Abstract: A point source module is provided, comprising: a Shack cube comprising a beam splitter cube with an attached spherical reference surface defining a reference arm; a test arm that is associated with transmission of optical radiation from a source to a sample; a point source of optical radiation whose emissions traverse both the reference arm and the test arm; and a detector associated with a surface of the beam splitter cube and receiving optical radiation from both the reference arm and the test arm and comprising a detector arm, an objective lens associated with the test arm, or both. Further, a method of aligning the point source module is provided, along with a method of using the point source microscope is provided. The apparatus and methods provide a compact, robust device and technique for measuring or locating optical or mechanical datum of parts that are being manufactured or assembled.

Abstract: Fringe image data obtained by use of the phase shift method is Fourier-transformed, so as to determine the carrier frequency and the complex amplitude which occur due to the deviation between the respective wavefronts from the object to be observed and a reference. According to the carrier frequency and the complex amplitude, the amount of translational displacement of phase shift and the amount of inclination are detected, so as to correct the results determined by the phase shift method. Thus, the influences of errors in the amount of inclination/amount of displacement in the phase shift element can be eliminated easily.

Abstract: Systems and methods for near-field, interferometric microscopy are disclosed in which a mask having an array of sub-wavelength apertures is used to couple near-field probe beams to a sample. The periphery of the mask further includes one or more larger apertures to couple light to the sample that forms the basis of an interferometric signal indicative of the relative distance between the mask and the sample. The interferometric signal can be the basis of a control signal in a servo system that dynamically positions the mask relative to the sample.

Abstract: Wavefront information for an optical system is calculated based on the intensity of an image of a plurality of gratings having different periods and orientations taken from at least two different planes a predetermined distance apart. The image of a plurality of gratings having different spatial frequencies or periods and orientations, the location of which are precisely known, are imaged in a nominal focal plane of the optical system, and, preferably, in two additional planes displaced a predetermined distance from the nominal focal plane. The phase shift, if any, from a fundamental frequency of the image intensity, is determined based on the known location of the grating and the grating image intensity. The grating image intensity is detected and measured in a first detection plane in a nominal focal plane and in a second detection plane a predetermined distance from the nominal focal plane. From these measurements wavefront information is calculated.

Abstract: The invention features methods and systems for interferometrically profiling a measurement object having multiple reflective surfaces, e.g., to profile a selected one of the multiple reflective surfaces. The methods and systems involve: positioning the measurement object within an unequal path length interferometer (e.g., a Fizeau interferometer) employing a tunable coherent light source; recording an optical interference image for each of multiple wavelengths of the light source, each image including a superposition of multiple interference patterns produced by pairs of wavefronts reflected from the multiple surfaces of the measurement object and a reference surface; and extracting phases of a selected one of the interference patterns from the recorded images by using a phase-shifting algorithm that is more sensitive (e.g.

Abstract: An improved wavefront sensor for characterizing phase distortions in incident light including optical elements that spatially sample the incident light and form a dispersed spot with a fringe pattern corresponding to samples of the incident light. An imaging device captures an image of the dispersed spot with said fringe pattern formed by said optical elements. And an image processor that analyzes the spectral components of the fringe pattern of a given dispersed spot to derive a measure of the local phase distortion without ambiguity in the corresponding sample of incident light. The optical elements may comprise refractive elements, diffractive elements or a combination thereof (such as a grism). The wavefront sensor may be part of an adaptive optic system (such as a large-aperture space telescope) to enable the measurement and correction of large phase steps across adjacent mirror segments of a deformable mirror.

Abstract: A method and apparatus for wavefront analysis including obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase, obtaining a plurality of intensity maps of the plurality of phase changed transformed wavefronts and employing the plurality of intensity maps to obtain an output indicating the amplitude and phase of the wavefront being analyzed.

Abstract: To provide a surface profile measurement apparatus capable of efficient measurement of the surface profile of an object. A diamond indenter (16) is movably mounted. The tip end of the diamond indenter (16) is irradiated by light, and the light reflected by the tip end (17) is condensed through a lens (46). The condensed light is observed by a photo sensor (42) for measurement of the curvature radius of the tip end (17). Meanwhile, the light reflected by the tip end (17) and the light reflected by a reference body (66) together cause an interference fringe. The interference fringe is observed by a CCD camera (44) to measure the surface profile of tip end (17).

Abstract: Apparatus and methods are disclosed for measuring a surface profile and/or a wavefront aberration of a target object. Exemplary target objects include mirrors, lenses, and lens systems. A representative apparatus configuration includes a light source, a light-flux optical system, a phase-state changing device, a detector, and a computer. The light-flux optical system (i) produces, from a light flux produced by the light source, measurement-light and reference-light fluxes, (ii) directs the measurement-light flux to the target object, (iii) provides the reference-light flux with a standard wavefront, and (iv) establishes interference between the two light fluxes. The phase-state changing device changes a phase state of the reference-light flux and/or the measurement-light flux relative to a respective standard. The detector detects interference fringes.

Abstract: A flatness measuring apparatus measures flatness of a substrate on which a specific pattern is to be formed by adjusting focus to a forming reference flat plane obtained based upon height data corresponding to specific measuring points of the substrate. The flatness measuring apparatus includes: an arithmetic operation device that obtains height data at predetermined measuring points of the substrate, determines a flatness judging criterion flat plane based upon height data at measuring points located at positions at which the specific measuring points are located through an arithmetic operation, determines quantities of displacement at the predetermined measuring points relative to the flatness judging criterion flat plane through an arithmetic operation, and measures the flatness of the substrate based upon the quantities of displacement.

Abstract: An apparatus and a method are provided which allow two opposite plane surfaces of a body to be interferometrically measured simultaneously using light from a single light source. From a parallel light beam (P) produced by a light source (1) partial light beams (A, B) having positive and negative diffraction angles are produced using a beam splitter (8) in the form of a diffraction grating. The partial light beams strike the respective surfaces (90, 91) of the body (9) to be measured and are reflected thereat. The reflected partial light beams (A, B) are interfered with the throughgoing partial light beam (P) having an order of diffraction of zero and the thus produced interference patterns are digitized and subtracted from each other, whereby the parallelism of both surfaces (90, 91) of the body can be determined.

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: In a fringe analysis method using Fourier transform, fringe image data is determined in a state where a wavefront from an object and a wavefront from a reference are relatively inclined with respect to each other by a minute amount, and a carrier fringe occurring due to this inclination is superposed on a fringe occurring due to wavefront information of the object. The inclination is set such that the carrier frequency occurring due to the inclination is a predetermined multiple of the basic frequency determined by the wavefront information of the object and observing means.

Abstract: A method of manufacturing a projection optical system (37) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface (38) of an optical element (36) which is a component in the projection optical system is measured by causing interference between light from the optical surface (38) and light from an aspheric reference surface (70) while the optical test surface (38) and said reference surface (70) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured.

Abstract: In an optical system for an oblique incidence interferometer, first and second prisms are used as luminous flux dividing means and luminous flux combining means, respectively. Reference light and measurement light are separated from each other at a surface where collimated coherent light enters or exits from the first prism, whereas the reference light and measurement light are combined together at a surface where the measurement light enters or exits from the second prism.

Abstract: An apparatus and a method are provided which allow two opposite plane surfaces of a body to be interferometrically measured simultaneously using light from a single light source. From a parallel light beam (P) produced by a light source (1) partial light beams (A, B) having positive and negative diffraction angles are produced using a beam splitter (8) in the form of a diffraction grating. The partial light beams strike the respective surfaces (90, 91) of the body (9) to be measured and are reflected thereat. The reflected partial light beams (A, B) are interfered with the throughgoing partial light beam (P) having an order of diffraction of zero and the thus produced interference patterns are digitized and subtracted from each other, whereby the parallelism of both surfaces (90, 91) of the body can be determined.

Abstract: An optical method and system for measuring three-dimensional surface topography by providing high resolution contour measurements of an object using interferometric methods. The invention utilizes co-sight detector technology to provide at least three independent images of exactly the same object location, with a known fringe pattern optically introduced to each of the images. Each of the fringe patterns have a known phase difference relative to the phase appearing on each of the other images. Furthermore, the images have the same perspective relative to the object and may be collected simultaneously. This simultaneous collection of multiple phase images allows very high speed 3D data generation. Previous limitations of phase shift technology such as sample motion and vibration can be eliminated. The method may use continuous or strobed illumination.

Abstract: In an interferometer optical system comprising a reference standard having an entrance surface on which a luminous flux from a light source is incident and a reference plane on which the luminous flux entering from the entrance surface is obliquely incident, an angle within the range of 10° to 30° is formed between the entrance surface and reference plane of the reference standard.

Abstract: An improved lateral shearing interferometer system for use with an original optical wavefront and a displaced optical wavefront having a phase difference from the original optical wavefront is disclosed. It comprises a lateral shearing interferometer that responds to the original optical wavefront and the displaced optical wavefront and develops an optical interference pattern representative of the optical phase differences. An optical detector located at the focal plane of the optical interference pattern provides a selective array of electrical signals representative of separated portions of the interference pattern. A data processor is programmed to indicate the separated portions of said interference pattern, which has pixels in non-adjacent locations in odd rows and no pixels in even rows. The pixels correspond to locations of actuators for correcting the phase difference.

Abstract: A two-beam interferometer illuminates a sample surface with light at grazing incidence angles for the purpose of analyzing a surface characteristic such as surface topography. The interferometer includes a diffractive-optic beam splitter, which separates an incoming light beam into measurement and reference beams and a diffractive-optic beam combiner, which produces an output beam by interfering portions of the reference beam with reflected portions of the measurement beam. Those portions of the reference wavefront and the measurement wavefront that interfere originate from substantially the same portion of the initial illumination wavefront.

Abstract: A full-field, geometrically-desensitized interferometer (GDI) instrument incorporates a combination of reflecting and refracting optics to perform beam splitting and recombining operations for surface profilometry. Symmetrically-positioned inbound and outbound optical subassemblies typically are arranged to direct inbound collimated beams from a light generator to the profiled surface of a test object and to direct outbound reflected beams to an imaging device as a single recombined outbound interference beam. Every point on the detector has a corresponding point on the object from which reflected illumination originated from both reflected beams. The optical path difference between the two inbound beams or between the two reflected outbound beams can be substantially independent of field position.

Abstract: There is disclosed a method for measuring the shape of objects which might have surface discontinuities using projected fringes, in which method the pitch of the fringes is varied over time and a sequence of phase-stepped images is recorded from which a three-dimensional complex intensity is calculated and either the phase of the distribution is unwrapped along the time axis or the Fourier transform of the distribution is calculated along the time axis.

Abstract: In machining such as lapping and polishing, the detection of interference fringes is carried out during the machining, and an interference fringe image of a size sufficient to determine the surface profile is obtained. The workpiece is mounted on a machining mechanism base, and a lapping tool mounted on the workpiece is rotated. The lapping tool has a measurement window and an interferometer is provided above the workpiece via the lapping tool. The interferometer captures plural interference fringe images at different positions of the measurement window, each including fringe images of the measurement window areas and shadow images of the areas obstructed by the lapping tool. The shadow images are eliminated from the interference fringe images on the basis of the reference value for the optical intensity of the shadow image, and the fringe images of the measurement window areas are synthesized to form consecutive synthesized interference fringe images for a wide range of interference fringes.

Abstract: An electronic distance measuring device that measures a distance from the electronic distance measuring device to an objective station. The electronic distance measuring device includes a radiation source for emitting frequency-modulated radiation towards a reflector disposed at the objective station, and a detector for detecting radiation reflected by the reflector. The distance of the objective station from the electronic distance measuring device is then calculated in accordance with the detected radiation. At least one radiation attenuating filter is positioned in a radiation path between the radiation source and the detector. The radiation attenuating filter is inclined with respect to a main axis of the radiation path so as to prevent incidence on the detector of an irregular reflection of the radiation by the attenuating filter.

Abstract: A light wave distance measuring apparatus includes a light-sending optical system and a light-receiving optical system, which are preferably arranged to be parallel to each other. Intensity-modulated light of the light-sending optical system is transformed into parallel rays of light and projected towards a target, reflected back towards the measuring apparatus and detected by the light-receiving optical system in order to calculate the distance of the target from a reference point.

Abstract: In a high range resolution ladar, a chirp signal waveform is propagated as a divergent laser light waveform and the target reflected return is collected and converted to a current proportional to power. An undelayed chirp signal is added in a mixer to the return current and then low pass filtered to recover a mixed intermediate frequency (IF) signal having a frequency proportional to the target range. Periodically, the light circuit is interrupted and the chirp signal is processed through the mixer and low pass filter without a target return current and this output, the mixer self-clutter, is stored. This stored self-clutter signal is subsequently subtracted from the mixed IF signal on a chirp by chirp basis to cancel the self-clutter produced by the mixer. The subtracted signal is then frequency analyzed to determine target range.