Light detection system and voltage determination method

A voltage determination method of determining a voltage in a light detection device, the light detection device comprising:

• a Fabry-Perot interference filter including a first mirror and a second mirror, a distance between the first mirror and the second mirror being variable;
• and
• a light detection unit including a light detector which light transmitted through the first mirror and the second mirror enters, the light detection unit configured to detect light in a wavelength range of a wavelength λ1 or more and a wavelength λ2 or less, wherein λ2>λ1
• in a case where the voltage is applied to the Fabry-Perot interference filter such that the distance changes in a distance range of a distance d1 or more and a distance d2 or less, wherein d2>d1, the voltage determination method comprising:
• a first step of determining a voltage V1 at which the distance equals the distance d1;
• and
• a second step of determining a voltage V2 at which the distance equals the distance d2,
• wherein, in the first step, for a transmission spectrum T1 (λ) (λ denotes a wavelength) of light transmitted through the first mirror and the second mirror in a case where the distance is the distance d1, the voltage V1 is determined such that a peak transmittance T1 (λa) at a wavelength λa corresponding to a single order appears within the wavelength range, a transmittance T1 (λ2) at the wavelength λ2 is less than or equal to 1%, the wavelength λ2 is longer than a wavelength at a bottom point of the transmission spectrum T1 (λ) that first appears on a long-wavelength side of the peak transmittance T1 (λa), and the transmittance T1 (λ2) is smaller than a transmittance T1 (λ1) at the wavelength λ1, and
• in the second step, for a transmission spectrum T2 (λ) of light transmitted through the first mirror and the second mirror in a case where the distance is the distance d2, the voltage V2 is determined such that a peak transmittance T2 (λb) at a wavelength λb corresponding to a single order appears within the wavelength range, a transmittance T2 (λ1) at the wavelength λ1 is less than or equal to 1%, the wavelength λ1 is shorter than a wavelength at a bottom point of the transmission spectrum T2 (λ) that first appears on a short-wavelength side of the peak transmittance T2 (λb), and the transmittance T2 (λ1) is smaller than a transmittance T2 (λ2) at the wavelength λ2.

A light detection system comprising:

• a Fabry-Perot interference filter including a first mirror and a second mirror, a distance between the first mirror and the second mirror being variable;
• a light detection unit including a light detector which light transmitted through the first mirror and the second mirror enters, the light detection unit configured to detect light in a wavelength range of a wavelength λ1 or more and a wavelength λ2 or less, wherein λ2>λ1;
• and
• a controller configured to apply a voltage to the Fabry-Perot interference filter such that the distance changes in a distance range of a distance d1 or more and a distance d2 or less, wherein d2>d1,
• wherein, for a transmission spectrum T1 (λ)(λ denotes a wavelength) of light transmitted through the first mirror and the second mirror in a case where the distance is the distance d1, a peak transmittance T1 (λa) at a wavelength λa corresponding to a single order appears within the wavelength range, and a transmittance T1 (λ2) at the wavelength λ2 is less than or equal to 1%,
• for a transmission spectrum T2 (λ) of light transmitted through the first mirror and the second mirror in a case where the distance is the distance d2, a peak transmittance T2 (λb) at a wavelength λb corresponding to a single order appears within the wavelength range, and a transmittance T2 (λ1) at the wavelength λ1 is less than or equal to 1%,
• the light detection unit further includes a band pass filter disposed on a side opposite to the light detector with respect to the Fabry-Perot interference filter or between the Fabry-Perot interference filter and the light detector,
• the band pass filter is configured to transmit light in the wavelength range, and
• a transmission spectrum T3 (λ) of light transmitted through the band pass filter includes at least one of a rising portion rising to the wavelength range and a falling portion falling from the wavelength range.