A Fourier transform infrared spectrophotometer includes a main interfersometer, a control interferometer, an infrared detector, a control light detector, and a beam splitter block. The beam splitter block is disposed between a beam splitter and the control light detector. The control light detector has an optical axis inclined with respect to an optical axis of a control interference light beam.

A Fourier spectroscopic analyzer includes: a first light source that emits light including a wavelength component in a first wavelength band which is a wavelength band in which a spectrum of light passing through a sample is acquired and a wavelength component in a second wavelength band different from the first wavelength band; a second light source that emits light including the wavelength component in the second wavelength band; an interferometer that acquires an interferogram which is coherent light from the light emitted from the first light source; a first light coupling optical system that couples light emitted from the second light source to at least one of light emitted from the first light source and the interferogram acquired by the interferometer; a light receiver that outputs a first light-reception signal acquired by receiving light including the wavelength component in the first wavelength band out of the wavelength components included in the light passing through the sample and a second light-reception signal acquired by receiving light including the wavelength component in the second wavelength band; and a signal processor that performs a Fourier transform process on the first light-reception signal and the second light-reception signal to acquire a spectrum of the wavelength component in the first wavelength band with noise removed therefrom.

A processer of an optical module is configured to control a voltage signal having a frequency for causing a movable mirror to resonate, and perform an intensity acquisition process. The intensity acquisition process is a process of acquiring a measurement light intensity of the interference light of the measurement light M times at a first time interval based on the frequency in each of a plurality of cycles among P cycles continuous in the voltage signal, acquiring an addition value of a plurality of the measurement light intensities mutually corresponding for the same number of times, acquiring a laser light intensity of the interference light of the laser light N times at a second time interval based on the frequency in each of the plurality of cycles, and acquiring an addition value of a plurality of the laser light intensities mutually corresponding for the same number of times.

Devices, systems and methods for optical spectroscopy using a Fourier transform that improve measurement speed, and relax the sampling rate and dynamic range requirements compared to conventional techniques, are described. One exemplary method for optical Fourier transform spectroscopy includes receiving a broadband signal, spectrally partitioning the broadband signal to generate a plurality of spectral channel interferograms, computing a one-dimensional Fourier transform of a function of each of the plurality of spectral channel interferograms to generate each of a plurality of channel spectrums, and reconstructing a spectrum of the broadband signal based on the plurality of channel spectrums. Embodiments of the disclosed technology include a free-space channel dispersed Fourier transform spectrometer and an integrated silicon-on-insulator Fourier transform spectrometer.

Technologies for a high resolution and wide swath spectrometer are disclosed. In the illustrative embodiment, an inverted image slicer converts a linear field of view into a grid shape, allowing for an interferometer of a Fourier transform spectrometer to operate on a narrow range of field of views, improving the average spectral resolution of the spectrometer.

Technologies for a high resolution and wide swath spectrometer are disclosed. In the illustrative embodiment, an inverted image slicer converts a linear field of view into a grid shape, allowing for an interferometer of a Fourier transform spectrometer to operate on a narrow range of field of views, improving the average spectral resolution of the spectrometer.

The present disclosure relates to a common-path cube-corner retroreflector interferometer with a large optical path difference and high stability, and an interference technique thereof. The interferometer adopts an asymmetric common-path beam splitting structure using right-angled cube-corner retroreflectors, comprising a semi-transmissive and semi-reflective beam splitter, a plane mirror, a first right-angled cube-corner retroreflector, a second right-angled cube-corner retroreflector and an optical path difference element. The incident light is divided into a first transmitted beam and a second reflected beam, which are respectively reflected by the plane mirror and the right-angled cube-corner retroreflectors several times and then split again, two beams of which become interference outputs along directions perpendicular to an incident direction of the incident light, and the other two beams become interference outputs along directions parallel to the incident light. The present disclosure also provides an interference technique based on the interferometer described above.

An interferometer apparatus for an achromatic interferometric superposition of electromagnetic fields, with a dual beam path interferometer, comprises a beam splitter being arranged for splitting an input beam into a first beam propagating along a first interferometer arm (A1) including at least one deflection mirror and a second beam propagating along a second interferometer arm (A2) including at least one deflection mirror, wherein the first and second interferometer arms have an identical optical path length, and a beam combiner being arranged for recombining the first and second beams into a constructive output and a destructive output, wherein reflective surfaces of the beam splitter and the beam combiner are arranged such that, in the first interferometer arm compared with the second interferometer arm, one additional Fresnel reflection at an optically dense medium is provided and a propagation of the electromagnetic fields of the first and second beams, when recombined by the beam combiner, results in a wavelength-independent phase difference of π between the contributions of the two interferometer arms to the destructive output, and the first interferometer arm includes a balancing transmission element being arranged for balancing a chromatic dispersion and Fresnel losses in the first and second interferometer arms. Furthermore, an interferometric measurement apparatus and an interferometric measurement method are described.

Disclosed herein is an all-digital phase and timing correction procedure for coherent averaging in dual-comb and multiheterodyne spectroscopy—applicable to any dual-comb spectroscopy setup. It can account for large frequency/phase instabilities of the used sources, yielding a significant reduction of the noise pedestal and an increase in signal-to-noise ratio (SNR) of the radio frequency (RF) beat notes. This technique is computationally efficient and can be conveniently implemented either as a post-processing algorithm or in a real-time data acquisition and processing platform without the necessity of adding any additional optical elements to the dual-comb spectroscopy system. By implementing this technique, the performance of any comb- or comb-like-source-based DCS system with a sufficient degree of mutual coherence between the optical modes can be improved in terms of SNR and number of spectroscopically-usable RF beat notes. The described technique is compatible with a DC-centered RF spectrum, where the negative frequencies are folded to the positive domain to double the number of beat notes within the detector bandwidth. The technique enables coherent averaging over extended time-scales even for free-running combs, thus increasing the sensitivity of absorption and dispersion DCS measurements.

An optical module includes a mirror unit and a beam splitter unit. The mirror unit includes a base with a main surface, a movable mirror, a first fixed mirror, and a drive unit. The beam splitter unit constitutes a first interference optical system for measurement light along with the movable mirror and the first fixed mirror. A mirror surface of the movable mirror and a mirror surface of the first fixed mirror follow a plane parallel to the main surface and face one side in a first direction perpendicular to the main surface. The movable mirror, the drive unit, and at least a part of an optical path between the beam splitter unit and the first fixed mirror are disposed in an airtight space.