Abstract: An ultra violet radiation detector comprises a slice of silica (10) having an entrance slit (18) from which radiation diverges to a curved reflective face (20, 22) which reflects it to a planar diffraction grating (28) as a convergent beam. The grating focuses a required spectral order on an array of UV detectors (24). Usually the first order spectrum is focused. The detector may be hand held.

Abstract: In a fiber optic gyro (FOG) with a photo-diode phase detector that produces a detector signal that is supplied to an A/D converter to generate a FOG information signal for use in a signal processor to produce a FOG control signal based on FOG controller equations, the photo-diode out is summed with a feedback signal from the signal processor to reduce a DC offset in the input to the A/D converter.

Abstract: A measuring apparatus and a method of operation are presented for rapid and accurate determination of the performance parameters of an optical fiber amplifier. The apparatus primarily includes an optical fiber path 2 having an acousto-optical modulator 3 for modulating reference light and an optical switching device 11 for enabling to bypass the modulator 3, to supply reference light to an optical coupler 5 which divides the reference light into first and second signals.

Abstract: A control system for an optical sheet sensor device, including at least one light emitter and at least one light detector associated therewith for sensing a sheet in a sheet travel path, having a control system for automatically adjusting the intensity of said light from said light emitter. The control system stores a light emitter current level corresponding to a known valid operating condition where, when a sheet is absent from the sheet travel path, light detected at a light detector beyond a threshold level. A current level at a preset amount off-set from said stored current level is determined. A current is applied to a light emitter, the applied current rising toward a level at which the threshold level for the light detector is reached. The instantaneous applied current level is compared with the determined current level, and an error signal is provided when the applied current level reaches the determined current level.

Abstract: Apparatus and associated methods of detecting optical carriers and measuring characteristics thereof provide optical carrier wavelength determination and measurement of other characteristics with improved precision. In a preferred embodiment, a method of detecting optical carrier wavelengths utilizes a controller to direct a stabilization circuit to adjust an optical filter to sample selected wavelength portions of an optical spectrum. The controller then evaluates the samples' intensities and directs the stabilization circuit to adjust the filter to sample other selected wavelength portions of the spectrum based upon the results of the evaluation.

Abstract: Complex atomic or molecular spectral signatures embedded in interfering background spectra are very rapidly recognized by a spectrometric device that employs precise sweep rate control with signal slope extraction. Very fast optics become feasible. High signal to noise ratios are attained in each of three operational modes. The first, PURGE, is frequently invoked and stores an ambient background pattern in differentiated form. The second, TARGET, stores a signature derived from a target substance placed within the invention's sensing range. The signature retains only signal derivatives that significantly depart from those encountered during PURGE. A SEEK mode employs a similar derivative extraction algorithm, and searches for matches to TARGET signatures stored in a memory bank. During SEEK, pattern correlations to stored targets are sensed, and results displayed.

Abstract: A folded acoustic traveling wave lens arrangement imparts multiple passes of an incident optical beam through the traveling wave lens, and thereby effectively maximize utilization of acoustic power. A lens of optically transmissive bulk material, such as quartz, is disposed in the path of an incident light beam which is spatially scanned by a light beam deflector. The bulk material of the lens element has a reflective layer disposed upon at least one of its surfaces, and is configured such that an incident light beam undergoes multiple passes through the acoustic wavefront propagating through the lens, prior to emerging from the lens. Aberration in the emerging beam due to multiple passes through the bulk material is corrected by a pupil plane correction plate.

Abstract: The apparatus for determining the color stimulus specification of translucent objects comprises two light sources to create on the surface of an object under test two light spots which have different size. The light is transmitted from the light sources to the object under test by means of an optically conducting fiber bundle. The light reflected by the object under test is received by a lens and led via an optically conducting fiber bundle to a spectrometer. Thereafter, the measurement signal is digitized and arithmetically evaluated in a microprocessor. Due to the fact that two differently sized light spots are used, the measurement error which results in determining the color specification value of a translucent object can be defined and corrected. For this purpose, use is made of reference measurement values which have been obtained by measuring opaque reference objects and which have been stored in a memory module of the apparatus.

Abstract: An improved Raman spectrometer is provided, having, in a preferred embodiment, a light source comprising an injection-locked laser diode array, a multipass cell to multiply the intensity of the light source, a dynamic gas sample focusing system, and an atomic vapor filter to remove the Rayleigh scattered light. The laser diode arrays are tuned to match an absorption band of the atomic vapor filter. The Raman scattered light passes virtually unattenuated through the filter to be recorded by a Fourier transform spectrometer or other spectrometer. This invention permits higher sensitivity and resolution than prior art Raman spectrometers, in particular permitting identification and measurement of Raman emissions that occur at low wave numbers. The light source of this invention can also be used in conjunction with optical notch filters and photodetectors to permit detection and measurement of preselected species in a sample.

Abstract: An improved method for minimizing interferences from random noise and correlated fluctuations which obscure electrical signals converted from optical emissions. In particular, an improved method for the removal of interferences from optical emission signals during endpoint determination in dry etching processes for the fabrication of micro-electronic devices which derives information in the presence of random noise, correlated fluctuations and periodic modulations of the plasma by maximizing the signal to random noise ratio and minimizing the obscuring effects of correlated fluctuation.

Abstract: Apparatus and method of determining presence or absence of light activity in an optical fiber without separation or disconnection thereof from other fibers or from apparatus to which the fiber is connected, and without interruption of transmission. The method involves contacting the fiber with a probe and moving it laterally to produce a macro-bend at which a portion of light traveling through the fiber, if any, escapes from the fiber. The escaping light is reflected from a concave surface in a fixture through which the fiber passes and is detected by a photocell in the probe which contacts and moves the fiber. The probe is engageable with the fixture in either of two rotational orientations to receive light reflected from two different areas of the reflecting surface, thereby indicating the direction of light travel. Initial calibration and positional adjustment of the probe relative to the fixture also permits determination of light intensity.

Abstract: An OTDR measurement device employs optical heterodyne wave detection to perform measurement on optical fibers. Optical pulses are incident on a measuring optical fiber, which in turn outputs backward scattering light. The device performs heterodyne wave detection on the backward scattering light as well as probe light whose frequency is set in proximity to a frequency of the backward scattering light, thus producing a detection voltage. The device provides a differential amplifier which performs amplification on a difference between the detection voltage and a reference voltage to produce a difference signal. An A/D converter converts the difference signal to a digital signal. Square addition is performed on the digital signal to produce a mean square signal representing property of the measuring optical fiber. Herein, calculations are performed on the mean square signal to produce a reference signal, which is then converted to the reference voltage.

Abstract: The present invention refers to a spectrometer device comprising a monochromator means, a light-measuring means receiving light from said monochromator means, and a calibration means comprising a calibration light source. The present invention provides a new spectrometer device whose light-measuring means comprises a plurality of light-measuring elements in an array extending in the direction of dispersion of the monochromator means, and whose calibration means carries out, on the basis of a spectral light measurement with the aid of the calibration light source, an association between the light-measuring elements and the wavelengths of the spectral light which is adapted to be detected by the respective light-measuring elements. These measures substantially facilitate the calibration and especially the automatic execution of said calibration, if desired simultaneously with a spectra measurement, and they improve the accuracy of the calibration.

Abstract: The description relates to a process for luminescence scanning microscopy with two-photon excitation, especially for examining biological objects (5). A laser pulse excites luminescent, especially fluorescing molecules and the luminescence emitted by the object (5) is measured and evaluated. In the process, the luminescent molecules in the object (5) are excited by laser pulses of over 10.sup.-12 second duration. A luminescence scanning microscope for implementing the process has a detector (2), a filter (7, 8) for separating the light emitted by the sample from the laser light (4) and a laser light source which is a laser (1) emitting pulsed or continuous radiation.

Abstract: A hand-held portable spectrophotometer that is contained in an enclosed housing and includes a source of illumination and a spectrograph, along with a transmittance cell and a reflectance cell. The transmittance cell is adapted to receive therein either a solid sample or a liquid sample through an access door in the top wall of the housing.

Abstract: The invention is directed to a machine for detecting anomalies in parts. A strip of parts (10) is transported through a sensor unit having light sources and photodetector pairs (118, 116; 132, 134; 136, 138) to detect pilot holes and the presence and position of parts. At least one of the light sources (136) is directed at an angle to detect out of plane deformations. Simple light sources and photodetectors are used to detect and identity misaligned contacts without the need for complex vision system components.

Abstract: To reduce the accumulative lock-in effects of the ring laser gyroscope, the dither circuitry is provided with low frequency dither amplitude modulation. Such modulation is achieved by first developing a pair of complementary low frequency dither noise signals. These low frequency dither noise signals are then utilized by a modulator to modulate the dither drive signal in conjunction with the low frequency dither noise signals. This results in a system which allows much more dither amplitude modulation with much less output from the drive amplifiers. Because of the ability to increase amplitude modulation, gyro performance is greatly improved.

Abstract: A technique for making precise spectrophotometric measurements illuminates a sample with two or more modulated light sources at two or more, typically closely spaced, wavelengths. Light from the sources is combined, homogenized, and directed to the sample, and the light from the sample is collected and detected by a photodetector. The optical output powers of two sources are modulated with the same periodicity and with a reversed amplitude. Variations in the concentrations of species in the sample affect the modulation amplitude representing the sum of the optical powers from two sources in such a way as to produce an output signal. That output signal, based on an electrical component varying with a periodicity at the fundamental frequency, provides a measure of the difference in the transmissions (or other optical properties) of the sample at the two wavelengths. Feedback methods, such as null-point detection, provide stable, sensitive measurements.

Abstract: The pixel position-to-wavelength calibration function of film measurement devices such as spectroscopic ellipsometers and spectroreflectometers may shift due to temperature and humidity changes and mechanical factors. One or more wavelength markers provided by the light source or reference sample may be used to correct the calibration function. The pixel positions of one or more persistent wavelength markers are noted during the calibration process and the current positions of such markers are again noted to account for shifts due to various factors to correct the calibration function.

Abstract: A short-width pulse generating apparatus for use in measurement of a reflection point, a sampling apparatus for use in measurement of a a reflection point, and a reflection point measuring apparatus each being able to specify a reflection position produced in an integrated high-frequency circuit or a reflection point produced in the inside of an optical element with high accuracy are provided. A short-width pulse generation apparatus comprises short-width optical pulse generating means for generating an optical probe pulse having a narrow pulse width and photoelectric conversion means for producing a short-width electric pulse on a signal transmission line when irradiated with an optical probe pulse, and a sampling apparatus comprises variable delay means for sequentially delaying an optical probe pulse and second photoelectric conversion means for sampling an electric potential on the signal transmission line by being irradiated with an optical probe pulse delayed by the variable delay means.