Abstract: A film thickness measurement apparatus has an image pickup part (32) for acquiring a plurality of single-band images corresponding to a plurality of wavelengths, and the image pickup part (32) acquires a plurality of reference single-band images representing a pattern on a reference substrate. A correction factor setting part (51) performs setting of a plurality of correction factors in accordance with distances from a specified pixel by using a plurality of reference single-band images. Subsequently, the image pickup part (32) acquires a plurality of measurement single-band images representing a pattern on an objective substrate and corrects a value of the specified pixel for each of a plurality of measurement single-band images by using the value of the specified pixel and values of pixels surrounding the specified pixel and the correction factors.

Abstract: A method and apparatus for reducing crosstalk between sensors in an inline Fabry-Perot (FP) sensor array. The inline FP sensor array comprises a plurality of fiber Bragg gratings arranged periodically along an optical fiber. The sensors are formed between each of the Bragg gratings. A light source provides multiplexed pulses as interrogation pulses for the array. The light pulses are applied to one end of the sensor array and a light detector detects reflected pulses. The detected pulses comprise a composite of reflections from all the Bragg gratings along the fiber. The apparatus processes the detected signals using an inverse scattering algorithm to detect an accurate phase response from each of the Bragg sensors while reducing crosstalk from other Bragg sensors within the array. One form of inverse scattering algorithm is a layer-peeling algorithm.

Abstract: A lithographic projection apparatus is presented, which includes a housing, which comprises therein a first exposure system that has at least one movable part (e.g. a movable first substrate holder or a movable second substrate holder in a twin stage apparatus). The apparatus also includes a position disturbance correction system for correcting a position of the first substrate holder with respect to the patterned projection beam due to the influence of gas pressure differences or gas movements, caused by movements of the movable part. A related device manufacturing method is also presented in which, during the exposure of a first substrate, the position thereof is corrected by means of position disturbance correction system.

Abstract: A method and system for optical measurement via a resonator having a non-uniform phase profile provides a mechanism for measuring and/or detecting sub-micron surface features with increased resolution. A second surface forming part of a resonator is illuminated through a first partially reflective surface that has a non-uniform phase profile that transitions from negative to positive phase with respect to a resonance phase value of the resonator. As a result, a reduced spot size is produced at the second surface, which enhances the resolution of a measurement and/or detection of surface features on the second surface. Additionally, if a discontinuity is provided in the non-uniform phase profile, interaction of the discontinuity with surface features of the second surface will provide enhanced resolution of the surface features. The resolution of the system is improved over the resolution that can be attained using a Fabry-Perot resonator.

Abstract: A remote sensor capable of imaging vibrations at many simultaneous points using high-speed imaging cameras is disclosed. The preferred embodiment operates in heterodyne detection mode using a single camera to capture signals to recover multi-pixel vibrations. One alternative embodiment employs two cameras and homodyne optical I/Q detection. A second alternative embodiment uses a single camera and temporally phase shifted local oscillator to also carry out homodyne optical I/Q detection. The disclosed sensors are capable of scalability to large numbers of pixels and can capture vibration frequencies over a wide range.

Abstract: A light source 10 is connected sequentially through a single mode optical fiber and a coupler to one end of a polarization maintaining optical fiber, the other end of which is connected to an optical waveguide of an optical integrated circuit having a branching optical waveguide which has a polarizing function with the polarization axis of the optical fiber being coincident with the direction of the TE mode in the optical waveguide. One end of each of polarization maintaining optical fibers are connected to two other ends of the optical waveguide with the polarization axis of the optical fibers being coincident with the direction of the TE mode in the optical waveguide. The other ends of the optical fibers are connected to one end of each of polarization maintaining optical fibers with their polarization axis displaced by an angle of 45° from each other. The other ends of the optical fibers are connected to the opposite ends of a single mode fiber optic coil.

Abstract: The present invention relates to a fiber-optic gyrometer including a Sagnac interferometer using two light waves propagating in opposite directions in a interferometer loop including a photodetector which delivers an electrical signal Ud representing the light intensity of the interference between the two waves, and for optically phase-shifting the waves controlled by a square-wave modulation signal Um suitable for controlling an optical phase variation at a frequency FO substantially equal to 1/(2to), where to is the propagation time of a wave through the guide. The photodetector is connected to at least a first sampling circuit and a second sampling circuit which are controlled in phase opposition by a clock. The gyrometer includes a means for inverting the phase of the clock at a frequency f, which is very much less than the frequency FO.

Abstract: The present invention provides a method and apparatus for reducing error in interferometric fringe stability and reproducibility in an interference fringe generator. In one aspect, the method for reducing error in interferometric fringe stability and reproducibility includes providing a light source, positioning a grating to receive light from the light source and positioning a projection lens having a focal length F to receive light from the grating. The projection lens projects the received light upon an object of interest positioned substantially at a distance d1 from the lens. Typically the lens is positioned substantially at a distance d2 from the grating. The values of d1, d2, and F are related by d2 being approximately equal to d1F/(d1?F).

Abstract: Spatial filtering is disclosed that improves the signal to noise ration of a sample inspection system of the type having a detector and collection optics that receive radiation scattered from a point on a sample surface and direct the scattered radiation toward the detector. The spatial filtering may screen the detector from substantially all of the forward-scattered radiation from back-scattered radiation that is scattered in a at an elevation angle less than about 45° with respect to a normal to the surface. Forward scattered noise is screened from the detector while backscattered signal reaches the detector. Programmable spatial filters may be used to selectively block scattered noise due to surface roughness while transmitting scattered signal due to surface defects.

Abstract: A sensor and method for using the same is disclosed. The sensor includes an optical cavity defined by first and second mirrors that have a spacing therebetween that varies in response to a force applied to the sensor and to a control voltage. The sensor has a drive circuit that measures light leaving an output port that samples light in said cavity and applies the control voltage to the optical cavity such that the spacing between the mirrors remains at a predetermined value independent of the force, the control voltage determining an output signal that provides a measurement of the force applied to the optical cavity. In one embodiment, the first mirror is fixed to the second mirror by a spring mechanism that causes the first mirror to move away from the second mirror, and the control voltage causes the first mirror to move toward the second mirror.

Abstract: In general, in one aspect, the invention features an interferometer assembly for use in a lithography tool used for fabricating integrated circuits on a wafer, wherein the lithography tool includes a support structure and a stage for positioning the wafer relative to the support structure, the interferometer assembly including an interferometer configured to direct a measurement beam between the stage and the support structure and combine the measurement beam with another beam to form an output beam which includes a phase related to a position of the stage relative to the support structure, wherein the interferometer is mechanically secured to the lithography tool through an interferometer surface selected to cause the phase of the output beam to be insensitive to thermal changes of the interferometer over a range of temperatures.

Abstract: A photonic crystal interferometric optical gyroscope system including a light source for providing a primary beam of light, a photonic crystal sensing coil having a rotational axis, and a beam controlling device configured to split the primary beam into first and second counter-propagating beams in the photonic crystal sensing coil and configured to direct return of the counter-propagating beams wherein the power of the returning counter-propagating beams represents the phase shift between the counter-propagating beams and is indicative of the rate of rotation of the coil about the rotational axis.

Abstract: An optical imaging apparatus has an optical scanning probe configured to irradiate low-coherence light onto a subject and to perform photo-reception of light scattered at the subject, and an observation device adapted to construct a cross-section image of the subject based on information from the light received through the optical scanning probe. The optical scanning probe is detachably connected to the observation device.

Abstract: An interferometric system including: an interferometer that directs a measurement beam at an object point to produce a return measurement beam, focuses the return measurement beam to an image point in an image plane, and mixes the return measurement beam with a reference beam at the image point to form a mixed beam; a beam combining layer located at the image plane which is responsive to the mixed beam and produces an optical beam therefrom, wherein the layer comprises a thin film with an array of transmissive openings formed therein and further comprises a fluorescent material associated with each of the openings of the array of openings; a detector that is responsive to the optical beam from the beam combining layer; and an imaging system that directs the optical beam from the beam combining layer onto the detector.

Abstract: Disclosed is an apparatus for autonomously compressing, phase-compensating and waveform-shaping an ultrashort light pulse that is fast and high in sensitivity in compensating for phase fluctuations and allows the use of a usual laser light source that is low in light intensity and has large temporal fluctuations in phase.

Abstract: A diaphragm optic sensor comprises a ferrule including a bore having an optical fiber disposed therein and a diaphragm attached to the ferrule, the diaphragm being spaced apart from the ferrule to form a Fabry-Perot cavity. The cavity is formed by creating a pit in the ferrule or in the diaphragm. The components of the sensor are preferably welded together, preferably by laser welding. In some embodiments, the entire ferrule is bonded to the fiber along the entire length of the fiber within the ferrule; in other embodiments, only a portion of the ferrule is welded to the fiber. A partial vacuum is preferably formed in the pit. A small piece of optical fiber with a coefficient of thermal expansion chosen to compensate for mismatches between the main fiber and ferrule may be spliced to the end of the fiber.

Abstract: Low-coherence interferometric apparatus for light-optical scanning of an object (18) with a low-coherence interferometer (6) comprising a low-coherent light source (7), a reference reflector (21) and a detector (25), wherein light emitted by the light source (7) is split into two optical paths (11,12), a first fraction of the light being irradiated as measurement light (16) onto the object and a second fraction of the light being irradiated as reference light (22) upon the reference reflector (21), and wherein, after reflection on the object (18) or the reference reflector (21) respectively, the measurement light (16) and the reference light (22) are combined at a beam junction (10) in such a manner that an interference signal which contains information about the reflection intensity of the measurement light, relative to the respective scan position is generated.

Abstract: Optical instruments having, inter alia, optics to process wavelengths of electromagnetic radiation to produce an interferogram. The instruments include at least one optical path and optical elements positioned along this path for splitting and recombining the wavelengths which interfere with each other to produce a plurality of different fringes of different wavelengths. In one group, the optics include matched gratings which are positioned along the optical path outside of the interferometer optics to produce first and second sets of spectrally dispersed beams. The interferometer optics also includes a beam splitter and first and second mirrors. The gratings may be positioned in a variety of locations along the optical path. In another group, the optics include a beam splitter having a plurality of surfaces, wherein each of the surfaces is either 100% reflective, 100% transmissive or 50% reflective and 50% transmissive.

Abstract: A mounting platform provides support and packaging for one or more fiber Bragg gratings and electronic circuitry (e.g., heaters, coolers, piezoelectric strain providers, temperature and strain sensors, feedback circuitry, control loops), which may be printed on or on the mounting platform, embedded in the mounting platform, or may be an “off-board” chip solution (e.g., the electronic circuitry may be attached to the mounting platform, but not formed on or defined on the mounting platform). The fiber Bragg gratings are held in close proximity to the electronic circuitry, which applies local and global temperature and/or strain variations to the fiber Bragg gratings to, for example, stabilize and/or tune spectral properties of the fiber Bragg gratings so that spatial variations in the fiber Bragg gratings that result from processing and manufacturing fluctuations and tolerances can be compensated for.

Abstract: An interferometer spectrometer that has reduced alignment sensitivity is described herein. Parallelism of an output ray pair formed by a single input ray is not affected by variations in relative alignment of the components. In comparison to other compensated interferometer designs, lateral separation errors in the output ray pair due to optical component misalignment are reduced. The reduced alignment sensitivity may be accomplished by utilizing simple planar components that are common to both light paths. The reduced alignment sensitivity and simplicity in design provides a more compact and more robust interferometer, with reduced manufacturing costs associated therewith. An elliptical field of view light source that utilizes an array of collimator lenses is also described. The light source provides a more compact design than a single circular collimator lens of the same area, and is suitable for single channel or multi-channel use.