Abstract: A fiber optic sensor system for acoustic measurements over a 6 kHz bandwidth, the design of which allows for multiplexity of the input side of the system, and where the optical part of the system is based on low coherence fiber-optic interferometry techniques which has a sensor Fabry-Perot interferometer and a read-out interferometer as well, that allows a high dynamic range and low sensitivity to the wavelength fluctuation of the light source, as well as the optical intensity fluctuations. A phase modulation and demodulation scheme takes advantage of the Integrated Optical Circuit phase modulator and multi-step phase-stepping algorithm for providing for high frequency and real time phase signal demodulation. The system includes fiber tip based Fabry-Perot sensors which have a diaphragm, which is used as the transducer. Pressure microphone, velocity sensor, as well as accelerometer, are built based on the fiber tip based Fabry-Perot sensors.

Abstract: A scanning force microscope is provided with a force-feedback sensor to increase sensitivity and stability in determining interfacial forces between a probe and a sample. The sensor utilizes an interferometry technique that uses a collimated light beam directed onto a deflecting member, comprising a common plate suspended above capacitor electrodes situated on a substrate forming an interference cavity with a probe on the side of the common plate opposite the side suspended above capacitor electrodes. The probe interacts with the surface of the sample and the intensity of the reflected beam is measured and used to determine the change in displacement of the probe to the sample and to control the probe distance relative to the surface of the sample.

Abstract: A plasma processing system that includes a plasma chamber, an open resonator movably mounted within the plasma chamber, and a detector. The open resonator produces a microwave signal, and the detector detects the microwave signal and measures a mean electron plasma density along a path of the signal within a plasma field. Alternatively, the plasma processing system includes a plasma chamber, a plurality of open resonators provided within the plasma chamber, a plurality of detectors, and a processor. The processor is configured to receive a plurality of mean electron plasma density measurements from the detectors that correspond to locations of the plurality of open resonators.

Abstract: An anodizing system for forming a anodized coating on at least a portion of a substrate thereby creating an anodized substrate is disclosed. The anodizing system includes a bath, a coating thickness monitor, at least one probe and at least one controller. The coating thickness monitor includes at least one radiation source directed at at least a portion of the anodized substrate; at least one probe for capturing at least a portion of the radiation reflected and refracted by the anodized coating on the anodized substrate, the captured radiation being at least a portion of the radiation directed the anodized substrate from the radiation source; and at least one detector in communication with the at least one probe, the at least one detector capable of processing the captured radiation to allow a determination of at least the thickness.

Abstract: A method and apparatus are disclosed for a two-dimensional Moiré type absolute position encoder and an associated control system. A reticle having a pattern variation in two orthogonal directions is illuminated with radiation from a source which is structured so as to create a two dimensional Moiré interference at the reticle. Radiation pulses from the radiation source are multiplexed in time and the resulting interference fringes are converted into electronic signals using a detector. A controller uses the electrical signals to determine the absolute position of the reticle in two dimensions to within the area of a particular cell. After determining the particular cell location, the controller also employs the signals from the groups of radiation stripes to calculate an accurate position of the reticle within the cell.

Abstract: A method and system for stabilizing and demodulating an interferometer at quadrature are described. In response to receipt of a signal indicative of optical power of the interferometer, an interferometer control system determines an optical path length correction required to stabilize the interferometer at quadrature utilizing signal amplitudes appearing at multiple harmonics of the signal. In a particularly preferred embodiment, the signal amplitudes are calculated utilizing the Goertzel algorithm, a computationally efficient discrete Fourier transform. The interferometer control system then outputs an error signal indicative of the optical path length correction. In a preferred embodiment, the error signal forms the DC component of a composite stabilization signal, whose AC component is the reference modulation signal utilized to excite a transducer to modulate the optical path length of the interferometer.

Abstract: A system for determining at least one condition of a seal including an optical fiber for transmitting light from a light source. The optical fiber is embedded in the seal and operatively coupled to an interferometric system. The interferometric system is operatively coupled to a processor. The interferometric system provides the processor with information relating to wear of the optical fiber, and the processor determines wear of the seal, rate of wear and remaining useful life of the seal based on the information relating to wear of the optical fiber.

Abstract: A non-contact apparatus and method for mapping the wave profile of capillary waves on a fluid surface to determine viscosity of the fluid. Two conducting blades coupled to a sine wave generator are positioned spaced laterally above and near the surface of the fluid to generate a standing capillary wave on the fluid surface between the blades. A laterally moveable fiber optic probe is coupled to a laser to transmit laser light toward the fluid surface and to receive reflected light from the fluid surface. Part of the laser light reflects from the end of the probe and creates an interference pattern with the light reflected from the fluid surface. The light reflected from the end of the probe and from the fluid surface are combined to form an interference signal which is analyzed to obtain the amplitude of the wave directly under the probe. By moving the probe laterally, nodes on the standing wave may be detected to find the wavelength of the capillary wave.

Abstract: A single laser is stabilized sequentially in time with respect to different wavelengths in conjunction with a continuous, preferably linear, wavelength transition for absolute optical interferometric measurement. During the wavelength transition, the number of the traversing interferences is counted in a measuring channel. The length of a measuring section may be measured in absolute terms to give known and stable wavelengths and phase measurements of the two wavelengths. Active integrated optics and residual phase measurement by compensation in the integrated optics make it possible to detect wavelength differences of 10−7 &lgr;.

Abstract: Disclosed are first and second embodiments of a 3-channel probe-plate structure of the fiber-optic interferometer, wherein low-coherent-length light from a superluminescent light-emitting diode is split by a tree splitter into three light branches which are coupled as separate light inputs to the probe-pate structure by single-mode, polarization-preserving optical fibers. For each of the 3 channels, the first embodiment of the probe-plate structure comprises an integrated polarizing lithium-niobate Y splitter-modulator for deriving separate reference-arm light and probe-arm light.

Abstract: A system and method for measuring the group delay of an optical device under test (DUT) utilizes an optical frequency counter in conjunction with a test interferometer to compensate for the non-uniform frequency changes of an input optical signal used by the test interferometer to measure the group delay. The group delay of the optical DUT is measured using the zero-crossings of an AC coupled heterodyne beat signal produced by the test interferometer from the input optical signal. In the measurement of the group delay, phase changes in the heterodyne beat signal caused by the non-uniform frequency changes of the input optical signal are compensated by using the measured optical frequency of the input optical signal. The optical frequency is detected by the optical frequency counter. The detected optical frequency is indicative of the non-uniform frequency changes of the input optical signal.

Abstract: It is the case of an interferometric measuring arrangement for superimposing at least two light waves, with a first coupling means for coupling the light waves coming from a light source into a sample arm and into a reference arm, and with a second coupling means for superimposing the light waves coming from the reference arm and the sample arm, which are led to at least one detector. The light waves at least within the reference arm are exclusively led in at least one fiber guide which they do not leave on their path between the coupling means, and with which the sample arm extends on both sides of the first coupling means.

Abstract: An interferometric measuring device for measuring surface characteristics, shapes, distances, and distance variations, e.g., vibrations, in particular in narrow, hollow spaces, of measuring objects, having a probe part and an optical fiber. Surface dimensions are able to be measured, even in very fine bore holes, in that, in a measuring head, at the free end of the probe part approaching the measuring object, the optical fiber projects out and is itself designed as a measuring fiber for illuminating a point of measurement and for picking up measuring light coming from this measuring point.

Abstract: A non-contact apparatus and method for mapping the wave profile of capillary waves on a fluid surface to determine viscosity of the fluid. Two conducting blades coupled to a sine wave generator are positioned spaced laterally above and near the surface of the fluid to generate a standing capillary wave on the fluid surface between the blades. A laterally moveable fiber optic probe is coupled to a laser to transmit laser light toward the fluid surface and to receive reflected light from the fluid surface. Part of the laser light reflects from the end of the probe and creates an interference pattern with the light reflected from the fluid surface. The light reflected from the end of the probe and from the fluid surface are combined to form an interference signal which is analyzed to obtain the amplitude of the wave directly under the probe. By moving the probe laterally, nodes on the standing wave may be detected to find the wavelength of the capillary wave.

Abstract: An optical probe apparatus for determining a position of an image sensor in a digital camera relative to a reference surface on the digital camera. The optical probe assembly includes a probe mounting surface adapted to be removably mountable to the digital camera and lockable in a predetermined orientation relative to the reference surface of the digital camera; an angle cleaved optical fiber emitting a beam of light; a lens disposed in the path of the beam of light and directing the beam of light along an axis normal to a plane of the lens toward the object; and a mounting member supporting the optical fiber such that the beam of light is directed along an axis normal to the plane of the lens and directed to the center of the lens. An optically transparent material (such as a pellicle or glass plate) is disposed intermediate the probe mounting surface and image sensor.

Abstract: A system for determining wear of an article including an optical fiber for transmitting light from a light source. The optical fiber is embedded in the article, and operatively coupled to an interferometric system. The interferometric system is operatively coupled to a processor. The interferometric system provides the processor with information relating to wear of the optical fiber, and the processor determines wear of the article rate of wear and remaining useful life of the article based on the information relating to wear of the optical fiber.

Abstract: Novel .omega.alkenyl silane monoadducts and bis-.alpha., .omega.-silyl alkanes are disclosed. The .omega.-alkenyl silanes or bis-.alpha.,.omega.-silyl alkanes are prepared by the selective addition of silane having chlorine, alkoxy or acyloxy groups to an .alpha.,.omega.-diene. The additions may be carried out in the liquid phase in the presence of free radical and/or metal and/or metal salt catalyst.