An optical device stack includes at least one of a photodetector or an optical emitter and a metasurface. The metasurface is disposed over a light-receiving surface of the photodetector or a light emission surface of the optical emitter. The metasurface includes a first conductive layer having an electrically-tunable optical property and an array of conductive nanostructures disposed on a first side of the first conductive layer. A second conductive layer is disposed on a second side of the first conductive layer. An electrical insulator is disposed between the first conductive layer and the second conductive layer. A change in an electrical bias between the metasurface and the second conductive layer, from a first electrical bias to a second electrical bias, tunes the electrically-tunable optical property from a first state to a second state, and changes an electrically-tunable optical filtering property of the metasurface.

An integrated optical spectrometer includes an optical bus configured to accept a light to be measured. Each ring resonator of an array of integrated ring resonators and detectors is optically coupled to the optical bus and to at least one detector. A matrix multiplication process is operatively coupled to each detector. The matrix multiplication process determines based on data from the array of integrated ring resonators and detectors and a calibration matrix of the array of integrated ring resonators and detectors, a spectral content of the light to be measured. A method of calibrating and operating an integrated optical spectrometer, a method to generate a calibration matrix for a ring array of a photonic integrated circuit (PIC) spectrometer, and a method for spectrum reconstruction for a photonic integrated circuit (PIC) spectrometer are also described.

Provided are a bandpass filter having a high light transmittance in a transmission band and a wide wavelength range showing a high transmittance in the transmission band, and a sensor. The bandpass filter is a bandpass filter including a reflective member A and a reflective member B, in which a difference between a reflection center wavelength of the reflective member A and a reflection center wavelength of the reflective member B is larger than a sum of a half width at half maximum of a reflection band of the reflective member A and a half width at half maximum of a reflection band of the reflective member B; the reflective member A has a first cholesteric liquid crystal layer and a second cholesteric liquid crystal layer, and birefringence Δn1 of the first cholesteric liquid crystal layer is larger than birefringence Δn2 of the second cholesteric liquid crystal layer; and the reflective member B has a third cholesteric liquid crystal layer and a fourth cholesteric liquid crystal layer, and birefringence Δn3 of the third cholesteric liquid crystal layer is larger than birefringence Δn4 of the fourth cholesteric liquid crystal layer.

Methods use a tunable notch filter for constructing a spectral map of electromagnetic radiation in a selected spectral band that is incident on a notch filter for a plurality of time periods. Electromagnetic radiation is passed by an electronically tuned notch filter to a detector array for the plurality of selected time periods, and the detector response is determined. For at least a first selected time period the notch filter is tuned to selectively attenuate the passing of one or more selected sub-bands of electromagnetic radiation in the selected spectral band. Information about the selectively attenuated radiation is determined and used along with information about the radiation passed to the detector array for each time period to construct a spectral map. Electronically tunable notch filters may be made with metamaterials such as patterned graphene.

An image processing method includes: an image pickup step of picking up an RGB image of a target object to be picked up, and picking up a spectroscopic image of the target object in a predetermined wavelength range and thus acquiring spectroscopic information peculiar to the target object in the wavelength range; and a display step of displaying a complemented image complemented by superimposing the spectroscopic information on the RGB image.

Methods use a tunable notch filter for constructing a spectral map of electromagnetic radiation in a selected spectral band that is incident on a notch filter for a plurality of time periods. Electromagnetic radiation is passed by an electronically tuned notch filter to a detector array for the plurality of selected time periods, and the detector response is determined. For at least a first selected time period the notch filter is tuned to selectively attenuate the passing of one or more selected sub-bands of electromagnetic radiation in the selected spectral band. Information about the selectively attenuated radiation is determined and used along with information about the radiation passed to the detector array for each time period to construct a spectral map. Electronically tunable notch filters may be made with metamaterials such as patterned graphene.

A spectral camera control device, being installed, along with a spectral camera provided with a liquid crystal tunable filter, in an aircraft capable of stationary flight. The spectral camera control device causes the spectral camera to capture a spectral image in a snapshot mode each time a transmission wavelength of the liquid crystal tunable filter is switched while the aircraft is in stationary flight, and the spectral camera control device causes a plurality of spectral images to be captured in succession at a same transmission wavelength when an SN ratio of the captured spectral image is less than a predetermined threshold.

A tunable optical filter, includes a light source configured to emit optical radiation to a sample; an input optical element configured to receive optical radiation reflected from the sample; a liquid crystal cell comprising electrodes, the liquid crystal cell contacting the input optical element; an output optical element, contacting the liquid crystal cell; and a control unit adapted to apply a preset voltage to the liquid crystal cell via the electrodes; wherein the input optical element and the output optical element have a same first refractive index, wherein, when voltage is not applied to the liquid crystal cell, the first refractive index is greater than a second refractive index of the liquid crystal cell for a wavelength range of incident optical radiation, and wherein the input optical element, the liquid crystal cell and the output optical element are tilted at an angle to the incident optical radiation.

A medical system comprising a hand-held imaging device comprising optical components including a light source to illuminate an area of medical interest, a liquid crystal variable retarder to receive light from the area of medical interest, and a retardance controller to provide a driving waveform to the variable retarder that controls retardance. The device also includes an image sensor configured to receive light from the variable retarder and to convert the received light into an output voltage signal for either the camera operation or the hyperspectral imaging operation, and communication circuitry configured to communicate imaging information based on the output voltage signal to a medical diagnostic system. The hand-held imaging device is configured to switchably perform a hyperspectral imaging and a camera operation such that the operations share at least one optical component. The diagnostic device is configured to receive the imaging information and to provide diagnostic information based thereon.

A spectral image capturing method using a spectral camera control device installed in aircraft, the method comprising:

a) setting an exposure time of the spectral camera so that a current exposure time is determined (S2),
b) determining whether or not either an amount of attitude change or an amount of position change of the spectral camera per exposure time exceeds a predetermined threshold based on a spatial resolution of the spectral camera (S4),
c1) when exceeding the predetermined threshold, resetting the current exposure time to be shorter (S5),
c2) when not exceeding the predetermined threshold, not resetting the current exposure time to be shorter, and
d) capturing a spectral image in a snapshot mode with the spectral camera using the reset exposure time,
wherein when the transmission wavelength of the liquid crystal tunable filter is switched while the aircraft is in a stationary flight, steps b) to d) are repeated.