JPH06118216A - Crystal optical filter - Google Patents

Abstract

PURPOSE:To improve moisture resistance, maintain good performance, and improve optical transmission factor by coating both optical principal planes of a color correcting glass with reflection preventing films made of aluminum oxide, pinching the films with multiple crystal plates, and integrally fitting them. CONSTITUTION:Both optical principal planes of a color correcting glass 1 are coated with thin films of aluminum oxide to form reflection preventing films 2. Adhesives 3 are applied on the reflection preventing films 2, the films 2 are pinched with crystal plates 4 from both sides, and they are integrally fitted. A polybutadiene or epoxy adhesive having strong adhesive strength is preferably used for the adhesives 3 for sticking the crystal plates 4. The aluminum oxide can obtain extremely good moisture resistance as compared with magnesium fluoride. The refraction factor of the aluminum oxide is 1.61 near the refraction factor 1.54 of crystal, the optical transmission factor can be improved, and the moisture resistance and optical performance can be remarkably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal optical filter used in electronic optical equipment such as a video camera.

[0002]

2. Description of the Related Art Conventionally, in an electro-optical device such as a video camera or an electronic still camera, for example, a quartz optical filter is used in an optical system in order to prevent reflection of an incident light ray and perform color correction. There is. As such a crystal optical filter, for example, one in which a magnesium fluoride (MgF2) film is formed on both main surfaces of a color correction filter is known. By the way, magnesium fluoride has a good adhesion to a glass substrate, but has a low adhesion strength to an adhesive. Therefore, the performance of the moisture resistance test of such a crystal optical filter is only 500 hours at the most, and there is a problem that the performance required for this type of optical filter cannot be satisfied.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to dramatically improve the moisture resistance, maintain a good performance for a long period of time, and obtain an optical property. It is an object of the present invention to provide a crystal optical filter capable of improving various transmittances.

[0004]

The present invention is characterized in that both optical main surfaces of color correction glass are coated with an antireflection film made of aluminum oxide, sandwiched between a plurality of quartz plates, and integrally bonded. Is.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the perspective view shown in FIG. In the figure, reference numeral 1 denotes a color correction glass, and an antireflection film 2 is formed by coating a thin film of aluminum oxide (Al2O3) on both optical main surfaces of the color correction glass. Then, the adhesive 3 is applied to the antireflection film 2.
Is applied and sandwiched between the crystal plates 4 from both sides to be integrally bonded. The adhesive 3 used to bond the crystal plate 4 is preferably a polybutadiene-based or epoxy-based adhesive that can obtain a strong adhesive strength.

With such a constitution, aluminum oxide can obtain remarkably excellent moisture resistance as compared with conventionally used magnesium fluoride. Therefore, the performance of 1000 hours or more can be exhibited even in the humidity resistance test. Furthermore, the refractive index of magnesium fluoride is 1.38, while the refractive index of aluminum oxide is 1.6.
Since it is 1, which is close to the refractive index of the crystal, 1.54, the optical transmittance can be improved. Therefore, the moisture resistance can be dramatically improved and the optical performance can also be improved.

[0008]

As described above in detail, according to the present invention, it is possible to provide a quartz optical filter which can remarkably improve the moisture resistance and has good optical performance.

[0009]

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Color correction filter 2 Antireflection film 3 Adhesive 4 Crystal plate

Claims (1)

[Claims] 1. A crystal optical filter characterized in that an antireflection film made of aluminum oxide is coated on both optical main surfaces of a color correction glass, sandwiched between a plurality of crystal plates, and integrally bonded.