Optical filter, optical filter module, spectrometric measurement apparatus, and optical apparatus

Abstract

An optical filter includes: a first variable wavelength bandpass filter that can extract light of a first wavelength band (400 to 460 nm), the first wavelength band having a first spectral band having a central wavelength equal to a first wavelength in the first wavelength band and a second spectral band having a central wavelength equal to a second wavelength in the first wavelength band; and a second variable wavelength bandpass filter that can extract light of a second wavelength band (480 to 540 nm) adjacent to the first wavelength band, the second wavelength band having a third spectral band having a central wavelength equal to a third wavelength in the second wavelength band and a fourth spectral band having a central wavelength equal to a fourth wavelength in the second wavelength band.

Description

[0001]This application claims priority to Japanese Patent Application No. 2010-154158 filed Jul. 6, 2010 which is hereby expressly incorporated by reference herein in its entirety.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to an optical filter, an optical filter module, a spectrometric measurement apparatus, an optical apparatus, and other apparatuses.[0004]2. Related Art[0005]An interference filter has been used in a spectrometric measurement apparatus and other optical apparatuses. A known aspect of the interference filter selects a wavelength of light that passes therethrough (Fabry-Perot etalon interference filter) (see JP-A-11-142752, for example). A transmissive variable wavelength interference filter described in JP-A-11-142752 (hereinafter sometimes referred to as a variable gap etalon filter or simply referred to as a variable gap etalon), which can select the wavelength of light passing therethrough, includes a pair of substrates held in parallel...

AI Technical Summary

Benefits of technology

[0008]An advantage of some aspects of the invention is, for example, an ability to reduce the moving range of a variable wavelength filter. Another advantage of some aspects of the invention is, for example, an ability to suppress the degree of complication of the structure of an optical film.

Problems solved by technology

The moving of the movable portion disadvantageously increases the moving range of the movable portion of the variable wavelength filter and hence increases the voltage for driving the movable portion.

Another problem with a wide wavelength range of the transmitted light is that the structure of the optical films for providing a necessary band of the variable wavelength filter is complicated.

In other words, the optical films need to be designed so that the entire desired wavelength band can be covered, resulting in a complicated structure of the optical films.

When the structure of the optical films is complicated, it increases a burden related to manufacturing processes and decreases the intensity of the transmitted light.

Other inconveniences also tend to occur.

In this case, the fact described above may cause the first wavelength band on the shorter wavelength side to be narrower than the second wavelength band so that it is difficult to allocate four spectral bands to the first wavelength band (that is, may make it difficult to provide four measurement points).

In this case, the burden of manufacturing the optical films increases.

Further, the noise, which results from a wide full width at half maximum transmittance of each filter and other factors, is a received light component corresponding to an unwanted band and superimposed on a received light signal provided from each filter.

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