Abstract: A system and method for coherent optical inspection are described. In one embodiment, an illuminating beam illuminates a sample, such as a semiconductor wafer, to generate a reflected beam. A reference beam then interferes with the reflected beam to generate an interference pattern at a detector, which records the interference pattern. The interference pattern may then be compared with a comparison image to determine differences between the interference pattern and the comparison image. According to another aspect, the phase difference between the reference beam and the reflected beam may be adjusted to enhance signal contrast. Another embodiment provides for using differential interference techniques to suppress a regular pattern in the sample.

Abstract: This invention provides a dynamic interconnection system which allows to couple a pair of optical beams carrying modulation information. In accordance with this invention, two optical beams emanate from transceivers at two different locations. Each beam may not see the other beam point of origin (non-line-of-sight link), but both beams can see a third platform that contains the system of the present invention. Each beam incident on the interconnection system is directed into the reverse direction of the other, so that each transceiver will detect the beam which emanated from the other transceiver. The system dynamically compensates for propagation distortions preferably using closed-loop optical devices, while preserving the information encoded on each beam.

Abstract: A wavefront measuring device is disclosed which is capable of measuring an average wavefront and the retardation of a lens including birefringence. The measuring device includes a light source for emitting a linearly polarized light; a polarization orientation setting member for switching the polarization orientation of the light flux from the light source between at least two orientations; a light synthesizing member for synthesizing the light flux after passing the light fluxes through an object to be measured and a reference surface; an analyzer for switching the polarization orientation so as to pass only the same polarized component as the polarized light incident on the object to be measured; an image pickup member for detecting interference information of the light flux obtained through the analyzer; and a calculating section for calculating the average wavefront and/or the retardation of the object to be measured.

Abstract: A common-path, point-diffraction, phase-shifting interferometer uses a half wave plate having a diffractive element, such as pin hole. A coherent, polarized light source simultaneously generates a reference beam from the diffractive element and an object beam from remaining portions of the light going through the half wave plate. The reference beam has a nearly spherical wavefront. Each of the two beams possesses a different polarization state. The object and reference beams are then independently phase modulated by a polarization sensitive phase modulator that shifts phase an amount depending on applied voltage and depending on polarization state of the incident light. A polarizer is then used to provide the object and reference beams in the same polarization state with equal intensities so they can interfere to create an interferogram with near unity contrast.

Abstract: An arrangement and method for reliably finding the wave form extrema of interference signals produced by a quadrature phase shift interferometer (QPSI) takes advantage of the quadrature property of I and Q signals. The zero-crossing points in the I and Q signals are determined. Peak detection is performed for peaks and valleys in the Q signal in close proximity to the zero-crossing points in the I signal, and for peaks and valleys in the I signal in close proximity to the zero-crossing points in the Q signal. These represent the maximum and minimum points of the I and Q signals. From these points, intensity envelopes are created and QPSI phase wrapping is performed to determine the phase angle and ultimately, out-of-plane displacement may be determined.

Abstract: The present invention concerns an interferometer comprising: an optical body adapted in operation to mount a measurement area comprising a film which is capable of acting as a two dimensional environment for surface plasmons and an adjacent reference area; an optical beam generation means for irradiating the reference and measurement areas with radiation capable of generating surface plasmon resonance; optical means for combining radiation reflected from the reference and measurement areas, and pixelated detection means for generating data representing two dimensional images of the combined radiation beams.

Abstract: An arrangement and method of measuring head-media spacing modulation (HMS_Wq) removes the portion of out-of-plane motion caused by disk modes from the dynamic measurements of hard disk surface topography. Employing time-domain measurement techniques, circumferential surface topographical measurements are made for a hard disk surface. A boundary wavelength is determined, and a first partial HMS_Wq value is determined based upon measurements taken at a first disk rotational speed. A second partial HMS_Wq value is determined based upon measurements taken at a second disk rotational speed. The first and second partial HMS_Wq values are combined to provide a complete and accurate HMS_Wq value, taking advantage of the principle that the disk mode location in the spatial domain topography spectrum converted from the measured time-domain data shifts when the disk rotation speed is changed during the measurement.

Abstract: The tilted relationship between the reference and test mirrors of a Fizeau interferometer is used to spatially separate the reflections from the two surfaces. The separate beams are filtered through a spatial polarization element that provides different states of polarization to the beams. The beams are subsequently recombined to form a substantially collinear beam that is processed using a spatial-phase-shift interferometer that permits quantitative phase measurement in a single video frame. Alternatively, two beams with orthogonal polarization are injected into the Fizeau cavity at different angles, such that after reflection from the reference and test optics they are substantially collinear. Unwanted reflections are blocked at the focal plane through the use of a circular aperture. Short coherence length light and a delay line may be used to mitigate stray reflections, reduce measurement integration times, and implement temporal phase averaging.

Abstract: A polarizing point-diffraction plate is used to produce common-path test and reference wavefronts with mutually orthogonal polarizations from an input wavefront. The common-path test and reference wavefronts are collimated, phase shifted and interfered, and the resulting interferograms are imaged on a detector. The interference patterns are then processed using conventional algorithms to characterize the input light wavefront.

Abstract: A method and arrangement for measuring head-media spacing modulation (HMS_Wq) employs a profilometer to measure the surface topography of a disk. A cumulative power spectral density (PSD) distribution is generated from the measured surface topography. Discontinuities and steps are identified in the PSD distribution. The discontinuities and steps are removed to create a corrected PSD distribution. A noise free spectrum is then reconstructed from the corrected PSD distribution.

Abstract: Interference measuring apparatus for detecting a plurality of different interference phase signals. The apparatus has a light dividing member for dividing linearly polarized light beams superposed one upon another into a plurality of light beams. The apparatus also includes a light transmitting member with a plurality of light passing portions having different light transmitting properties in conformity with the incidence positions of the plurality of light beams divided by the light dividing member. In addition, the apparatus has a polarizing plate to receive the plurality of light beams that passed through the light transmitting member.

Abstract: A method and apparatus for using a dual-beam interferometer to test surface flatness is provided. The interferometer directs two beams focused at distinct points on a testing surface, such as the surface of a magnetic recording disc. An offset distance “d” between the two beams is provided on the target surface. In the present invention, the separation distance “d” is adjustable. The feature of adjustable separation distance in the interferometer allows the interferometer to meet the different spatial frequency requirements of various applications. In operation, first and second reflected beams are returned to an intensity beam splitter, where they are split and then recombined into two new beams of substantially equal intensity. The second of the two new light beams is constructed by the interference of half intensity of the first and half intensity of second beams, and is sent to a photodiode.

Abstract: A common-path, point-diffraction, phase-shifting interferometer uses a half wave plate having a diffractive element, such as pin hole. A coherent, polarized light source simultaneously generates a reference beam from the diffractive element and an object beam from remaining portions of the light going through the half wave plate. The reference beam has a nearly spherical wavefront. Each of the two beams possesses a different polarization state. The object and reference beams are then independently phase modulated by a polarization sensitive phase modulator that shifts phase an amount depending on applied voltage and depending on polarization state of the incident light. A polarizer is then used to provide the object and reference beams in the same polarization state with equal intensities so they can interfere to create an interferogram with near unity contrast.

Abstract: Diffraction grating based fiber optic interferometric systems for use in optical coherence tomography, wherein sample and reference light beams are formed by a first beam splitter and the sample light beam received from a sample and a reference light beam are combined on a second beam splitter. In one embodiment, the first beam splitter is an approximately 50/50 beam splitter, and the second beam splitter is a non 50/50 beam splitter. More than half of the energy of the sample light beam is directed into the combined beam and less than half of the energy of the reference light beam are directed into the combined beam by the second beam splitter. In another embodiment, the first beam splitter is a non 50/50 beam splitter and the second beam splitter is an approximately 50/50 beam splitter. An optical circulator is provided to enable the sample light beam to bypass the first beam splitter after interaction with a sample.

Abstract: The method for determining local structures in optical materials, especially crystals, includes observing schlieren visually in a material to be tested with divergent white light in a first step; measuring birefringence of polarized laser light in the material to determine local defects and structure faults in the material with a spatial resolution of 0.5 mm or better in a second step if the material is judged to be suitable in the first step and then interferometrically measuring the material to determine the faults in the material by interferometry in a third step if the material is judged to be suitable in the first and second steps. This method can be part of a method for making optical components, especially for microlithography.

Abstract: A method of generating a part program for use in an image-measuring system and in an image-measuring instrument is provided. The method can be employed easily by an operator without complicated operations to efficiently generate a part program for a CNC image-measuring instrument. This method facilitates the operator to visually identify a work to be measured, through reading CAD data of the work; setting measurement conditions and a positioning coordinate system; calculating a size of the work when it is practically imaged; and displaying an image of the CAD data with the same size. Then, through setting tolerance information; and selecting an objective graphic to be measured, an edge detection tool is placed for a graphic element of the objective graphic selected.

Abstract: An interferometric measuring device for measuring the shape of a surface of an object having a radiation source which emits a short-coherent radiation, a beam splitter for forming an object beam which is directed via an object light path to the object, and a reference beam which is directed via a reference light path to a reflective reference plane, and having an image converter which picks up the radiation reflected back by the surface and the reference plane and brought to interference, and sends it to an analyzing device for determining a measuring result pertaining to the surface, the optical length of the object light path being changed relative to the optical length of the reference light path for analyzing the interference peak.

Abstract: Described is a method for screening for alterations in exocytosis of a population of cells. The cells are sorted by a FACS machine by assaying for alterations in at least three of the properties selected from the group consisting of light scattering, fluorescent dye uptake, fluorescent dye release, annexin granule binding, surface granule enzyme activity, and the quantity of granule specific proteins. Methods for screening for bioactive agents capable of modulating exocytosis in a cell are also described. The methods provide for reduced background and increased specificity without increasing the time or steps involved in assaying for exocytosis.

Abstract: An integrated imaging element for an interferometer generates at least one image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density polarizing array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated because multiple phase-shifted interference image information for a small region of an object is provided within a small region on the detector device.

Abstract: An integrated imaging element for an interferometer generates at least one interference image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density relative retarder array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard-like pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated.

Abstract: A method and apparatus for using a dual-beam interferometer to test surface flatness is provided. The interferometer directs two beams focused at distinct points on a testing surface, such as the surface of a magnetic recording disc. An offset distance “d” between the two beams is provided on the target surface. In the present invention, the separation distance “d” is adjustable. The feature of adjustable separation distance in the interferometer allows the interferometer to meet the different spatial frequency requirements of various applications. In operation, first and second reflected beams are returned to an intensity beam splitter, where they are split and then recombined into two new beams of substantially equal intensity. The second of the two new light beams is constructed by the interference of half intensity of the first and half intensity of second beams, and is sent to a photodiode.

Abstract: An interferometric measuring device for measuring the shape of a surface of an object has a radiation source which emits a short-coherent radiation, a beam splitter for forming an object beam which is directed via an object light path to the object and a reference beam which is directed via a reference light path to a reflective reference plane. The interferometric measuring device also has an image converter which picks up the radiation that has been brought to interference and reflected back from the surface and the reference plane and sends it to an analyzing device for determining a measurement result pertaining to the surface. To analyze the interference peak by scanning, the optical length of the object light path is altered relative to the optical length of the reference light path, or an intermediate image of the surface produced in the object light path is scanned.

Abstract: An optical arrangement of the Michelson interferometer type having a measuring arm for measuring optical properties of at least two mutually spaced regions in an optically transparent and/or diffusive object. A reference arm has a path length variation unit which generates a periodic change in path length for the radiation in the reference arm. Arranged in the measuring arm upstream of the object is a detour unit. The detour unit imparts a detour which is larger than at least one second measuring beam into at least one measuring beam. The detour unit selects a detour to be equal to a distance between regions to be measured in the object. Using the optical arrangement the object is irradiated with the aid of a number of measuring beams corresponding to the number of regions. In each case two measuring beams have an optical path difference which corresponds to a geometrical distance between two regions.

Abstract: An arrangement and method of measuring head-media spacing modulation (HMS_Wq) removes the portion of out-of-plane motion caused by disk modes from the dynamic measurements of hard disk surface topography. Employing time-domain measurement techniques, circumferential surface topographical measurements are made for a hard disk surface. A boundary wavelength is determined, and a first partial HMS_Wq value is determined based upon measurements taken at a first disk rotational speed. A second partial HMS_Wq value is determined based upon measurements taken at a second disk rotational speed. The first and second partial HMS_Wq values are combined to provide a complete and accurate HMS_Wq value, taking advantage of the principle that the disk mode location in the spatial domain topography spectrum converted from the measured time-domain data shifts when the disk rotation speed is changed during the measurement.

Abstract: Interferometric method(s) and apparatus for accurately measuring aspherical surfaces and transmitted wavefronts, particularly of the type having relatively large diameters and departure employed in lithographic applications used in the fabrication of integrated circuits and the like. An interferometer, preferably of the Fizeau type, is provided with at least one aspherical reference surface that is positioned adjacent the test optic. The test optic can be either rotationally or non-rotationally symmetric, a reflecting aspherical test surface, or a refracting system that is illuminated by an aspherical wavefront or produces a transmitted aspherical wavefront. In any case, the departure of the test optic from its intended performance is ultimately determined. The aspherical reference surface is illuminated by an aspherical wavefront provided by upstream optics structured so that the incident aspherical wavefront propagates normal to the aspherical reference surface across its entire surface.

Abstract: The present invention provides a continuous-zoom imaging device of an interferometer. Reflected lights of a reference plane and a test plane interfere with each other to generate an interference pattern. A collimation device converts a parallel light of the interference pattern into a convergent light. An optical path adjustment means guides the light to a polarizing beam splitter. A continuous-zoom device adjusts the magnification ratio of the interference pattern on the imaging passageway and to output an object image, which is then imaged on a charge-coupled device. The present invention can improve the quality of the interference pattern without using any rotating diffuser, and thus has the characteristics of reduced number of components, lowered cost, and shrunk volume. Besides, the present invention can utilize a joint device to connect the continuous-zoom device and an attenuator so as to achieve automatic light adjustment and convenient operation.

Abstract: A measurement system (10) for accurately measuring the surface geometry of a part (32) in three dimensions includes a laser (12) for emitting a laser beam (14). The laser beam (14) is transmitted to a birefringent crystal (16) which splits the laser beam (14) into a pair of beams (18,20). The pair of beams (18,20) are then subjected to a phase shift by a liquid crystal system (24) as controlled by a computer (26). The pair of beams (18,20) are then expanded in order to form a fringe pattern (30) on the surface of the part (32) to be measured.

Abstract: The invention relates to optical engineering, in particular to methods for measuring a microrelief, the distribution of optical material constants of a near-surface layer and can be used for microelectronic engineering, nanotechnology, material science, medicine and biology. The aim of the invention is to improve spatial resolution for mearsuring geometrical parameters of the relief and the distribution of the optical material constants, extend the range of defined constants including optical anisotropy constants, significantly increasing the accuracy of definition of the material constant and extending the number of objects studied. The inventive method for measuring microrelief and optical characteristics of the near-surface layer and a modulation interference microscope for carrying out said method are also disclosed.

Abstract: A method and apparatus for interferometnc measurement of a medium surface is disclosed. More particularly, a quadrature phase shift interferometer and a process for unwrapping phase are described. The interferometer has a reduced number of optical components though yields results sufficient to measure surface of a hard disc for final inspection. Defects on such a surface are characterized by their out-of-plane displacement with nanometer resolution.

Abstract: A detection apparatus includes a differential interference contrast microscope, a device for changing the amount of retardation between the two polarized components, a device for photographing the image of an object to be observed, and a device for performing a calculation with respect to the image captured by this photographing device. In the detection apparatus, amounts of retardation between two polarized components split in an illumination optical system of the differential interference contrast microscope are detected to form two differential interference contrast images relative to the object in which the amounts of retardation between the polarized components are equal, but have different signs. Subsequently, in the two differential interference contrast images, a differential calculation and a summed calculation are performed with regard to respective corresponding pixels to obtain a differential image and a summed image.

Abstract: An integrated imaging element for an interferometer generates at least one interference image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density relative retarder array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard-like pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated.

Abstract: An integrated imaging element for an interferometer generates at least one image that includes multiple interference portions with different relative phase shifts interleaved in a pattern having a high spatial frequency in the image. The interleaved pattern is at least partially determined by the pattern of a high density polarizing array used in the integrated imaging element. In various embodiments, the multiple interference portions are interleaved in a checkerboard pattern across the entire surface of a detector device. As a result, various non-common mode errors present in various interferometers that generate separate non-interleaved images for each relative phase are reduced or eliminated because multiple phase-shifted interference image information for a small region of an object is provided within a small region on the detector device.

Abstract: An apparatus for measuring the surface shape of the surface to be measured of an optical system to be measured includes a rotary stage holding the optical system to be measured thereon and rotatable about the optical axis of the optical system to be measured, a device for detecting the rotation azimuth of the rotary stage, an irradiating optical system for sequentially applying a coherent light beam to the plurality of measuring diameter positions of the surface to be measured of the optical system to be measured held on the rotary stage, a light receiving element for detecting the reflected light of the coherent light beam from the surface to be measured as an interference signal, and a calculating system for effecting the measurement of the surface shape of the surface to be measured on the basis of the result of the detection of the interference signal at each of the plurality of measuring diameter positions of the surface to be measured and the result of the detection by the rotation azimuth detecting dev

Abstract: The invention measures a thickness variation at a high accuracy around a wide range of a thin plate by a comparatively large spot diameter between 0.5 mm and 2 mm. A polarization beam splitter separating a laser beam emitted from a laser generator and transmitting through an isolator into a measurement light and a reference light is provided. A quarter wavelength plate is provided between the polarization beam splitter and a measurement surface, and between the polarization beam splitter and a reference surface. A focusing and reflecting means for focusing and reflecting the measurement light reflected by the measurement surface and reflected by the polarization beam splitter, and the reference light reflecting by the reference surface and transmitting through the polarization beam splitter is provided. A half mirror reflecting the measurement light and the reference light which return from the polarization beam splitter is provided.

Abstract: The present invention provides a continuous-zoom imaging device of an interferometer. Reflected lights of a reference plane and a test plane interfere with each other to generate an interference pattern. A collimation device converts a parallel light of the interference pattern into a convergent light. An optical path adjustment means guides the light to a polarizing beam splitter. A continuous-zoom device adjusts the magnification ratio of the interference pattern on the imaging passageway and to output an object image, which is then imaged on a charge-coupled device. The present invention can improve the quality of the interference pattern without using any rotating diffuser, and thus has the characteristics of reduced number of components, lowered cost, and shrunk volume. Besides, the present invention can utilize a joint device to connect the continuous-zoom device and an attenuator so as to achieve automatic light adjustment and convenient operation.

Abstract: In a phase interference detecting system with use of an interferometer, a height from a reference surface on a measurement surface is detected by receiving interference components of reflection lights from the reference surface and a measurement surface, which lights are divided from a laser beam and are modulated with a frequency being different therefrom, i.e., by irradiating only one laser beam. A light detector is constructed with a line type sensor for receiving the interference components of the reflection lights, and has a plurality of pixel groups for common use of a measurement surface and a plurality of pixel groups for exclusive use of a reference surface, which are provided at both thereof.

Abstract: An evaluation light 100 from a light source 1 is split to obtain a divided evaluation signal 120 and a reference signal 110, the divided evaluation signal 120 and the reference signal 110 being shone, respectively, onto a sample surface 32 and a reference surface 11 that is made of the same material as the sample, after which a reflected divided evaluation signal 121 and a reflected reference signal 111, which are reflected respectively on the sample surface 32 and the reference surface 11, are caused to interfere for analysis of the sample surface 32.

Abstract: A conventional interleaver, based on a stack of waveplates, relies on the orientation and the birefringence of the waveplates to differentiate the polarizations of one set of channels from another, so that the one set of channels can be separated from the other. The present invention relates to a virtual waveplate that is used to replace a birefringent waveplate. A virtual waveplate imposes a phase delay between the extraordinary ray and the ordinary ray by separating one from the other and differentiating the actual path lengths taken thereby, before recombining them. An interleaver constructed with the virtual waveplates of the present invention can be substantially a-thermal and potentially chromatic dispersion free.

Abstract: An interferometer or an interference position measuring device is constituted so that a low coherency light source (multi-mode semiconductor layer) or a plurality of light sources with different wavelengths are used as a light source, a light flux is split into two light fluxes in a light transmitting member, one light flux (reference light flux) is emitted to a reference mirror fixed to an optical head, and the other light flux is emitted to an object to be measured which moves or displaces, the respective reflected light fluxes are multiplexed in the transmitting member so that an interference light flux is obtained, a specified wavelength light is extracted by a wavelength selecting filter through which only a specified wavelength light transmits so as to be detected by a light receiving element.

Abstract: A dual beam interferometer device is disclosed that enables moving an optics module in a direction, which changes the path lengths of two beams of light. The two beams reflect off a surface of an object and generate different speckle patterns detected by an element, such as a camera. The camera detects a characteristic of the surface.

Abstract: A shape measuring apparatus is provided, which is capable of accurately measuring the shape of an observed surface of an object to be measured and which can be designed to be compact in size and light in weight. An optical reflected image from an observed surface of an object to be measured and an optical reflected image from a reference surface are interfered with each other to generate interference light. The interference light is dispersed into at least three beams, which are shifted in phase by respective predetermined phase shifting amounts. At least three interference fringe images are simultaneously captured by at least one image pickup device which is smaller in number than the interference fringe images.

Abstract: The invention measures a thickness variation at a high accuracy around a wide range of the thin plate by a comparatively large spot diameter between 0.5 mm and 2 mm. A polarization beam splitter separating a laser beam emitted from a laser generator and transmitting through an isolator into a measurement light and a reference light is provided. A quarter wavelength plate is provided between the polarization beam splitter and a measurement surface, and between the polarization beam splitter and a reference surface. A focusing and reflecting means for focusing and reflecting the measurement light reflecting by the measurement surface and reflecting by the polarization beam splitter, and the reference light reflecting by the reference surface and transmitting through the polarization beam splitter is provided. A half mirror reflecting the measurement light and the reference light which return from the polarization beam splitter is provided.

Abstract: A measurement system (10) for accurately measuring the surface geometry of a part (32) in three dimensions includes a laser (12) for emitting a laser beam (14). The laser beam (14) is transmitted to a birefringent crystal (16) which splits the laser beam (14) into a pair of beams (18,20). The pair of beams (18,20) are then subjected to a phase shift by a liquid crystal system (24) as controlled by a computer (26). The pair of beams (18,20)are then expended in order to form a fringe pattern (30) on the surface of the part (32) to be measured.

Abstract: A differential interference contrast (DIC) microscope system is provided comprising: (a) an illumination source for illuminating a sample; (b) a lens system for viewing the illuminated sample, including an objective, defining an optical axis; (c) a DIC prism having a shear angle for separating an input light beam into two, orthogonally polarized output beams that are separated by the shear angle; (d) at least one detector system for receiving a sample image; (e) a mechanism for modulating the phase of the DIC image; (f) a mechanism for selecting the wavelength of light used in acquiring at least two sets of DIC data taken in a single shear direction; and (g) a mechanism for manipulating the multiple DIC data sets to synthesize data that appear to have been taken at a longer synthetic wavelength. The various approaches disclosed and claimed herein permit the measurement of surfaces with a greater slope than is possible with a single wavelength or shear distance.

Abstract: A wavefront measuring device is disclosed which is capable of measuring an average wavefront and the retardation of a lens including birefringence. The measuring device includes a light source for emitting a linearly polarized light; a polarization orientation setting member for switching the polarization orientation of the light flux from the light source between at least two orientations; a light synthesizing member for synthesizing the light flux after passing the light fluxes through an object to be measured and a reference surface; an analyzer for switching the polarization orientation so as to pass only the same polarized component as the polarized light incident on the object to be measured; an image pickup member for detecting interference information of the light flux obtained through the analyzer; and a calculating section for calculating the average wavefront and/or the retardation of the object to be measured.

Abstract: A light interception structure for an automatic focus detection surveying instrument includes a telescopic optical system having an objective optical system and an ocular optical system, a beam splitting optical element which splits object light transmitted through the objective optical system from the telescopic optical system, and a focus detector having a light receiver which receives the object light split by the beam splitting optical element. One surface of the beam splitting optical element upon which external light entering the telescopic optical system through the ocular optical system is first made incident after the external light passes through or is reflected by a beam splitting surface of the beam splitting optical element is subject to an anti-reflection treatment.

Abstract: A method and an apparatus capable of filtering based on desired spatial frequency characteristics without loss of Fourier spectrum frequency components, and of matched filtering of high recognition capability without losing functions of data recording and reconstruction as well as high-speed transmission and retrieval features and mass storage capacity characteristic of a holographic memory. Fourier transformed object light with 0° polarization of a target image is stored as a hologram using reference light having a spatial polarization distribution such that a daughter wavelet on scale m has 90° polarization. The hologram is retrieved using the Fourier transformed object light with 0° polarization. The hologram yields diffracted light in the form of a spatial frequency component which corresponds to scale m and is polarized 90° with respect to the other spatial frequency components. A polarizing element is used to extract only the spatial frequency component corresponding to scale m.

Abstract: A technique and apparatus for non-contact scanning measuring of the dynamic parameters of micro and macro devices using an acousto optic scanning laser vibrometer are disclosed. The system includes an acousto optic deflector to induce scanning in the laser beam. The apparatus also includes either a heterodyne or homodyne system for laser scanning. The heterodyne detection technique involves two acousto optic deflectors driven by a common signal generator. The invention may include an interference technique in which the measuring scanning beam emitted by the acousto optic deflector interferes with the reference-scanning beam. For some applications, this acts as a second measuring beam. With this technique, the frequency shift induced in the laser beam on scanning with the acousto optic deflector is canceled due to fact that the two acousto optic deflector are of same specification and driven by a common driver. The invention may also include an apparatus and technique for homodyne detection.

Abstract: An apparatus and method for performing optical coherence domain reflectometry. The apparatus preferably includes a single output light source to illuminate a sample with a probe beam and to provide a reference beam. The reference beam is routed into a long arm of an interferometer by a polarizing beamsplitter. A reflected beam is collected from the sample. A 90° double pass polarization rotation element located between the light source and the sample renders the polarizations of the probe beam and reflected beam orthogonal. The polarizing beamsplitter routes the reflected beam into a short arm of the interferometer. The interferometer combines the reference beam and the reflected beam such that coherent interference occurs between the beams. The apparatus ensures that all of the reflected beam contributes to the interference, resulting in a high signal to noise ratio.

Abstract: Presented is a speckle interferometer for measuring displacement of an optically irregular surface of a specimen having, a laser for producing a beam of coherent radiation, an adjustable polarizing beam splitter for dividing the radiation into a first portion of the radiation and into a second portion of the radiation. The reflected radiation is then passed through a pair of collimating lenses onto the optically rough surface of the specimen. The reflection off of the specimen is captured by an imaging system that processes the reflection to measure strains on the surface.