Abstract: Embodiments of the present invention relate to an apparatus (i.e. an automatic teller machine) comprising an optical sensor. The optical sensor is configured to detect thickness of paper. Advantages of some embodiments of the present invention are that by determining a thickness of paper, it can be confirmed that two pieces of paper are not stuck together. For example, if two substantially identical pieces of paper are stuck together, then their thickness will be approximately twice the thickness of a single sheet. Accordingly, upon detection of two or more sheets of paper stuck together, a device, that automatically handles paper, may cause the sheets of paper to be separated.

Abstract: An optical coupler 13, a reflection attenuation amount measurement photodetector 14, and an APC photodetector 15 are provided in a variable-wavelength light source apparatus 1 and the reflection attenuation amount can be measured simply by connecting a device under test without using any external optical power meter, etc, and when wavelength calibration is executed, an external wavelength calibration gas cell 18 and a total reflection termination 20 are connected, whereby the wavelength of an optical signal output from a variable-wavelength light source 11 can be measured and controlled with higher accuracy.

Abstract: Faraday rotators each have a Faraday element which rotates light and a magnetic field generator for applying a magnetic field to the Faraday element. A wavelength plate is disposed between the Faraday rotators and it retards the light. A polarizer transmits, of the light, light having a predetermined plane of polarization which has been rotated by the Faraday rotators and retarded by the wavelength plate. An optical receiver receives the light transmitted by the polarizer and outputs a light receiving signal which corresponds to the amount of light received. A signal generator outputs a control signal for polarizing the light to be measured into at least four polarization states to the magnetic field generator. A signal processor determines Stokes parameters which indicate the polarization state of the light to be measured based on the four polarization states, and the light receiving signal corresponding to each of the four polarization states.

Abstract: A method is provided for changing the polarization of at least one of the photons emitted from a photon pair source into various partial ray paths using an electro-optical modulator (EOM), which is positioned in the particular partial ray path being traversed by the photon to be influenced and which, in the activated state, is able to alter the polarization of a photon, the modulator being activated as a function of time such that the probability that the photon is found in the region of the electro-optical modulator in the activated state is at a maximum.

Abstract: An optical arrangement for directing illumination light to a sample and for directing the detection light proceeding from the sample to a detector has a spectrally selective influencing means in the beam path of the detection light, which influences the polarization properties of the illumination light reflected or scattered from the sample in such a way that a polarizing beam splitter splits the illumination light reflected or scattered from the sample out of the detection light.

Abstract: A method and apparatus for combining the spectral outputs of multiple light sources to provide a high-efficiency broad-band illuminator for optical metrology is disclosed. The illuminator combines the output radiation from a plurality of broad-band lamps in a novel optical arrangement that creates a virtual source and avoids the use of beam-splitters. Consequently, the illuminator offers increased performance at reduced cost. The illuminator can be optimized and configured for application in a broad class of optical metrology instruments.

Abstract: The invention relates to a method and apparatus for determining the polarization properties of light emitted, reflected or transmitted by a material using a laser scanning microscope with the tested material being illuminated point by point with a laser beam of known polarization state. According to the invention the light beam with a polarization state modified by the material or the light emitted by the material is being examined by measuring the intensity of two different polarization components of a selected light beam received from each point of said material essentially at the same time and assigning a signal obtained by processing the two intensity signals to a respective point of an image of said material.

Abstract: Light having polarization is irradiated onto an article, and then quality of the article is diagnosed using a pre-input correlation function between quality of the article and a variation of polarization of the light reflected from the article. Further, the quality of the article is diagnosed by measuring a reflection absorbance difference or a reflection absorbance ration of light from the article between two wavelenghts, and by measuring a depolarization degree of polarized light of the reflected light from the surface of the article. The quality of the article can be non-destructively diagnosed using a simple system. Further, defects can be identified of factor-by-factor basis.

Abstract: A polarization stabilizing device and method based on controlling the phase retardation of a pair of variable phase retarders with a controller such that the first of the variable retarders has its phase retardation switched between first and second values whenever the phase retardation of the second of the variable retarders reaches an upper or a lower limit. The upper and lower limits of the second retarder and the first and second values of the first retarder are chosen so that discontinuities in the power of the output optical signal are avoided when the first variable retarder is switched, thereby providing endless polarization stabilization using phase retarders that themselves have only limited retardation ranges.

Abstract: 1. Method and apparatus for spatially resolved polarimetry.

Abstract: Sensing devices and techniques based on motion of a mechanical oscillator caused by electromagnetic interaction, such as a magnetic polarization with a magnetic field or an electric polarization with an electric field.

Abstract: A wavelength detector is described. The wavelength detector includes a beamsplitter having a wedged back surface with respect to the front surface to reflect the incoming optical signal into two paths. Filters, at least one of which varies with wavelength of the optical signal are in each of the said paths. The filtered light in the two paths is detected by a photodetector and the output electrical signals are log amplified. The log amplified signals are applied to a difference amplifier whose output is indicative of the wavelength or polarization of the incident optical signal.

Abstract: Optical imaging systems and methods use polarized illumination and a coordinated pupil filter to achieve high contrast. An imaging system includes a light source to generate light for illuminating an object having features aligned in a first direction and features aligned in a second direction, a lens for imaging the illuminated object onto a surface, a spatial selection device, such as a pupil filter, selective in a first mode of light corresponding to features of the illuminated object aligned in the first direction and selective in a second mode of light corresponding to features of the illuminated object aligned in a second direction, a polarization device optically coupled to the spatial selection device and selective in the first mode of s-polarized light corresponding to the first direction and selective in the second mode of s-polarized light corresponding to the second direction, and a controller for selecting operation in the first mode or in the second mode.

Abstract: A method and a device for measuring the half-wave voltage of a Mach-Zehnder type optical modulator accurately and without depending on the bias variation of an optical modulator. The method of measuring the half-wave voltage of the Mach-Zehnder type optical modulator comprising the steps of applying a high-frequency AC signal 34 and a monitoring low-frequency AC signal 35 in a superimposed manner to a Mach-Zehnder type optical modulator 1, or applying the both respectively to separately constituted electrodes, and observing the low-speed response of an output light from the optical modulator 1, wherein the half-wave voltage at a frequency to be measured of the Mach-Zehnder type optical modulator 1 is measured by using the voltage amplitude of the high-frequency AC signal 34 when the intensity change of an out put light by the monitoring low-frequency AC signal 35 is almost zero with the voltage amplitude of the high-frequency AC signal 34 kept variable.

Abstract: Methods and apparatus for detecting objects. In one embodiment, a person entering a secured or “Safe Zone™” is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected and measured. In a preferred embodiment, concealed weapons are detected by calculating the difference of a pair of differences (Delta A and B) of different polarized reflected energy (upper and lower curves in the two graphs) in the time domain, and by using signal processing methods and apparatus to improve the reliability of the detection process.

Abstract: A system and method for detecting defects in semiconductor wafers in a rapid non-destructive manner. Defects in semiconductor wafers can include micropipes and screw dislocations, stress striations, planer defects, polytype inclusions, and others. When a wafer is illuminated by polarized light, the defects induce birefringence of the polarized light that can be visualized by a polariscope to detect defects in wafers. Defects can cause linearly inputted polarized light to emerge as elliptically polarized light after transmission through a wafer having defects. Placing the wafer between a set of polarizers under the cross poles condition allows for a rapid non-destructive system and method for delineating and locating defects within a semiconductor wafer.

Abstract: A device capable of efficiently detecting a single-photon signal preserves a photon characteristic such as polarization or angular momentum. The device can include a beam splitter that splits an input photon state into modes that are distinguished by states of a characteristic of signal photons in the input photon state, a non-destructive measurement system capable of measuring a total number of photons in the modes without identifying a photon number for any individual one of the modes; and a beam combiner positioned to combine the modes after output from the non-destructive detection system.

Abstract: This optical polarimetric detector comprises: a first active detector element having a photoconductor (1) with which a first diffraction grating (3) is associated allowing incident light from a first specific polarization direction to be coupled in the first detector element and allowing the latter to detect the light having this first polarization direction; a second active detector element having a photoconductor (1′) with which a second diffraction grating (3′) is associated allowing incident light from a second polarization direction to be coupled in the second detector element and allowing the latter to detect the light having this second polarization direction. Furthermore, a detector (2) is provided making it possible to eliminate the background noise detected by previous detectors.

Abstract: An apparatus and a method for detecting an amount of depolarization of a linearly polarized beam transmitted by a birefringent medium in the direction of the optical axis thereof includes a first beam splitter for separating an on-axis portion of the linearly polarized beam into the orthogonal components, two photodetectors for detecting each component, a second beam splitter for separating an off-axis portion of the linearly polarized beam into the orthogonal components, the second beam splitter being disposed off-axis of the incident linearly polarized beam, a second set of photodetectors for detecting the components separated by the second beam splitter, and a subtracting device for subtracting the signals received by the second set of photodetectors from the respective signals received by the first two photodetectors.

Abstract: A spectroscopic ellipsometer comprising a light source (1) emitting a light beam, a polarizer (2) placed on the path of the light beam emitted by the light source, a sample support (9) receiving the light beam output from the polarizer, a polarization analyzer (3) for passing the beam reflected by the sample to be analyzed, a detection assembly which receives the beam from the analyzer and which comprises a monochromator (5) and a photodetector (4), and signal processor means (6) for processing the signal output from said detection assembly, and including counting electronics (13). Cooling means (12) keep the detection assembly at a temperature below ambient temperature, thereby minimizing detector noise so as to remain permanently under minimum photon noise conditions. It is shown that the optimum condition for ellipsometric measurement is obtained by minimizing all of the sources of noise (lamps, detection, ambient).

Abstract: A polarizing filter includes a portion with a filtering layer having a plurality of openings extending therethrough, where this portion has a maximum physical thickness in a radiation travel direction which is less than approximately one wavelength of the radiation being filtered. A method of making the filter includes: forming a filtering layer over a substrate; creating a plurality of openings through a portion of the filtering layer; and separating the filtering layer from the substrate.

Abstract: A polarization transformer can be constructed using a continuously adjustable polarization transforming device and a limited-range adjustable polarization transforming device. In general, the response time of the limited-range adjustable polarization transforming device is faster than that of the continuously adjustable polarization transforming device. When the two devices are properly controlled using error signals derived from a transformed optical signal, the polarization state of the optical signal can be adjusted with sufficient speed and without the loss of control associated with reset cycles.

Abstract: A confocal scanning microscope system (10) using cross polarization effects and an enhancement agent (acetic acid) to enhance confocal microscope reflectance images of the nuclei of BCCs (basal cell carcinomas) and SCCs (squamous cell carcinomas) in the confocal reflectance images of excised tumor slices. The confocal scanning microscope system having a laser (11) for generating an illumination beam (12), a polygon mirror (18) for scanning the beam to a tissue sample (22) and for receiving a returned beam from the tissue sample and detector (28) for detecting the returned beam to form an image. The system further includes a half-waveplate (13) having a rotatable stage (14) and a quarter-wave plate (21) having a rotatable stage (20) disposed in the optical path of the illumination beam and at least a linear polarizer (24) having a rotatable stage (25) disposed in the optical path of the returned beam from the tissue sample.

Abstract: Work piece feeding machine capable of correctly and efficiently setting a work piece in a through-hole of a carrier. The machine includes a positioning unit which detects the amount of displacement of the work piece with respect to the through-hole and corrects the position of the work piece in the though-hole. The positioning unit includes: a lighting source provided on the work piece side or the carrier side and directing polarized light on the work piece and the carrier; a camera provided on the carrier side or the work piece side and receiving the polarized light from the lighting source so as to catch images of an out edge of the work piece and an inner edge of the through-hole in a visual field thereof; and an image processor which measures the amount of displacement on the basis of positions of the outer edge and the inner edge.

Abstract: A trigger system including a photosensor having a polarizing light filter n positioned in a light receiving end of a housing. A lens is disposed in the housing for focusing light onto a transducer. A switch is electronically coupled to the transducer for selecting either a passive or active mode. In the active mode, a light source is directed at the photosensor, whereby a trigger signal is generated when an object disrupts the received light. In the passive mode, an opaque screen is spaced from the photosensor and a source of light is directed at the opaque screen, whereby a trigger signal is generated from the light reflected from an object positioned between the screen and photosensor. The trigger system may be electronically linked to a photographic system for high speed or action photography.

Abstract: The contrast between solder balls and substrate of a Ball Grid Array (BGA) as visualized by a camera of a computer vision system is improved sufficiently to enable reliable recognition in the poor contrast situation when the balls are silver colored and the substrate background is white or light colored by illuminating the BGA with polarized light, and the camera viewing the light reflected from the BGA via a polarization filter oriented to not pass light reflected from the solder balls but to pass light reflected from the substrate.

Abstract: A compact force measurement system having high sensitivity and a wide dynamic range. A polymer transducer is capable of measuring static, dynamic and transient force changes in tension and compression using changes in optical properties at the molecular level of a pre-stressed polymer or birefringent crystalline material under a loaded condition. A force sensing linkage acts as a load sensor which measures both compression or tension type forces. The transducer is capable of directional force, pressure, and acceleration measurements and is extremely accurate for measuring small-force levels. Since the force transducer of the present invention is based upon optical techniques it is relatively immune to electronic noise and allows measurement of rapidly changing loads. The invention can be miniaturized to accommodate a wide variety of measurements requiring miniature force and/or pressure measurement devices.

Abstract: The degree of polarization of an optical signal is measured by a polarimeter and used for providing a feedback signal to adjust adaptive optics of a polarization mode dispersion compensator. The polarization properties of the polarimeter are determined with high accuracy to match the polarimeter through calibration and used to produce the feedback signal.

Abstract: A single pulse laser beam of linear polarization is irradiated to a glass region such that the condensing point is located inside of the glass region, thereby to form, at the condensing point, a periodic structure region in which high refractive-index zones and low refractive-index zones are repeatedly being generated at pitches of 1 &mgr;m or less. Planes in which the high refractive-index zones or the low refractive-index zones are being joined to one another, are formed in parallel to the polarized magnetic field direction of the pulse laser. It is therefore possible to prepare an optical structural body having a submicron-order fine periodic structure which can readily be produced.

Abstract: A retroreflective photoelectric sensor may be of a biaxial type or of a coaxial type. A sensor of the biaxial type includes a light-emitting optical system having a light-emitting element, a first polarizer and a light-emitting lens arranged sequentially in this order, a light-receiving optical system having a light-receiving lens, a second polarizer and a light-receiving element arranged sequentially in this order, and a phase shifter inserted between the first polarizer and the light-emitting lens of the light-emitting optical system. The polarizer axes of the first and second polarizers are mutually perpendicular. A phase shifter such as a ½ wave plate may further be placed between the first polarizer and the light-emitting lens of the light-emitting optical system.

Abstract: A static attitude measurement device measures the static attitude of a target, such as a head suspension assembly or component, and reduces the possibility of measurement errors due to stray spots and internal reflections. The device includes a light source for producing a light beam, a beam splitter for directing the light beam toward the target from which a reflected beam is returned, a detector for detecting the reflected beam at a predetermined polarization state and a polarization component for producing the predetermined polarization state in the reflected beam, the polarization component positioned between the beam splitter and the target. The polarization component preferably is a quarter-wave plate to produce a reflected beam that is orthogonally polarized with respect to the incident beam. In addition, the directional optics preferably include a polarizer positioned between before the beam splitter to reduce reflection off of the light source.

Abstract: A measurement system is provided for a ball joint of a crash test dummy. The measurement system includes a light source operatively supported by a movable ball of the ball joint and a position sensitive detector operatively supported by a fixed member of the ball joint. The measurement system also includes a controller electrically connected to the light source to provide power to the light source for emitting light and electrically connected to the position sensitive detector that receives the emitted light to measure at least two angles between the ball and the fixed member.

Abstract: On a plate of birefringent crystal made of an LiNbO3 crystal or an LiTaO3 crystal, a conductive substance is adhered to the whole periphery of side surfaces of the plate that intersect an incident surface of a laser beam, thereby to form a wave plate. A polarizer is provided at the latter stage of the wave plate. A wavelength is monitored based on an output from the polarizer. With this arrangement, based on the use of the LiNbO3 crystal or the LiTaO3 crystal that can be manufactured by a large quantity at low cost, it is possible to obtain polarization characteristics and wavelength discrimination characteristics that are stable against environmental changes such as temperature and external stress, by suppressing the pyroelectric effect and the piezoelectric effect of these materials.

Abstract: The present invention concerns an apparatus for combining light from at least two laser light sources, preferably in the context of confocal scanning microscopy, and in order to make laser light sources of low output power usable as light sources, in particular for confocal scanning microscopy, is characterized in that the light from the laser light sources has at least approximately the same wavelength; and that at least one beam combining unit that combines the light beams in at least largely lossless fashion is provided.

Abstract: The invention relates to a device for detecting the location of an edge (2) of a transparent, anisotropic material (3,3′) comprising at least one sensor (1) with a light source (4), two polarization filters (6,7) with transmission axes (8,9) meeting at a 90° angle as well as a light detector (10), whereby the light source (4) and one polarization filter (6) are located on one side of the edge (2) to be detected and the second polarization filter (7) and the light detector are located on the other side. This type of device is to be configured in such a way that it can be used for detecting material (3,3′) with optical axes (14) in various directions without requiring assembly. This is achieved by at least one of the sensors (1) being configured and/or adjustable so that various angles (32) between the transmission axis of the first polarization filter (6) and the optical axis (14) of the transparent, anisotropic material (3,3′) are possible.

Abstract: A method for screening fiber polarization mode dispersion using a polarization optical time domain reflectometer. A pulse radiation is emitted into the fiber under test, and the backscattered radiation is measured by the POTDR and used to obtain a POTDR trace. The POTDR trace is then analyzed to compare the variation of signals along the length of the fiber, the variation in signals relating to the level of PMD along the length of the fiber. Because high levels of PMD correspond to localized levels of low variability, by setting the variability of signal threshold sufficiently low, fibers having unacceptably high localized PMD can be identified and removed.

Abstract: A confocal scanning microscope system (10) using cross polarization effects and an enhancement agent (acetic acid) to enhance confocal microscope reflectance images of the nuclei of BCCs (basal cell carcinomas) and SCCs (squamous call carcinomas) in the confocal reflectance images of excised tumor slices. The confocal scanning microscope system having a laser (11) for generating an illumination beam (12), a polygon mirror (18) for scanning the beam to a tissue sample (22) and for receiving a return beam from the tissue sample and detector (28) for detecting the returned beam to form an image. The system further includes a half-waveplate (13) having a rotatable stage (14) and a quarter-wave plate (21) having a rotatable stage (20) disposed in the optical path of the illumination beam and at least a linear polarizer (24) having a rotatable stage (25) disposed in the optical path of the returned beam from the tissue sample.

Abstract: A nonlinear optical crystal is composed of 2-adamantyl-5-nitorpyridine (AANP) allowing the type 2 phase matching to the sampling light and a measuring object light, emitting a sum frequency light of the measuring object light and the sampling light, with the polarization directions thereof being perpendicular to each other, when the sampling light and measuring object light multiplexed by a multiplexer are entered. When the sum frequency light is emitted through the nonlinear optical crystal, a control portion controls the polarization direction of the sampling light so as to be parallel to a predetermined reference axis located within a plane perpendicular to a phase matching direction of the nonlinear optical crystal. The predetermined reference axis is a single axis maintaining parallelism with the crystal axis of the nonlinear optical crystal even if the wavelength of the inputted light is changed.

Abstract: A spectral ellipsometer includes a light incident optical system for focusing a incidence spot of polarized light of multi-wavelengths onto a sample surface. A detecting optical system receives the reflected light influenced by the sample surface so that the amount of change in an elliptical polarization will be characteristic of the sample surface. A spherical prism polarizer is employed in the light incident optical system having complimentary curved light incident and light exit surfaces to enable the focusing of the incident light so that each of the ray traces of the range of wavelengths are focused at the same position on the sample surface.

Abstract: A normal incidence spectroscopic polarimeter is combined with an oblique incidence spectroscopic polarimeter to provide an accurate characterization of complex grating structures, e.g., structures with sloping sidewalls, with notches and with multiple underlying layers. The normal incidence spectroscopic polarimeter includes a polarizing element that is in the path of the normal incidence light beam such that the light beam is transmitted through the polarizing element before reaching the sample and after being reflected off the sample. The two systems may advantageously share a single light source and/or the spectrophotometer.

Abstract: Illumination apparatus includes a light source which directs a polarized source beam in a downstream direction along an optical axis and desirably focuses the beam. A polarization-altering element downstream from the source alters the polarization in a portion or portions of the source beam, so that the altered beam includes portions having different polarization directions. The altered beam passes downstream through a polarization-selective filter. The output beam from the polarization-selective filter can include either portion depending on the orientation of the filter. The arrangement can be used to provide a spot of a given size and shape at the focal location in a scanner such as a bar code scanner. The size and depth of field of the spot can be varied dynamically during operation.

Abstract: A trigger system including a photosensor having a polarizing light filter n positioned in a light receiving end of a housing. A lens is disposed in the housing for focusing light onto a transducer. A switch is electronically coupled to the transducer for selecting either a passive or active mode. In the active mode, a light source is directed at the photosensor, whereby a trigger signal is generated when an object disrupts the received light. In the passive mode, an opaque screen is spaced from the photosensor and a source of light is directed at the opaque screen, whereby a trigger signal is generated from the light reflected from an object positioned between the screen and photosensor. The trigger system may be electronically linked to a photographic system for high speed or action photography.

Abstract: An apparatus and a method for detecting an amount of depolarization of a linearly polarized beam transmitted by a birefringent medium in the direction of the optical axis thereof includes a first beam splitter for separating an on-axis portion of the linearly polarized beam into the orthogonal components, two photodetectors for detecting each component, a second beam splitter for separating an off-axis portion of the linearly polarized beam into the orthogonal components, the second beam splitter being disposed off-axis of the incident linearly polarized beam, a second set of photodetectors for detecting the components separated by the second beam splitter, and a subtracting device for subtracting the signals received by the second set of photodetectors from the respective signals received by the first two photodetectors.

Abstract: The present invention is directed to a method for changing the polarization of at least one of the photons emitted from a photon pair source into various partial ray paths using an electro-optical modulator (EOM), which is positioned in the particular partial ray path being traversed by the photon to be influenced and which, in the activated state, is able to alter the polarization of a photon, the modulator being activated as a function of time such that the probability that the photon is found in the region of the electro-optical modulator in the activated state is at a maximum.

Abstract: An automatic polarization controller is described that includes an optical input that receives a polarization multiplexed optical pulse train that comprises a first and a second polarized optical pulse train. A dither modulation signal is superimposed on at least one of the first and the second polarized optical pulse trains. A polarization transformer transforms an input polarization state of the polarization multiplexed optical pulse train to an output polarization state in response to a control signal that is applied to a control input of the polarization transformer. A polarization selective element receives the transformed polarization multiplexed optical pulse train and passes a polarized optical pulse train including the dither modulation signal. A detector receives the polarized optical pulse train including the superimposed dither modulation signal and generates a signal that is proportional to the amplitude of the dither modulation signal.

Abstract: An interleaver employs two birefringent crystals with opposite behavior under temperature variations and chromatic dispersion to achieve temperature stability and to compensate for chromatic dispersion. The interleaver employs a third birefringent crystal made of a birefringent material different from the materials of the other two crystals so that the wavelength components of radiation passing through the interleaver conform to the predetermined International Telecommunications Union grid. One of the three birefringent crystals includes a Faraday rotator placed in a magnetic field. By changing the direction of the magnetic field relative to the optical paths of beams passing through the interleaver, the behavior of the interleaver can be fine tuned to achieve temperature stability and chromatic dispersion compensation in a way that does not require very accurate dimension control of the three crystals.

Abstract: There is disclosed an apparatus in which when a surface having a curved portion, for example, a tire surface is visually inspected, light is uniformly illuminated on the surface. In this apparatus, an image pickup operation is performed by a CCD for a region to be visually inspected, which is illuminated by turning on LEDs. Based on the image pickup result, a density distribution of the region to be visually inspected is prepared. A difference between a target light quantity and light quantity, which is obtained for each field angle of the density distribution at which the region to be visually inspected is illuminated by each light source unit, is calculated and corrected. This correction allows the quantity of light reflected from the region to be visually inspected on the inner peripheral surface to become uniform.

Abstract: A combination metrology tool is disclosed which is capable of obtaining both thermal wave and optical spectroscopy measurements on a semiconductor wafer. In a preferred embodiment, the principal combination includes a thermal wave measurement and a spectroscopic ellipsometric measurement. These measurements are used to characterize ion implantation processes in semiconductors over a large dosage range.

Abstract: In a detecting system for detecting polarization state of light or a Stokes meter for detecting Stokes parameters, the polarization state can be detected with a compact structure or in a shortened measurement time. The detecting system uses a first divider for dividing incident light into two light beams having the same polarization state as the incident light, a detector for detecting one of the two light beams from the first divider, through a polarizer, and an acquisition unit for acquiring information regarding the polarization state of the incident light on the basis of an output of the detector.

Abstract: A metrology device with a rotatable polarizer is calibrated to align the transmission axis of the polarizer with the axis of orientation of a sample, such as a diffraction grating. The axis of orientation of the diffraction grating can be either the TE or TM axis. The system offset angle between the transmission axis of the polarizer in its home position and an axis of motion of the stage, such as a polar coordinate stage, is determined. Whenever a new substrate is loaded onto the stage, the sample offset angle between the axis of motion of the stage and the axis of orientation of a sample is measured. The polarizer offset angle, which is the angle between transmission axis of the polarizer and the axis of orientation of the sample, is the sum of the system offset angle and the sample offset angle. Thus, by rotating the polarizer by an amount equivalent to the sum of the system offset angle and the sample offset angle, the polarizer offset angle is reduced to zero.