Abstract: A laser system for measuring dimensional aberrations across a target surface includes a laser diode for producing a diverging beam of laser emission. A mask spaced from the diode in the beam has an aperture therein and can be moved so as to translate the aperture to selected locations laterally with respect to the beam. The mask blocks emission from impinging on the target except for emission transitting the aperture. Emission reflected from a segment to the target returns through the aperture back into the laser diode. An AC current is added to the driver current to modulate the emission. A lock-in amplifier of a photodetector signal adds feedback current to the driver current to lock in phase angle, so that the feedback current is a measure of the aberrations.

Abstract: This flow cytometer includes flow cell containing a flowing stream of a number of particles which flow one at a time in a straight line based on hydrodynamic methods, a radiator for radiating a light on the particles flowing through the flow cell, a forward scattered light detector for detecting a light scattered in the same direction as the radiating light, a right angle signal light detector for detecting light radiated in a right angle with respect to the direction of the radiating light, whereby the right angle signal light detecting assembly is disposed on a mount, with one end of the mount being elastically supported on a supporting member and the other end being disposed on another supporting member by an adjustment mechanism, whereby adjusting the inclination of the light axis of the right angle signal light detecting assembly is made easier so that the light axis can always be perpendicular to the radiated light.

Abstract: A method of profiling a rough surface of an object includes moving the object along a z axis so that a highest point of the rough surface is optically aligned with and outside of the focus range of a solid-state imaging array. An interferogram of the rough surface then is produced by means of a two beam interferometer. The solid-state imaging array is operated to scan the rough surface along x and y axes to produce intensity data for each pixel of the solid-state imaging array for a plurality of frames each shifted from the other by a preselected phase difference. The modulation for each pixel is computed from the intensity data. The most recently computed modulation of each pixel is compared with a stored prior value of modulation of that pixel. The prior value is replaced with the most recently computed value if the most recently computed value is greater.

Abstract: An acousto-optic spectrometer/polarimeter for analyzing an incident broad-band beam including an acousto-optic tunable filter (AOTF) for separating the incident broad-band beam into a diffracted extraordinary narrow-band beam, a diffracted ordinary narrow-band beam, and at least one undiffracted broad-band beam; first, second and third detectors respectively positioned to respectfully receive at least a portion of the diffracted extraordinary narrow-band beam, the diffracted ordinary narrow broad-band beam and the at least one undiffracted broad-band beam, and to respectively provide first, second and third signals based thereon; a subtracter for providing a polarimeter output by taking the difference between the first and the second signals; and an adder for providing a spectrometer output by adding the first and the second signals.

Abstract: The relative height variation and the thickness of a film of an object are simultaneously measured. A first interference pattern is produced for a calibration surface at a first wavelength and detected. Intensities of the first interference pattern are measured and used to compute a first group of phase values for each pixel. Intensity values of a point of the calibration samples are measured and used to compute a corresponding phase. A second interference pattern for the calibration surface is produced at a second wavelength and detected. Intensities of the second interference pattern are measured and used to compute a second group of phase values for each pixel. Intensity values of the point of the calibration surface are measured and used to compute a corresponding phase. A value for the surface height change .DELTA.h is computed by obtaining a linear combination of the corresponding phase values of the data groups.

Abstract: A probe for in situ quantitative detection of the concentration of an analyte in a sample includes a hollow elongated body adapted for single ended contact with the sample. The body has at least one optical fiber extended through the body for transmitting modulated light through the body, out a window at the forward end of the body, and along an optical axis into the sample to optically excite the analyte. A pressure transducer mounted beyond the window and spaced laterally away from the optical axis detects an acoustic response of the analyte to the modulated light. This probe is particularly suitable for performing remote photoacoustic analysis of analyte concentration in a sample.

Abstract: A laser length measuring instrument in which a first and a second sinusoidal wave interference signals differing in phase by .pi./2 are generated from a plurality of interference wave signals received from an interferometer; a plurality of third sinusoidal wave interference signals differing in phase by m.pi./2 n (where n=integer 2 or greater; m=positive integer sequentially selected from among 0<m.pi./2n<.pi.

Abstract: Disclosed herein is a Ring Laser Gyroscope Mount comprising a low coefficient of expansion metal Invar sleeve and mount coupler. The sleeve may be secured to the gyroscope pedestal by being screwed and affixed to a relatively high coefficient of thermal expansion material pedestal, such as HyMu 80. The sleeve is attached also to the glass frame by cementing it at selected locations within the central mounting aperture of the gyroscope frame. This securement procedure makes the assembly stiffer in directions perpendicular to the axis of the coupler. At least one concentric groove which surrounds the coupler is machined into at least one side of the frame to reduce stress at gyroscope mirror surfaces during thermal excursions. The clearance gap where the cement is placed, the groove depth and shape, and the sleeve and coupler are designed to be stiff but not induce distortion.

Abstract: In a fiber optic interferometer rotation rate sensor reset by phase ramp via a digital control circuit to undertake the reversal required to obtain the scale factor error information, a reciprocal, alternating phase shift that is not a function of the angle of rotation, but has a fixed timing, is synchronized with gyroscope modulation frequency to avoid lock-in, and scale factor nonlinearities, particularly in the case of low rates of rotation. Even in the case of low rates of rotation, a scale factor error correction is possible and lock-in, caused by variations in bias in the case of the modulation deviation reversal, is avoided.

Abstract: A method is used for processing signals, particularly for oximetric measurements on living human tissue. Spurious signals are suppressed with respect to information signals. The spurious signals have a frequency lying in a first frequency range, and the information signals have a frequency lying in a second frequency range being different from said first frequency range. The signals are conducted over a filter having essentially a blocking characteristic in said first frequency range and having essentially a transmission characteristic in said second frequency range. An output signal of the filter is further processed.In order to eliminate distorting effects from the filter on the information signal, a first function is determined representing the deviation of the frequency response of the filter in said frequency range from an ideal transmission characteristic. A second function inverted with respect to said first function is generated.

Abstract: A fiber-optic probe which is useful for measuring Raman spectra of samples remote from the light source and detector. The probe head contains optical components which selectively remove unwanted fluorescence and Raman scattering arising from the interaction between the Raman excitation source radiation and the input optical fiber. The optics also filter the Raman excitation source into a return optical fiber leading to a spectrometer or detector. In one embodiment, the disposition of optical components provides a compact probe geometry with parallel input and output fibers at one end and a sampling port at the other end. An encasement for the optics is also disclosed, for sealing the components against the environment, and for coupling the probe to specialized sampling attachments, such as for conducting Surface Enhanced Raman Spectroscopy.

Abstract: A method and apparatus for nondestructively, quickly and accurately measuring concentration of a material in a sample, for example carbon concentration in a carbon-containing sheet, by optically sensing a two-dimensional portion of the carbon-containing sheet and converting the sensed portion into a two-dimensional array of points, each having a digital value related to the sensed optical intensity at the point. Preferably, each point has a gray scale value of the sensed optical intensity at the point. An average digital gray scale value for the two-dimensional gray scale array of points is obtained and compared to the average digital gray scale value of a carbon-free sheet to obtain an optical density. The obtained optical density correlates highly with the carbon concentration, as measured by chemical concentration measurement techniques which are slow and destructive.

Abstract: Apparatus for analyzing particles in which the particles traverse a sensing zone one at a time. A first detector measures variations in the conductivity of the fluid caused by the presence of a particle in the sensing zone. A laser irradiates the sensing zone and a second detector is provided responsive to light scattered by particles in the sensing zone. Additional detectors are provided responsive to fluorescence from the particles. The signals from each of the detector means are digitized and stored and then compared. The differences in successive waveforms from each detector indicate the presence of abnormal particles. Waveform shape is also used as an indication of the shape of the particles.

Abstract: The turbidity of liquids, including oil contaminated water, may be measured by an apparatus having a first elongated shell member defining a turbid liquid measurement chamber and opposed head members forming windows for transmitting a light beam through the measurement chamber between a light source and photosensitive element. A second shell member is disposed around the first shell member and defines with the first shell member and the opposed head members clear liquid supply chambers for supplying a clear liquid to wash over the windows and prevent contact of the turbid liquid with windows during operation of the apparatus. A flow of clear liquid, such as water, may be controlled by a pump and a throttling valve with orifices in each flow line to limit the flow of clear liquid. A mixture of clear liquid and turbid liquid is discharged from the turbidity measurement chamber into a discharge manifold formed between the shell members.

Abstract: Two laterally-displaced images of a test object interfere with each other to form a shearogram. Two shearograms, taken while the object is unstressed and stressed, respectively, are compared electronically to yield a composite interference pattern. According to the invention, each shearogram is formed by the interference of pairs of distinct rays of coherent light, reflected from different points on the object. The first ray of each pair is reflected from the object, strikes a mirror spaced from the object, and is reflected from the mirror. At the same time, the second ray of each pair is reflected from the object and strikes a beam splitter positioned beside the mirror. The beam splitter directs a portion of the second ray in the same direction as the reflected first ray, and a portion of the first ray passes through the beam splitter without being reflected. Since the two rays have the same polarization angle, and are mutually parallel, the rays interfere.

Abstract: An apparatus and method for making a photometric determination regarding the contents of a sample, such as the absorbance characteristic of a blood serum sample. The improvement allows measurements to be taken after a reduced warm-up period and compensates for variations in the lamp intensity during the period over which measurements are taken. A feedback circuit is provided between a reference photodetector and the light source for causing the light source intensity to asymptotically approach a final stable value in a smooth exponential curve. Signal processing means processes outputs of the reference and sample photodetectors taken at different times so as to compensate for variations in the source intensity over the time period during which the outputs are taken. Still further, the photometer allows resonant frequency mixing of the contents of a cuvette while disposed in the photometer by causing the entire optical assembly, in which the cuvette is mounted, to vibrate at its resonant frequency.

Abstract: An apparatus for detecting and identifying a biological object. A transparent plate has a first surface onto which a light beam is projected and a second surface onto which a biological object to be detected and identified is placed. The light beam projected toward the first plate surface is transmitted through the plate and toward the object on the second surface, from which the light beam is reflected and retransmitted through the plate toward and through the first surface thereof and received and detected by an optical detector. The detection of a biological object is confirmed by comparing the change of the wavelength characteristics of the reflected and detected light beam in a predetermined time sequence according to the object being first placed upon and then pressed upon the second surface of the transparent plate with respective, known such characteristics thereof.

Abstract: A device for measuring entrained air in concrete, includes a needle tube for insertion into the concrete, the needle tube having a distal end; an optical fiber extending through the needle tube to the distal end, with the end of the optical fiber and the distal end of the needle tube being ground to have a sharp conical angle; a laser diode which produces laser light; a coupling device which supplied the laser light from the laser diode to the optical fiber and which separates the light reflected back through the optical fiber; and a photodetector which converts the received light from the coupling device to an electrical signal corresponding to the intensity of the reflected light.

Abstract: A method and system for evaluating signals from a fiber optical gyro employs a 3.times.3-coupler which makes it possible to ascertain a precise Sagnac-Signal in spite of the fact that the fluctuations of the optical characteristics of the fiber coil are unknown. Thus, a high precision is assured, while simultaneously reducing the quality requirments for the optical components of the system.

Abstract: A method and apparatus for measuring the optical attenuation of optical mediums characterized by a first transmitter and a second receiver being connected to one output of the optical medium and the second transmitter and first receiver being connected to the other output. Thus, four measuring processes can be obtained, which include measuring the signal from the first transmitter after it passes through the optical medium by the first receiver, measuring the signal from the first transmitter in the second receiver before it passes through the optical medium, measuring the signal from the second transmitter after it has passed through the optical medium by the second receiver and measuring the signal from the second transmitter by the first receiver before it passes through the optical medium. These four values are then processed to determine the exact attenuation of the optical medium.