Abstract: An apparatus and associated method for testing a non-symmetric (e.g., phi-polynomial) surface. The apparatus uses several simple (singlet) optical elements (e.g., an Offner null configuration) and a tilted optic under test in combination with an active optical element (e.g., actuated, deformable membrane mirror, optical phase modulator, etc.) that together form a null or quasi-null that allows for conventional null-based interferometry. This solution solves the problem of exceeding the dynamic range of a conventional interferometer when trying to test non-symmetric optical surfaces.

Abstract: The present invention discloses a wavelength scanning interferometer and a method for an aspheric surface measurement. The wavelength scanning interferometer comprises a set of tunable lasers (7) used as a light source, a Twyman-Green interferometer used for generating interference fringes, a translation platform (1) used for scanning an optical path difference along an optical axis, an image card (11) used for converting interference data to a digital signal and transmitting the digital signal to a computer (12), and a data card (13) used for synchronizing the actions of a CCD camera (9) and the translation platform (1). Different from the traditional aspheric surface measurement method, the interferometer is capable of measuring a surface with a high aspheric surface degree or a wavefront, and without the need of a zero compensation mirror. In addition, the method does not need a complex and usually expensive multi-dimensional movement platform.

Abstract: An apparatus and a method capable of measuring large deformation with a high accuracy and dynamically, using speckle interference, utilizes an optical path where one laser beam out of two laser beams becomes non-collimated light and a plane parallel transparent plate, and can form carrier fringes. More specifically, the transparent plate is arranged on the optical path where the non-collimated light is formed, or is removed from the optical path, or a refractive index, or a thickness of the transparent plate arranged on the optical path, or a tilt angle relative to an optical axis is changed. The phase analysis can be performed from fringe images corresponding to the deformation, by performing repetitively the above-described processing and acquisition of the speckle interference pattern.

Abstract: In-line holography to create images of a specimen, such as one or more particles dispersed in a transparent medium. Analyzing these images with results from light scattering theory yields the particles' sizes with nanometer resolution, their refractive indexes to within one part in a thousand, and their three dimensional positions with nanometer resolution. This procedure can rapidly and directly characterize mechanical, optical and chemical properties of the specimen and its medium.

Abstract: A ring light source system for an interferometer with adjustable ring radius and ring radial width may comprise a laser light source, an expander and collimator optical system, an adjustable aperture, a binary phase grating, a variable-focus optical system, and a spatial filter. The expander and collimator optical system is configured to convert a light beam from the light source into a parallel light beam. The adjustable aperture is configured to adjust a diameter of the parallel light beam. The light beam with the diameter adjusted by the adjustable aperture is incident perpendicularly onto the binary phase grating, followed by the variable-focus optical system. The filter is positioned on a back focal plane of the variable-focus optical system, and is configured to receive a ring light source. The ring radius and radial width of the light source are adjustable by adjusting a focus length f1 of the variable-focus optical system.

Abstract: An instrument for measuring aspheric optical surfaces includes both an optical wavefront sensor and a single-point optical profilometer. The optical wavefront sensor measures surface height variations throughout one or more areas of an aspheric test surface. The single-point profilometer measures surface height variations along one or more traces on the aspheric test surface. At least one of the traces intersects at least one of the areas, and respective spatial frames of reference for the traces and areas are relatively adapted to each other by minimizing differences between points of nominal coincidence between the areas and traces.

Abstract: An interferometry method and associated system and computerized media for testing samples under test including those with high aberrations, comprising: situating a sample under test between a tilt mirror and a reference mirror, the tilt mirror tiltable with at least one degree of freedom about at least one tilt mirror axis, and further translatable along an axial line defined by a direction of propagation of a test wavefront from a source thereof; propagating the test wavefront toward the tilt mirror; after the test wavefront has been reflected by the tilt mirror, further propagating the test wavefront toward a reference mirror; and deriving a substantially complete first-tilt-alignment wavefront metrology of the sample under test from a plurality of first-tilt-alignment interferograms taken with the tilt mirror held fixed at a first predetermined tilt mirror angle while discreetly varying a displacement between the sample under test and the reference mirror.

Abstract: A method of minimizing fringe print-through in a phase-shifting interferometer, includes the steps of: (a) determining multiple transfer functions of pixels in the phase-shifting interferometer; (b) computing a crosstalk term for each transfer function; and (c) displaying, to a user, a phase-difference map using the crosstalk terms computed in step (b). Determining a transfer function in step (a) includes measuring intensities of a reference beam and a test beam at the pixels, and measuring an optical path difference between the reference beam and the test beam at the pixels. Computing crosstalk terms in step (b) includes computing an N-dimensional vector, where N corresponds to the number of transfer functions, and the N-dimensional vector is obtained by minimizing a variance of a modulation function in phase shifted images.

Abstract: Measuring a shape of an optical surface (14) of a test object (12) includes: providing an interferometric measuring device (16) generating a measurement wave (18); arranging the measuring device (16) and the test object (12) consecutively at different measurement positions relative to each other, such that different regions (20) of the optical surface (14) are illuminated by the measurement wave (18); measuring positional coordinates of the measuring device (16) at the different measurement positions in relation to the test object (12); obtaining surface region measurements by interferometrically measuring the wavefront of the measurement wave (18) after interaction with the respective region (20) of the optical surface (14) using the measuring device (16) in each of the measurement positions; and determining the actual shape of the optical surface (14) by computationally combining the sub-surface measurements based on the measured positional coordinates of the measuring device (16) at each of the measurement

Abstract: The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. The invention and its advantages are applicable to optical coherence tomography as well as conventional white light interferometry.

Abstract: A compensation optical apparatus for obtaining and image of an object without reduction in image quality irrespective of aberration compensation, includes: a division unit for dividing a return beam from a measured object; an aberration measurement unit for measuring an aberration caused by the measured object, with a divided beam from the division unit; an aberration compensation unit for performing aberration compensation based on the aberration measured by the aberration measurement unit; a projection unit for projecting a beam obtained by the aberration compensation in the aberration compensation unit to the measured object; an acquirement unit for acquiring a value exhibiting a state of the measured object based on the return beam from the measured object, which is obtained by the beam projected from the projection unit; and a control unit for retreating the division unit from an optical path based on the value acquired by the acquirement unit.

Abstract: Measuring a shape of an optical surface (14) of a test object (12) includes: providing an interferometric measuring device (16) generating a measurement wave (18); arranging the measuring device (16) and the test object (12) consecutively at different measurement positions relative to each other, such that different regions (20) of the optical surface (14) are illuminated by the measurement wave (18); measuring positional coordinates of the measuring device (16) at the different measurement positions in relation to the test object (12); obtaining surface region measurements by interferometrically measuring the wavefront of the measurement wave (18) after interaction with the respective region (20) of the optical surface (14) using the measuring device (16) in each of the measurement positions; and determining the actual shape of the optical surface (14) by computationally combining the surface region measurements based on the measured positional coordinates of the measuring device (16) at each of the measurem

Abstract: A system and method for wavefront measurement of an EO sensor is performed in-situ using the sensor's EO detector in a manner that disambiguates the local wavefront measurements for different sub-pupils in time and maximizes the dynamic range for measuring the local wavefronts. A single sub-pupil sized optical beam is traced in a spatial pattern over the EO sensor's entrance pupil to serially illuminate a temporal sequence of sub-pupils to form a serially addressed sub-pupil screen. The EO detector and video card capture a video signal for one sub-pupil at a time as the optical beam traces the spatial pattern. The video signal is routed to a computer processor that generates a spatio-temporal mapping of the spatial positions of the sub-pupils in the sub-pupil screen to the temporal positions of frames in the video signal. The computer processor uses the mapping to process the video signal to compute a wavefront estimate spanning the entrance pupil.

Abstract: A low coherent light from a white light source is emitted to a sample surface. A detour distance in a detour section is adjusted such that an optical path difference between a reference light and a sample light is equal to or shorter than a coherence length of interference light. The interference light is incident on an image sensor only when an inclination angle of a diffraction grating plate and a wavelength of the interference light satisfy a predetermined condition. Thus, an interference fringe image is formed. Based on each of the interference fringe images taken on a wavelength-by-wavelength basis of the interference light and an optical distance between a reference surface and the sample surface along an optical path of a measuring light at the time of taking the interference fringe image, a shape of the sample surface is measured.

Abstract: An apparatus for measuring a shape of a surface, comprises a measurement head which measures a distance between a reference point and the surface by detecting interference between test light obtained when light that passes through the reference point is emitted, is reflected by the surface, and returns to the reference point, and reference light, a scanning mechanism which scans the measurement head, and a processor which calculates the shape of the surface based on the distance measured using the measurement head and coordinates of the reference point.

Abstract: The present invention provides a measurement apparatus which measures a surface shape of a measurement target surface, the apparatus including an optical system configured to split light from a light source into measurement light and reference light, guide the measurement light onto the measurement target surface, and guide the reference light onto a reference surface, a detection unit configured to detect an intensity of the measurement light reflected by the measurement target surface, an intensity of the reference light reflected by the reference surface, and an interference pattern formed between the measurement light reflected by the measurement target surface and the reference light reflected by the reference surface, and a processing unit configured to obtain a surface shape of the measurement target surface based on an interference signal of the interference pattern detected by the detection unit.

Abstract: A method of measuring a deviation of an optical surface from a target shape and a method of manufacturing an optical element. This method of measuring the deviation includes: performing a first interferometric measurement using a first diffractive measurement structure, which is arranged to cover a first area of the optical surface, to provide a first interferometric measurement result, performing a second interferometric measurement using a second diffractive measurement structure, which is arranged to cover a second area of the optical surface different from the first area, to provide a second interferometric measurement result, and determining a deviation of the optical surface from the target shape.

Abstract: Systems and methods are presented to enhance and isolate residual signals indicative of the speckle field based on measurements taken by optically based metrology systems. Structural irregularities such as roughness and topographical errors give rise to light scattered outside of the specularly reflected component of the diffracted light. The scattered light interferes constructively or destructively with the specular component in a high numerical aperture illumination and detection system to form a speckle field. Various methods of determining residual signals indicative of the speckle field are presented. Furthermore, various methods of determining structural irregularities based on analysis of the residual signals are presented. In various embodiments, illumination with a high degree of spatial coherence is provided over any of a wide range of angles of incidence, multiple polarization channels, and multiple wavelength channels.

Abstract: Disclosed herein is a defect inspection apparatus including: a light source for emitting laser light; a mirror group for splitting the wave surface of incident laser light emitted by the light source into a plurality of component wave surfaces, arranging the component wave surfaces to form an array oriented in one direction and aligning the component wave surfaces to form a single wave surface after propagating the laser light through a moving object of measurement; an interferometer for splitting the single wave surface into two partial wave surfaces to create an interference stripe; an imaging section for taking an image of the interference stripe created by the interferometer; and an analysis section for detecting a defect existing on the surface of the moving object of measurement on the basis of changes of the image, which has been taken as the image of the interference stripe, with the lapse of time.

Abstract: A grazing incidence interferometer includes: a beam splitting section configured to split a beam from a beam source section into a measuring beam emergent to a measurement surface and a reference beam serving as a measurement reference, and configured to cause the measuring beam to emerge obliquely to the measurement surface; a beam combining part configured to combine the reference beam and the measuring beam reflected at the measurement surface, to obtain a combined beam; a detecting section configured to detect a profile of the measurement surface based on an interference fringe formed by the combined beam; and an image inverting part configured to invert an orientation of a wave front of the measuring beam or the reference beam, the image inverting part being provided in an optical path of the measuring beam or the reference beam leading from the beam splitting section to the beam combining section.

Abstract: An optical tomographic imaging apparatus includes a first splitting unit configured to split a first beam and a second beam respectively into a reference beam and a measuring beam, an interference unit configured to acquire a first interference beam and a second interference beam by combining return beams being acquired by irradiating an inspection object with the respective measuring beams split by the splitting unit and the respectively corresponding reference beams, a second splitting unit configured to split the first interference beam into a third interference beam and a fourth interference beam, a selection unit configured to select either the second interference beam or the fourth interference beam, and an imaging unit configured to generate a tomographic image from the third interference beam and the second interference beam, or from the third interference beam and the fourth interference beam.

Abstract: An apparatus for measuring a shape of a surface, comprises a measurement head which measures at least one of a distance between a reference point and the surface and a direction of a normal from the surface to the reference point, a scanning mechanism which scans the measurement head, and a processor which calculates the shape of the surface based on a measurement result measured using the measurement head and coordinates of the reference point, wherein the coordinates of the reference point are calibrated using a measurement result measured by scanning the measurement head along a scanning path in association with a first surface to be measured, and a shape of a second surface to be measured is calculated based on a measurement result measured by scanning the measurement head along the same scanning path in association with the second surface, and the calibrated coordinates of the reference point.

Abstract: Apparatus (20) for 3D mapping of an object (28) includes an illumination assembly (30), including a coherent light source (32) and a diffuser (33), which are arranged to project a primary speckle pattern on the object. A single image capture assembly (38) is arranged to capture images of the primary speckle pattern on the object from a single, fixed location and angle relative to the illumination assembly. A processor (24) is coupled to process the images of the primary speckle pattern captured at the single, fixed angle so as to derive a 3D map of the object.

Abstract: Described are a method and device for determining three-dimensional position information of a surface of a translucent object having a wavelength-dependent transmittance and reflectance characteristics. The method includes illuminating the surface of the translucent object with optical radiation at a predetermined wavelength emitted from a pair of optical sources. Radiation scattered from the surface and below the surface is detected, and a phase of the optical radiation from one of the optical sources relative to a phase of the optical radiation from the other optical source is changed before again detecting the scattered radiation. The predetermined wavelength is selected so that the optical radiation scattered from below the surface and detected provides a substantially constant background intensity with respect to the optical radiation scattered from the surface and detected. Three-dimensional position information of the surface is calculated in response to the detected radiation.

Abstract: An optical measuring instrument for measuring aspheric surfaces includes an optical measuring arm and a multi-axis drive platform. The optical measuring arm provides for illuminating and imaging the aspheric surfaces. The multi-axis drive platform relatively moves the optical measuring arm with respect to the aspheric surfaces through a plurality of subaperture measurement positions. A focus of adjustable focusing optic is maintained at a nominal center of curvature of the aspheric surfaces. A variable optical aberrator adds aberration to an illumination wavefront to match the illumination wavefront to the intended local shape of the aspheric surface. Fitted low-frequency shape information is distinguished from a remainder of the local shape information yielding mid-frequency topographic measurements of the subapertures, which can be assembled to construct a profile measurement of the aspheric surface.

Abstract: A surface profile measurement apparatus, which measures a surface profile of an object, includes a wavefront measurement unit, a driving unit and a rotation unit. The wavefront measurement unit has an image sensor and emits a detecting light. The driving unit has a plurality of stages for moving the object or the wavefront measurement unit. The rotation unit has a rotation axis, is disposed on one of the stages of the driving unit, and holds the object. When measuring the object, the rotation unit rotates the object and the image sensor simultaneously exposes and acquires a measurement data, formed by the detecting light reflected from the object. An alignment method of the surface profile measurement apparatus and an improved sub-aperture measurement data acquisition method are also disclosed.

Abstract: A Fizeau interferometer includes: a reference spherical surface; and a measuring apparatus including an intensity obtaining section and a form calculating section, wherein: a focal point of the reference spherical surface is aligned with a center of curvature of the spherical surface in order to set the center of curvature as a center position, and two positions equidistant from the center position are set as a start position and an end position, the intensity obtaining section obtains the intensity maps of the interferograms at n positions at equal intervals; and the form calculating section measures the form of the spherical surface using a phase analysis method in which a coefficient of the intensity maps of the interferograms at an i-th position and a coefficient of the intensity maps of the interferograms at an (n?i+1)th position have a same value.

Abstract: There is a situation in that, although a speckle interference optical system is effective for clarification of a process of deformation of a specimen, resolution is insufficient, and execution of a phase shift method for improving the resolution involves a costly apparatus. A phase shift image for an initial fringe pattern is acquired, and a phase variation between phase information on an initial image and a next image is derived by a phase shift method. After that, a phase shift image for the next image is computed by calculation based on the acquired information.

Abstract: The present invention provides a measurement apparatus which measures a wavefront of light traveling from a member to be measured, the apparatus including a first reference surface, a second reference surface configured to function as a reference surface for the first reference surface, an optical system configured to form a first interference pattern of light traveling from the member to be measured and light traveling from the first reference surface, and a second interference pattern of light traveling from the first reference surface and light traveling from the second reference surface, a detection unit configured to detect the first interference pattern and the second interference pattern, respectively, and a calculation unit configured to calculate a wavefront of light traveling from the member to be measured based on the first interference pattern and the second interference pattern detected by the detection unit.

Abstract: An optical element having an optical surface (12; 103), which optical surface has an actual shape, the actual shape deviating from a desired shape by maximum 0.2 nm, wherein the desired shape is either: a free-form surface having a deviation from its best-fitting sphere of at least 5 ?m or a substantially rotationally symmetrical surface having a deviation from its best-fitting sphere of at least 0.5 mm.

Abstract: A grazing incidence interferometer includes a light source, a light beam divider configured to divide original light coming from the light source, an illuminator configured to apply measurement light to a measurement subject, a light beam combining module configured to combine the measurement light reflected from the measurement subject with reference light, and a photodetector configure to detect a combined light beam. The grazing incidence interferometer includes an interferometer main body, a stage configured to hold the measurement subject, a moving mechanism capable of moving the interferometer main body along the measurement subject, and an auxiliary reflector disposed on an extension of an axis of movement of the interferometer main body, an auxiliary light beam separator configured to separate auxiliary light from the original light and to apply the auxiliary light to the auxiliary reflector, and an auxiliary photodetector configured to detect the auxiliary light reflected by the auxiliary reflector.

Abstract: Methods and apparatus to perform wavefront analysis, including phase and amplitude information, and 3D measurements in optical systems, and in particular those based on analyzing the output of an intermediate plane, such as an image plane, of an optical system. Measurement of surface topography in the presence of thin film coatings, or of the individual layers of a multilayered structure is described. Multi-wavelength analysis in combination with phase and amplitude mapping is utilized. Methods of improving phase and surface topography measurements by wavefront propagation and refocusing, using virtual wavefront propagation based on solutions of Maxwell's equations are described. Reduction of coherence noise in optical imaging systems is achieved by such phase manipulation methods, or by methods utilizing a combination of wideband and coherent sources.

Abstract: A system for structural analysis of an object, including a device for generating an input light beam arranged so as to cause the input beam generated to interact with at least one portion of the object, and a device for receiving the output light beam resulting from the interaction between the input beam and the object. In this system, the receiving device include a wavefront analyzer arranged so as to measure the electromagnetic field of the wave of the output beam received, and the generating device has a spatial coherence adapted to that of the receiving device. A structural analysis method implementing such a system is presented.

Abstract: An apparatus and associated method for testing a non-symmetric (e.g., phi-polynomial) surface. The apparatus uses several simple (singlet) optical elements (e.g., an Offner null configuration) and a tilted optic under test in combination with an active optical element (e.g., actuated, deformable membrane mirror, optical phase modulator, etc.) that together form a null or quasi-null that allows for conventional null-based interferometry. This solution solves the problem of exceeding the dynamic range of a conventional interferometer when trying to test non-symmetric optical surfaces.

Abstract: An adaptive algorithm is tailored to fit the local fringe frequency of single-frame spatial-carrier data under analysis. Each set of data points used sequentially by the algorithm is first processed with a Fourier Transform to find the local frequency of the fringes being analyzed. That information is then used to adapt the algorithm to the correct phase step thus calculated, thereby optimizing the efficiency and precision with which the algorithm profiles the local surface area. As a result, defects are identified and measured with precision even when the slope of the surface varies locally to the point where the algorithm without adaptive modification would not be effective to measure them. Once so identified, the defects may be measured again locally with greater accuracy by conventional temporal PSI.

Abstract: A method of determining a shape of an optical test surface (14) comprises the steps: adapting a wavefront of a measuring beam (30) to a desired shape of the optical test surface (14) by means of adaptation optics (20) and interferometric measurement of the shape of the optical test surface (14) by means of the adapted measuring beam, irradiating the adapted measuring beam at different angles of incidence onto the optical test surface and respectively measuring the wavefront of the measuring beam after the interaction of the latter with the optical test surface (14), establishing the effect of the adaptation optics (20) upon the interferometric measurement result from the wavefronts measured for the individual angles of incidence, and determining the shape of the optical test surface (14) by removing the established effect of the adaptation optics (20) from the interferometric measurement result.

Abstract: A method of measuring a deviation of an optical test surface from a target shape is provided. The method includes directing an incoming beam of electromagnetic radiation onto the test surface to generate a measuring beam that has interacted with the test surface, causing the ray that has interacted with the test surface to pass through an interferometer on a deviated path, performing an interferometric measurement by superimposing a reference beam with the measuring beam to determine a wave front deviation of the measuring beam from the reference beam, determining a retrace error in the wave front deviation, and correcting the measured wave front deviation by eliminating the retrace error therefrom. The differences in aberrations accumulated by the ray having traveled on the deviated path from fictitious aberrations that would have been accumulated by a ray that had traveled on an undeviated path cause the retrace error.

Abstract: Measuring a shape of an optical surface (14) of a test object (12) includes: providing an interferometric measuring device (16) generating a measurement wave (18); arranging the measuring device (16) and the test object (12) consecutively at different measurement positions relative to each other, such that different regions (20) of the optical surface (14) are illuminated by the measurement wave (18); measuring positional coordinates of the measuring device (16) at the different measurement positions in relation to the test object (12); obtaining surface region measurements by interferometrically measuring the wavefront of the measurement wave (18) after interaction with the respective region (20) of the optical surface (14) using the measuring device (16) in each of the measurement positions; and determining the actual shape of the optical surface (14) by computationally combining the sub-surface measurements based on the measured positional coordinates of the measuring device (16) at each of the measurement

Abstract: A method of aligning at least two wave shaping elements, a method of measuring a deviation of an optical surface from a target shape and a measuring apparatus for interferometrically measuring a deviation of an optical surface from a target shape.

Abstract: An optical system includes an optical interferometer that generates interference phenomena between optical waves to measure multiple distances, thicknesses, and indices of refraction of a sample. An excitation-emission device allows an electromagnetic excitation and emission to pass through an objective in optical communication with the sample. An electromagnetic detector receives the output of the optical interferometer and the excitation-emission device to render a magnified image of the sample. A digital delay generator synchronizes the optical interferometer and excitation-emission device to operate in substantially unison to generate a noninvasive depth of field of the portion of the sample that corrects a plurality of optical aberrations in real-time.

Abstract: A measurement method of the present invention is a measurement method for measuring a shape of a target T from an interference pattern generated by interference between a reflected light of the target and a reference spherical surface. The measurement method includes a first measurement step which positions the target T in a first region 30a at a light source side with respect to a focal position 20 of the reference spherical surface to measure the interference pattern, and a second measurement step which positions the target T in a second region 30b opposite to the first region with respect to the focal position 20 of the reference spherical surface to measure the interference pattern.

Abstract: A beam director subsystem and method for use in a weapons system. The beam director subsystem includes a source of electromagnetic radiation for generating a high energy laser (HEL) beam. The electromagnetic radiation is directed to a secondary mirror that reflects the electromagnetic radiation to a primary mirror for output of the HEL beam. The secondary mirror is generally curved and expands the electromagnetic radiation received from the source prior to outputting the HEL beam from the primary mirror. The subsystem further includes a track telescope coupled to the housing. The track telescope has a track detector configured to receive electromagnetic radiation originating from the HEL and electromagnetic radiation emitted from an illuminator and reflected from an airborne target.

Abstract: A metrology system for measuring aspheric test objects by subaperture stitching. A wavefront-measuring gauge having a limited capture range of wavefront shapes collects partially overlapping subaperture measurements over the test object. A variable optical aberrator reshapes the measurement wavefront with between a limited number of the measurements to maintain the measurement wavefront within the capture range of the wavefront-measuring gauge. Various error compensators are incorporated into a stitching operation to manage residual errors associated with the use of the variable optical aberrator.

Abstract: A system for providing enhanced background rejection in thick tissue contains an aberrating element for introducing controllable extraneous spatial aberrations in an excitation beam path; at least one mirror capable of directing received laser pulses to the aberrating element; an objective; a beam scanner imaged onto a back aperture of the objective so that the beam scanner steers beam focus within the thick tissue; and a detector for recording signals produced by the tissue. An associated method comprises the steps of acquiring two-photon excited fluorescence of thick tissue without extraneous aberrations; introducing an extraneous aberration pattern in an excitation beam path; acquiring two-photon excited fluorescence of the thick tissue having the introduced extraneous aberration pattern; and subtracting the two-photon excited fluorescence with extraneous aberrations from the acquired standard two-photon excited fluorescence of the thick tissue without extraneous aberrations.

Abstract: An optical element having an optical surface (12; 103), which optical surface has an actual shape, the actual shape deviating from a desired shape by maximum 0.2 nm, wherein the desired shape is either: a free-form surface having a deviation from its best-fitting sphere of at least 5 ?m or a substantially rotationally symmetrical surface having a deviation from its best-fitting sphere of at least 0.5 mm.

Abstract: A measurement apparatus which measures spatial coherence in an illuminated plane illuminated by an illumination system, comprises a measurement mask which has at least three pinholes and is arranged on the illuminated plane, a detector configured to detect an interference pattern formed by lights from the at least three pinholes, and a calculator configured to calculate the spatial coherence in the illuminated plane based on a Fourier spectrum obtained by Fourier-transforming the interference pattern detected by the detector.

Abstract: A system and method for dispersion-force-based actuation are disclosed. In some embodiments, a light beam is used to change the dispersion force between two spaced apart surfaces. The change in the dispersion force causes a change in the gap between the surfaces. The actuation system can be used in conjunction with a deformable mirror to provide an improved adaptive optics system.

Abstract: A wavefront measurement apparatus includes a light source that emits a light beam; a light splitting unit that splits the light beam emitted from the light source into an object light beam and a reference light beam; an objective lens that converges the object light beam at a predetermined position of a test object; a light combining unit that superimposes the object light beam returning from the test object and the reference light beam; a light deflecting unit that guides the object light beam returning from the test object towards the light combining unit; an imaging unit that captures an image of an interference pattern formed by combined wavefronts; and a light quantity adjusting filter that adjusts a light quantity, and that is arranged in a optical path between the light deflecting unit and the light combining unit that allows only the transmission of the object light beam from the test object.

Abstract: A method of aligning at least two wave shaping elements, a method of measuring a deviation of an optical surface from a target shape and a measuring apparatus for interferometrically measuring a deviation of an optical surface from a target shape.

Abstract: An optical wavefront sensor comprising a light manipulation device; a detector for detecting light signals having been subjected to the light manipulation device; and a controller coupled to the manipulation device, the controller controlling the manipulation device to function as a lenslet array, each lenslet of the array focussing an incident portion of a wavefront onto the detector. The controller may also control the distance between the detector and the manipulation device. The spatial resolution of Shack-Hartmann sensors can be increased by digital scanning the wavefront with the manipulation device. The wavefront sensing can be dynamic adaptive by setting of parameters of the manipulation device.