Abstract: A gel defect detection system for the optical inspection of defects in oriented transparent and translucent sheet. The system utilizes two polarizing filters with adjustable orientations so that the transmission axis is from about 70 degrees to about 110 degrees or from about 80 degrees to about 100 degrees. The system uses these polarization filters to help distinguish gel defects from the surrounding oriented sheet.

Abstract: A single-channel gas concentration measurement method and apparatus. According to the method, a radiant source is employed to generate a measuring signal, the measuring signal is subsequently directed to a measurement object containing a gas mixture to be measured, the measuring signal is subsequently bandpass filtered using at least two passband wavelengths, and the filtered measuring signals are detected by a detector. According to the invention, the bandpass filtering step is implemented by a single electrostatically tunable, short-resonator Fabry-Perot interferometer.

Abstract: The present invention is a directional reflectometer that measures the optical bidirectional reflectance distribution function [BRDF] of a surface in situ on a finished article, e.g. a vehicle, to provide information on its surface emissivity. The light wavelength may be IR, near-IR or visible. Light, preferably focused to a small spot on the surface, is projected onto the surface at an angle adjustable in azimuth and elevation. A wide angle mirror and/or lens system transfers light scattered from the surface onto an imaging sensor, preserving scattering angle information and thereby permitting the BRDFs for a given incidence angle and all scattering angles to be measured simultaneously. A hand held or laptop computer sets the incidence angle, reads the sensor outputs and renders judgments on the quality of the surface in a factory or field environment.

Abstract: Apparatus and method for rapid detection of explosives residue from the deflagration signature thereof. A property inherent to most explosives is their stickiness, resulting in a strong tendency of explosive particulate to contaminate the environment of a bulk explosive. An apparatus for collection of residue particulate, burning the collected particulate, and measurement of the optical emission produced thereby is described. The present invention can be utilized for real-time screening of personnel, cars, packages, suspected devices, etc., and provides an inexpensive, portable, and noninvasive means for detecting explosives.

Abstract: An optical measuring system comprises an illumination arrangement including a light source, grating, and lens, and an image acquisition arrangement, including a lens, grating, and camera. A mechanical translation device moves the grating in a plane parallel to a reference surface to effect a phase shift of a projected image of the grating on the contoured surface to be measured. A second mechanical translation device moves the lens to effect a change in the contour interval. A first phase of the points on the contoured surface is taken, via a four-bucket algorithm, at a first contour interval. A second phase of the points is taken at a second contour interval. A controller, including a computer, determines a coarse measurement using the difference between the first and second phases. The controller further determines a fine measurement using either the first or second phase.

Abstract: A method and resulting system for directing generally collimated illumination from a source at an oblique angle to a surface under inspection (SUS) to produce scattered nonspecular energy substantially normal to the SUS and for observing the scattered nonspecular energy in one of a plurality of fractional windows of a viewed image of the SUS via a plurality of focussing elements. Such arrangement results in simultaneous and significant throughput and sensitivity enhancement over existing art. The method can be enhanced further wherein the observing step is performed through suitable relative motion of the scattering image over the imaging plane to permit over sampling. Furthermore, the DMT is significantly simplified because imaging is utilized to electronically scan the wafer instead of using opto-mechanical scanning means. Imaging sensors with an aggregate 2000.times.2000 pixel resolution could image a 200 mm wafer to 100 microns pitch.

Abstract: A diffuse reflectance probe is disclosed which employs in an exemplary embodiment, fiberoptic light transmitting elements and a light pipe for collecting light. The fiberoptic light transmitting elements surround the light pipe and a window having a beveled surface communicates with the light transmitting fiberoptics to direct illuminating radiation in a relatively large field of view in a close working distance with the probe.

Abstract: A method for imaging objects in turbid media. According to one embodiment of the invention, the method comprises the steps of (a) illuminating the object through the turbid medium with a pulse of light, the light emergent from the turbid medium consisting of a ballistic component, a snake-like component and a diffusive component, the diffusive component including Fermat photons and non-Fermat photons; (b) gating the light emergent from the turbid medium to preferentially select Fermat photons; and (c) forming an image of the object using the gated light. Preferably, a spatial gate is used to preferentially select Fermat photons from the emergent light. This may be done by orienting the source of the illuminating light and a light detector to lie along a most favorable path travelled predominately by Fermat photons. A time gate, such as a streak camera or the like, may be used in addition to the spatial gate to more carefully select Fermat photons from the emergent light.

Abstract: An optical device for forming an image of an uneven surface, including a plane-parallel plate with a pair of parallel plane surfaces which is made of a transparent material having a refractive index larger than that of water and transparent to illuminating light. An uneven object (object having an uneven surface) is placed in close contact with one plane surface of the plane-parallel plate. A light source illuminates the uneven object through the plane-parallel plate. Among light rays scattered back into the plane-parallel plate by the uneven object and totally reflected at the other plane surface of the plane-parallel plate, only light that is totally reflected at an angle larger than the critical angle at the boundary between the plane-parallel plate and water is taken in by an image-forming device.

Abstract: In an article identification system comprising a plurality of identification regions affixed on an article, a light emitting device for impinging an illuminating light beam onto at least some of the identification regions, a light receiving device for detecting light diffracted by the identification regions, and a determination unit for determining the authenticity of the article according to a pattern of diffracted light detected by the light receiving device, the identification regions consist of a combination of effective and ineffective identification regions which are hardly distinguishable by naked eyes. Thus, the potential forger is not able to know which regions are indeed effective without having any access to a genuine optical reader/writer, and has to duplicate all of the identification regions at a substantial cost and requiring a substantial amount of effort.

Abstract: A method for refractometer measuring, in which a beam of rays emitted from a light source is transmitted to the interface between the optical window of a refractometer and the liquid to be measured, whereby part of the beam of rays is reflected back from the liquid and part is absorbed into the liquid and an image is produced in which the position of the boundary between a light and dark area depends on the critical angle of total reflection, the critical angle being a function of concentration of liquid, and in which the boundary between the light and dark area of the image is determined by light detectors arranged in a line. For good resolution, to the measuring data obtained from the light detectors is applied a mathematical model corresponding with the information provided by the measuring data and the position of the boundary is determined by means of this model.

Abstract: A device and method for grading gemstones. The device utilizes an band pass filter and detector array to obtain the spectral response of a complete image. The gemstone is illuminated in a way that provides for analysis of both reflected and transmitted light. The device utilizes multiple lighting angles to construct an composite image that is used to perform the grading of the gemstone. The device provides spectral photometric data for each individual pixel of the image, or any portion of the gemstone image.

Abstract: A method of exposing images of measuring patterns formed on a mask on a photosensitive substrate through a projection optical system, measuring positional deviation quantities of the exposed images of the measuring patterns in a measuring direction and thus measuring imaging characteristics of the projection optical system on the basis of the measured positional deviation quantities. In this method, periodic patterns are used as the measuring patterns, wherein bright and dark portions are arranged at a predetermined pitch in a direction corresponding to the measuring direction. The positional deviation quantity is measured by assuming the image of the periodic pattern as an image of the pattern consisting of the single dark portion on the whole when measuring the positional deviation quantity of the periodic pattern image exposed on the photosensitive substrate in the measuring direction.

Abstract: A calibration method especially for calibrating a reflection spectrometric gauge, such as an oil film gauge. In the method, calibration is conducted by measuring the gauge response by means of a calibration unit and a solid, stable permanent sample (37) provided on it as a calibration sample. A change that simulates a certain substance concentration is generated by the stable permanent sample (37) in the reflection spectrum, and the gauge response is calibrated on the basis thereof. In the invention, the gauge response is calibrated by using at least two calibration samples (37, 39) having different absorption responses, said two calibration samples being said permanent sample (37) and a second calibration sample (39). For calibration, roughness compensation is performed, in which the gauge response is corrected on the basis of the measurement of the optical response of the surface to be measured and the known data on roughness dependence.

Abstract: Disclosed are a method and apparatus for performing photon diagnostics using a portable and durable apparatus which incorporates the use of a remote sensing probe in fiberoptic communication with an interferometer or spectrometer. Also disclosed are applications for the apparatus including optically measuring high velocities and analyzing plasma/emission spectral characteristics.

Abstract: An optical sensor system includes a housing having an open end; first and second windows situated in the housing; a fastener for situating the first window closer to the open end than the second window and permitting an air exchange between a sensing region and the second window; a hermetic seal between the second window and the housing; and an optical sensor situated between the second window and a wall of the housing such that the air exchange does not occur inside the optical sensor. The first and second windows can include materials selected from the group consisting of sapphire, quartz, and glass; the optical sensor to be protected can include silicon carbide; and the sensing region can include a combustion region.

Abstract: A long-range, wide-area remote sensor system(s) to detect trace levels of atmospheric constituents using bistatic configurations to measure differential absorption (BDIAL) of source beams tuned to the absorption line center and off-peak "wing" in the spectra of species of interest. Potential platforms for the probe beam and detector subsystems include satellites and airborne vehicles, and mapping of large geographical regions is accomplished by tomographic reconstruction of recorded columnar absorption data. The use of bistatic geometries reduces power requirements on the probe beam, as compared to standard backscatter DIAL, and allows detection with platforms at large stand-off ranges, subject to atmospheric conditions. Operation in spectral regions including UV, visible and IR is feasible, provided that there are no overlapping absorption lines when many substances are present. Use of multiple frequency sources and multi-spectral detectors will reduce identification ambiguities.

Abstract: An apparatus and method for optically measuring concentrations of components allow enhancement in measurement accuracy of concentration. The apparatus includes a cell, a light irradiator, a photodetector, and an arithmetic unit. The cell presents different optical path lengths at different locations and is to contain a sample therein. The light irradiator, which includes a variable-wavelength laser generator and a measuring system composed of convex lenses, outputs a collimated, enlarged laser beam, and makes the laser beam incident upon the cell. The photodetector comprises a multiplicity of photodetectors arranged in parallel to the surface of the cell, so that it can detect intensity of rays of transmitted light that have traveled over different optical path lengths at positions of an equal distance from the cell.

Abstract: In order to measure the optical quality of the surface of a transparent sheet, the second surface of the sheet is placed in contact with a flexible material which is wetted with an index liquid. In the case of soda lime glass, water is suitable. The optical measurement can be carried out by traditional methods, ombroscopy in particular.

Abstract: A method and apparatus using either two or three input laser beams in a nonlinear degenerate four-wave mixing arrangement for ultrasensative analytical measurements of an analyte. In accordance with a first embodiment of the present invention, a two input beam F-D4WM arrangement is used to generate two phase conjugate signal beams. The input beams are narrowly focused to intersect within a very small volume of an analyte. The analyte may be in any physical state (e.g., liquid, solid, or gas). The intensity of the signal beam is used to detect trace concentrations of particular substances. The beam spot of each of the input beams can be focused to less than 34 .mu.m, thus allowing the present invention to directly focus the input beams within a capillary tube of a HPCE or a column of a HPLC system. In accordance with the second embodiment of the present invention, the input laser beams of a F-D4WM method are directed to points on a lens by immobilized fiber optic cables.