7 and Table 5.

Note) Material shelf A = AI! 0*M = After the mixture was temporarily fixed and after it was fully cured, light was incident on the laminated film at an incident angle of 30'' and the spectral transmittance was measured, but as shown in FIG. 9, there was no difference at all.

[Example 3] On a carrier prism having the same shape as in Example 2, 19 layers of Tie and AIJ* were alternately deposited as shown in Figure 1O and Table 6, and further 9 layers of the mixture and A110m were alternately deposited on top of that. Layers were deposited. The vapor deposition conditions for each material are as shown in Table 1 above.

Note) Material column A: Altos T: Ti1t
M: After the mixture was deposited, this prism was taken out and bonded with another bonded prism (made of BK?) as shown in FIG. 1 to create a red reflective dichroic prism. The bonding was carried out according to the conditions shown in Table 1.

The spectral transmittance characteristics of the prism were examined after temporary fixing and after main curing under the same conditions as in Example 2, but no difference was found as shown in FIG.

〔Effect of the invention〕

When creating a dichroic filter by bonding another prism to the laminated surface of a prism made of multiple dielectric thin films with an ultraviolet curing adhesive, and extracting the desired colored light from a light source,
By applying the composite layer of the laminated material of the present invention, it has become possible to eliminate the phenomenon of variation in transmittance optical characteristics due to the adhesion of the dichroic filter.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a dichroic filter. FIG. 2 is a cross-sectional view of the layer structure of a conventional dichroic filter as a comparative example. Figure 3 shows the spectral transmittance curve of a conventional Dichroi Ivy filter as a comparative example. FIG. 4 is a sectional view of the layer structure of the dichroic filter of Example 1. FIG. 5 is a sectional view of the dichroic filter of Example 1. FIG. 6 is a spectral transmittance curve of the dichroic filter of Example 1. FIG. 7 is a sectional view of the layer structure of the dichroic filter of Example 2. FIG. 8 is a sectional view of the dichroic filter of Example 2. FIG. 9 is a spectral transmittance curve of the dichroic filter of Example 2. FIG. 10 is a sectional view of the layer structure of the dichroic filter of Example 3. FIG. 11 is a sectional view of the dichroic filter of Example 3. FIG. 12 is a spectral transmittance curve of the dichroic filter of Example 3.

Claims (2)

[Claims] (1) A multilayer thin film in which a high refractive index layer and a low refractive index layer are laminated and supported on the carrier optical member surface, and the optical member surface is bonded with an ultraviolet curing adhesive by sandwiching the formed laminated film. A multilayer thin film optical element, wherein at least one of the two layers closest to the bonded optical member surface is a layer of a mixed material containing praseodymium oxide and titanium oxide. (2) As the high refractive index layer, the hybrid layer, titanium oxide,
2. The multilayer thin film optical element according to claim 1, wherein one of zinc sulfide, zirconium oxide, and cerium oxide is used, and one of aluminum oxide, yttrium oxide, magnesium oxide, and calcium fluoride is used as the low refractive index layer. .