Optical filter and analytical instrument

Abstract

An optical filter includes: a lower substrate; a lower mirror provided to the lower substrate; a lower electrode provided to the lower substrate; an upper substrate disposed so as to be opposed to the lower electrode; an upper mirror provided to the upper substrate, and opposed to the lower mirror; and an upper electrode provided to the upper substrate, and opposed to the lower electrode, wherein the upper substrate has a groove surrounding the upper mirror in a plan view, the groove includes a first side surface section, a second side surface section, a bottom surface section, a first end section located between the first side surface section and the bottom surface section, and a second end section located between the second side surface section and the bottom surface section, in a cross-sectional view, and the first end section and the second end section each have a curved surface.

Description

BACKGROUND[0001]1. Technical Field[0002]The present invention relates to an optical filter and an analytical instrument.[0003]2. Related Art[0004]In the past, as an optical filter for selecting a light beam having a target wavelength from the incident light beams and then emitting the light beam, there has been known an optical filter of an air-gap type and of an electrostatic-drive type, in which a pair of substrates are disposed so as to be opposed to each other, each of the surfaces of the substrates opposed to each other is provided with a mirror, electrodes are respectively disposed in the peripheries of the mirrors, a diaphragm section is disposed in the periphery of one of the mirrors, and the diaphragm section is displaced due to electrostatic force generated between the electrodes to thereby vary the gap (air gap) between the mirrors, thus taking out the light beam having a desired wavelength (e.g., JP-A-2003-57438).[0005]In such an optical filter, it is required to control...

AI Technical Summary

Benefits of technology

[0007]An advantages of some aspects of the invention is to provide an optical filter and an optical module equipped with the optical filter each capable of preventing the degradation of strength of the diaphragm section even in the case of thinning the diaphragm section on the ground of holding down the applied voltage, and as a result, enhancing the strength of the diaphragm section while reducing the maximum applied voltage, varying the gap stably, and being driven preferably.

[0009]The optical filter according to this aspect of the invention has a curved surface in each of the end sections of the groove. Thus, the stress concentration to the end sections of the groove caused when varying the gap can be eased to thereby enhance the strength of the diaphragm section. As a result, a stable gap variation becomes possible, and it becomes possible to preferably drive the gap.

[0011]Thus, it becomes possible to prevent a crack or the like in the upper electrode due to the distortion of the groove from occurring.

[0013]Thus, it is possible to prevent the propagation of the light beam entering the upper mirror from being blocked by the side surface sections of the diaphragm, thereby making preferable sensing possible.

[0015]By arranging that the first and second substrates each have a light transmissive property as described above, the transmittance of the light beam in the substrate is improved, and the strength of the light beam taken out is also raised. Therefore, the efficiency of taking out the light beam is improved.

[0017]By using the wet-etching process in the manufacturing process, it becomes easy to provide a curved surface shape to the end section, thereby making it possible to ease the stress concentration to the end sections, and thus the strength of the diaphragm section can be improved. Further, by combining the dry-etching process and the wet-etching process with each other, it becomes possible to reduce the time necessary for forming the groove, and at the same time to provide a structure in which the end sections of the groove each have a curved surface, thus the stress concentration to the end sections can be eased to thereby improve the strength of the diaphragm section. As a result, a stable gap variation becomes possible, and preferable drive becomes possible.

Problems solved by technology

However, thinning the diaphragm section causes degradation of strength, and in the optical filter repeatedly varying the gap stress is applied to the diaphragm section every time the gap is varied, and therefore, there arises a problem that the degradation of strength directly causes breakage of the diaphragm section.

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