A wavefront sensor includes a mask and a sensor utilized to capture a diffraction pattern generated by light incident to the mask. A reference image is captured in response to a plane wavefront incident on the mask, and another measurement image is captured in response to a distorted wavefront incident on the mask. The distorted wavefront is reconstructed based on differences between the reference image and the measurement image.

A method for evaluating the quality of the measurement of an optical wavefront, said measurement being obtained by means of a wavefront analyzer by direct measurement, the method comprising: the acquisition (10) of an optoelectronic signal for the measurement of the wavefront by means of a wavefront sensor, said sensor comprising a two-dimensional detector; the determination (11) on the basis of said optoelectronic signal of at least one parameter characteristic of a parasitic component of the optoelectronic signal; the evaluation (12) of a quality factor of the measurement of the wavefront as a function of said at least one parameter characteristic of the parasitic component of the signal; the display (13) to a user of a level of quality of the measurement as a function of said quality factor.

A defect detection device 10 includes: an excitation source 11 capable of being placed at any position on a surface of an inspection target object S, the excitation source 11 being configured to excite an elastic wave within the inspection target object S, the elastic wave being predominant in one vibration mode and propagating in a predetermined direction; an illumination unit (pulsed laser light source 13, illumination light lens 14) configured to perform stroboscopic illumination on an illumination area of the surface of the inspection target object by using a laser light source; a displacement measurement unit (speckle shearing interferometer 15) configured to collectively measure a displacement of each point in a front-back direction within the illumination area in at least three different phases of the elastic wave, by speckle interferometry or speckle shearing interferometry; and a reflected wave/scattered wave detector 16 configured to detect either one or both of a reflected wave and a scattered wave of the elastic wave, based on the displacement measured by the displacement measurement unit.

A metrology system includes a first beam analysis system for analyzing at least one first measurement beam that was coupled from the excitation laser beam before a reflection on the target material and a second beam analysis system for analyzing at least one second measurement beam that was coupled from the excitation laser beam after a reflection on the target material. Each of the first beam analysis system and the second beam analysis system has at least one wavefront sensor system.

The present invention relates to a method comprising reception of an incident electromagnetic wave (9) by a diffractive element (2) and conversion of this incident electromagnetic wave (9) into a diffracted electromagnetic wave (10) by the diffractive element (2); reception of the diffracted electromagnetic wave (10) by a matrix-array sensor (4) comprising a matrix-array of pixels that are aligned along one or two axes of pixel alignment (13, 14). The method comprises a plurality of acquisitions, by the matrix-array sensor (4), of a signal of the diffracted electromagnetic wave (10) corresponding to a plurality of relative positions between the diffractive element (2) and the matrix-array sensor (4). The invention also relates to a device (1) implementing this method.

Projection objective wave-front aberration detecting device and a detecting method thereof, wherein the projection objective wave-front aberration detecting device comprises a light source and illuminating system, an object plane grating, an object plane displacement stage, a measured projection objective, an image plane grating, a two-dimensional photoelectric sensor, an image plane displacement stage and a control processing unit. According to the invention, by controlling the length of the object plane grating line, or the periodic structure of the object plane grating perpendicular to the shearing diffraction direction, or the object plane grating to adopt a sinusoidal grating, or the image plane grating to adopt an amplitude-phase hybrid grating, the complexity of an interference field is reduced, and the wave-front aberration detection speed and precision are improved, and the precision and speed of in-situ wave-front aberration detection can be improved.

A wavefront sensor system suitable for integration into an integrated circuit light detector may provide for wave angle sensors having varying functional relationships between the wave angle and signal to provide improved dynamic range. These wave angle sensors may be combined with integrated circuit phase angle sensors for a more complete analysis of the waveform.

A system and method for measuring refractive index inhomogeneity between plates of a Lightguide Optical Element (LOE) uses an innovative measuring technique based on a shearing interferometric technique conventionally used to observe interference and test the collimation of light beams. Another feature of the current implementation is an innovative method for analyzing the characteristics of the generated interferogram to characterize discrepancies between adjacent plates in an LOE.

A method for wavefront measurement of optical imaging system based on grating shearing interferometry, the grating shearing interferometer comprising: a light source and illumination system, an optical imaging system to be tested, a one-dimensional diffraction grating plate, a two-dimensional diffraction grating plate, a two-dimensional photoelectric sensor and a computing unit. The one-dimensional diffraction grating plate and the two-dimensional diffraction grating plate are respectively placed on the object side and the image side of the optical imaging system to be tested. By collecting N sets of interferograms with a $\frac{2\pi }{N}$
phase-shifting interval (where, $N=2\left(\mathrm{fix}\left(\frac{\mathrm{ceil}\left(1/s\right)}{2}\right)+1\right),$
s is the shear ratio of the grating shearing interferometer), combined with a certain phase retrieval algorithm, the influence of all high-order diffraction beams on the phase retrieval accuracy is eliminated, and finally the wavefront measurement accuracy for the optical imaging system is improved.

Method for detecting wavefront aberration for optical imaging system based on grating shearing interferometer, the grating shearing interferometer system comprising a light source and illumination system, an optical imaging system to be tested, a one-dimensional diffraction grating plate, a two-dimensional diffraction grating plate, a two-dimensional photoelectric sensor, and a computing unit. The one-dimensional and two-dimensional diffraction grating plates are respectively placed on the object plane and the image plane of the optical imaging system to be tested. By collecting interferograms with phase-shifting amounts of 0, π/2, π, 3π/2 and N sets of α, π-α, 2π-α (where, $N=2\left(\mathrm{fix}\left(\frac{\mathrm{ceil}\left(1\text{/}s\right)}{2}\right)+1\right),$
s is the shear ratio of the grating shearing interferometer system), combined with a certain phase retrieval algorithm, the influence of all high-order diffraction beams on the phase retrieval accuracy is eliminated, and finally the detection accuracy of wavefront aberration for the imaging system to be tested is improved.