214 results about "Polarimetry" patented technology

An optical scanner system for contiguous three-dimensional topographic or volumetric imaging of a surface from an aircraft or spacecraft is disclosed. A servo controller synchronizes the rotation rates of a pair of wedge scanners with high precision to the multi-kilohertz laser fire rate producing an infinite variety of well-controlled scan patterns. This causes the beam pattern to be laid down in precisely the same way on each scan cycle, eliminating the need to record the orientations of the wedges accurately on every laser fire, thereby reducing ancillary data storage or transmission requirements by two to three orders of magnitude and greatly simplifying data preprocessing and analysis. The described system also uses a holographic element to split the laser beam into an array that is then scanned in an arbitrary pattern. This provides more uniform signal strength to the various imaging detector channels and reduces the level of optical crosstalk between channels, resulting in a higher fidelity three-dimensional image.

A method, apparatus, and computer program product for identifying features in a sample by analyzing Mueller matrices to calculate an average degree of polarization, a weighted average degree of polarization, a degree of polarization map, a degree of polarization surface. Also, a method, apparatus, and computer program product for identifying features in a sample by analyzing Mueller matrices to calculate depolarization relative to a retardance axis and / or a diattentuation axis, and to calculate a ratio of diattenuation to polarizance or ratios of row and column magnitudes. Also, a method for retinal polarimetry, including a non-depolarizing light tube configured for insertion into the eye.

A new generation polarimetry apparatus and methodology is disclosed, which involve passing polarized light through a sample including a chiral analyte, where the analyte is under the influence of a periodically varying magnetic field. The apparatus also utilizes optical heterodyne detection and lock-in detection at higher order harmonics of the magnetic field modulation frequency to improve sensitivity and detection limits of optical properties of chiral analytes.

Plural electronic or optical images are provided in a streak optical system, as for instance by use of plural slits instead of the conventional single slit, to obtain a third, fourth, etc. dimension—rather than only the conventional two, namely range or time and azimuth. Such additional dimension or dimensions are thereby incorporated into the optical information that is to be streaked and thereby time resolved. The added dimensions may take any of an extremely broad range of forms, including wave-length, polarization state, or one or more spatial dimensions—or indeed virtually any optical parameter that can be impressed upon a probe beam. Resulting capabilities remarkably include several new forms of lidar spectroscopy, fluorescence analysis, polarimetry, spectropolarimetry, and combinations of these, as well as a gigahertz wavefront sensor.

An exposure apparatus includes an illumination optical system configured to illuminate a reticle, a projection optical system configured to project a pattern of the reticle onto a substrate, a polarization adjuster configured to independently adjust each polarization state of plural areas in an effective light source distribution used to illuminate the reticle, a polarization measurement unit configured to measure a polarization state of light that has passed the polarization adjuster, and a controller configured to independently control each polarization state of the plural areas via the polarization adjuster based on a measurement result of the polarization measurement unit.

A system and method of identifying changes utilizing radio frequency polarization includes receiving a reflected and / or transmitted polarized radio frequency signal at a receiver, filtering, amplifying and conditioning the received signal, converting the received signal from an analog format to a digital format, processing the digital signal to elicit a polarization mode dispersion feature of the received signal, and comparing the polarization mode dispersion features to a known calibration to detect a change in a characteristic of the target object.

A system for simultaneously producing multiple images substantially identical images on multiple separate detector planes is disclosed. A reflective spatially beam-splitting element preferably comprising multiple reflective areas is preferably placed at a location substantially coincident with the pupil or aperture of the system. In non-diffraction limited systems, each area preferably comprises an actual cross section that is circular or has the rotational symmetry (or a multiple thereof) of the number of images to be formed. In diffraction limited systems, all of the areas preferably comprise actual cross sections that have the same shape, size and orientation with respect to the incoming optical beam. Each individual actual cross section may be due to the shape of each area, optionally in combination with a mask. Appropriate selection of filters enables real-time multi-spectral scientific imaging, imaging polarimetry, or high dynamic range imaging (HDRI) for photography and cinematography, even with a moving camera and / or moving subjects.

The present invention relates to near-field scanning optical microscopy (NSOM) and near-field / far-field scanning microscopy methods, systems and devices that permit the imaging of biological samples, including biological samples or structures that are smaller than the wavelength of light. In one embodiment, the present invention permits the production of multi-spectral, polarimetric, near-field microscopy systems that can achieve a spatial resolution of less than 100 nanometers. In another embodiment, the present invention permits the production of a multifunctional, multi-spectral, polarimetric, near-field / far-field microscopy that can achieve enhanced sub-surface and in-depth imaging of biological samples. In still another embodiment, the present invention relates to the use of polar molecules as new optical contrast agents for imaging applications (e.g., cancer detection).

Plural electronic or optical images are provided in a streak optical system, as for instance by use of plural slits instead of the conventional single slit, to obtain a third, fourth etc. dimension—rather than only the conventional two, namely range or time and azimuth. Such additional dimension or dimensions are thereby incorporated into the optical information that is to be streaked and thereby time resolved. The added dimensions may take any of an extremely broad range of forms, including wavelength, polarization state, or one or more spatial dimensions—or indeed virtually any optical parameter that can be impressed upon a probe beam. Resulting capabilities remarkably include several new forms of lidar spectroscopy, fluorescence analysis, polarimetry, spectropolarimetry, and combinations of these.

Measurements at multiple distinct polarization measurement states are taken to define the polarization state of an input, for example to calculate a Stokes vector. High accuracy and / or capability of frequent recalibration are needed, due to the sensitivity of measurement to retardation of the input signal. A multiple measurement technique takes a set of spatially and / or temporally distinct intensity measurements through distinct waveplates and polarizers. These can be optimized as to orientation and retardation using initial choices and also using tunable elements, especially controllable birefringence elements. A device matrix defines the response of the device at each of the measurement states. The matrix can be corrected using an iterative technique to revise the device matrix, potentially by automated recalibration. Two input signals (or preferably the same signal before and after a polarization transform) that are known to have a common polarization attribute or other attribute relationship are measured and the common attribute and / or attribute relationship is derived for each and compared. The device matrix is revised, for example by iterative correction or by random search of candidates to improve the accuracy of the device matrix. Optional tunable spectral and temporal discrimination provide additional functions.

An optical scanner system for contiguous three-dimensional topographic or volumetric imaging of a surface from an aircraft or spacecraft is disclosed. A servo controller synchronizes the rotation rates of a pair of wedge scanners with high precision to the multi-kilohertz laser fire rate producing an infinite variety of well-controlled scan patterns. This causes the beam pattern to be laid down in precisely the same way on each scan cycle, eliminating the need to record the orientations of the wedges accurately on every laser fire, thereby reducing ancillary data storage or transmission requirements by two to three orders of magnitude and greatly simplifying data preprocessing and analysis. The described system also uses a holographic element to split the laser beam into an array that is then scanned in an arbitrary pattern. This provides more uniform signal strength to the various imaging detector channels and reduces the level of optical crosstalk between channels, resulting in a higher fidelity three-dimensional image.

A programmable multifunction spectral and / or polarization imager. In one example, such an imager includes an imaging optical subsystem configured to receive electromagnetic radiation from a distant scene, a focal plane array configured to produce an image of the scene, and a programmable polarimetry subsystem electrically switchable between an ON state in which the polarimetry subsystem receives the electromagnetic radiation and provides polarized electromagnetic radiation to the focal plane array, and an OFF state in which the polarimetry system is configured as a first substantially clear aperture that passes the electromagnetic radiation to the focal plane array. In certain examples, the imager includes a programmable spectral imaging sub-system configurable between an ON state and an OFF state.

A method measuring the birefringence of an object. A measurement beam having a defined input polarization state is generated, the measurement beam being directed onto the object. Polarization properties of the measurement beam after interaction with the object are detected in order to generate polarization measurement values representing an output polarization state of the measurement beam after interaction with the object. The input polarization state of the measurement beam is modulated into at least four different measurement states in accordance with a periodic modulation function of an angle parameter α, and the polarization measurement values associated with the at least four measurement states are processed to form a measurement function dependent on the angle parameter α. A two-wave portion of the measurement function is determined and analysed in order to derive at least one birefringence parameter describing the birefringence, preferably by double Fourier transformation of the measurement function.

To effectively reduce a measurement error in a parameter indicating two-dimensional spatial distribution of a state of polarization generated by variations in retardation of a birefringent prism pair due to a temperature change or other factors, while holding a variety of properties of an imaging polarimetry using the birefringent prism pair. By noting that reference phase functions φ1(x, y) and φ2(x, y) are obtained by solving an equation from each vibration component contained in an intensity distribution I(x, y), the reference phase functions φ1(x, y) and φ2(x, y) are calibrated concurrently with measurement of two-dimensional spatial distribution S0(x, y), S1(x, y), S2(x, y), and S3(x, y) of Stokes parameters.

A system for performing single wavelength ellipsometry (SWE) on a thin film on a multi-layer substrate such as silicon-on-insulator (SOI) applies a measurement beam having an absorption distance less than the thickness of the superficial layer of the multi-layer substrate. For example, for an SOI substrate, the measurement beam is selected to have a wavelength that results in an absorption distance that is less than the superficial silicon layer thickness. The system can include a cleaning laser to provide concurrent cleaning to enhance measurement accuracy without negatively impacting throughput. The measurement beam source can be configured to provide a measurement beam at one wavelength and a cleaning beam at a longer wavelength, so that the absorption depth of the measurement beam is less than the superficial layer thickness while the absorption depth of the cleaning beam is greater than the superficial layer thickness.

The invention provides an optical coherence domain polarization measurement device with an optical path scanning position and speed correction function. The optical coherence domain polarization measurement device comprises a wide-spectrum light source, a polarization device to be measured, an optical path correlator, an optical path scanning correction device and an interference signal detecting and processing device. The optical coherence domain polarization measurement device is characterized in that the added optical path scanning correction device is composed of a laser light source, an optical fiber 3*3 coupler, a movable reflection mirror in the optical path scanning device, a faraday rotating mirror and a photoelectric detector, the optical fiber 3*3 coupler conducts phase shifting on an interference signal to complete passive signal modulation of a Michelson type optical fiber interferometer, the faraday rotating mirror is used for eliminating polarization declination of the interferometer, and high-precision and rapid measurement of the optical path scanning position and the optical path scanning speed is achieved on the basis of a dual-detector correction algorithm. According to the device, precision and uniformity of optical path scanning are improved, and the device has the advantages of being small in size, high in measurement accuracy, capable of being easily combined with an existing application structure, and the like, and is widely applied to interference optical path scanning and testing for measuring the remote distance on the basis of white light interference.

A new generation polarimetry apparatus and methodology is disclosed, which involve passing polarized light through a sample including a chiral analyte, where the analyte is under the influence of a periodically varying magnetic field. The apparatus also utilizes optical heterodyne detection and lock-in detection at higher order harmonics of the magnetic field modulation frequency to improve sensitivity and detection limits of optical properties of chiral analytes.

A system and method of identifying changes utilizing radio frequency polarization includes receiving a reflected and / or transmitted polarized radio frequency signal at a receiver, filtering, amplifying and conditioning the received signal, converting the received signal from an analog format to a digital format, processing the digital signal to elicit a polarization mode dispersion feature of the received signal, and comparing the polarization mode dispersion features to a known calibration to detect a change in a characteristic of the target object.

To effectively reduce a measurement error in a parameter indicating two-dimensional spatial distribution of a state of polarization generated by variations in retardation of a birefringent prism pair due to a temperature change or other factors, while holding a variety of properties of an imaging polarimetry using the birefringent prism pair. By noting that reference phase functions φ1(x, y) and φ2(x, y) are obtained by solving an equation from each vibration component contained in an intensity distribution I(x, y), the reference phase functions φ1(x, y) and φ2(x, y) are calibrated concurrently with measurement of two-dimensional spatial distribution S0(x, y), S1(x, y), S2(x, y), and S3(x, y) of Stokes parameters.

The invention relates to a radiation spectrum measurement system of the sky polarized light, belonging to the optical electron testing technology field, which is applicable to measuring the sky polarized light and spatial and temporal distribution analysis. The measurement system is consisted of a polarization measurement head, a telescopic optical system, a fiber spectrometer system and a computer. Arranging the polarization measurement head comprises: arranging a cylindrical rotary head on the inside of an interface (1); screwing down a ding screw; then putting a wafer-shaped polarizer in the lumen of the rotary head; using an annular pressing ring to compress and fix the polarizer on the rotary head via two bolts. An equatorial is arranged on an A-frame. Then a refractor is arranged above the equatorial. The back-end of anti-ultraviolet optical fiber is connected on a spectrograph. Then a cosine corrector is arranged on the front-end of the anti-ultraviolet optical fiber. And then the probe-end of the cosine corrector is inserted into an interface (2) and the ding screw is screwed down. The system is provided with strong currency, wide application range and convenient operation.

Provided is a polarization resistance single line polarization interference and single Woodward prism spectral homodyne laser vibrometer, belonging to the laser interference measuring field. An interference portion utilizes a half-wave plate, a quarter-wave plate and an NBS to generate + / -45 DEG linear polarization reference light and linear polarization measuring light orthorhombic in a one way polarization direction and having light paths overlapped; the reference light and measuring light of a detection portion are split and generate four paths of optoelectronic signals with a phase position difference of 90 DEG through a same Woodward prism, thereby restraining outstanding features of non-linear errors from an optical path structure and principle. The vibrometer realizes four channel homodyne orthogonal laser interference measurement, effectively solves the problems that, in the prior art, polarization leakage and polarization aliasing exist in the optical path, output signals exist direct current biased errors and nonopiate errors, and non-linear errors of measuring results are obvious, and possesses significant technical advantages in an ultra-precision vibration measuring field.

Remotely sensing a target may include generating a first beam of optical radiation that is modulated at a first frequency and polarized at a first polarization. A second beam of optical radiation that is modulated at a second frequency and polarized at a second polarization may also be generated. The first and second beams of optical radiation may be transmitted to the target. Radiation at the first polarization and radiation at the second polarization may be detected from the target using a phase sensitive technique and the first and second frequencies.

The invention discloses a fiber grating sensing system capable of simultaneously measuring transverse pressure and temperature based on polarization measurement, and belongs to the field of optical fiber sensing. The fiber grating sensing system mainly comprises a tunable laser with high stability, an optical isolator, an optical circulator, a Bragg fiber grating, a polarization-dependent loss tester and a spectrum analyzer. When the fiber grating is subject to the simultaneous action of transverse pressure and temperature, the polarization-dependent loss property of the transmission end obviously changes due to the dual-deflection effect, and the size of the transverse pressure can be demodulated through the measurement of the polarization-dependent loss tester. The reflective light of the fiber grating is inputted to the spectrum analyzer through the optical circulator, and the temperature is measured by analyzing the movement of the center wavelength of the reflective light spectrum. The fiber grating sensing system has the advantages that the dual parameters of the transverse pressure and the temperature can be simultaneously measured, the sensitivity is high, the structure is simple, and the full-light sensing is realized.

The invention relates to an anti-polarization-mixing double-line polarization interference and single Wollaston prism beam splitting homodyne laser vibrometer, which belongs to the field of laser interferometry. An interference part produces double-line polarization direction orthogonality of + / -45 degrees, a linear polarization reference light and a linear polarization measuring light through a half wave plate, a quarter wave plate and a polarization eliminating spectroscope NBS, wherein the optical paths of the linear polarization reference light and the linear polarization measuring light coincide. After beam splitting, the detection part reference light and the measuring light produce four photoelectric signals through the same Wollaston prism, wherein the phase difference among the photoelectric signals is 90 degrees. The outstanding characteristic of nonlinearity error suppression is acquired from an optical path structure and principle. According to the invention, four-channel homodyne orthogonality laser interferometry can be realized; the problems of optical path polarization leakage and mixing, output signal direct current offset error and non-orthogonal error, distinct measurement result nonlinear error and the like in the prior art can be effectively solved; and the vibrometer has a significant technical advantage in the field of ultra-precision vibration measurement.

Optical systems and methods that simultaneously measure optical constants (n, k) and thickness of thin films. The systems and methods use of differential polarimetry (differential analysis of spectroscopic multi-angle reflection and ellipsometric data) to measure optical constants (n k) and thickness of ultra-thin films.

The invention discloses a light beam stokes parameter measuring device and a measuring method thereof. The polarization measuring device is composed of a beam splitter prism group, a phase retarder array, a polarization analyzer, a photoelectric detector array and a signal processing system, wherein all units of the photoelectric detector array correspond to all units of the phase retarder array one by one. The measuring method is realized through the following steps: adopting the phase retarder array to replace the rotational phase retarder; according to the polarization direction of a to-be-measured light beam, adjusting the direction of a light-transmitting shaft of the polarization analyzer to be parallel to or vertical to the polarization direction of the to-be-measured light; measuring the polarization parameters of the to-be-measured light beam; processing data as per light intensity signals detected by the photoelectric detector array so as to realize the real-time high accuracy measurement of the light beam stokes parameters. Though adopting the method, the stokes parameters of the light beam can be measured in real time, and furthermore, the influences on the measurement accuracy of the light beam polarization state caused by the phase delay error of phase delaying devices, the fast-shaft direction error, the direction error of the light-transmitting shaft of the polarization analyzer and the extinction ratio error are reduced.

The invention belongs to the field of laser interference measurement, and relates to a quadrature error-free double-path polarization interference and double-Wollaston prism light-splitting type homodyne laser vibration meter. An interference part generates double paths of linear polarization reference light and linear polarization measurement light whose polarization directions are orthogonal and light paths are overlapped through a quarter-wave plate and a polarization-eliminating beam splitter NBS, and in a detection part, reference light and measurement light generate four paths of photoelectric signals with a phase difference of 90 degrees through two Wollaston prisms whose spatial rotation angles around light beams form a specific relation, thereby obtaining an outstanding characteristic of inhibiting a nonlinear error from a light path structure and in principle. The quadrature error-free double-path polarization interference and double-Wollaston prism light-splitting type homodyne laser vibration meter provided by the invention adopts less optical elements to realize four-channel homodyne quadrature laser interference measurement, can effectively solve the problems in an existing technical scheme that polarization leakage and polarization aliasing exist in the light paths, a direct current biased error and a non-quadrature error exist in an output signal, and a nonlinear error of a measurement result is obvious, and thus has remarkable technical advantages in the field of ultra-precise vibration measurement.