Single-shot, adaptive metrology of rotationally variant optical surfaces, such as toroids, off-axis conies and freeform surfaces. An adaptive interferometric null test uses a high definition liquid crystal phase-only spatial light modulator (SLM) as the reconfigurable null element, on which a simulated nulling phase function is encoded, based on the specifications of the surface under test to generate a null interferogram. The power component of the surface sag is nulled by system design, not the SLM, enabling the SLM to fully compensate the residual departure without the need to tilt the optic or use a custom Offner-null. By wrapping the phase function at multiples of 2*pi radian, the upper limit in sag of the optic under test is theoretically removed.

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.

The disclosed method involves: recording, under illumination of a diffractive measurement structure (110, 210, 310, 410, 510, 610) via an illumination device, a plurality of diffraction images which differ from one another in terms of the region of the measurement structure that contributes to the respective diffraction image, and ascertaining transmission properties and/or reflection properties of the diffractive measurement structure based on the plurality of diffraction images, wherein the steps of recording a plurality of diffraction images and of ascertaining transmission properties and/or reflection properties of the diffractive measurement structure in a plurality of recording sequences are carried out repeatedly in a plurality of recording sequences, wherein these recording sequences differ from one another with respect to the illumination angles that are respectively set during the illumination of the diffractive measurement structure and at which the diffractive measurement structure is illuminated.

System and method for monitoring of performance of a mirror array of a digital scanner with a use of a lateral shearing interferometer (operated in either static or a phase-shifting condition) to either simply identify problematic pixels for further troubleshooting or measure the exact magnitude of the mirror's deformation.

The ROC value of a test surface is measured with a single spectrally-controlled interferometric measurement using a reference source of known ROC. The test surface is placed at the confocal position of the reference surface and the light source is modulated so as to produce localized interference fringes at the location of the test surface. The interference fringes are then processed with conventional interferometric analysis tools to establish the exact position of the test surface in relation to the reference surface, thereby determining the distance between the test surface and the reference surface. The radius of curvature of the test surface is obtained simply by subtracting such distance from the known radius of curvature of the reference surface.

A method and apparatus for characterizing the surface form of an optical element, in particular a mirror or a lens element of a microlithographic projection exposure apparatus, includes: carrying out a plurality of interferometric measurements, in each of which an interferogram is recorded between a test wave emanating from a portion of the optical element in each case and a reference wave, the position of the optical element relative to the test wave being altered between these measurements, and calculating the figure of the optical element on the basis of these measurements. This calculation is carried out iteratively in such that, in a plurality of iteration steps, the figure of the optical element is ascertained in each case by carrying out a forward calculation, each of these iteration steps being based in each case on a reference wave that was adapted based on the preceding iteration step.

Provided is a device for measuring a lens three-dimensional profile based on laser wavenumber scanning, including: a semiconductor laser for emitting coherent light; a beam splitter for dividing the coherent light into two parts; an optical wedge; a CCD camera for capturing an interference image; a computer for processing image information; a laser controller for adjusting an operating temperature and an operating current of the semiconductor laser; and a bilateral telecentric lens. The coherent light is reflected by the optical wedge and then reaches the bilateral telecentric lens through the beam splitter, to form a first reflected light path. The coherent light is reflected by the measured lens, and then reaches the bilateral telecentric lens through the beam splitter, to form a second reflected light path. The first reflected light path and the second reflected light path form an interference image after passing through the bilateral telecentric lens.

The imaging quality of an optical imaging system is interferometrically measured. A wavefront measurement has a first imaging scale .sub.1 in a first direction and a second imaging scale .sub.2 in a second, perpendicular direction. The second imaging scale differs from the first imaging scale by a scale ratio (.sub.1/.sub.2)1 (anamorphic imaging system). A first measurement structure (MS1) on a first structure carrier arranged on the object side of the imaging system has a two-dimensional mask structure suitable for shaping the coherence of measurement radiation. A second measurement structure (MS2) on a second structure carrier arranged on the image side of the imaging system has a diffraction grating. The first and second measurement structures are mutually adapted, taking account of the scale ratio so that an interference pattern arises upon imaging the first measurement structure onto the second measurement structure using the anamorphic imaging system.

A device for measuring the parameters of phase elements and dispersion of optical fibers, characterized in that it contains: a light source, serially connected to fiber optic coupler, one of whose arms constitutes a part of the reference arm, and whose second arm constitutes a part of the measurement arm of the device, and a motorized linear stage is mounted on the arm of the device. One of the arms of the device is connected to at least one detector, and at least one collimator is placed in at least of the arms of the device, at least before the phase element. A method of measuring the parameters of the phase element and the dispersion of optical fibers is conducted in two stages, wherein the first stage assumes the calibration of the device and the second stage is the proper measurement.