JP2717702B2 - Optical element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a beam splitter having various prism shapes used for an optical memory head, a color copying machine, and a TV projection device.

(Prior art)

In recent years, the need for large-capacity data storage devices has increased, and optical disk devices, magneto-optical disk devices, and the like have been widely used. In these devices, data is read using an optical head. A beam splitter is used in the optical head. For example, a high refractive index dielectric substance and a low refractive index dielectric substance are vacuum-deposited on one surface of a prism processed into a predetermined shape. To form the laminated optical films alternately laminated. Thereafter, this prism and another prism are joined with an adhesive to form a beam splitter.

As a bonding agent used for bonding the two prisms, there are two types, a thermosetting type and an ultraviolet setting type. Comparing these two types of adhesives in terms of workability and production efficiency,
First, the thermosetting adhesive is as follows: 1) The thermosetting adhesive interposed between the two prisms is pressurized and heated to lower the viscosity of the adhesive and flow between the prism and the bonding jig. The prism and the bonding jig are adhered to each other, so that not only is the removal difficult, but the prism may be damaged. 2) The jig is heated while the two prisms are aligned with each other. Stress and thermal expansion occur, which tends to cause misalignment between prisms. 3) Reproduction is difficult if bubbles or the like are generated during bonding. 4) Although it differs slightly depending on the type of adhesive, it is generally an ultraviolet curing type. It has the disadvantage of requiring a longer curing time than that of.

On the other hand, the ultraviolet curable adhesive has the following advantages.

1) Since the polarizing beam splitter is taken out of the bonding jig in a temporarily fixed state (irradiation of ultraviolet light for several seconds to several tens of seconds), the polarizing beam splitter is easily detached and the prism is hardly damaged.

2) Since there is no need to heat the bonding jig, misalignment between the prisms hardly occurs.

Inspection at the time of positional deviation and generation of bubbles is possible in the temporarily fixed state, and even if positional deviation and generation of bubbles occur, reproduction can be easily performed.

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

As described above, from the viewpoint of mass production, the ultraviolet curable adhesive is overwhelmingly advantageous. However, when the bonding is performed using ultraviolet rays, there is a disadvantage that the characteristics of the laminated film are greatly changed. In particular, this is remarkable when titanium oxide is used as the high refractive index substance.

FIG. 7 shows the characteristics of a polarizing beam splitter using BK7 as a prism material, silicon dioxide as a low-refractive-index substance, and titanium oxide as a high-refractive-index substance as an example of a 45 ° incident polarizing beam splitter.

Curve (a) shows the characteristics after temporary fixing, and curve (b) shows the characteristics after full curing.

It is apparent from the figure that the transmittance of both waves is deteriorated after the main curing (after the completion of the joining).

[Object of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated optical film whose characteristics are not impaired by a bonding method using an ultraviolet-curable adhesive which is excellent in workability and efficiency in mass production.

[Configuration of the invention]

The object of the present invention is to stack and support a high refractive index layer and a low refractive index layer on the carrier optical member surface, sandwich the formed laminated film, and bond the optical member surface with an ultraviolet curable adhesive. In the bonded optical element, at least the high refractive index layer closest to the surface of the bonded optical member contains praseodymium oxide and titanium oxide and is hybridized.

As an embodiment of the present invention, it is preferable to use silicon oxide, typically SiO ₂ , or magnesium fluoride, typically MgF ₂ for forming the low refractive index layer combined with the hybrid high refractive index layer. .

The number of layers can be arbitrarily determined as necessary. In the present invention, it is sufficient if the high refractive index layer closest to the surface of the joined optical member is the hybrid high refractive index layer, but all the high refractive index layers are hybrid. It is preferably a high refractive index layer. The ratio of praseodymium / titanium in the hybrid layer is 0.5-5,
Preferably it is 2-3.

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

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

For forming the laminated optical film, various vapor deposition methods, for example, a physical vapor deposition method such as vacuum vapor deposition, sputtering, or ion beam vapor deposition, or a CVD method while controlling a reaction gas, are arbitrarily used.

〔Example〕

 Next, the present invention will be specifically described with reference to examples.

Example 1 A mixture containing praseodymium oxide and titanium oxide as main components (for example, trade name "Substance 2" manufactured by E. Merck;
Hereinafter, 23 layers were alternately laminated on a carrier glass prism (material: BK7) by using vacuum evaporation, using the mixture as a high refractive index substance and SiO ₂ as a low refractive index substance. During deposition, the substrate heating temperature is 35
It was 0 ° C. The vacuum at the start of deposition is 1 × 10 ^-5 Torr, the mixture is deposited at a deposition rate of 4 ° / sec, and SiO ₂ is deposited at a rate of 10 ° / sec.
Oxygen gas was introduced into the vacuum chamber so as to maintain a vacuum of 2 × 10 ⁻⁴ Torr during the vapor deposition.

After the vapor deposition, the prism was taken out into the atmosphere, and bonded to a bonded glass prism (material: BK7) using an ultraviolet-curable adhesive (No. 61 manufactured by Norland). Ultraviolet rays having an intensity of 10 mw / cm ² were irradiated for 5 seconds for temporary fixing and 10 minutes for main curing to prepare an optical element shown in FIG.

The spectral transmittance is shown when light is vertically incident on the prism after the temporary fixing and after the main curing (the incident angle on the laminated film is 45 °) (FIG. 3). No difference was observed between after temporary fixing and after full curing.

 The layer configuration of the laminated film is as shown in Table 1.

Example 2 The same substance as in Example 1 was applied to the carrier prism shown in FIG. 2 (material: B
K7), and bonded with a bonding prism using an ultraviolet-curing adhesive to produce a long-pass filter with a transmittance of 50% and a cut wavelength of about 650 nm. The deposition conditions and bonding conditions were the same as in Example 1, and the laminated film was composed of 29 layers.

After the temporary fixing and the main curing, light was incident on the laminated film at an incident angle of 30 °, and the spectral transmittance was measured. As a result, no difference occurred. FIG. 4 shows the transmittance curve after the main curing.

 The layer configuration of the laminated film is as shown in Table 2.

Example 3 26 layers of TiO ₂ and SiO ₂ were alternately vapor-deposited on a carrier prism having the same shape as in Example 2, and a single layer of a hybrid layer was further vapor-deposited thereon.

TiO ₂ is 4Å / sec under oxygen gas pressure of 3 × 10 ^-4 Torr
Was deposited at the following speed. The other conditions were the same as those of the above-described embodiment. The prism and the cemented prism were adhered under the same joining conditions as in the above-described embodiment, to produce a long-pass filter.

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

 FIG. 5 shows a measurement curve after the main curing.

 The configuration of the laminated film is as shown in Table 3.

Example 4 A hybrid layer and Mg were formed on a carrier prism having the same shape as in Example 1.
Depositing alternate laminated film of F ₂ layer, by bonding the bonding prisms, the P-wave of about 4: to produce a polarizing beam splitter for splitting one.

MgF ₂ was deposited at a rate of 8 ° / sec at a vacuum degree of 3 × 10 ⁻⁵ Torr or less, and the mixture was deposited under the same conditions as in the above example, and nine alternate layers were laminated. After vapor deposition, bonding was performed in the same manner as in the above example, and after temporary fixing, and after main curing, the transmittance of P-waves and S-waves was measured. FIG. 6 shows the measurement curve. Table 4 shows the configuration of the laminated film.

Note that the film thickness can be made uniform by introducing an inert gas such as Ar into the vapor deposition apparatus during the MgF ₂ vapor deposition. If a fluorine-based gas (for example, CF ₄ ) is introduced, the film thickness can be made uniform and the film quality can be improved.

[Effects of the Invention] As described above, it has been found that the use of the hybrid layer according to the present invention as compared with the conventional one shown in FIG. 7 enables the realization of an optical element whose characteristics are not deteriorated even when an ultraviolet curing adhesive is used.

[Brief description of the drawings]

FIG. 1 shows the forms of the optical elements of Examples 1 and 4, and FIG. 2 shows the forms of the optical elements of Examples and 3. 3 and 6 are graphs showing the transmittance of Tp and Ts, and FIGS. 4 and 5 are the transmission spectra of white light. DESCRIPTION OF SYMBOLS 1 ... Carrier prism 2 ... Laminated optical film 3 ... Ultraviolet curable adhesive layer 4 ... Junction prism L ... Incident light

Claims (2)

(57) [Claims] 1. A high-refractive-index layer and a low-refractive-index layer are laminated and supported on the surface of a carrier optical member, and the formed laminated film is sandwiched therebetween.
In the optical element in which the joining optical member surfaces are joined by an ultraviolet curing adhesive, at least the high refractive index layer closest to the joining optical member surface contains praseodymium oxide and titanium oxide, and is mixed. Optical element. 2. The optical element according to claim 1, wherein said low refractive index layer is formed of silicon oxide or magnesium fluoride.