An apparatus for determining a topological charge of one of more optical beams. For single beams, a trapezoidal optical element having a front face and an opposing rear face that is not parallel to the front face is oriented so that the optical beam is reflected in a direction other than along the optical path. The reflection of the optical beam by the trapezoidal optical element produces an interference pattern that can be captured by an optical imager and that can be decoded to determine the topological charge of the optical beam. For a plurality of superpositioned beams, an air spaced trapezoidal optical element may oriented to reflect the plurality of beams onto an optical imager to capture the interference pattern. The interference pattern may be interpreted to identify the topological charge of each of the plurality of optical beams.

A method for testing a tire by interferometry in a pressure chamber of a tire testing device includes capturing phase images at different pressures in the pressure chamber, generating partial phase difference images between successive phase images, and summing the partial phase difference images to form an overall phase difference image. The pressure in the pressure chamber is changed in a first direction during a first measurement phase and the pressure is changed in the opposite direction during a second measurement phase, wherein at least one partial phase difference image from the first measurement phase and at least one partial phase difference image from the second measurement phase are included in the summation.

A measuring device including a light source emitting a light beam, a first beam splitter disposed on a light path of the light beam, an optical grating, a reflector, and a sensor is provided. The light beam is divided into first and second light beams by the first beam splitter. The optical grating is disposed on light paths of the first and second light beams. The first beam splitter enables the first light beam to be delivered to the optical grating. The reflector is disposed on the light path of the second light beam. The first beam splitter enables the second light beam to be delivered to the reflector and reflected to the optical grating. The first and second light beams are diffracted by the optical grating to generate multiple first and second diffraction light beams at different angles respectively, which are received by the sensor after interference.

A light intensity fluctuation-insensitive projection objective wave aberration detection device and a detection method thereof, comprising a light source and illumination system, an object plane marking plate, an object plane displacement table, a tested projection objective, an image plane marking plate, a two-dimensional photosensor, an image plane displacement table and a control processing unit; the object plane marking plate and the image plane marking plate are provided with grating marks for shear interference test and marks for light intensity test, the shear interferograms and the light intensity information are simultaneously received through the two-dimensional photosensor, the light intensity fluctuation error corresponding to each phase-shifting interferogram is corrected through the light intensity information, improving the detection precision, reducing the complexity and the cost of the system, and improving the detection speed.

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 method for testing a tire by interferometry in a pressure chamber of a tire testing device includes capturing phase images at different pressures in the pressure chamber, generating partial phase difference images between successive phase images, and summing the partial phase difference images to form an overall phase difference image. The pressure in the pressure chamber is changed in a first direction during a first measurement phase and the pressure is changed in the opposite direction during a second measurement phase, wherein at least one partial phase difference image from the first measurement phase and at least one partial phase difference image from the second measurement phase are included in the summation.

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, /2, , 3/2 and N sets of , -, 2- (where,

[00001]$N=2.Math.\left(\mathrm{fix}\left(\frac{\mathrm{ceil}\left(1.Math.\text{/}.Math.s\right)}{2}\right)+1\right),$

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.

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

[00001]$\frac{2.Math.}{N}$

phase-shifting interval (where,

[00002]$N=2.Math.\left(\mathrm{fix}\left(\frac{\mathrm{ceil}\left(1/s\right)}{2}\right)+1\right),$

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.

An optical system for determining the optical phase of an object of interest located at an input plane of the system. The system may include a variable-focus optical imaging system for creating an image of the object of interest at an output plane of the imaging system. An optical detector may be provided at the output plane for receiving the image of the object. A controller may be operably connected to the vari-focal element to adjust the optical power of the variable-focus optical imaging system. The controller may also be configured to create a plurality of defocused images of the object at the output plane and be connected to the detector to capture each of the plurality of defocused images.