Abstract: An interferometric system for measuring the radius of curvature of a measurement object that includes a tunable coherent radiation source capable of emitting a radiant energy beam having a characteristic wavelength and of scanning the characteristic wavelength over a range of wavelengths; an unequal path interferometer which during operation includes a reference object and the measurement object and which receives a portion of the radiant energy beam from the tunable radiant energy source and generates an optical interference pattern; a detecting system including a detector for receiving the optical interference pattern; and a system controller connected to the tunable radiant energy source and the detecting system.

Abstract: The invention features methods and systems in which wavelength-tune PSI data is analyzed in the frequency domain to produce spectrally separated frequency peaks each corresponding to a particular pair of surfaces in an interferometric cavity defined by multiple pairs of surfaces. Each frequency peak provides optical path length information about a corresponding pair of surfaces in the cavity. As a result, the interferometric data from such cavities provides simultaneous information about multiple surfaces.

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts. A spherical or partial spherical wavefront is generated from a known origin along an optical axis. The test optic is aligned with respect the optical axis and selectively moved along it relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency.

Abstract: There is provided an interferometer for measuring a surface shape of an optical element using interference, including a reference wave-front deformation system for deforming a wave front of reference light.

Abstract: Apparatus and methodology by which the radius of curvature of individual optics may be determined through the interferometric measurement of the optical length of a spherical cavity established from null tests of combinations of the individual optics and an algorithm that mutually intercompares the measured cavity lengths and radii of curvature of the individual optics.

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts by comparing known and unknown spherical and aspherical shapes. Preferably, a spherical or partial spherical wavefront or reflecting surface is defined with respect to a known origin along a scanning axis. The test optic is aligned with respect the scanning axis and selectively moved along it relative to the known origin so that the spherical shape intersects the test optic at the apex of the aspherical shape and at radial positions where the spherical shape and the aspheric shape intersect at points of common tangency.

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 method and system for determining three-dimensional refractive gradient index distribution. The method and system of the present invention determine inhomogeneity data and calculate index of refraction changes in three-dimensions (3D). The method and system provide 3D modeling of an optical object or system that determines the three-dimensional distribution of the refractive index in the object. In one embodiment, the optical object is a blank. In different embodiments, the optical system is more than one blank. In alternative embodiments, the optical system can be a projection optics system that can include optical components such as lenses, filters, plates, and prisms. The present invention also provides a method for selecting a plurality of preferred optical elements to assemble a composite optical system with predetermined parameters.

Abstract: Interferometric method and apparatus for measuring aspheric surfaces and wavefronts by directing a spherical wavefront of known design at a wavelength &lgr;1 at a reference sphere with known measured surface properties to generate a first electronic signal containing information about the optical path differences between the reference and measurement wavefronts generated an interferometer and directing an aspherical wavefront of known design at a wavelength &lgr;2 at an aspherical surface or wavefront to be tested to generate a second electronic signal containing information about the optical path differences between the reference and measurement wavefronts generated by the interferometer.

Abstract: Interferometric apparatus and methods by which aspheric surfaces and wavefronts may be precisely measured. The apparatus is provided with two modes of operation. In one mode, the apparatus is configured generally as a Fizeau interferometer in which an aspheric reference surface is used to permit the rapid, robust measurement of the difference between the aspheric reference surface and an aspheric test optic or wavefront. In another mode of operation, the aspheric test surface itself is completely characterized through in-situ use of an interferometric scanning technique using a spherical reference surface.

Abstract: To measure a convex mirror, a reference beam and a measurement beam are both provided through a single optical fiber. A positive auxiliary lens is placed in the system to give a converging wavefront onto the convex mirror under test. A measurement is taken that includes the aberrations of the convex mirror as well as the errors due to two transmissions through the positive auxiliary lens. A second, measurement provides the information to eliminate this error. A negative lens can also be measured in a similar way. Again, there are two measurement set-ups. A reference beam is provided from a first optical fiber and a measurement beam is provided from a second optical fiber. A positive auxiliary lens is placed in the system to provide a converging wavefront from the reference beam onto the negative lens under test. The measurement beam is combined with the reference wavefront and is analyzed by standard methods.

Abstract: Methods are disclosed for measuring the surface profile of a “test surface” of an object such as an optical element, which can be a lens or reflective element (mirror). The “test surface” can have any of various profiles, including (but not limited to) spherical or aspherical. In a method embodiment, respective phase distributions of interference fringes, produced by interference of a reference light and light reflected from the test surface, and interference of the reference light and a respective light reflected from at a reference standard and/or a verification standard. A profile difference is computed from the respective phase distributions of interference fringes produced with respect to the test surface and the reference standard and/or verification standard.

Abstract: In certain aspects, the invention features scanning interferometry systems and methods that can scan an optical measurement surface over distances greater than a depth of focus of imaging optics in the interferometry system, while keeping an optical measurement surface in focus (i.e., maintaining an image of the optical measurement surface coincident with the detector). The optical measurement surface refers to a theoretical test surface in the path of test light in the interferometer that would reflect the test light to produce an optical path length difference (OPD) between it and reference light that is equal to a constant across a detector.

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: A profiling method compensates for phase changes associated with the presence of multiple or varying material in the area to be measured. The profiling method measures at least a portion of the height profile of the area of interest. The phase of the different materials in the region are also obtained and used to generate a correction factor. Depending on the type of material in the region of interest, the correction factor may be the material specific phase difference of the materials in the region, e.g., when at least one of the materials is opaque to the wavelength of light used to measure the height profile, or the relationship between the thickness and phase of the material for a desired thickness range, e.g., when one or more of the materials is transparent to the wavelengths used to measure the height profile. The correction factor is then used to correct and/or convert the measured phase profile to an actual height profile.

Abstract: An aspherical reference surface 2 is manufactured with such a shape accuracy that an interference band appears according to the aspherical shape of a surface 1 to be measured, an aspherical wave front 3 is formed using the reference surface, and a large aspherical surface is measured from interference within a short time. The aspherical reference surface is an aspherical surface optical element 10 manufactured by fly-cutting or ELID-grinding, that produces the interference band from light reflected from the aspherical surface and predetermined reference light, and thereby measures the shape of the aspherical surface from interference. The aspherical surface optical element should be an aspherical reflecting mirror with such a shape accuracy that an interference band is generated and parallel light is reflected in the direction normal to the surface to be measured. Thus, the shape can be measured in a short time without using an aspherical surface standard.

Abstract: An amplitude variation detection circuit that can reliably detect the mirror portion independently of the type of optical recording medium, as well as a type of information regenerating apparatus that contains said amplitude variation detecting circuit. Voltage division of top envelope signal Ste and bottom-hold signal Sbh of RF signal Srf is performed by voltage divider (16); then, after amplification by gain control amplifier (19) with a gain that corresponds to the type of optical disc (1), a prescribed offset is added by offset circuit (22) to the signal, and the resulting signal is input as mirror detection threshold signal Smt to comparator (24). The high-frequency noise component of bottom envelope signal Sbe of RF signal Srf is removed by low-pass filter (21); after amplification by gain control amplifier (20) with a gain that corresponds to the type of optical disc (1), the signal is input to comparator (24).

Abstract: Interferometer for measuring a phase difference between a reference beam (37) and an object beam (36′) transformed by an optical element (10), comprising light source means (2), an optical device (3) and detection means (4) in a detection plane (34). The optical device (3) comprises a first light conductor (30) having a first output surface (31) that generates an object beam (36) having a spherical wave front and a second light conductor (32) having a second output surface (33) that generates a reference beam (37) having a spherical wave front, directed onto the detection plane (34), wherein the set-up of the first light conductor (30) and the optical element (10) is such that the transformed object beam (36′) interferes with the reference beam (37) in the detection plane (34).

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts. A spherical or partial spherical wavefront is generated from a known origin along an optical axis. The test optic is aligned with respect the optical axis and selectively moved along it relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency.

Abstract: An aspheric microlens, particularly a conic constant of the microlens, may be evaluated and this evaluation may be used to determine an optimal process for creating the aspheric microlens. Such evaluation may include a curve fitting or a numerical expression of the wavefront.

Abstract: Interferometric apparatus and methods by which aspheric surfaces and wavefronts may be precisely measured. The apparatus is provided with two modes of operation. In one mode, the apparatus is configured generally as a Fizeau interferometer in which an aspheric reference surface is used to permit the rapid, robust measurement of the difference between the aspheric reference surface and an aspheric test optic or wavefront. In another mode of operation, the aspheric test surface itself is completely characterized through in-situ use of an interferometric scanning technique using a spherical reference surface.

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics having spherical, mildly aspherical and multiple, mildly aspherical surfaces. At least a partial spherical wavefront is generated from a known origin along a scanning axis through the use of a spherical reference surface positioned along the scanning axis upstream of the known origin. A test optic is aligned with respect to the scanning axis and selectively moved along said scanning axis relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions.

Abstract: Disclosed is an interferometer that enables high-speed and high-precision measurement of a surface shape of an article and a method of producing such interferometer. Also disclosed is a method of measuring a surface shape of an article by use of such interferometer. The interferometer includes an optical system having an optical element being effective to make, into an aspherical wave, a wavefront of light to be projected on the article to be inspected, and also being arranged to be replaceable by another optical element.

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts by comparing known and unknown spherical and aspherical shapes.. Preferably, a spherical or partial spherical wavefront or reflecting surface is defined with respect to a known origin along a scanning axis. The test optic is aligned with respect the scanning axis and selectively moved along it relative to the known origin so that the spherical shape intersects the test optic at the apex of the aspherical shape and at radial positions where the spherical shape and the aspheric shape intersect at points of common tangency.

Abstract: Focusing means to focus a beam upon a reflective-transmissive surface. Reflecting means to reflect a central portion of the beam from the reflective-transmissive surface. Transmitting means to transmit a portion of the beam that lies outside the central portion. Receiving means to receive the transmitted portion of the beam and combining means to combine the reflected central portion of the beam with a test beam to generate an interference pattern.

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: A measurement system is used in particular to detect defects in test objects. To that end, the test object is lighted from a lighting unit that includes a plurality of laser diodes. The beam cones of the individual laser diodes generate a common lighting spot on the test object. The object being measured is observed interferometrically, where the interferometer is part of a measurement head. An electronic pattern sensor detects interference patterns generated by the interferometer.

Abstract: The invention relates to a point diffraction interferometer which measures a profile irregularity on a surface to be measured by, irradiating light irradiated from a light source to a pinhole mirror via a collective optical system, irradiating a part of the light diffracted from a pinhole provided in the pinhole mirror to the surface to be measured as a luminous flux for measurement, making the luminous flux for measurement reflected by the surface to be measured interfere with a reference luminous flux which is an other part of light diffracted from the pinhole, and detecting the state of an interference fringe caused by the interference. In the invention, a diameter range of the pinhole is: &lgr;/2≦&phgr;PH≦&lgr;/NA (wherein &lgr; is a wavelength of light irradiated from the light source, NA is a numerical aperture of the collective optical system, and &phgr; PH is a diameter of the pinhole).

Abstract: Apparatus and methods are disclosed for measuring the surface topography of a test surface, such as a spherical or aspherical surface of a refractive or reflective optical element. The test surface is measured by detecting the state of interference fringes generated by interference of a reference light beam and a measurement light beam that interacts (e.g., reflects from) the test surface. The reference and measurement beams are produced by a point light source having a reflective surface. The point light source is disposed between a source of input light and the test surface. The measurement beam (after interacting with the test surface) and the reference beam are caused to interfere with each other to produce a first interference-fringe state. The distance between the point light source and the test surface can be changed between production of the first interference-fringe state and production of a second interference-fringe state.

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: The sensor measures diffusion of a fluorescent marker in cavities. The sensor has a Mach-Zehnder micro-interferometer having a reference arm and a measurement arm. The reference arm has a deposit of a sensitive layer whose refractive index is modified when the sensitive layer is in contact with the fluorescent marker. In one embodiment, the micro-interferometer has a diode laser configured to generate a source beam, a substrate of silicon micro-machined with two Y junctions, where a first Y junction is configured to divide the source beam into a measurement beam along the measurement arm and a reference beam along the reference arm, a piezo-electric transducer configured to shift the frequency of the reference beam in phase by an acoustic modulation, wherein a second Y junction combines the measurement bean and the shifted reference beam to generate a combined beam; and a photo-detector configured to detect the combined beam.

Abstract: An interferometer includes a beamsplitter for splitting a source beam into a test beam and a reference beam, an imaging device for detecting an interference pattern, a mirror disposed in a path of the test beam for reflection of the test beam toward the imaging device, a micromirror disposed in a path of the reference beam for reflection of a portion of the reference beam toward the imaging device, and a focusing mechanism disposed for focusing the reference beam on the micromirror. The micromirror has a lateral dimension not exceeding the approximate lateral dimension of a central lobe of the reference beam focused thereon by the focusing mechanism. A spatial filter for reducing effects of aberration in a beam includes a reflector disposed upon a transparent base wherein the reflector has a lateral dimension not exceeding the approximate lateral dimension of a central lobe of the spatial intensity distribution of the beam focused upon the reflector.

Abstract: The invention features an interferometry system for a measuring a surface profile or thickness of a measurement object.

Abstract: The invention provides an apparatus for measuring a property of a sample (using, e.g., ISTS) that includes: 1) an excitation laser that generates an excitation laser beam; 2) an optical system aligned along an optical axis that separates the excitation laser beam into at least three sub-beams; 3) an imaging system aligned along the optical axis that collects the sub-beams and focuses them onto the sample to form an optical interference pattern that generates a time-dependent response in the sample; 4) a probe laser that generates a probe laser beam that diffracts off the time-dependent response to form a signal beam; 5) a detector that detects the signal beam and in response generates a radiation-induced electronic response; and 6) a processor that processes the radiation-induced electronic response to determine the property of the sample.

Abstract: A laser scanner sensor for measuring the spatial properties of objects in a scene within a range less than a predetermined maximum object distance. Applications of the laser scanner system includes measurement of the dimensional weight of parcel(s) being transported by a moving forklift. In the laser scanner sensor, a laser diode supplies a laser beam that is intensity-modulated by a reference waveform from a waveform generator. A variation of the optical scanning sensor system scans a field of measurement which the moving forklift traverses. The forklift has at least three retroreflectors attached to act as calibration targets within the viewing field.

Abstract: A laser range finding apparatus 10 comprises a pulsed laser 12, a light deflecting device 14, photo-receiver arrangement 16 and a reference object 18 arranged at a defined spacing from the light deflecting device 14. In this respect the reference object 18 has at least one triple element consisting of three mirror surfaces arranged at an angle of 90.degree. to one another.

Abstract: A laser scanner for measuring the spatial properties of objects in a scene within a range less than a predetermined maximum object distance. A laser diode supplies a laser beam that is intensity-modulated by a reference waveform from a waveform generator. An optical scanning system scans the scene with the intensity-modulated laser beam, and receives reflected intensity-modulated light and supplies it to an optical processing system that includes an aperture that transmits a first percentage of light reflected from the maximum object distance and a second, lesser percentage of light reflected from objects closer than the maximum object distance. A photodetector receives the processed light and converts the energy into an amplitude-modulated range signal. A mixer down-converts the frequency into an IF frequency, and a first circuit converts the range signal to the form of a square wave.

Abstract: A device and method of electronically obtaining range or distances from the device to the target utilizing a central processing unit (CPU) in combination with a pulse repetition frequency generator, a plurality of photodetectors and a transistor to transistor clock counter, in a lightweight and portable configuration. The device obtains a plurality of samples, which enables the CPU to determine filter delay, range resolution and count deviations so as to accurately determine range or distance measurement to within plus or minus one centimeter.

Abstract: An electronic distance measuring device which includes a radiation source for emitting frequency-modulated radiation along one of two paths. The electronic distance measuring device also has a device for switching the emitted radiation from one of the two paths to the other of the two paths, a detector for detecting the radiation emitted along the paths, and a device for determining a difference in phase between the emitted radiation and the detected radiation. The detection of the phase difference is performed twice between two consecutive switchings of the light paths. A distance of the electronic distance measuring device from an objective station is then calculated in accordance with the determined phase difference.

Abstract: A position detecting apparatus utilizing optical interferometry changes the wavelength of a light beam from the light source. The variation in the wavelength causes an increment and decrement Cx, Co in the number of waves in the measurement and reference lengths Lx, Lo. The position data calculating section calculates the measurement length Lx on the basis of the detected increment and decrement Cx, Co and the reference length Lo according to an equation, Lx=Lo(Cx/Co). The position detecting apparatus can easily detect an absolute position of an object to be detected.

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.