JP-2026076245-A - Light detection system and voltage determination method

Abstract

[Problem] To provide a photodetection system and a voltage determination method that can accurately detect light of a desired wavelength. [Solution] The light detection system comprises a Fabry-Perot interference filter having a pair of mirrors whose distance from each other is variable, a light detection unit configured to detect light in the wavelength range of λ1 to λ2, and a control unit that applies a voltage to the Fabry-Perot interference filter so that the distance changes in the distance range of d1 to d2. When the distance is d1, the light transmission spectrum T1(λ) has a peak transmittance T1(λa) at λa corresponding to a single order, which appears within the wavelength range, and the transmittance T1(λ2) at λ2 is 1% or less. When the distance is d2, the light transmission spectrum T2(λ) has a peak transmittance T2(λb) at λb corresponding to a single order, which appears within the wavelength range, and the transmittance T2(λ1) at λ1 is 1% or less. [Selection Diagram] Figure 6

Inventors

• 笠原 隆
• 柴山 勝己
• 大山 泰生
• 蔵本 有未

Assignees

• 浜松ホトニクス株式会社

Dates

Publication Date

20260511

Application Date

20260121

Claims (2)

1. A Fabry-Perot interference filter having a first mirror and a second mirror whose distance from each other is variable, A photodetector having a photodetector into which light transmitted through the first mirror and the second mirror is incident, and configured to detect light in the wavelength range of wavelength λ1 or greater and wavelength λ2 (>λ1) or less, The system includes a control unit that applies a voltage to the Fabry-Perot interference filter such that the distance changes within a distance range of d1 or greater and d2 or less (>d1), When the distance is the distance d1, the transmission spectrum T1(λ) (where λ is wavelength) of light passing through the first mirror and the second mirror is such that the peak transmittance T1(λa) at wavelength λa corresponding to a single order appears within the wavelength range, and the transmittance T1(λ2) at wavelength λ2 is 1% or less. A photodetection system in which, when the distance is the distance d2, the transmission spectrum T2(λ) of light transmitted through the first mirror and the second mirror has a peak transmittance T2(λb) at wavelength λb corresponding to a single order appearing within the wavelength range, and the transmittance T2(λ1) at wavelength λ1 is 1% or less.
2. A Fabry-Perot interference filter having a first mirror and a second mirror whose distance from each other is variable, A photodetector comprising a photodetector into which light transmitted through the first mirror and the second mirror is incident, and a photodetector configured to detect light in the wavelength range of wavelength λ1 or greater and wavelength λ2 (>λ1) or less, A voltage determination method for determining the voltage when applying a voltage to the Fabry-Perot interference filter such that the distance changes within a distance range of d1 or greater and d2 or less (>d1), The first step is to determine the voltage V1 such that the distance is the distance d1, The second step is to determine a voltage V2 such that the distance is the distance d2, In the first step, the voltage V1 is determined such that, when the distance is the distance d1, the transmission spectrum T1(λ) (where λ is wavelength) of light transmitted through the first mirror and the second mirror is such that the peak transmittance T1(λa) at wavelength λa corresponding to a single order appears within the wavelength range and the transmittance T1(λ2) at wavelength λ2 is 1% or less. A voltage determination method in which, in the second step, the voltage V2 is determined such that, when the distance is the distance d2, the transmission spectrum T2(λ) of light transmitted through the first mirror and the second mirror is such that the peak transmittance T2(λb) at wavelength λb corresponding to a single order appears within the wavelength range and the transmittance T2(λ1) at wavelength λ1 is 1% or less.

Description

This invention relates to a photodetection system and a voltage determination method. A photodetector is known that comprises a Fabry-Perot interference filter having a first mirror and a second mirror whose distance from each other is variable, a photodetector that detects light transmitted through the first and second mirrors, and a bandpass filter positioned on the opposite side of the Fabry-Perot interference filter from the photodetector (see, for example, Patent Document 1). Japanese Patent Publication No. 2001-228326 This is a block diagram of a photodetection system according to one embodiment.This is a cross-sectional view of the light detection device shown in Figure 1.Figure 2 is a perspective view of the Fabry-Perot interference filter shown.Figure 3 is a cross-sectional view of a Fabry-Perot interference filter along the IV-IV line.This is a flowchart of a voltage determination method according to one embodiment.Figure 1 is a graph showing the transmission characteristics of the light detection device.Figure 2 is a graph showing the relationship between the peak wavelength and the full width at half maximum in the Fabry-Perot interference filter.This graph shows the transmission characteristics of a modified photodetector.This is a diagram illustrating the configuration of a modified optical detection device. Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted. [Configuration of the photodetection system] As shown in Figure 1, the photodetection system 100 comprises a photodetector 1 and a control unit 50. The control unit 50 is electrically connected to the photodetector 1. The control unit 50 performs input and output of electrical signals to the photodetector 1. As an example, the control unit 50 includes an integrated circuit such as an FPGA (field-programmable gate array), a non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), and a PC (Personal Computer). [Configuration of the light detection device] As shown in Figure 2, the photodetector 1 comprises a package 2. Package 2 is a CAN package having a stem 3 and a cap 4. The cap 4 includes a cylindrical side wall 5 and a top wall 6. The side wall 5 and top wall 6 are integrally formed from a metal material. The stem 3 is formed in a plate shape from a metal material. The stem 3 is hermetically bonded to the cylindrical side wall 5, facing the top wall 6. A wiring board 7 is fixed to the inner surface 3a of the stem 3. The substrate material of the wiring board 7 can be, for example, silicon, ceramic, quartz, glass, or plastic. A photodetector 8 and a temperature compensation element such as a thermistor (not shown) are mounted on the wiring board 7. The photodetector 8 is an infrared detector, such as a quantum sensor using InGaAs, a thermopile, or a bolometer. When detecting light in the ultraviolet, visible, and near-infrared wavelength ranges, a silicon photodiode can be used as the photodetector 8. The photodetector 8 may have a single light-receiving section, or multiple light-receiving sections may be arranged in an array. Furthermore, multiple photodetectors 8 may be mounted on the wiring board 7. Multiple spacers 9 are fixed to the wiring board 7. The material of each spacer 9 can be, for example, silicon, ceramic, quartz, glass, or plastic. A Fabry-Perot interference filter 10 is fixed to the multiple spacers 9. The light-transmitting region 10a of the Fabry-Perot interference filter 10 faces the light-receiving portion of the photodetector 8. Note that the spacers 9 may be integrally formed with the wiring board 7. Furthermore, the Fabry-Perot interference filter 10 may be supported by a single spacer 9 instead of multiple spacers 9. Multiple lead pins 11 are fixed to the stem 3. Each lead pin 11 penetrates the stem 3 while maintaining electrical insulation and airtightness between it and the stem 3. Each lead pin 11 is electrically connected via wires 12 to electrode pads provided on the wiring board 7, terminals of the photodetector 8, terminals of the temperature compensation element, and terminals of the Fabry-Perot interference filter 10, respectively. The control unit 50 is electrically connected to each lead pin 11 via wiring (not shown). This allows the control unit 50 to perform input and output of electrical signals to the photodetector 8, temperature compensation element, and Fabry-Perot interference filter 10, respectively. The package 2 has an opening 2a. More specifically, the opening 2a is formed in the top wall 6 of the cap 4 so as to face the light transmission region 10a of the Fabry-Perot interference filter 10. A light-transmitting member 13 is hermetically bonded to the inner surface 6a of the top wall 6 so as to close the opening 2a. The light-transmitting member 13 has a light-incident sur