# US 11,307,478 B2 · Wavelength tunable optical filter, optical module, and electronic apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,307,478 B2 - Document ID: US11307478B2 - Status: Granted - Kind: B2 - Application number: 16/117,380 - Filed: 2018-08-30 - Published: 2019-02-28 - Granted: 2022-04-19 - Earliest claimed: 2017-08-31 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Susumu Shinto; Akira Sano; Teruyuki Nishimura - Web page: https://patentgrep.com/patent/US11307478B2 ## CPC - G02F 1/21: by interference - G01J 3/26: using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters - G01J 3/32: Investigating bands of a spectrum in sequence by a single detector - G01J 3/42: Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08) - G01J 3/50: using electric radiation detectors - G02B 26/001: {based on interference in an adjustable optical cavity (interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26)} - G02B 26/007: {the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light} - G02F 1/213: {Fabry-Perot type} - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An optical filter includes a substrate, a first reflective film provided on the substrate, a second reflective film disposed to face the first reflective film, and a supporting portion provided on the substrate and supporting the second reflective film. The first reflective film is protected with a first protective film so as not to be exposed and the second reflective film is protected with a second protective film so as not to be exposed. ## Claims ### Claim 1 A wavelength tunable optical filter comprising: a substrate; a first encased reflective film provided on the substrate, the first encased reflective film including a first reflective film and a first protective film entirely encasing the first reflective film; a second encased reflective film, the second encased reflective film including a second reflective film and a second protective film entirely encasing the second reflective film, the second reflective film facing the first reflective film, and a supporting portion provided over the substrate, the supporting portion supporting the second encased reflective film at a predetermined distance from the first encased reflective film, the supporting portion having an inner circumferential wall defining a cylindrical interior space between the first encased reflective film and the second encased reflective film; wherein the second encased reflective film has a plurality of through-holes collectively forming a circular array by being disposed along a circumference of a circle in a plan view of the second encased reflective film, a center of the circular array and a center of the cylindrical interior space are concentric in the plan view, and wherein for every through-hole of the circular array of the second encased reflective film, a distance from the corresponding through-hole to the inner circumferential wall of the supporting portion along a corresponding line segment passing through both (i) the center of the circular array and (ii) the corresponding through-hole is equal to or greater than a diameter of the circular array. ### Claim 2 (depends on 1) The wavelength tunable optical filter according to claim 1, wherein each of the first reflective film and the second reflective film is a metal film. ### Claim 3 (depends on 2) The wavelength tunable optical filter according to claim 2, wherein each of the first reflective film and the second reflective film is an Ag film or an Ag alloy film. ### Claim 4 (depends on 3) An optical module comprising: the wavelength tunable optical filter according to claim 3; and a casing having an internal space and accommodating the wavelength tunable optical filter in the internal space. ### Claim 5 (depends on 4) An electronic apparatus comprising: the optical module according to claim 4; and a control unit that controls the optical module. ### Claim 6 (depends on 2) An optical module comprising: the wavelength tunable optical filter according to claim 2; and a casing having an internal space and accommodating the wavelength tunable optical filter in the internal space. ### Claim 7 (depends on 6) An electronic apparatus comprising: the optical module according to claim 6; and a control unit that controls the optical module. ### Claim 8 (depends on 1) The wavelength tunable optical filter according to claim 1, wherein each of the first protective film and the second protective film is a conductive film. ### Claim 9 (depends on 8) The wavelength tunable optical filter according to claim 8, wherein the first protective film and the second protective film transmit light. ### Claim 10 (depends on 8) An optical module comprising: the wavelength tunable optical filter according to claim 8; and a casing having an internal space and accommodating the wavelength tunable optical filter in the internal space. ### Claim 11 (depends on 10) An electronic apparatus comprising: the optical module according to claim 10; and a control unit that controls the optical module. ### Claim 12 (depends on 1) The wavelength tunable optical filter according to claim 1, further comprising: a shape maintaining film overlapping the second reflective film. ### Claim 13 (depends on 1) The wavelength tunable optical filter according to claim 1, wherein a surface of each through-hole is protected with the second protective film so as not to be exposed. ### Claim 14 (depends on 1) The wavelength tunable optical filter according to claim 1, wherein a thickness of each of the first reflective film and the second reflective film is 10 nm or more and 80 nm or less. ### Claim 15 (depends on 1) The wavelength tunable optical filter according to claim 1, wherein a material of the supporting portion is silicon oxide or a resin material. ### Claim 16 (depends on 1) The wavelength tunable optical filter according to claim 1, further comprising: an actuator having a first electrode provided on the substrate and a second electrode supported by the supporting portion, wherein the first reflective film also functions as the first electrode and the second reflective film also functions as the second electrode. ### Claim 17 (depends on 1) The wavelength tunable optical filter according to claim 1, further comprising: an actuator having a first electrode provided on the substrate and a second electrode supported by the supporting portion, wherein, when a distance between the first reflective film and the second reflective film is defined as an inter-reflective film distance and a distance between the first electrode and the second electrode is defined as an inter-electrode distance, the inter-electrode distance is longer than the inter-reflective film distance. ### Claim 18 (depends on 17) The wavelength tunable optical filter according to claim 17, wherein the second reflective film is connected to the second electrode, the first reflective film is separated from the first electrode, a voltage between the first electrode and the second electrode is controlled, and an electric capacitance between the first reflective film and the second reflective film is measured. ### Claim 19 (depends on 1) An optical module comprising: the wavelength tunable optical filter according to claim 1; and a casing having an internal space and accommodating the wavelength tunable optical filter in the internal space. ### Claim 20 (depends on 19) An electronic apparatus comprising: the optical module according to claim 19; and a control unit that controls the optical module.