Abstract: This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample.

Abstract: The method and device for measuring the spectral phase or combined spectral and spatial phases of ultra short light pulses, consisting of performing: a decomposition of the light pulse to be measured in two identical replies called signal pulse and primary reference pulse, respectively, of different polarization or direction and the phase characteristics of which are essentially identical to the original pulse, a temporal filtering of the primary reference pulse by a nonlinear interaction generating a secondary reference pulse of average frequency essentially identical and of spectral width greater than the spectral width of the primary reference pulse, a spectral interferometry measurement by recombination of this secondary reference pulse and the signal pulse with a given temporal offset.

Abstract: The present invention is directed generally to an apparatus and methods that combine a novel four-port dual-source interferometer with double modulation FT-VCD or FT-VLD measurements to obtain a spectrometer with enhanced signal quality (S/N), and lower susceptibility to detector saturation. In the novel apparatus of the present invention, a linear polarizer or tandem array of identically-oriented polarizers is placed in front of each of the two sources in a four-port dual-source interferometer, with the polarization state of one of the linear polarizers (or tandem array of polarizers) vertical and the polarization state of the other linear polarizer (or tandem array of polarizers) horizontal, i.e., with the polarization axes of the polarizers orthogonal to one another. Methods for measuring these spectra using the various aspects of the apparatus of the present invention are also provided.

Abstract: Application of digital light processor (DLP) systems in monochromator, spectrophotometer or the like systems to mediate selection of individual wavelengths, and/or to image elected regions of a sample in an imaging ellipsometer, imaging polarimeter, imaging reflectometer, imaging spectrophotometer, and/or to provide chopped beams.

Abstract: The cavity in the mirror arm of a conventional interleaver is replaced by a wedge integral with the beamsplitter structure of the interleaver. Thus, the light reflected from the AR-coated surface of the wedge is dispersed away from the optics of the device. The beam emerging from the wedge surface is directed toward a tilted mirror that reflects it totally on-axis. As a result of the diversion of the light reflected from the wedge surface and the non-parallel disposition of the wedge surface with respect to the mirror, phase errors are virtually eliminated. In another embodiment, a second wedge is used with a second antireflective surface disposed in parallel to the first wedge's antireflective surface, and with a mirror normal to the optical axis of the device.

Abstract: This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample.

Abstract: The present invention relates to a spectrally dispersive interferometric optical apparatus having a light source, generating a phase shift, measuring the intensity of the interference signals, selectively measuring the intensity of the interference signal and determining the phase angles and/or a relative phase shift of the intensity of the interference signals. In accordance with the invention, the generating of a phase shift between components of different polarization directions in at least one of the branches of the interferometer includes a diffraction grating. The selective determination of the intensity of the interference signal in dependence on the polarization moreover permits determination of the respective intensity for the TE components and for the TM components of the interference signal with respect to the coordinate system of the diffraction grating.

Abstract: An apparatus for producing an inhomogeneously polarized optical beam from a homogeneously polarized input optical beam includes a first phase shifter, a second phase shifter, and one or more polarization beam splitters. The first phase shifter shifts at least one portion of a first part of the input optical beam by a first phase. The second phase shifter shifts at least one portion of a second part of the input optical beam by substantially the first phase. The one or more polarization beam splitters split the input optical beam into the first part and the second part and combine the phase shifted portion and substantially all other portions of the first part of the input optical beam with the phase shifted portion and substantially all other portions of the second part of the input optical beam to produce the inhomogeneously polarized optical beam.

Abstract: Input light is split by a PBS into orthogonal polarized waves. One of the polarized waves is reflected by a mirror HR, and input to a 7?/8 plate. The other is phase-controlled by a phase controller, and input to the 7?/8 plate. The respective light beams to which a phase bias is applied by the 7?/8 plate are input from a 2R mirror having reflectances that differ depending on a polarized wave to a GT resonator. The light beams output from the GT resonator again pass through the 7?/8 plate, inversely travel the original optical path, and enter the PBS. Then, the light beams are output from an output 1 or 2 depending on a polarized wave.

Abstract: The disclosure generally relates to a method and apparatus for multi-wavelength imaging spectrometer. More specifically, in one embodiment, the disclosure relates to an optical filter for passing photons therethrough. The filter includes a first filter stage and a second filter stage. The first filter stage may include a first retarder element and a first liquid crystal cell. The first element may include an input face and an output face. One of the first element faces is not oriented substantially normal to the trajectory of photons passing through the filter.

Abstract: Remote sensing of the temperature of a greybody or blackbody radiator is effected by passing its radiation (24) through a modulated infrared filter spectrometer. The infrared filter comprises, in sequence, a band pass filter (20), a first polariser (21) which polarises the radiation, an electro-optical element (22) which splits the polarised radiation into two orthogonally polarised components, and a second polariser (23). A lens (28) images the radiation leaving the second polariser onto a detector (27). The electrical signal from the detector (27) is input to a numerical analyser. The electro-optical element (22), typically comprising a birefringent crystal assembly (25) and a birefringent trim plate (26), is configured so that the net optical delay of the orthogonally polarised components passed through it is such that the recombined components are at or near a peak or trough in their interferogram.

Abstract: A telecommunication system includes a transmitter configured to modulate a forward link RF carrier with a first set of data; a receiver configured to demodulate a second set of data from a return link RF carrier; an orthomode transducer having two linear ports and a circular waveguide port, where one of the linear ports is connected as an input from the transmitter and another linear port is simultaneously connected as an output to the receiver; an antenna; and a linear-to-circular polarizer connected to the circular waveguide port and connected to the antenna, where the linear-to-circular polarizer is configured so that a first linear polarization at the circular waveguide port results in a first circular polarization at the antenna and a second circular polarization at the antenna results in a second linear polarization at the circular waveguide port.

Abstract: An interferometer uses birefringent elements for splitting and combining beams of orthogonal polarization, and for changing the relative phase between the orthogonally polarized beams. A polarization sensitive detector is used to detect a fringe pattern whose periodicity is dependent on the relative optical paths traversed by the orthogonally polarized beams. In an embodiment of the invention, a birefringent beam splitter has an input path and first and second output paths. A birefringent beam combiner has first and second input paths and an output path, the first and second input paths of the birefringent beam combiner aligned respectively with the first and second output paths of the birefringent beam splitter. A polarization sensitive detector is disposed on the output path of the birefringent beam combiner to detect the periodicity of the fringe pattern.

Abstract: This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample.

Abstract: This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample. As an example, input light in two different optical propagation modes (e.g., the first and second modes) is directed through a common input optical path to the optical probe head which sends a portion of input light in the second mode to the sample. The probe head directs both the light in the first mode and the returned light from the sample in the second mode through a common optical path to a detection module.

Abstract: A diagnostic system (24) for a PEM (20) provides optically determined information about the retardance characteristics induced by the PEM (20). The diagnostic system (24) is integrated with the PEM (20) so that the PEM (20) performance may be diagnosed or monitored during operation of the PEM (20). Specifically, the diagnostic system (24) is used alongside an optical setup (22) that employs a primary light beam (28) for conventional purposes such as polarimetry, optical metrology, etc. The diagnostic system (24) includes its own diagnostic light source (50) that is directed through the optical element (32) of the PEM (20) at a location remote from the primary aperture (38) of the PEM (20). Thus, the diagnostic system (24) and the primary PEM (20) operation can be undertaken simultaneously, with one not interfering with the other. The output of the diagnostic system reflects the actual retardance characteristic provided by the PEM (20) and can be used as feedback to adjust the PEM control as needed.

Abstract: Apparatus for making wavelength-resolved polarimetric measurements comprises an interferometric source (10,12), for example a broadband source (10) and an optical interferometer unit (12), and a polarization generator unit (16) for generating different states of polarization of light received from the interferometric source and applying same to a device-under-test (30). A polarimeter unit (20) receives and polarimetrically-analyzes light from the device-under-test, converts the polarimetrically-analyzed light into electrical signals, and, using Fast Fourier Transform numerical analysis, computes therefrom the wavelength-resolved polarimetric measurements. Placing the optical interferometer unit (10,12) “upstream” not only of the device-under-test (30), but also of the polarisation generator unit (16), means that the latter substantially eliminates polarization dependent effects introduced by the former.

Abstract: A scanning spot microscope for performing a Fourier spectral analysis has means for performing a repeatable scanning operation which includes scanning an incident light spot to successive locations of a specimen. An interferometer is placed across an optical light path of the microscope, the interferometer including a birefringent device between polarizing devices in the path and introducing a given path difference. Means are provided for receiving and recording an optical signal due to the incident light spot from each successive specimen location. In use the given path difference is maintained during each scanning operation but is varied between scanning operations so that the optical signals relating to these specimen locations and the values of the given path difference can be recorded.

Abstract: In a process of forming a film on a surface of a wafer by thermal processing, laser light generated by a light source is depolarized by a depolarizer and the deporlarized light is irradiated upon the surface of wafer. As for the light reflected from the surface of wafer, polarization components in predetermined two directions perpendicular to each other are extracted by a beam splitter, and optical sensors receive the extracted light components to detect each intensity. An analytical processing unit determines a thickness of a formed film based on a change in a difference in intensity.

Abstract: State of polarization detectors and polarization control systems are disclosed. For example, the invention features an integrated optical assembly including: (i) a series of polarization-sensitive interfaces defining an optical beam path for an input optical beam to pass through the assembly, wherein each polarization-sensitive interface derives a sample beam from the input beam; and (ii) one or more retardation layers each positioned between a different pair of the polarization-sensitive interfaces, wherein the retardation layers are integrally coupled with the polarization-sensitive interfaces, and wherein the retardation layers and polarization-sensitive interfaces cause each sample beam to have an intensity that provides different information about the state of polarization of the input beam.

Abstract: A two-beam interferometer splits an incident light in two optical paths, combines and outputs split lights together again. The two-beam interferometer generates at least one or more combined light made from two beams each having a polarization different from each other. A polarization state detector detects a variation in the polarization of the combined light generated by the two-beam interferometer. An electric circuit calculates an wavelength of the incident light based on the variation in the polarization detected by the polarization state detector. The two optical paths of the two-beam interferometer has a difference in length between a point of splitting the incident light and a point of combining the split lights, for the detection of polarization variation in the combined light by the polarization state detector. The optical path length difference between the two paths is fixed.

Abstract: Interleavers are a useful tool in wavelength division multiplexing (WDM) to separate a signal with closely spaced channels into two signals, e.g. odd and even ITU channels, each with twice the channel spacing. Alternatively, two signals with a large channel spacing can be combined into a single beam with half the channel spacing. The invention relates to an optical interferometer using rhomb prisms as resonant cavities, which, when properly designed, provide the necessary phase shifts for interleaving or de-interleaving sets of optical wavelength channels. The present invention utilizes the differential phase shift between orthogonally polarized components induced by total internal reflection (TIR) off the surfaces of the rhomb prisms. Dispersion reducing techniques are also disclosed, including multiple rhomb interleavers and multi-pass rhomb interleavers.

Abstract: A spectral image input device has an image forming optical system for forming an image of image light on an image forming surface and a phase difference generating unit disposed anterior to the image forming surface in the direction of image light travel. The phase difference generating unit constitutes, sequentially in the direction of image light travel, a polarizer for transmitting only polarized light in a specific direction, an optical element formed of a solid material having a birefringence, and arranged such that the principal refraction index axis is inclined 45° relative to the polarization angle of the analyzer, the optical element generating a phase difference in accordance with the wavelength of the image light based on the difference in the physical thickness of the optical element in the direction of image light travel and an analyzer for transmitting only the image light of a polarization angle of 90° relative to the direction of the polarized light of the polarizer.

Abstract: An apparatus for detecting the relative displacement of a surface to be detected, and an apparatus and method for recording information on a hard disc of a hard disk drive using such a detecting apparatus, the detecting apparatus comprising an interference optical system for condensing a light beam on the surface to be detected, and making the reflected light from the surface to be detected interfere with the condensed light beam to thereby form an interference light beam, light receiving means for receiving the interference light beam and outputting bright and dark signals attributable to the relative displacement of the surface to be detected, and condensed light information supplying means for separating part of the reflected light from the surface to be detected from the optical path until the reflected light arrives at said light receiving means, and utilizing the separated light beam to detect the condensed state of the incident light beam onto the surface to be detected or make the condensed state obse

Abstract: A telecommunication system includes a transmitter configured to modulate a forward link RF carrier with a first set of data; a receiver configured to demodulate a second set of data from a return link RF carrier; an orthomode transducer having two linear ports and a circular waveguide port, where one of the linear ports is connected as an input from the transmitter and another linear port is simultaneously connected as an output to the receiver; an antenna; and a linear-to-circular polarizer connected to the circular waveguide port and connected to the antenna, where the linear-to-circular polarizer is configured so that a first linear polarization at the circular waveguide port results in a first circular polarization at the antenna and a second circular polarization at the antenna results in a second linear polarization at the circular waveguide port.

Abstract: A spectrometer for determining the concentration of a substance within a sample comprises a. a radiation source (11) for supplying radiation to the sample to be measured; b. a filter (15) for filtering radiation transmitted by the sample, the filter having a number of pass bands at wavelengths corresponding to absorption peaks in the absorption spectrum of the sample to be detected, the filter being responsive to an applied signal to modulate the wavelengths of the pass bands; and, c. a detector (16) for detecting the filtered radiation, the detector being responsive to the applied signal to determine the relative intensities of the maxima and minima in the absorption spectra of the substance, characterized in that the radiation source is selectively activated in response to the applied signal.

Abstract: The invention is an instrument for sensing the state of polarization (SOP), and for transforming the SOP of a beam of light from an incident continuously-varying arbitrary SOP to a desired exit SOP, using a polarization compensator under feedback control. A polarization sensor uses two or three samples of a beam to sense the Poincare sphere latitude and longitude error in SOP. A polarization controller adjusts the SOP of light, which is then sensed by the polarization sensor, which develops signals to drive the polarization compensator using feedback methods. Unlike prior-art systems, the feedback seeks a mid-point rather than an extremum in the sensed signals, so there is no sign ambiguity in the feedback control. Further, the sensor signals indicate orthogonal displacements in SOP that correspond to specific elements in the polarization controller, so there is no ambiguity as to which element needs adjustment in order to correct a given error in SOP.

Abstract: Fourier Transform Spectroscopy is performed using a birefringent device to vary path difference systematically for all regions of an image simultaneously, so that a separate interferogram is collected for each image region by combining intensity values in multiple images. The optics may allow a theoretical efficiency of 100% in light throughout.

Abstract: The invention provides methods and apparatus for encoding information pertaining to the polarimetric state of transversely propagated radiation—for example, electromagnetic waves—as a modulation of the radiation's frequency power spectrum. In a preferred embodiment, suitable for examining light, the radiation passes consecutively through two birefringent media, each having mutually perpendicular fast and slow axes both perpendicular to the propagation axis. The fast axis of the first medium is rotated with respect the fast axis of the second medium to form an acute angle therebetween. The output of the second birefringent medium comprises a complementary pair of interference fringe systems. The power spectrum of each interference system is modulated in a manner characteristic of the polarization state of the radiation. One of the systems is selected by a linear polarizer. The invention is suitable for use in conjunction with a conventional imaging spectrograph and detector.

Abstract: The surface form of a semiconductor thin film such as a polysilicon film 13 formed on a semiconductor substrate 11 is measured through spectro-ellipsometry or measured by performing an IPA quantitative analysis through GC. Mass (gas chromatography) after exposing the semiconductor thin film to IPA (isopropyl alcohol) vapor and drying the semiconductor thin film. Through either of these methods the surface form of the polysilicon film easily and quickly measured.

Abstract: The method utilizes the physical phenomenon known as dispersion of the optical rotation. After passage of linearly polarized electromagnetic radiation through the optically active environment (rotator), with the rotating power characterized by a parameter p, and then through the analyzing polarizer, the function R(p) can be measured. For the given active medium and the relative orientation of polarization planes of the input light beam and the analyzing polarizer, R(p) has an unambiguous relation with the spectrum I(&lgr;) of the analyzed radiation (&lgr; stands for wavelength) and allows its unambiguous determination by special mathematical methods. In devices based on the above mentioned principle a linearly polarized collimated beam of analyzed radiation propagates through the optical rotator then passes through the analyzer and strikes a single-channel or multi-channel detector which measures R(p) as a function of the parameter p.

Abstract: A laser wavelength meter determines the unknown wavelength of a laser by measuring the phase difference between two orthogonally polarized beams derived from the laser. The orthlogonally polarized beams propagaic along two optical paths of different length as defined, for example, by a polarizing beam splitter or a stepped reflector with a defined step height. An in situ reference laser of known wavelength allows calculation and monitoring of the path difference between the two optical paths.

Abstract: A birefringent interferometer system is described which uses nematic liquid crystal cells to produce variable optical path differences (OPD) between light of different polarization states that are interfered at a polarizing analyzer. Fixed retarders may also be incorporated to extend the range of OPD. The interferometer provides wide field-of-view, continuously variable path difference over a large range, and an on-board monitor of OPD for ensuring accurate settings of path difference, and hence, an accurate wavelength scale in the spectra produced by the apparatus. The system can further incorporate additional polarizing optics so it responds equally well to light of any incident polarization state without loss of efficiency.

Abstract: A method of spectroscopically analyzing amplitude and phase information of a particular sample (510) is disclosed, comprising providing a femtosecond laser source (502) positioned in an angularly distal relationship to the sample, generating from the laser source a primary light pulse (504) of substantial peak intensity and spectral bandwidth directed at the sample, and providing a reference medium (512) interposed between the light source and the sample, fixed in position with respect to the sample. A portion of the primary light pulse is directed through the reference medium generating a reference second harmonic signal (514) directed at the sample, which propagates collinearly with the primary light pulse towards the sample. A spectrometer (520) is provided, positioned in an angularly distal relationship to the sample and opposing the laser source, to receive second harmonic reflections of the primary pulse and reference signal (516 and 514, respectively) from said sample.

Abstract: A spectrometer for determining a spectrum of a light by using a mirror to reflect the light so that the light forms an intensity standing wave pattern through superposition of an incident portion of the light and a reflected portion of the light. The spectrometer is equipped with an intensity detector whose thickness is less than a shortest wavelength of the light being examined and which is semitransparent over the spectrum. The spectrometer has a mechanism to provide relative movement between the mirror and the intensity detector such that the intensity detector registers a variation of the intensity standing wave pattern. An analyzer, such as a Fourier transform analyzer, is employed to determine the spectrum of the light from that variation of the intensity standing wave pattern.

Abstract: A double-beam interferometer for electromagnetic radiation and a method for the compensation of dispersion or increase in the spectral resolution of such an interferometer. Using a polarizer, which is brought into the optical radiation path, a defined polarization state P½0 is produced for the electromagnetic partial waves flowing into the arms of the interferometer. This polarization state is wavelength-independent and can vary for both partial beams. Optical elements modify the polarization state P½0 of the electromagnetic partial waves as a function of wavelength &lgr; and each spectral component &lgr;i is coded with a polarization P½ (&lgr;i). An analyzer, fitted to the output of the interferometer, transmits an adjustable polarization state Pdet, whereby an additional wavelength-dependent phase difference &ggr;(&lgr;) occurs between the partial waves of the spectral components.

Abstract: A double pass etalon based spectrometer. Spectral components of a diffused beam are angularly separated as they are transmitted through an etalon. A retroreflector reflects the transmitted components back through the etalon. Twice transmitted spectral components are focused onto a light detector which in a preferred embodiment is a photo diode array. The spectrometer is very compact producing precise fringe data permitting bandwidth measurements with precision needed for microlithography for both &Dgr;&lgr;FWHM and &Dgr;&lgr;95%.

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: Apparatus for measuring very low levels of polarization mode dispersion of optical devices, that is inexpensive, robust and portable, comprises a broadband source and a polarizer for directing substantially completely polarized broadband light into the device under test with the polarization in a plane substantially perpendicular to the propagation direction of the light. Light leaving the device is analyzed spectrally to produce a spectrum of intensity in dependence upon wavelength or frequency of such light for each of at least two mutually orthogonal polarization axes in a plane perpendicular to the propagation axis of the light leaving the device. The spectra are used to compute Stokes parameters s1, s2 and |s3| for each of a plurality of wavelengths within the bandwidth of the broadband light.

Abstract: The present invention relates to multifunctionalized alkoxy, the alkoxy functionality Y being introduced onto a suitable polyhydrooorganosiloxane by a dehydrogenation/condensation reaction from the alcohol from which Y derives and then the functionality W by a hydrosilylation reaction from the olefinic compound from which W derives. The multifunctionalized alkoxy polyorganosiloxanes can be used as antiadhesion modulators in silicone compositions and as silica covering agents in silicone compositions containing fillers.