Abstract: A pulsed electromagnetic radiation (EMR) source and an interferometer are used to obtain spectra from the surface of a sample. The pulsed EMR source uses a broadband radiation source and a monochromator to generate monochromatic radiation. Alternatively, a tunable laser can be used as the monochromatic radiation source. The modulated radiation impinges on the surface of interest where it is absorbed. The absorption of radiation causes the surface of the sample to expand. This change in dimension is then detected by an interferometer which employs a monochromatic radiation source to measure the instantaneous distance between the sample surface and the interferometer. The detection system of the interferometer can be an imaging device such as a video camera to obtain the spatial distribution of chemical composition of the sample surface.

Abstract: A gas sample chamber that is particularly advantageous for use with a semiconductor laser has the form of an elongated hollow tube with a specularly reflective inside surface, a semiconductor laser located at one end of the tube and a detector located at the opposite end of the tube. In one embodiment, apertures in the wall of the tube permit a gas to enter and leave the sample chamber by free diffusion. In another embodiment the gas flows into the hollow tube from a pressurized source through a port or is drawn through the tube by a suction pump. In other embodiments, the tube is partitioned into two successive sections by means of a window located within the tube. The window is transparent to radiation of two different wavelengths that coincide with the absorption bands of two different gases. The semiconductor laser is tuned to these wavelengths successively so that two gas components can be detected and measured simultaneously.

Abstract: A luster detector arranged such that an output light beam of an LED is applied to a surface through a light projecting lens as an irradiating light beam having a predetermined width. Rays of light reflected from the surface are applied through a condenser lens to a line sensor. Of the rays of light reflected from the surface, the rays of light reflected regularly form a light spot on a light detecting section extending in the longitudinal direction of the light detecting section. Hence, even if the light receiving position is shifted, the light detecting operation is positively achieved. A detecting circuit determines the light reception distribution of the sensor to detect the luster of the surface.

Abstract: The present invention is a method for analyzing irregular-shaped chunked silicon for low-level contaminates. The method comprises selecting a zonable-chunk of silicon and float-zoning the chunk of silicon to effect a distribution of surface contaminates into the bulk of a monocrystal of silicon. The float-zoned monocrystalline silicon is then processed into a wafer suitable for analysis for low-level contaminates.

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: A system and method for generating a desired displacement of an object, i.e., a target, from a reference position with ultra-high accuracy utilizes a Fabry-Perot etalon having an expandable tube cavity for resolving, with an Iodine stabilized laser, displacements with high accuracy and for effecting (as an actuator) displacements of the target. A mechanical amplifier in the form of a micropositioning stage has a platform and a frame which are movable relative to one another, and the tube cavity of the etalon is connected between the platform and frame so that an adjustment in length of the cavity effects a corresponding, amplified movement of the frame relative to the cavity. Therefore, in order to provide a preselected magnitude of displacement of the stage frame relative to the platform, the etalon tube cavity is adjusted in length by a corresponding amount. The system and method are particularly well-suited for use when calibrating a high accuracy measuring device.

Abstract: A polarizing optical arrangement wherein a linearly polarized signal beam cluster is generated. The signal beam cluster is created from interfering partial beam clusters and is linearly polarized. The azimuth of oscillation of the linearly polarized signal beam cluster is dependent on the mutual phase relationship of the aforementioned partial beam clusters. A splitter grating splits the linearly polarized signal beam cluster into partial beam clusters that are analyzed by analyzers, detected by photoelectric transducers and phase-shifted electrically from one another.

Abstract: An interferometer used as a rotation sensor is constructed using a strand of optical fiber, a portion of which is formed into a sensing loop. A pair of light waves are caused to counterpropagate in the sensing loop and are combined to form an optical output signal that has an intensity that varies in accordance with the difference in the phases of the two counterpropagating light waves. A phase modulator is positioned on the optical fiber in the sensing loop at a location such that the two counterpropagating light waves are modulated approximately 180 degrees out of phase. The time-varying phase modulation causes a time-varying phase difference that is combined with a rotationally-induced Sagnac effect phase to provide a total phase difference that is detected by a photodetector. The photodetector provides an electrical output signal this is processed to determine the Sagnac phase difference. The rotation rate is then calculated from the Sagnac phase difference.

Abstract: A displacement information measuring apparatus comprising light emitting source for emitting two light fluxes, acoustic optical device for giving a predetermined frequency difference to the two light fluxes from the light emitting source, optical system having a diffraction grating upon which at least one light flux of two light fluxes having the predetermined frequency difference given by the acoustic optical device is vertically incident so that the light fluxes are diffracted, the optical system causing at least one light flux from the diffraction grating to be incident upon an object in which the displacement information is to be measured, and detector for performing a detection by interference of one light flux incident upon said object and emergent from said object with the other of the two light fluxes, the displacement information of the object being obtained from a beat signal corresponding to the frequency difference and obtained from the detector, wherein the optical system is constituted such that

Abstract: An optical fiber surface plasmon resonance (SPR) sensor includes both a metal layer and an overlay or underlay material on its surface. Existing fiber based SPR devices are inherently incapable of monitoring aqueous systems which have a refractive index ranging between 1.33 and 1.35, and existing prism based SPR sensors have proved too cumbersome for online chemical and biochemical analyses. Inclusion of the overlay or underlay material on the SPR sensor allows monitoring media with a refractive index from 1.00 to the 1.39 barrier and above. Hence, the SPR sensor allows monitoring important biochemical and chemical aqueous processes where the media typically have a refractive index between 1.33 and 1.35. In operation, samples are simply applied to the sensing region of the SPR sensor where the metal layer and overlay or underlay materials are coated, introducing a polarized beam of light into the optical fiber, and detecting surface plasmon resonance.

Abstract: A laser light, whose wavelength is to be measured, is introduced into an etalon, a concentric circular interference stripe derived from the etalon is irradiated onto a one-dimensional photodetector array and a diameter of the interference stripe is measured to measure the wavelength of the laser light. Alternatively, if a reference laser light of known wavelength is introduced into the etalon, as described above, a wavelength measurement of extremely high accuracy can be made without being affected by positional deviations of the optical system.

Abstract: An novel interferometric apparatus and method for measuring the topography of aspheric surfaces, without requiring any form of scanning or phase shifting. The apparatus and method of the present invention utilize a white-light interferometer, such as a white-light Twyman-Green interferometer, combined with a means for dispersing a polychromatic interference pattern, using a fiber-optic bundle and a disperser such as a prism for determining the monochromatic spectral intensities of the polychromatic interference pattern which intensities uniquely define the optical path differences or OPD between the surface under test and a reference surface such as a reference sphere. Consequently, the present invention comprises a "snapshot" approach to measuring aspheric surface topographies such as the human cornea, thereby obviating vibration sensitive scanning which would otherwise reduce the accuracy of the measurement.

Abstract: A wedge-type interferometer is disclosed that is supported three-dimensionally by a cast inner shell, which contains a readily removable optical cartridge supporting the fixed and movable wedge-shape prisms of the interferometer. The fixed prism is supported from one side of a centerpiece of the cartridge while the movable prism is supported from the other side of the centerpiece for linear, scanning movement. The cartridge may be mechanically and optically aligned prior to insertion into the inner shell, and is easily removed if additional adjustments are required. A first corner cube mirror is supported by a plate secured to one wall of the inner shell and is aligned by micropositioner adjustment in the X-axis. A second corner cube mirror is supported by a plate secured to another wall of the inner shell and is aligned by micropositioner adjustment in the Y-axis. After alignment, the micrometers are removed, and the inner shell may be mounted in an outer, hermetically-sealed casting.

Abstract: The invention provides a laser interferometric measuring apparatus in which there is provided a corner-cube prism which includs a reflecting surface for selectively reflecting or transmitting a beam in accordance with the polarization condition of the beam and a transmitting surface for sending out a beam. A light source, a movable mirror, a fixed mirror, a detector and the corner-cube prism so arranged that the corner-cube prism receives a reference beam and a measuring beam from the light source through the reflecting surface, sends out the reference beam to the fixed mirror and the measuring beam to the movable mirror respectively through the transmitting surface, receives the reflected reference beam from the fixed mirror and the reflected measuring beam from the movable mirror through the transmitting surface and selectively sends out the reflected reference beam and the reflected measuring beam to the detector in accordance with their polarization condition through the reflecting surface.

Abstract: The sensor system monitors solutes in a liquid stream by analyzing the amount of light absorbed in a liquid in a particular wavelength band. The sensor system is arranged for selectability of the type of fiber used for transmission and adjustability of the liquid gap length in the liquid so that individual installations can be arranged with optimum characteristics for sensing particular chemical species in solution by absorption spectroscopy.

Abstract: The present invention inhibits quenching of a laser following a radiation event by providing a radiation sensing arrangement connected to the discharge current control circuitry controlling the discharge current of the laser, for sensing a radiation event and for controlling the discharge current control circuitry in such a way that quenching of the laser for a predetermined amount of time after a radiation event is inhibited.

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: 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.