Abstract: An optical alignment system for aligning a multiple gap tape head assembly of a tape drive, including a cartridge plate insertable in a tape drive and having a first surface mirror that is parallel to a reference plane for the drive when the plate is inserted in the drive, a microscope objective imaging lens for providing images of the head gaps of the tape head assembly, a video camera and display for providing an operator viewable display of the output of the imaging lens, translation apparatus for moving the imaging lens, and an interferometer cooperating with the first surface mirror for maintaining the imaging lens at a constant distance relative to the first surface mirror as the translation apparatus moves the imaging lens from one head gap to another, such that the imaging lens moves in a plane parallel to the reference plane for the drive.

Abstract: A method and apparatus for analyzing fluid by a multi-fluid modulation mode is characterized by subjecting a plurality of sample fluids (which may be different or a single sample fluid divided into a plurality of systems) to a fluid modulation by reference fluids at various frequencies, respectively. An analytical portion provided with only one sensor is simultaneously and continuously supplied with the respective sample fluids. An output signal from the sensor in the analytical portion is divided into signal components of the respective modulation frequencies for the respective sample fluids to rectify and level, whereby obtaining analyzed values about the respective sample fluids is achieved.

Abstract: A method is described for a systematic method of interpreting interference fringes obtained by using a corner cube retroreflector as an alignment aid when aigning a paraboloid to a spherical wavefront. This is applicable to any general case where such alignment is required, but is specifically applicable in the case of aligning an autocollimating test using a diverging beam wavefront. In addition, the method provides information which can be systematically interpreted such that independent information about pitch, yaw and focus errors can be obtained. Thus, the system lends itself readily to automation.

Abstract: An apparatus is described which detects the presence or absence of coherent light and provides an estimate of the coherent light's wavelength. The apparatus employs a common-path "polarization interferometer" in which the two linear polarization paths act as interferometer legs. Electro-optic modulation is used to effect periodic differential path length changes in the interferometer. The apparatus performs synchronous time-integrating detection on the light emerging from the interferometer to measure coherent contributions in the presence of obscuring incoherent light.

Abstract: The fiber-optic rotation sensor comprises a sensing loop using an optical fiber which essentially performs a single polarization when bent, both end portions of the sensing loop being disposed with the principal axes of polarization thereof orthogonal to each other and the end portions being joined by an evanescent wave coupling to form a ring interferometer, a device for introducing to an input end of the interferometer a linearly polarized light at a bearing of 45.degree. relative to the principal axis of polarization of the interferometer, and a retardation measuring system provided at an output end of the interferometer for picking up an electrical output proportional to a rotational angular velocity applied to the interferometer. When the linearly-polarized light is introduced to the input end of the coupling portion of the ring interferometer at a bearing of 45.degree.

Abstract: A fluorescent lamp light output is maximized by cooling the cathode regions. Mercury vapor pressure is maintained at an optimum or desired level for light production by cooling the cathode areas of the lamp. The cooled cathode areas of the lamp collect cathode emissive material and mercury vapor condensates. Thus, the light output remains uniform and constant. The functional length of the lamp is not degraded by the deposition of either cathode material or mercury vapor condensates. Cooling can be effected by forcing cool air against the exterior of the lamp adjacent the cathodes or by using forced water heat exchangers. By cooling the respective cathode regions equally, the amount of deposition in the respective regions is substantially the same. Thus, gradations of deposition are avoided. The constant high output fluorescent lamp can be used with electronic inspection equipment and machine vision measurement devices.

Abstract: An apparatus for and a method of evaluating a multilayer thin film of the present invention. An interference light beam in a predetermined wave number region is projected as a parallel beam onto a multilayer thin film sample and the interference light beam reflected by the sample is detected to find an interferogram. The interferogram is subject to Fourier transform, filtering and reverse Fourier transform so that a spatialgram is provided. Thereby the variation in incident angle of the light beam incident on the sample and in incident surface is reduced, and the spatialgram can be provided with accurate information of the multilayer thin film.

Abstract: An optical transmittance apparatus has a pair of reference channels of glass rods and a pair of sample channels containing sample fluid. A beam splitter and mirror pass a first portion of an incident beam through an ingoing reference channel, and a second portion through an ingoing sample channel. The first portion is reflected back through an outgoing reference channel, and the second portion back through an outgoing sample channel. The beam splitter and mirror directs the outgoing beams into a common outlet path. A partial disk selectively passes either portion. For positioning the disk, poles of a magnet mounted on the disk axle face windings made about an axis perpendicular to the axle, the windings being on the opposite side of a barrier plate from the poles. Current of one polarity through the windings effects one orientation of the disk, and reversed olarity reorients it perpendicularly.

Abstract: A roof surface measuring method including the making of a collimated bundle of rays incident upon roof surfaces at a predetermined incident angle, laterally displacing a part of the wavefront reflected by the roof surfaces in a direction parallel with an edge line defined by the intersection of the roof surfaces by a displacing means, and making the laterally displaced wavefront and the original wavefront incident upon a measuring surface in a manner which causes an interference therebetween. The invention is also directed to a measuring apparatus for effecting the method.

Abstract: An inexpensive fiber optic gyro using a fiber optic sensing coil that is fed from two single-mode light carriers such as an optical waveguide or optical fibre. The light carriers obtain their energy, through a mode splitter, from a double-mode light carrier. The double-mode carrier is, in turn, energized by an at least partially coherent light source through a single-mode light carrier. The light source is preferably a laser. Detectors are attached to light carriers which tap different predetermined positions along the double-mode waveguide to produce substantially sinusoidal signal functions of sensed rotation.

Abstract: In multi-telescope arrays that comprise multiple telescopes, a beam-combining module, and flat mirrors for directing light beams from the multiple telescopes to the beam combining module, a laser metrology system is used for monitoring various pathlengths along a beam path where deviations are likely. Some pathlengths are defined simply by a pair of retroreflectors or reflectors at both ends. Lengths between pairs of retroreflectors are measured and monitored by laser interferometers. One critical pathlength deviation is related to the displacement of the flat mirror. A reference frame is set up relative to the beam-combining module to form and define the coordinate system within which the positions of the flat mirrors are measured and monitored. In the preferred embodiment, a pair of retroreflectors along the optical axis of the beam-combining module defines a reference frame. A triangle is formed by the reference frame as the base and another retroreflector at the flat mirror as the vertex.

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 microelectronic 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: The temperature and radiant energy emissivity of a semiconductor substrate or wafer undergoing processing are monitored by combining indications derived from an interferometer and the intensity of radiant energy emitted from the substrate. The radiant energy intensity is detected at adjacent maxima or minima in the intensity of the interference pattern.

Abstract: An apparatus and method for measuring the volume and hemoglobin concentration of individual red blood cells in a whole blood sample provides for isovolumetrically sphering the red blood cells of the sample using a sphering reagent and forming a stream of individual, spaced-apart cells sheathed in an electrolytic liquid in a flow chamber. The red blood cells in the stream are passed through a light scattering channel in which the intensity of light scattered by each cell into a preselected angular interval in the forward direction is measured. Each cell in the stream is also passed through a resistance pulse sizing aperture for measuring the volume of the cell.

Abstract: A method of processing the interference signals form a correlation microscope to provide images of a surface being examined. The interference signals for a plurality of x,y locations at a plurality of z positions are transformed to provide an intensity envelope of the signals along the z axis for each x,y location. The intensity envelope can then be processed to provide desired images.

Abstract: A process and a device for measuring, through a holographic technique, the deviation of the light rays of a laser beam by more or less transparent objects. The angular deviations (a) of light rays that have passed through the object are measured by an angular measuring instrument (2) located behind an optical system traversed by the light emanating from the object or a hologram formed from the object. The optical system comprises for example one or several lenses (l1, l2), the holographic images forming in the object focal plane of the system, and a diaphragm (D3) located in its image focal plane. The measuring can also be carried out, for example, by turning over the obtained hologram of the transparent object and examining it through a diaphragm. The present invention has application, for example, in the study of flames, of liquid or gaseous flows with strong density variations, of turbulent gaseous mixtures in the combustion chambers of engines, etc.

Abstract: The present invention relates to a method for greatly extending the effective coherence length of non-stabilized lasers allowing one to use them in interferometers with large optical path differences. The embodiment described as an example comprises a robust Twyman-Green interferometer for accurate measurement of extended displacements.

Abstract: Displacement measurement apparatus (1) shown in FIG. 1 measures the position of a reading means (4) relative to a coded track (2) which carries a sequence of code elements (5). The track is encoded with a binary sequence such that reading a binary word at any position along the track uniquely identifies its position. The binary word is remotely sensed by a decoding means (18) via a fibre optic link (12). Position information is encoded optically by the reading means using an interferometer to frequency modulate the transmitted light and the decoding means has a second interferometer to analyse received light and produce an electrical output representing the binary word.

Abstract: An apparatus and method for optically measuring the functional capacity of blood platelets and the blood clotting system. The invention includes a mechanical specimen-handling apparatus with one or more optical end-point detectors. The apparatus incubates a small quantity of diluted whole blood with added solid or liquid reagents at body temperature, and mixes the blood via rocking and rotational motions so as to expose the blood uniformly to the reagents. The optical end-point detectors then measure the activity of platelets within the blood specimen and the clotting cascade. Several intermediate measures are also available.

Abstract: An interferometer suitable for length measurements, comprising a laser light source, a beam splitter to divide light stemming from the laser light source into a measuring beam and a reference beam, and recombination means at which the reference beam being guided along a reference path and the measuring beam interfere. The measuring beam travels along a measuring path that leads over a movable measuring reflector and partly through a gaseous ambient medium. The interferometer further comprises photodetector means to analyze optical interference signals stemming from the recombination means. At least one static etalon of a known length is provided to determine or compensate for variable environmental conditions (variable refractive index) of the ambient medium. The etalon comprises two reflection surfaces and is illuminated by light stemming from the laser light source. The space lying inbetween these reflection surfaces is filled with the ambient medium.