Abstract: An instrument for determining spectral content of an input light. The instrument has a rotating optical element that separates an input light into two partial beams and thereby introduces a variable OPD between the partial beams. The instrument then records an interferogram as a function of the variable OPD and thereby Fourier or Fast Fourier transforms the interferogram into a spectrogram so that the spectral content of the input light is revealed.

Abstract: An optical profiler is modified in a way which allows it to image a MEMS device at various points during the movement of the MEMS device. The light source is synchronized with a desired movement of the MEMS device. The light source produces pulse at each synchronization period. During each pulse, an interferometric measurement is carried out. So long as the pulse is short enough such that the device does not move significantly, a detection of the position of the device can be accurately obtained.

Abstract: The invention relates to a process and to a device for measuring the thickness of transparent materials. More particularly, but not exclusively, the invention concerns the thickness measurement of glass materials and, even more precisely, the thickness measurement of flat glass, in particular float glass. According to the invention, a light beam with modulated frequency is focused, two light beams or rays reflected by each of the surfaces of the transparent material are received, interference is created between them, the number of oscillations per modulation period of the interference signal is determined, the path difference (&dgr;) between the two beams and the thickness (e) of the transparent material are deduced and the phase shift (&phgr;) of the said interference signal is determined. This determination of the phase-shift between the two signals each coming from one of the surfaces of the transparent material can then be used to deduce other characteristics of the said material.

Abstract: A distributed sensor (10) includes a plurality of stages (24, 28, 32, 36, 40) connected in series, each stage incorporating a length of polarization maintaining fiber (12) exposed to a phenomena such as mechanical deformation or temperature to be sensed. Inter-mode couplers are provided between the sensing fibers (26, 30, 34, 38) of the various stages. The overall transfer function of the device at a plurality of wavelengths is deconvoluted to determine the birefringence of each sensing region and does monitor plural phenomena independently of one another.

Abstract: The crosstalk-inhibiting arrangement is used on a switching cell in which an optical signal from an input waveguide is alternatingly directed to first and second output waveguides, depending upon whether there is fluid in a region between the input waveguide and the first output waveguide. The fluid has a refractive index selected to promote propagation of light energy through the fluid. However, in the absence of fluid, the light is reflected toward a second switching mechanism via an intermediate waveguide. The intermediate waveguide is at an angle greater than 90° relative to the input waveguide. The second switching mechanism is also fluid-manipulable and is used to inhibit leakage reflection from passing to the second output waveguide. Preferably, the angle between the intermediate waveguide and the input waveguide is in the range of 95° to 150°.

Abstract: A bonding apparatus has a probe for causing an LED chip to emit light before the LED chip is bonded on a board, an imaging system for recognizing the center of a light-emitting area of the LED chip and recognizing coordinates of a contour reference point of the LED chip with respect to the recognized center of the light-emitting area, and a light-emitting-element holding mechanism for positioning the LED chip in a bonding position on the board based on the recognized coordinates of the contour reference point. The center of the light-emitting area of the LED chip can be positioned highly accurately in a desired position on the board without being adversely affected by variations in the contour dimensions of the LED chip.

Abstract: Interferometers utilizing polarization preserving optical systems by plane polarized beams are deviated through preselected angles without changing their linear state of polarization. The interferometers utilizing such optical systems have a variety of applications and are particularly suitable for use in the field of distance measuring interferometry (DMI) to enhance measurement accuracy by reducing undesirable polarization effects that can introduce errors associated with an otherwise present undesirable polarization rotation found in classical retroreflectors. Prismatic optical elements are preferably used to construct assemblies which can include polarization beam splitting coating arrangements and/or birefringent materials to enhance the extinction ratio between orthogonally polarized beams propagating through such systems.

Abstract: An imaging system wherein an optical signal is transmitted to both a sample to be measured and a rotating element which is calibrated to the system. A return signal is detected by the system, and a scan analyzer and correction unit uses the system calibration information along with synchronization information to correct for return signal degradation or errors due to imperfections in the rotating element in real time. This allows for an accurate measurement of the sample. The system can also include a coarse path-length adjustment unit to allow the system to track a region of interest within a sample to further allow for accurate sample measurement.

Abstract: A substantially vertical sample stage for interferometric testing of computer-drive disks is positioned along an inclined trackway. The stage includes three pressure tips that provide a fixed, aligned plane against which the back surface of the disk being tested is positioned in optical alignment with the reference surface of the instrument. The degree of protrusion of two of the pressure tips can be adjusted to set the proper tip/tilt of the disk. Each disk being tested is allowed to roll down the trackway by gravity to a rubber stop in front of the stage. The trackway is also tilted slightly to cause the disk to roll on edge and lean against the sidewall of the trackway. After the disk is stopped in front of the stage, a retractable finger engages the forward edge of the disk and produces a slight backward motion to release the disk from the rubber stop and align it with the stage.

Abstract: An apparatus that can measure a space between a first surface and a second surface. The apparatus may include a light source that can reflect a light beam from the first and second surfaces. A birefringent element may split the reflected light beam into an ordinary beam and an extraordinary beam. The ordinary and extraordinary beams are detected by a photodetector. The apparatus may include a controller that is coupled to the photodetector and which can compute the space from a phase value that is determined from data collected when the mechanism varies the phase between the ordinary and extraordinary beams, and a ratio between a first modulation amplitude detected from light reflected from the first and second surfaces and a second modulation amplitude detected from light reflected from the first surface when the second surface is not adjacent to the first surface. The ratio can also be used to compute the reflectance and index of refraction of the second surface.

Abstract: The present invention is an optical sensor that senses the movement of a shaft. Detection of radial movement is made when a portion of light incident on the shaft sensor-target is blocked. For detection of axial movement, a disk with flat surface is mounted and used to block a portion of light. The variation in the amount of light allowed to pass through is a measure of the position of the shaft. As proposed by this invention, significant improvement is made with respect to sensitivity and linearity of the system when the light is permanently partially blocked. To accomplish this goal this invention adds a boss to the system. To eliminate possible drift of system performance due to LED degradation or temperature variation, a feedback feature is added to the system.

Abstract: An alignment system includes two or more alignment devices arranged in close proximity and sharing a common processing device. The alignment devices are located adjacent to one another, yet while one substrate is being processed, a second substrate can be prepared for processing without affecting or interfering with the first substrate, thereby resulting in greater utilization of the process resource.

Abstract: A nonlinear interferometer wavelength separation mechanism for use in a dense wavelength division multiplexer is provided. The mechanism includes a first glass plate optically coupled to a second glass plate, forming a space therebetween; a mechanism for introducing a phase shift at least one channel of an optical signal; and a mechanism for broadening a pass band of the optical signal. The nonlinear interferometer of the present invention allows a dense wavelength division multiplexer to have an ease in alignment and a higher tolerance to drifts due to the increase in the width of the pass band. It also has the added ability of being passively stable to temperature.

Abstract: Polarization interferometric architectures, preferably plane mirror types, having first and second measurement legs are provided with retardation elements, preferably, at least one set of split waveplates, comprised of two segments, tilted slightly (e.g., 2 mrad) in opposite directions with respect to each other to reduce the effects of undesirable ghost beams that otherwise would travel along the same path as the principal beams to produce significant cyclic errors. With the use of the split waveplates, double reflection ghost beams have net tilts relative to the principal measurement beam, and therefore do not contribute to interference effects. This effectively eliminates waveplate ghost reflections as a source of error. Use of the such split, tilted waveplates may be made in a variety of polarization interferometers including, but not limited to, uncompensated plane mirror, high stability plane mirror, differential plane mirror, double differential plane mirror, and dual linear/angular types.

Abstract: A dual sensor wavefront correction system is adaptable to correcting wavefronts including wavefronts that are severely scintillated. The system includes a Hartmann wavefront sensor as well as a unit shear lateral shearing interferometer (LSI) wavefront sensor. The optical output signals from the Hartmann wavefront sensor are applied to a real reconstructor which provides an estimation of the distortion in the wavefront during most conditions except for conditions of severe turbulence. In order to provide compensation for the phase discontinuities in a scintillated wavefront, a unit shear lateral shearing interferometer (LSI) wavefront sensor is provided. The optical output signals from the unit shear LSI wavefront sensor are processed by a complex reconstructor in order to provide relatively accurate estimates of the tilt signals at the discontinuities.

Abstract: In an alignment apparatus, an alignment mark formed on a substrate is illuminated through an illuminating optical system, and an image of the alignment mark is projected onto a light receiving surface of a CCD camera through an enlarging optical system. The enlarging optical system includes a parallel flat plate, the inclination of which can be adjustable, for parallel-translating an eccentric component of coma.

Abstract: A method and apparatus for determining a phase relation of a signal in which a spectrum thereof includes a spectral component at a central optical frequency f.sub.0 and frequency spikes f.sub.n =f.sub.0 .+-.nF, where n is an integer. The apparatus includes device (29, 26, 28, 30 and 32) for producing signals representative of phase differences between two frequency spikes for each pair of adjacent frequency spikes of the frequency spikes f.sub.n.

Abstract: A phase-shifting point diffraction interferometer system (PS/PDI) employing a PS/PDI mask that includes a PDI focus aid is provided. The PDI focus aid mask includes a large or secondary reference pinhole that is slightly displaced from the true or primary reference pinhole. The secondary pinhole provides a larger capture tolerance for interferometrically performing fine focus. With the focus-aid enhanced mask, conventional methods such as the knife-edge test can be used to perform an initial (or rough) focus and the secondary (large) pinhole is used to perform interferometric fine focus. Once the system is well focused, high accuracy interferometry can be performed using the primary (small) pinhole.

Abstract: An optical position measuring system that has a scale graduation with a graduation period, TP, and connected with a first object that has a graduation and a scanning unit connected to a second object that moves relative to the first object, so that there is a displacement between the scale graduation and the scanning unit. The scanning unit includes a scanning plate with a first and second scanning fields that are arranged offset from each other in a measuring direction (x) by a distance, D. A first deflection element associated with the first scanning field and a second deflection element associated with the second scanning field, wherein the first and second deflection elements spatially separate the phase-shifted partial signals from the first and second scanning fields. First and second detector elements are placed downstream of the scanning plate and associated with the first scanning field.

Abstract: A method and apparatus for inspecting photomasks having phase shifting elements which shift the phase of light but are otherwise transparent. A coherent light source is directed through a mask to be inspected, through an objective lens, through an 180.degree. phase shifting unit, and to an image divider. The coherent light source is also directed through a transparent reference substrate to the image divider. The mask to be inspected is formed on a transparent mask substrate having the same thickness and formed from the same material as the transparent reference substrate. The intensity of the light exiting the image divider is proportional to the square of the cosine of 1800 plus the phase angle between the light exiting the reference substrate and the light exiting the mask under test. The light exiting the image divider is directed to a CCD image sensor. An image computer compares the output of the CCD image sensor with an image formed from the image database and identifies defects in the mask under test.