A characterization method of a light beam includes separating the light beam into first and second sub-beams; propagating the first and second sub-beams over first and second optics respectively; the first sub-beam, which forms a reference beam, and the second sub-beam, which forms a characterized beam, being separated by a time delay ?; recombining the reference and characterized beams so that they spatially interfere and form a two-dimensional interference pattern; measuring the pattern to obtain a temporal interferogram; calculating the Fourier transform in the frequency domain of a spatial point of the interferogram, the Fourier transform having a frequency central peak and first and second frequency side peaks; calculating the Fourier transform in the frequency domain for the first or second time side peaks calculating the spectral amplitude and the spatial-spectral phase for the first or second frequency side peak of the Fourier transform in the frequency domain.

Interfering internal beams can be used to generate an internal reference interferogram. This interferogram can be used to compensate for changes in FTIR instrument performance in response to variable environmental conditions or other instrument variations. Acquisition of such internal interferograms can be done during, after, or prior to acquisition of actual sample data.

An on-chip Fourier transform spectrometer based on a double-layer spiral waveguide comprises, in order, a waveguide input coupler, a 1?N optical splitter, N double-layer waveguide Y-branch structures, N double-layer spiral waveguides with incremental lengths, N double-layer waveguide Y-branch structures arranged in opposite directions, and N germanium-silicon detectors. The group index difference between the odd mode and the even mode in the double-layer waveguide makes the double-layer spiral waveguide function like an asymmetric Mach-Zehnder interferometer. N double-layer spiral waveguides with incremental lengths are used to achieve a spatial heterodyne based Fourier transform spectrometer. Spectral reconstruction from the measured interference fringes can be achieved by a regression algorithm. The invention meets the application need for miniaturization and portability of Fourier transform spectrometers, and has lower temperature sensitivity compared with the existing on-chip spectrometers on the silicon platform.

An embodiment of a ruggedized interferometer is described that comprises a light source that generates a beam of light; a fixed mirror; a moving mirror that travels along a linear path; a beam splitter that directs a first portion of the beam of light to the fixed mirror and a second portion of the beam of light to the moving mirror, wherein the beam splitter recombines the first portion reflected from the fixed mirror and the second portion reflected from the moving mirror; and a servo control that applies a substantial degree of force to the moving mirror at initiation of a turnaround period, wherein the substantial degree of force is sufficient to redirect the moving mirror traveling at a high velocity to an opposite direction of travel on the linear path.

An optical measurement method in which a series of light pulses are generated using a pulsed laser having a set of different mode hop sequences (e.g., an external-cavity quantum cascade laser (EC-QCL)), the light pulses are detected with the detector to generate a respective pulse data set for each of the light pulses, and the pulse data sets are sorted into classes based on correlation coefficients. Sorting the pulse data sets into classes allows the pulse data sets originating from each of the mode hop sequences of the pulsed laser to be treated independently of the pulse data sets originating from others of the mode hop sequences in subsequent processing.

In one aspect, an apparatus includes a first light source that applies first light having a first wavelength as a center wavelength to an object, a second light source that applies second light having a second wavelength as a center wavelength longer than the first wavelength to the object, an optical filter that includes first and second regions and that transmits third light produced by the first and second light each passed through or reflected by the object, first and second optical detectors that determine first and second amounts, respectively, of the third light passed through the first and second regions. The transmission ranges of spectral transmission curves of the first and second regions are located between the first wavelength and the second wavelength. The spectral transmission curve of the first region has a width at half maximum different from that of the spectral transmission curve of the second region.

Disclosed herein is a method for calibrating a spectrometer device. The spectrometer device includes at least one detector device including at least one optical element configured for separating incident light into a spectrum of constituent wavelength components and further includes a plurality of photosensitive elements. The method includes the following steps: a) illuminating, by using at least one broadband light source, the spectrometer device through at least one optical interferometer; b) determining for the plurality of photosensitive elements a plurality of detectors signals depending on the illumination through the optical interferometer in step a); and c) determining at least one item of calibration information from the plurality of detector signals.

Further disclosed herein are a system for calibrating a spectrometer device, a computer program and a computer-readable storage medium for performing the method.

A full-range imaging method doubles imaging range of conventional techniques by removing mirror images of an imaged object that limit conventional images to a half-range and that are caused in part by the loss of phase information in a detected signal. Phase information of the detected signal is reconstructed with an averaging technique based on a modulated phase induced in the detected signal during scanning.

The process and device for diagnosing the quality of compression of an ultrashort pulse, consist of performing an approximation of the Strehl ratio by: a first step allowing the measurement of spatio-spectral images of the ultrashort light pulse brief initial (Ii) using one or more parallel imaging spectrometers; a second step allowing an interaction of said pulse with a nonlinear optical material (DMNL), the aforementioned interaction generating, by a nonlinear optical mechanism of an n order, a secondary pulse (Is) of intensity proportional to the temporal intensity aforementioned ultrashort light pulse (Ii) raised to the power of n; a third step allowing the measurement of the spatio-spectral image or images of the secondary pulse (Is); the processing of the images thus obtained will be translated into an expression of the ratio of the maximum intensity obtained by that which could be obtained for the pulse without phase distortion.

A characterization method of a light beam includes separating the light beam into first and second sub-beams; propagating the first and second sub-beams over first and second optics respectively; the first sub-beam, which forms a reference beam, and the second sub-beam, which forms a characterized beam, being separated by a time delay ; recombining the reference and characterized beams so that they spatially interfere and form a two-dimensional interference pattern; measuring the pattern to obtain a temporal interferogram; calculating the Fourier transform in the frequency domain of a spatial point of the interferogram, the Fourier transform having a frequency central peak and first and second frequency side peaks; calculating the Fourier transform in the frequency domain for the first or second time side peaks calculating the spectral amplitude and the spatial-spectral phase for the first or second frequency side peak of the Fourier transform in the frequency domain.