JPH07244215A - Interference filter for infrared ray - Google Patents

Abstract

PURPOSE:To obtain a filter excellent in durability, free from the shift of band or the change of bandwidth by forming each of layers from two kinds of materials of Si and SiO2 in an interference filter for infrared ray composed of plural layers. CONSTITUTION:In the interference filter for infrared ray composed of plural layers, each of layers is formed from two kinds of materials of Si and SiO2. In this case, the durability is improved by forming each of layers from Si and its oxide which are excellent in mutual adhesibility. At the time of forming the layers by vacuum deposition method, the refractive index of the film can be changed by introducing gaseous O2 into a chamber and then the bandwidth of the interference filter is easily changed. By forming a spacer layer of Si having a high density, the shift of the band due to the environmental change such as pressure is suppressed to be small.

Description

Detailed Description of the Invention

[0001]

The present invention relates to materials such as Si and SiO _2.
The present invention relates to an infrared interference filter using.

[0002]

2. Description of the Related Art An infrared interference filter is attached to a light receiving part of an infrared detecting device such as a pyroelectric infrared sensor using a pyroelectric effect or a semiconductor HgCdTe type infrared sensor, and among the light incident on the light receiving part. It is used for the purpose of relatively increasing the signal intensity by blocking visible light and transmitting only infrared light.

Conventionally, as materials for infrared interference filters, PbTe, ZnS, CaF ₂ , MgF ₂ , CeF ₃ , ThF ₄ , Na ₃ AlF ₆ ,
Ge, single crystal Si, etc. have been used. In order to manufacture an infrared interference filter, a material having a different refractive index or absorption coefficient is appropriately combined and selected from these materials, and formed by a vacuum deposition method or the like so that the film thickness of each layer becomes appropriate. It has been done by. The infrared interference filter manufactured in this manner can cause an interference effect that increases the transmittance only in the infrared region, and thus functions as an infrared interference filter.

[0004]

By the way, in the conventional infrared interference filter, since the adhesion of each layer of the multilayer structure is poor, the film is deformed or peeled off when the use environment changes greatly, and the band shifts. And there was a problem that durability is poor. Further, when the materials used for the respective layers have greatly different refractive indexes, it is difficult to adjust the bandwidth.

The present invention aims to solve these problems.

[0006]

As a result of earnest research for solving the above problems, the present inventors have found that Si and its oxide are
By using SiO ₂ as a material for each layer of the multilayer film, the adhesion is improved, the band shift due to the change of use environment is small, the durability is excellent, and the infrared interference filter with easy bandwidth adjustment is provided. The inventors have found that they can be obtained and have completed the present invention.

Therefore, the first aspect of the present invention is that "in an infrared interference filter comprising a plurality of layers, each layer is made of Si and SiO.
₂ provides an infrared interference filter characterized by comprising two kinds of substances, and secondly, "in the infrared interference filter according to claim 1, the spacer layer is formed of Si. A third feature of the present invention is to provide "a characteristic infrared interference filter", and thirdly, "introduce O ₂ gas into the chamber to perform vacuum deposition while maintaining a constant degree of vacuum, whereby the vacuum deposition is performed. And a method for producing an infrared interference filter, which comprises forming each layer of the infrared interference filter.

[0008]

[Function] Since Si and SiO ₂ which is an oxide thereof are materials having good adhesiveness, durability can be improved by forming each layer by using them. Then, when these layers are formed by vacuum vapor deposition, the refractive index of the film can be changed by introducing O ₂ gas into the chamber,
Thereby, the bandwidth of the interference filter can be easily changed. Further, by forming the spacer layer with high-density Si, it is possible to suppress the band shift due to environmental changes such as pressure.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0010]

[Embodiment 1] FIG. 1 is a schematic diagram of an infrared interference filter manufactured in this embodiment, using Si and SiO ₂ which is an oxide thereof as a material for each layer. During vapor deposition, while introducing O ₂ gas into the chamber, Si and its oxide SiO 2
_An infrared interference filter was manufactured by forming ₂ in multiple layers. The measurement result of the spectral transmittance characteristic is shown in FIG. 2 (solid line).

[0011]

Example 2 An infrared interference filter having the same structure as that of Example 1 was prepared, except that the amount of O ₂ gas was changed from that of Example 1. The measurement result of the spectral transmittance characteristic is shown in FIG. 2 (dotted line). O ₂
It can be seen that by changing the amount of gas, only the bandwidth is changed without shifting the band.

[0012]

As described above, according to the present invention, it is possible to improve the adhesion of each layer of the multilayer structure and easily adjust the bandwidth. Further, by using Si having a high packing density for the spacer layer, it is possible to suppress the band shift due to environmental changes such as pressure.

[Brief description of drawings]

FIG. 1 shows Si according to the present invention and SiO ₂ which is an oxide thereof.
FIG. 3 is a conceptual diagram showing a vertical cross-sectional structure of an infrared interference filter using as a material for a film.

FIG. 2 is a measurement result of a spectral transmittance characteristic of an infrared interference filter of Example 1 (solid line) and a measurement result of a spectral transmittance characteristic of an infrared interference filter of Example 2 (dotted line). that's all

Claims (3)

[Claims] 1. An infrared interference filter comprising a plurality of layers, wherein each layer is composed of two kinds of substances, Si and SiO ₂ . 2. The infrared interference filter according to claim 1, wherein a spacer layer is formed of Si. 3. Forming each layer of the infrared interference filter according to claim 1 or 2, by introducing O ₂ gas into the chamber and performing vacuum deposition while keeping the degree of vacuum constant. A method for manufacturing a featured infrared interference filter.