A spectral imaging device (12) includes an image sensor (28), a tunable light source (14), an optical assembly (17), and a control system (30). The optical assembly (17) includes a first refractive element (24A) and a second refractive element (24B) that are spaced apart from one another by a first separation distance. The refractive elements (24A) (24B) have an element optical thickness and a Fourier space component of the optical frequency dependent transmittance function. Further, the element optical thickness of each refractive element (24A) (24B) and the first separation distance are set such that the Fourier space components of the optical frequency dependent transmittance function of each refractive element (24A) (24B) fall outside a Fourier space measurement passband.

A grating element has an interface configured to cause light beams, include N visible color lights, incident to the interface to diffract at different orders. An imaging lens is configured to focus the N visible color lights diffracted by the grating element. A sensor is configured to receive and detect the focused N visible color lights. The focused N visible color lights include at least a first color light and a second color light. The first color light is diffracted in a first diffraction order and corresponds to a first wavelength resolution for the first color light. The second color light is diffracted in a second diffraction order and corresponds to a second wavelength resolution for the second color light. The first diffraction order is higher than the second diffraction order and the first wavelength resolution is smaller than the second wavelength resolution.

A grating element has an interface configured to cause light beams, include N visible color lights, incident to the interface to diffract at different orders. An imaging lens is configured to focus the N visible color lights diffracted by the grating element. A sensor is configured to receive and detect the focused N visible color lights. The focused N visible color lights include at least a first color light and a second color light. The first color light is diffracted in a first diffraction order and corresponds to a first wavelength resolution for the first color light. The second color light is diffracted in a second diffraction order and corresponds to a second wavelength resolution for the second color light. The first diffraction order is higher than the second diffraction order and the first wavelength resolution is smaller than the second wavelength resolution.

A method of controlling a spectroscopic module that includes a measurement light source, a variable-wavelength optical filter, a photodiode, and a conversion circuit for converting a drive signal voltage into a gap displacement amount. The spectroscopic module has a reference light source for emitting a reference light beam of a known wavelength. The controlling method involves varying a gap for the incident reference light beam, extracting two maximum points among data output from the photodiode, and updating a first conversion formula provided in the conversion circuit through use of drive signal voltages and gap amounts corresponding to the two points.

A spectrometer that includes: a first diffraction grating configured to spectroscopically process provided light; a first detection unit configured to condense light spectroscopically processed by the first diffraction grating and to output an electrical signal corresponding to condensed light; a second diffraction grating configured to spectroscopically process 0.sup.th order light provided by the first diffraction grating; and a second detection unit configured to condense light spectroscopically processed by the second diffraction grating and to output an electrical signal corresponding to condensed light.

An imaging spectrometer and method are provided. In one example, the imaging spectrometer includes foreoptics positioned to receive electromagnetic radiation from a scene, a diffraction grating positioned to receive the electromagnetic radiation from the foreoptics and configured to disperse the electromagnetic radiation into a plurality of spectral bands, each spectral band corresponding to a diffraction grating order of the diffraction grating, and a single-band focal plane array configured to simultaneously receive from the diffraction grating overlapping spectra corresponding to at least two diffraction grating orders.

A spectral imaging device (12) includes an image sensor (28), a tunable light source (14), an optical assembly (17), and a control system (30). The optical assembly (17) includes a first refractive element (24A) and a second refractive element (24B) that are spaced apart from one another by a first separation distance. The refractive elements (24A) (24B) have an element optical thickness and a Fourier space component of the optical frequency dependent transmittance function. Further, the element optical thickness of each refractive element (24A) (24B) and the first separation distance are set such that the Fourier space components of the optical frequency dependent transmittance function of each refractive element (24A) (24B) fall outside a Fourier space measurement passband.

A spectral imaging device (12) for generating an image (13A) of a sample (10) includes (i) an image sensor (30); (ii) a tunable light source (14) that generates an illumination beam (16) that is directed at the sample (10); (iii) an optical assembly (22) that collects light from the sample (10) and forms an image of the sample (10) on the image sensor (30); and (iv) a control system (32) that controls the tunable light source (14) and the image sensor (30). During a time segment, the control system (32) (i) controls the tunable light source (14) so that the illumination beam (16) has a center wavenumber that is modulated through a first target wavenumber with a first modulation rate; and (ii) controls the image sensor (30) to capture at least one first image at a first frame rate. Further, the first modulation rate is equal to or greater than the first frame rate.

A method of controlling a spectroscopic module that includes a measurement light source, a variable-wavelength optical filter, a photodiode, and a conversion circuit for converting a drive signal voltage into a gap displacement amount. The spectroscopic module has a reference light source for emitting a reference light beam of a known wavelength. The controlling method involves varying a gap for the incident reference light beam, extracting two maximum points among data output from the photodiode, and updating a first conversion formula provided in the conversion circuit through use of drive signal voltages and gap amounts corresponding to the two points.

An imaging spectrometer and method are provided. In one example, the imaging spectrometer includes foreoptics positioned to receive electromagnetic radiation from a scene, a diffraction grating positioned to receive the electromagnetic radiation from the foreoptics and configured to disperse the electromagnetic radiation into a plurality of spectral bands, each spectral band corresponding to a diffraction grating order of the diffraction grating, and a single-band focal plane array configured to simultaneously receive from the diffraction grating overlapping spectra corresponding to at least two diffraction grating orders.