Systems and methods disclosed herein provide for gas imaging. A gas imaging system comprises a lenslet array configured to receive thermal radiation from a scene and transmit a plurality of substantially identical sub-images of the thermal radiation; a birefringent polarization interferometer configured to generate an optical path difference for each ray of the plurality of sub-images based on a respective position of each ray entering the BPI, the optical path differences combining to form an interference fringe pattern; and an infrared focal plane array configured to capture a thermal image of the plurality of sub-images modulated by the interference fringe pattern due to the optical path differences through the BPI. The captured thermal image may represent a plurality of interferogram sample points of the thermal radiation from the scene, and may be used to construct a plurality of hyperspectral images of the thermal radiation from the scene.

A method for performing optical wavefront sensing includes providing an amplitude transmission mask having a light input side, a light output side, and an optical transmission axis passing from the light input side to the light output side. The amplitude transmission mask is characterized by a checkerboard pattern having a square unit cell of size . The method also includes directing an incident light field having a wavelength to be incident on the light input side and propagating the incident light field through the amplitude transmission mask. The method further includes producing a plurality of diffracted light fields on the light output side and detecting, at a detector disposed a distance L from the amplitude transmission mask, an interferogram associated with the plurality of diffracted light fields. The relation $0<L<\frac{1}{8}\frac{{}^2}{}\mathrm{or}\frac{1}{4}\frac{{}^2}{}\left(2n-1\right)<L<\frac{1}{4}\frac{{}^2}{}\left(2n+1\right)$
is satisfied, where n is an integer greater than zero.

Provided is an operating method of a measuring apparatus measuring a wavefront of a target. The operating method includes measuring a measurement wavefront on the basis of the wavefront of the target, measuring reference slope information and first to third slope information respectively corresponding to a reference direction and first to third directions on the basis of the measurement wavefront, obtaining first to third rotation angles on the basis of the measured reference slope information and first to third slope information, and outputting a wavefront of which an error is corrected, which is generated by rotation errors on the basis of the obtained first to third rotation angles, wherein the first to third rotation angles are differences in angle between the reference direction and the first to third directions.

A point diffraction interferometric wavefront aberration measuring device comprising an optical source, an optical splitter, a first light intensity and polarization regulator, a phase shifter, a second light intensity and polarization regulator, an ideal wavefront generator, an object precision adjusting stage, a measured optical system, an image wavefront detection unit, an image precision adjusting stage, and a data processing unit. The center distance between the first output port and the second output port of the ideal wavefront generator is smaller than the diameter of the isoplanatic region of the measured optical system and is greater than the ratio of the diameter of the image point dispersion speckle of the measured optical system over the amplification factor thereof. A method for detecting wavefront aberration of the optical system is also provided by using the device.

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.

A method for characterizing a light beam includes separating the light beam by a separator optic into first and second sub-beams; propagating the first and second sub-beams over first and second optics, respectively, said first and second optics being respectively arranged so that the sub-beams on leaving the optics are separated by a time delay ; recombining the sub-beams so that they spatially interfere and form a two-dimensional interference pattern; measuring the frequency spectrum of at least part of the interference pattern; calculating the Fourier transform in the time domain of at least one spatial point of the frequency spectrum, the Fourier transform in the time domain having a time central peak and first and second time side peaks; calculating the Fourier transform in the frequency domain for one of the side peaks; calculating the spectral amplitude A.sub.R() and the spatial-spectral phase .sub.R(x,y,) for the Fourier transform in the frequency domain.

A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L.sub.12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L.sub.21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

A point diffraction interferometric wavefront aberration measuring device comprising an optical source, an optical splitter, a first light intensity and polarization regulator, a phase shifter, a second light intensity and polarization regulator, an ideal wavefront generator, an object precision adjusting stage, a measured optical system, an image wavefront detection unit, an image precision adjusting stage, and a data processing unit. The center distance between the first output port and the second output port of the ideal wavefront generator is smaller than the diameter of the isoplanatic region of the measured optical system and is greater than the ratio of the diameter of the image point dispersion speckle of the measured optical system over the amplification factor thereof. A method for detecting wavefront aberration of the optical system is also provided by using the device.

An apparatus and method for measuring amplitude and/or phase of a molecular vibration uses a polarization modulated pump beam and a stimulating Stokes beam on a probe of a scanning probe microscope to detect a Raman scattered Stokes beam from the sample. The detected Raman scattered Stokes beam is used to derive at least one of the amplitude and the phase of the molecular vibration.

A method for performing optical wavefront sensing includes providing an amplitude transmission mask having a light input side, a light output side, and an optical transmission axis passing from the light input side to the light output side. The amplitude transmission mask is characterized by a checkerboard pattern having a square unit cell of size . The method also includes directing an incident light field having a wavelength to be incident on the light input side and propagating the incident light field through the amplitude transmission mask. The method further includes producing a plurality of diffracted light fields on the light output side and detecting, at a detector disposed a distance L from the amplitude transmission mask, an interferogram associated with the plurality of diffracted light fields. The relation

[00001]$0<L<\frac{1}{8}.Math.\frac{{}^2}{}.Math..Math.\mathrm{or}.Math..Math.\frac{1}{4}.Math.\frac{{}^2}{}.Math.\left(2.Math.n-1\right)<L<\frac{1}{4}.Math.\frac{{}^2}{}.Math.\left(2.Math.n+1\right)$

is satisfied, where n is an integer greater than zero.