Abstract: The present invention is applicable generally to Spectroscopic Rotatable and Rotating Element Ellipsometers which utilize a relatively large range of wavelengths. Disclosed is a system and method for controlling the polarization state of a polarized beam of light so that it is in a range where the sensitivity of a Polarization State Detector used to measure changes in said polarized beam of light resulting from interaction with a Sample System, to noise and measurement errors etc., is reduced. Exemplified is a system, and method of use, for simultaneously setting both measured ellipsometric ALPHA, and ellipsometric BETA parameter values, (or equivalents), within ranges, in which ranges the sensitivity of transfer functions, and mathematical regressions which utilize said ellipsometric ALPHA and ellipsometric BETA values in the calculation of sample system characterizing PSI and DELTA constant values, to noise and errors in measurement etc., is found to be negligible.

Abstract: An ellipsometer comprising several photodetectors and an electronic processing unit (4) produces a beam of light modulated at a modulation frequency (Fm) which is reflected by a sample. The photodetectors measure fluxes from parts of the reflected luminous beam, producing measured analog signals in input channels (6), and the electronic processing unit (4) calculates physical parameters of the sample. This electronic processing unit (4) comprises a multiplexing and digitizing unit (7) successively switching to the input channels (6) at a switching frequency (Fe) and a sequencer (19). The sequencer (19) comprises means (24, 35) to allow setting the switching frequency (Fe) as a multiple of the modulation frequency (Fm). The ellipsometer takes optical measurements in real time, in particular for depositing films on substrates.

Abstract: A multiple beam scanning apparatus in which a plurality of light beams are repeatedly scanned at the same time, including a light source unit defining an optical axis and including plural laser diodes, collimator lenses for respectively converting light beams emitted by the laser diodes to respective parallel light fluxes, and a beam composing unit for superposing the light beams and emitting the superposed light beams therefrom. The light source unit is rotatively adjustable around the optical axis and is constructed such that respective light fluxes emitted from the beam composing unit are emitted with predetermined respective different angles at least in a main scanning direction.

Abstract: An optical reader for reading indicia such as bar codes comprises a first and second light source for generating first and second light beams of mutually orthogonal polarization orientations, and a polarized beam splitter for combining the beams without the effects of parallax or vignetting. One of the light sources is a short range light source and the other is a long range light source. The reader may be a scanner or a field of view reader. In addition, an optical reader is provided capable of reading all 2D symbologies comprising a flying spot laser scanner arrangement and a field of view reader. The respective laser sources generate light at different wavelengths and a dichroic filter is provided to allow either system to be used without parallax effects. The laser scanner beam can be used to aim the reader when carrying out field of view reading.

Abstract: A fingerprint enhancement system has a platen with a liquid contacting and finger-touching surface. Two collimated interrogating light beams lie below and are opposite sides of the finger-touching surface. The horizontal extensions of the light beams assume an angle of approximately forty-five degrees with the finger longitudinal axis. Side surfaces of the platen are oriented normal to the incident colliminated light beams prior to interrogation. The light beam modulated by the fingerprint passes to a reflecting mirror, imaging means and a scanner below the platen. A polarizing filter lies between the platen and reflecting mirror. A second polarizing filter lies above the platen. A contrast enhancement circuit increases the modulation of the scanned fingerprint signal and automatically adjusts the level of the modulated signal without saturation. Circuit filtering eliminates spurious input signals. Finger position sensing by a light emitting diode and photo transistor is also provided.

Abstract: An optical scanning device includes a light deflection unit for deflecting a light beam emitted by a light source to be incident on an object to be irradiated, a polarization state adjusting unit for adjusting the polarization state of the light beam, so that the light beam to be incident on the object to be irradiated has a predetermined polarization state with respect to the object to be irradiated, and a rotary driving unit for rotating the light deflection unit and the polarization state adjusting unit together so that the light beam deflected by the light deflection unit scans the object to be irradiated.

Abstract: An LCD panel test apparatus automatically detects defects of the LCD panel under test.

Abstract: A method and apparatus for inspecting a reflective surface, or material on such surface, such as lubricant and planarizing layers on a magnetic media storage disk. A beam of controlled polarization impinges obliquely at a spot in the plane of the disk. A collector such as an integrating sphere is spaced away from the disk and has an opening oriented to catch the oblique specular reflectance from the surface. Preferably the opening is substantially larger than the beam, so that disk run out does not send the beam astray or defeat its measurement, and the oblique beam is aimed at an angle lying between the Brewster angle of the lubricant and that of the adjacent layer. A temperature-controlled laser diode with constant-current driver provides a beam that is free of wavelength hops and amplitude changes, making beam aiming repeatable and allowing point-by-point comparisons of the detected reflectance.

Abstract: A polarization mode dispersion measuring apparatus includes a variable wavelength light source for providing light of a variety of wavelengths; a light intensity modulator optically connected to the light source to provide light of modulated intensity; a polarization controller optically connected to the light intensity modulator to provide light of controlled polarization; a beam splitter optically connected to the polarization controller to provide beams of p and s polarization components; an O/E conversion unit optically connected to the beam splitter to provide electrical signals with respect to the beams of the p and s polarization components; and an analyzing unit for controlling the light intensity modulator to provide a sine wave of a predetermined frequency and a predetermined intensity, and the light source and the polarization controller to determine parameters of Jones matrix from the electrical signals and a polarization mode dispersion defined by the parameters, thereby measuring a polarization

Abstract: An object reflector detecting apparatus for identifying an object reflector by emitting a light from a polarized light source toward the object reflector and then detecting a reflected light from the object reflector characterized in that the light emitted from said polarized light source is a polarized light of which direction of polarization is specially defined, the polarized lights between said reflected light and said emitted light are different in the direction of polarization, and said object reflector detecting apparatus is adapted to detect only a component of the direction of polarization from said object reflector.

Abstract: An optical-modulation-type sensor comprises an input condenser lens for collecting light from a light source, a polarizer for linearly polarizing the light from the input condenser lens, a light-transmissive piezo-oscillator which is provided with an oscillator circuit and to which the linearly polarized light is introduced from the polarizer, an analyzer for linearly polarizing the light from the piezo-oscillator, and an output condenser lens for converging the linearly polarized light from the analyzer.

Abstract: Apparatus for the automated real-time detection and classification of defects during the machining of ceramic components employs an elastic optical scattering technique using polarized laser light. A ceramic specimen is continuously moved while being machined. Polarized laser light is directed onto the ceramic specimen surface at a fixed position just aft of the machining tool for examination of the newly machined surface. Any foreign material near the location of the laser light on the ceramic specimen is cleared by an air blast. As the specimen is moved, its surface is continuously scanned by the polarized laser light beam to provide a two-dimensional image presented in real-time on a video display unit, with the motion of the ceramic specimen synchronized with the data acquisition speed. By storing known "feature masks" representing various surface and sub-surface defects and comparing measured defects with the stored feature masks, detected defects may be automatically characterized.

Abstract: A sorting system (10) propels a stream of randomly arranged PET and PVC articles (12, 14) through an inspection zone (20) including a first light polarizer/analyzer combination (24, 26), an article-detecting gap (G), and a second light polarizer/analyzer combination (28, 30). The first and second polarizer/analyzer combinations are oriented to extinguish normally incident light in the absence of articles in the inspection zone and are offset 45 degrees relative to each other such that at least one polarizer/analyzer combination detects a principal axis of birefringence of PET articles. The gap is employed to detect the presence of an article in the inspection zone. A video camera (22) includes first, second, and third CCD arrays (58, 60, 62) positioned to receive respective light rays (48, 64, 50) from the first light polarizer/analyzer combination, the gap, and the second light polarizer/analyzer combination and to generate first, second, and third video signals representative of the light each receives.

Abstract: Disclosed is a dispersive optics system, in the context of ellipsometer or polarimeter and the like systems, which, in use, produces a plurality of "Orders" of essentially single wavelength beams of light from a polychromatic beam of light. In use the availability of more than one "Order" of essentially single wavelength beams of light allows simultaneous measurement of more essentially single wavelength beams of light than would be possible were only one "Order" of essentially single wavelength beams of light present. Filters are present to reduce the effects of stray light on detector elements and to allow separating the wavelengths in overlapping regions of adjacent Orders.

Abstract: In a photomask inspecting method, a photomask is inspected on the basis of the difference between the polarized state of elliptical light produced upon superposition of two linearly polarized light beams having orthogonal polarization directions and passing through two different optical paths and the polarized state of elliptical light produced when two linearly polarized light beams are superposed on each other after a target portion of a photomask is set in the optical path of one of the linearly polarized light beams. A photomask inspecting apparatus is also disclosed.

Abstract: In an ellipsometer, a phase-modulated, polarized light beam is applied to a sample, electrical signals are obtained representing the orthogonal planes of polarization of the light after it has interacted with the sample and the constants of the sample are calculated from the two resulting electrical signals. The phase modulation is sufficiently small so that the calibration errors are negligible. For this purpose, the phase modulator, phase modulates the light within a range of no more than ten degrees peak to peak. The two electrical signals are expanded by Fourier analysis and the coefficients thereof utilized to calculate psi and delta.

Abstract: It is an object to realize a measuring head capable of maintaining high Z direction accuracy even with a measured sample having fine, complicated and very uneven pattern configuration, in an atomic force microscope. A light beam (141) of non-linear polarization is incident upon an end portion (110a) of an upper main surface of a cantilever body (110) having a probe (2). The cantilever body (110) is a polarizing plate, and its refractive index is given by tan (a Brewster's angle of the light beam (141)). Accordingly, a reflected light beam (142) reflected at the end portion (110a) becomes light of linear polarization. A light position detector (150) including an analyzing window (150a) including a polaroid thin film as an analyzing material transmits only the light oscillating in the same direction as the electric vector of the linearly polarized reflected light beam (142) to detect its positional change.

Abstract: An apparatus and method are provided for remotely detecting ice on a polarization preserving surface. A target location on the surface is irradiated with two cross-polarized beams of coherent light. A determination is then made as to whether the speckle patterns from each of the two beams interfere with one another. If interference of the speckle patterns from the two beams is detected, ice or some other birefringent material is said to be present on the surface.

Abstract: A light switching apparatus includes an optically non-linear etalon, a first optical part for applying a signal light of a linear polarization to the optically non-linear etalon, and a second optical part for applying a control light of a circular polarization or elliptical polarization to the optically non-linear etalon. The control light varies a refractive index of an optically non-linear substance of the optically non-linear etalon to thereby perform a switching operation on the signal light.

Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.

Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.

Abstract: To observe film thickness and/or refractive index of a sample, light beams from a white light source are irradiated onto the surface of the solid or liquid sample such that the reflected light beams are colored by partial extinction of the reflected light beams. A difference 17 film thickness and/or refractive index of the sample is observed according to color difference of the reflected light beams.

Abstract: In a light receiving module of a first aspect of the invention, a transparent plate is provided therein in such a way as to be tilted so that polarized light dependency generated thereby is equal to that generated by tilting a light receiving element and moreover in a positional relationship of being perpendicular to the latter in tilting direction. As a result, even if incident light is varied in polarized state, polarized light dependencies generated by the transparent plate and the light receiving element cancel each other to restrain the polarized light dependency of the incident light as a whole. In a light receiving module according of a second aspect of the invention, the light-emitting end surface of an optical fiber is formed in the same positional relationship relative to the light receiving surface of the light receiving element as that of the transparent plate of the first aspect of the invention.

Abstract: A fibre Bragg grating is used to stabilize the intensity and frequency fluctuations of two diode lasers simultaneously. The polarized optical output from the diode lasers is collimated and directed through a beam combiner device which combines the separate beams into a single beam, thus summing the optical power. The combined beam is directed into an optical fibre containing a fibre Bragg grating which reflects a fraction of the light back into each diode laser to cause low-coherence, stable operation of each laser.

Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.

Abstract: A high-resistance compound semiconductor 12 is epitaxially grown on a low-resistance compound semiconductor 11 and a dielectric reflecting film 13 is formed thereon, thereby forming a monolithic sensor 10. As the low-resistance compound semiconductor 11, a compound semiconductor is used which has a large bandgap so as to enable probe light to pass therethrough without being absorbed and which has a lattice constant and a thermal expansion coefficient, which are close to those of the high-resistance compound semiconductor. In addition, since the low-resistance compound semiconductor 11 also serves as an electrode, a compound semiconductor which has a resistivity of 10.sup.+1 .OMEGA.cm or less is used. Since the shorter the wavelength of the probe light used, the larger the retardation change and the larger the signal output, a compound semiconductor which has a large bandgap is used as the high-resistance compound semiconductor 12 so that light of short wavelength can be used.

Abstract: An identifying procedure and system for identifying a visual object, the object to be identified (1) being marked with a polarizing surface (2) provided in the region of the object. Observation of the object is accomplished by utilizing the lighting prevailing at the object and in its ambience, on the basis of the polarized light (4a) reflected by said polarizing surface.

Abstract: A symbology reader which reduces the effects of specular reflection. A plurality of illumination sources emit light toward a target object. A first polarization filter receives the unpolarized light from the illumination sources and transmits only light polarized in a first direction. Light reflected from the target object travels back to the reader where it is received by a second polarizer which is oriented to block light polarized in the first direction and transmit only light polarized in a second direction orthogonal to the first polarization direction. Non-specularly reflected light reflected from the target object is largely transmitted by the second polarizer to a detector assembly within the symbology reader. In one embodiment the polarization filters are part of a window which covers an output aperture of the reader. The polarization filters are implemented as discrete pieces of laminar polarizing film attached to a transparent window base.

Abstract: There is disclosed a method for measuring retardation .DELTA.nd of a liquid crystal cell in which a linearly polarized light beam is impinged upon a liquid crystal cell, the liquid crystal cell is rotated in a plane perpendicular to an optical axis of a measuring optical system so that the transmission through the liquid crystal cell for the light beam having a polarization parallel to that of the incident light beam becomes maximal, the wavelength of the incident light beam is varied to detect at least one wavelength .lambda..sub.s at which the transmission has an extreme and, finally, .DELTA.nd is calculated from .DELTA.nd=.lambda..sub.s .sqroot.m.sup.2 -(1/4) for the case of m-th minimal transmission or from .DELTA.nd=.lambda..sub.s .sqroot.m.sup.2 +m for the case of m-th maximal transmission.

Abstract: In an optical pickup apparatus, a laser beam is generated from a laser source toward a lens group for reading out information written on an information recording medium. The lens group determines paths of an incident beam to the information recording medium and a reflected beam from it. The lens group includes a polarization converting element such as a .lambda./4 plate, a .lambda./8 plate, or a 80/16 plate for polarizing a beam transmitted therethrough and a birefringent prism to refract the beam depending on the polarized state and an objective lens through which the beam is transmitted to be focused on the information recording medium. The laser source generates an ordinary ray composed of a linearly polarizing component to be refracted ordinarily in the birefringent prism. A photodetector receives the beam polarized and refracted by the lens group. The lens group is arranged in the order of the diffraction grating, the birefringent means, and the polarization converting means from the bottom.

Abstract: An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

Abstract: An apparatus and a method are provided for measuring an ambient physical parameter applied to a highly birefringent sensing fiber. A light source emits a low coherence light beam into a sensing fiber subjected to an ambient physical parameter. A collector receives the output light beam of the sensing fiber and a splitter divides the output light beam into two orthogonally polarized output beams and subjects the two orthogonally polarized output beams to a range of relative delays. A recombiner combines the two orthogonally polarized output beams to produce an interference pattern, and a detector detects intensities of the interference pattern over the range of delays. A calculating device determines the ambient parameter from the intensities with improved accuracy.

Abstract: An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a stationary compensator, positioned between an analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The use of a light fiber to carry light from a source thereof, to a polarization state generator, is also disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

Abstract: A direct, noncontact temperature sensor includes an ellipsometer (104-106) to determine absorptance for layered structures and a pyrometer (102) to determine emissive power and combines the two measurements to determine temperature.

Abstract: A general-purpose magnetic field sensor capable of sensitively measuring uniform magnetic fields includes a magneto-optic (Faraday-effect) sensor and a flux concentrator. Both the magneto-optic sensor and the flux concentrator have high magnetic permeability. The magneto-optic sensor is positioned in close proximity to the flux concentrator. The combination of the high-permeability magneto-optic material and the flux concentrator creates a magnetic circuit which efficiently concentrates the magnetic field into the magneto-optic sensor, and greatly enhances the measurement sensitivity. The preferred embodiment uses a pair of cylindrical flux concentrators in axial alignment. A sensing beam passes through a central axis hole in the cylindrical flux concentrators. The Faraday effect sensor is co-axially aligned with the holes in the cylindrical flux concentrators. The concentrators and Faraday effect sensor create a continuous flux concentrating magnetic circuit.

Abstract: A polarization based optical sensor for detecting the presence, composition, or both of substances (26) on a transparent material's (12) surface (14). A polarized-light source (18) introduces light (22) into the material (12). Within the material (12), the light (22) undergoes one or more total internal reflections (18, 20) whether or not the substance to be detected or analyzed (26) is present. The presence of the substance causes a shift in the polarization of the light (22). This shift is detected by a polarized-light detector (20) when the light (22) exits the material (14).

Abstract: A method and apparatus for rapidly and accurately determining fiber orientation of paper which is at a standstill or moving in a paper machine employs a projector which projects a light beam perpendicularly to an incident surface of the paper to be tested. The light beam reflected by the incident paper surface is caught by eight or more light receivers distributed on a circumference of a circle on the incident surface side of the paper. The circle is defined in a plane extending in parallel to the paper surface and having an axis at the point where the above-mentioned parallel plane intersects an axis of the incident light beam. A light information signal output from the light receivers are subjected to a processing to obtain the fiber orientation characteristics, such as fiber orientation index value and fiber orientation angle.

Abstract: A polarization-modulation scanning laser microscope includes a conventional laser scanning microscope, which has been improved by addition of: a polarization state generator; a polarization state analyzer; a photo-detector for receiving laser light transmitted though a sample; a signal demodulator providing two signals in response to the transmitted laser light, one of the signals being indicative of polarization orientation, and the other signal being indicative of magnitude of the transmitted polarized light. A relay interface toggles between the two signals provided by the signal demodulator and at least one other signal provided either by the photodiode of the laser scanning microscope, or by an external optical beam induced current, or both. A signal processing unit provides an image output to a display device.

Abstract: A part for projecting a measuring light beam onto a sample and a light receiving part are arranged on the same side of a sample surface so that the measuring light beam is concentric with the light receiving part, the measuring light beam which is converted to a linearly polarized light beam through a polarizing element is projected to the sample so that the measuring light beam outgoing from the sample to the projecting side is received and detected through the same polarizing element. A plurality of sets of polarizing elements and light receiving parts are set so that the polarizing elements have different polarization directions, to calculate retardation from transmitted light intensity levels as obtained.

Abstract: A photodetector includes a polarizer array and an array of photodetector elements. The polarizer array includes a plurality of polarizers having axes of polarization spaced apart by selected angles such that each optical signal incident on the polarizer array has a polarization component along at least one of the axes of polarization. The array of photodetector elements is arranged such that each of the photodetector elements receives light from a selected one of the polarizers. At least one of the photodetector elements receives parallel polarization components from the optical signals to form an electrical signal indicative of interference between the optical signals.

Abstract: An inspection apparatus which automatically inspects a bottom border portion of a transparent glass vessel for a foreign article accurately is disclosed. Light is projected and received by way of first and second polarization filters through a rotating glass vessel to image the vessel obliquely from below by a solid state image pickup elements of a camera. Brightness values of outputs of the elements of the camera are compared with threshold values for binary digitization and determined as abnormality values when they are higher. The threshold values are varied and the abnormality values are corrected in accordance with the positions of the elements of the camera, and then presence or absence of a foreign article is determined from the corrected abnormality values or the sum of them.

Abstract: A polarization-independent optical detection apparatus for measuring light output from optical fibers comprises an optical detector having an input port for receiving input light by way of an optical path and an output for a corresponding detection signal. A polarization-transformation element is rotatably mounted in the optical path so that the input light passes through the element to reach the input port. A drive motor rotates the polarization-transformation element in a plane extending transversely of the optical path. The polarization-transforming element is selected to transform the polarization state of the input light reaching the detector, as the element spins, so that, for any given input polarization state, the time averaged electrical signal from the detector is approximately the average electrical signal from the detector over all input polarization states.

Abstract: The invention is directed to an integrated dual imaging detector on a single silicon chip comprising a beam interleaving polarization analyzer bonded to a charge-coupled device, serial shift register and associated image transfer circuitry, analog signal processors, and analog-to-digital converters. The invention permits the simultaneous acquisition and processing of two polarization images of rapidly changing subjects.

Abstract: A radiation pyrometer for measuring the true temperature of a body is provided by detecting and measuring thermal radiation from the body based on the principle that the effects of angular emission I.sub.1 and reflection I.sub.2 on the polarization states p and s of radiation are complementary such that upon detecting the combined partial polarization state componentsI.sub.p =I.sub.1p +I.sub.2pI.sub.s =I.sub.1s +I.sub.2sand adjusting the intensity of the variable radiation source of the reflected radiation I.sub.2 until the combined partial radiation components I.sub.p and I.sub.s are equal, the effects of emissivity as well as diffusivity of the surface of the body are eliminated, thus obviating the need for any post processing of brightness temperature data.

Abstract: In a foreign particle inspecting method and apparatus in which a polarized beam is applied to a surface to be inspected through a light transmitting member mounted thereon, in which scattered light from a foreign particle on the surface to be inspected is received by a light receiving device through the light transmitting member, and in which the foreign particle is discriminated based on a detection signal from the light receiving device, the detection signal is corrected in conformity with the transmittance of the light transmitting member for polarized incident scanning light and the transmittance of the light transmitting member for non-polarized light scattered from the foreign particle, for various angles of incidence of the polarized light and emergence of the non-polarized light. Foreign particle data may be indicated by a mapping method.

Abstract: A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser's wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects.

Abstract: A three-phase angular position sensor is described in which three beams of light having polarization directions rotated 60.degree. to each other are passed through a polarizer, the rotational position of the polarizer representing an angle to be measured. The intensities of the beams transmitted through the polarizer uniquely encode its angle over a 180.degree. range. This range may be doubled, for example, by including a binary track. A two-phase angular position sensor is also described in which two beams have polarization directions oriented 45.degree. with respect to one another.

Abstract: A defect estimating apparatus includes a laser radiating unit For obliquely radiating laser light on a surface to be observed of an object to be inspected, an observing unit for observing, through the surface to be observed, scattered light produced From internal defects or particles of the object by refracted light of the laser light, and observing scattered light or reflected light produced from flaws or particles on the surface by tile laser light, and a component separating unit for allowing the observing unit to perform observation by using both light containing primarily a p-polarized light component of the laser light and light containing primarily an s-polarized light component of the laser light.

Abstract: In method and apparatus for measuring a refractive index and a thickness of a thin film formed on a substrate, the thin film has m (m.gtoreq.1) layers and a transparent uppermost layer is set as a first layer. A total of (3m+1) parameters include a refractive index n(0) of an incident medium, a refractive index n(j) (j=1 to m) of a j-th layer, absorption coefficients k(j) (j=2 to m) of second to m-th layers, a refractive index n(m+1) and an absorption coefficient k(m+1) of the substrate, and thicknesses d(j) (j=2 to m) of the second to m-th layers. Arbitrary one of the (3m+1) parameters is unknown and the other 3m parameters are known. This method and apparatus measure the unknown parameter. Monochromatic light having a wavelength is incident to the film having the m-layers at a predetermined incident angle from a first layer side in the incident medium to measure reflectances about S and P polarized light.

Abstract: In an ellipsometer, a phase-modulated, polarized light beam is applied to a sample, electrical signals are obtained representing the orthogonal planes of polarization of the light after it has interacted with the sample and the constants of the sample are calculated from the two resulting electrical signals. The phase modulation is sufficiently small so that the calibration errors are negligible. For this purpose, the phase modulator phase modulates the light within a range of no more than ten degrees modulations peak to peak. The two electrical signals are expanded by Fourier analysis and the coefficients thereof utilized to calculate psi and delta.