Abstract: A system for automatically locking a control laser in a Rydberg atomic sensor may comprise an atomic vapor cell, a probe laser configured to excite the atoms in the atomic vapor cell to an intermediate energy state, and a control laser configured to excite the one or more atoms in the atomic vapor cell from the intermediate energy state to a higher energy state. The light generated by the control laser may be dithered at a pre-determined frequency. The system further comprises a photodiode configured to convert light received from the vapor cell into an electrical signal, a lock-in amplifier configured to generate an error signal based on the electrical signal received from the photo diode and a received reference oscillation frequency, and a servo configured to receive the generated error signal from the lock-in amplifier and adjust a frequency of the control laser based on the received error signal.

Abstract: An image processing apparatus includes a change detection unit configured to detect phase changes in multiple predetermined directions from among phase changes in a luminance image in units of mutually different resolutions, and a reliability estimation unit configured to estimate reliability of the detected phase change based on temporal amplitude change information in the multiple directions determined in the luminance image. The reliability estimation unit may estimate the reliability using an amplitude change of multiple resolutions and using a value of an amplitude change equal to or greater than a predetermined threshold value among images having multiple resolutions. The reliability may become a greater value as the amplitude change becomes larger.

Abstract: A method and apparatus for measuring a 3-D refractive index tensor are presented. The method for measuring a 3-D refractive index tensor according to an embodiment comprises the steps of: controlling incident light of a plane wave with respect to at least one angle and polarization; and measuring, in a polarization-dependent manner, the 2-D diffracted light of a specimen with respect to the incident light incident at the at least one angle and polarization, wherein the birefringence value and the 3-D structure of an alignment direction of molecules in the specimen having birefringence may be measured.

Abstract: A wavelength converter includes a polarization beam splitter configured to separate input light into a first polarization and a second polarization that are orthogonal to each other a non-linear optical medium configured to include a first incident end on which the first polarization separated by the polarization beam splitter is incident and a second incident end on which the second polarization separated by the polarization beam splitter is incident at a position different from a position of the first incident end, an optical multiplexer configured to multiplex the first polarization that has passed through the non-linear optical medium and the second polarization that has passed through the non-linear optical medium, and an optical element arranged between the non-linear optical medium and the optical multiplexer, and configured to correct a polarization axis of at least one of the first polarization and the second polarization incident on the optical multiplexer.

Abstract: At least three dark field images of a feature on a semiconductor wafer can be formed using an optical inspection system. Each of the at least three dark field images is from a different channel of the optical inspection system using an aperture that is fully open during image generation. The dark field images can be fused into a pseudo wafer image that is aligned with a corresponding design. This alignment can improve care area placement.

Abstract: Disclosed is a transient-state THz spectrometer applied to cells and biological macromolecules, including a femtosecond laser amplifier. A femtosecond laser output by the femtosecond laser amplifier is divided into two beams of pump light and probe light after passing through a beam splitter of which a transmission-reflection ratio is 7:3, the pump light is focused to irradiate a gap between electrodes of a nonlinear photoconductive antenna and emit a terahertz wave after successively passing through a half wave plate, a silver-plated reflector and a first lens, the terahertz wave forms a terahertz wave collineation after successively passing through a second lens, a slab waveguide, a third lens and an ITO film, the terahertz wave collineation and the probe light form a probe light collineation of wavefront tilt which is perpendicularly incident on a ZnTe crystal and detected and recorded by using a CCD camera.

Abstract: An optical voltage sensor assembly includes an input fiber-optic collimator positioned and configured to collimate input light beam from a light source. A crystal material is positioned to receive the input light beam from the light source and configured to exhibit the Pockels effect when an electric field is applied through the crystal material. An output fiber-optic collimator is positioned to receive an output light beam from the crystal material and configured to focus the output light beam from the crystal onto a detector. Methods of using the optical voltage sensor assembly are also disclosed.

Abstract: Provided is a polymer resin orientation evaluation method including: setting an axis intersecting a front surface of an object to be inspected as an inspection axis, and acquiring an optical characteristic value of the object to be inspected with respect to a plurality of polarization directions of a terahertz wave around the inspection axis; and evaluating orientation of a polymer resin that constitutes the object to be inspected on the basis of a variation amount of the optical characteristic value with respect to change of the polarization direction.

Abstract: The invention discloses a method for measuring a complex degree of coherence of a random optical field by using a mutual intensity-intensity correlation, including the steps of: building a test optical path; rotating a quarter-wave plate to enable the fast axis of the quarter-wave plate to be consistent with a polarization direction of reference light, to obtain light intensity distribution information of a first combined light; rotating the quarter-wave plate to enable the slow axis of the quarter-wave plate to be consistent with the polarization direction of the reference light, to obtain light intensity distribution information of a second combined light; blocking the reference light to obtain light intensity distribution information of to-be-tested light; blocking the to-be-tested light to obtain light intensity distribution information of the reference light; and calculating the amplitude and phase of a complex degree of coherence of the to-be-tested light.

Abstract: A multi-photon optical probe includes a probe housing, a lateral scanning stage coupled to a lateral mirror assembly and a remote axial scanning stage coupled to an axial mirror assembly. The lateral scanning stage is adapted to scan output laser energy over a planar scan area of the sample by moving the lateral mirror assembly. The axial scanning stage is adapted to scan the output laser energy over a vertical depth range of the sample, which, combined with the planar scan area, forms a 3-dimensional volume. A controller operates in conjunction with a number of remote actuating legs coupled to the axial mirror assembly in order to provide level imaging plane which in turn provides for a clear scanned image.

Abstract: The hybrid measurement system includes an evanescent prism coupling spectroscopy (EPCS) sub-system and a light-scattering polarimetry (LSP) sub-system. The EPCS sub-system includes an EPCS light source optically coupled to an EPCS detector system through an EPCS coupling prism. The LSP sub-system includes an LSP light source optically coupled to an optical compensator, which in turn is optically coupled to a LSP detector system via a LSP coupling prism. A support structure supports the EPCS and LSP coupling prisms to define a coupling prism assembly, which supports the two prisms at a measurement location. Stress measurements made using the EPCS and LSP sub-systems are combined to fully characterize the stress properties of a transparent chemically strengthened substrate. Methods of processing the EPCS and LSP measurements to improve measurement accuracy are also disclosed.

Abstract: A system may include a laser source, an acousto-optic modulator (AOM) coupled to the laser source, an atom trap, and at least one optical medium coupled between the AOM and the atom trap. Furthermore, at least one piezoelectric transducer may be coupled to the at least one optical medium, and a beam polarization controller may be coupled to the at least one piezoelectric transducer.

Abstract: Systems and methods are provided for optimizing the energy output of a laser system, such as a Light Detection and Ranging (LIDAR) system, by allowing the laser system to be tuned while the laser is in operation. For example, in an embodiment, a sensor, such as a photoresistor, is used to perform a scan to determine whether turning the crystal will result in increased energy. Crystal turners, such as servo motors, can be used to turn the crystal until the energy stops increasing.

Abstract: A polarimeter includes a Polarization Maintaining (PM) coupler with an input configured to receive input light and split the input light to a first output and a second output; a first PM fiber coupled to the first output; a second PM fiber coupled to the second output; a first polarization device coupled to the first PM fiber; a second polarization device coupled to the second PM fiber; and a plurality of detectors coupled to the first polarization device and the second polarization device, wherein outputs i1, i2, i3, i4 are determined based on outputs of the plurality of detectors, the outputs i1, i2, i3, i4 are linear projections of corresponding Stokes Parameters of the input light.

Abstract: Example position detection means and displacement detection devices are described. A relative position detection means optically detects a relative position of displacement of an object to be measured in a measuring direction, including a target mounted on the object to be measured and irradiated with light from a light source; a light receiver for detection of relative position for receiving light by changing polarization state of reflected light at the target with respect to the light; and a relative position information output unit for outputting relative position information based on displacement of the target in the measuring direction based on change of polarization state of the reflected light. The target includes a reflector mounted on the object to be measured and a birefringent member on the reflector and having a thickness changing from a tip to a base end along the measuring direction.

Abstract: A polarization tracking device that tracks polarization fluctuation of light using a Stokes vector, includes: an updating unit configured to express a fluctuation amount of the Stokes vector on a Poincare sphere in an xy plane perpendicular to a travelling direction of a light wave using a first and a second angles, the first angle being an angle between a direction of an electric field of the light wave and y axis, and the second angle being a phase difference between a component of the optical electric field in a direction of the y axis and a component of the optical electric field in a direction of an x axis; and an application unit configured to rotate the Stokes vector using an inverse polarization rotation matrix expressed with the first and the second angles.

Abstract: A polarized image acquisition apparatus includes a rotatable diaphragm to restrict a passage region of light passed through an objective lens to two regions mutually opposite across the central axis in 4n equal regions divided rotationally symmetrically in the plane orthogonal to the traveling direction of the light passed through the objective lens, and to change the angle of the passage region so that each two regions of the 4n equal regions become passage regions in order; and a rotating half-wave plate to convert, for each angle of the passage region, a P-polarized component passed through the diaphragm, in the same direction as the angle of the passage region, and an S-polarized component passed through the diaphragm, orthogonal to the angle of the passage region, into polarized waves in orthogonal first and second directions.

Abstract: Monochromatic cameras and methods for using such cameras to obtain a still or video color image of an object or scene. The image sensor of such cameras is clear, without a color filter array. A diffused-dispersed and optionally randomized image of the object or scene obtained at the image sensor is processed directly into a number R<K of spectral images in R wavebands. K?R spectral images are interpolated from the R spectral images. A color image is then reconstructed using the directly processed R spectral images and the K?R interpolated spectral images. The interpolated images may exemplarily be obtained using a spline subdivision algorithm.

Abstract: An optical inspecting apparatus includes a first light source, a beam splitter, a first lens, a first light detector, and pinhole plates. The first light source emits a first light beam. The beam splitter transmits or reflects the first light beam. The first lens provides the first light beam to transmit through a transparent substrate of a photomask and forms a first focusing spot on a first surface of the transparent substrate or a top surface of a photomask pattern formed on the transparent substrate. The first light detector detects a first reflection light beam generated by reflecting the first light beam from the first surface of the transparent substrate or the top surface of the photomask pattern. The pinhole plates are disposed in front of the first light detector to filter noise in the reflection light beam.

Abstract: A device and method for inspecting the deposition of hot melt onto an object to be assembled. A comparison is made between sensed images of the object after application of the hot melt and a predetermined standard to determine if the construction integrity of the object made with the hot melt is within the range established by the standard. Composite images from a sensor operating in the infrared band and another sensor reveal physical features of the object, as well as provide registration information about the placement of the hot melt on the assembled object. Composite images also present a way to visually ascertain ongoing or past production operations in order to trace problems with the raw material used for the object, as well as for the construction process of the object with the hot melt.

Abstract: Disclosed is an optical fiber pressure sensor including: a polarization beam splitter that splits input light from a broadband light source into two beams; a polarization controller through which vertically and horizontally polarized light coming out of the polarization beam splitter pass; a pressure chamber in which the polarization beam splitter and the polarization controller may be placed; and an optical spectrum analyzer into which vertically and horizontally polarized light passing through the polarization controller and getting out of the polarization beam splitter is introduced, wherein the pressure chamber includes a polarization-maintaining fiber and an optical fiber Bragg grating.

Abstract: A birefringence measurement system includes a lens mounted for selective movement into and out of use in the optical setup so that a wide range of sample types can be handled by the system without reconfiguring the primary components of the optical setup of the system (moving the detector, changing the light source power, etc.) in a manner that would sacrifice the cost effectiveness, efficiency, mechanical reliability and repeatability of measurements for such systems.

Abstract: Techniques and devices for measuring polarization crosstalk in birefringence optical media including polarization maintaining fiber.

Abstract: Apparatus and methods for measuring mode spectra for ion-exchanged glass substrates having a steep index region are disclosed. An interfacing fluid is provided between the coupling prism and the glass substrate. The interfacing fluid thickness is selected so that the variation in modal birefringence with fluid thickness is reduced to an acceptable level. The coupling prism can include a prism coating on the coupling surface so that the substrate-prism interface includes the prism coating. The coupling prism can also include stand-off members that serve to define the thickness of the interfacing fluid.

Abstract: A system for measuring linear or circular diattenuation in an optical element includes a sample rotation stage for securing an optical element sample; a light source module for generating a source light beam and a detector module. The light source module and detector module are arranged with the sample rotation stage between them, thereby permitting the source light beam to propagate through a sample that may be secured in the sample stage and to the detector module. Linear motion control of the light source module and the detector module, as well as tilt control of the light source module, the sample rotation stage and the detector module is provided, thereby to facilitate detection, by the detector module of the modulated light intensity information corresponding to a diattenuation characteristic of the optical sample secured in the sample stage.

Abstract: A device for enhancing transmission of incident electromagnetic radiation at a predetermined wavelength is presented that includes an aperture array structure in a thin film. The structure includes a repealing unit cell having more than one aperture including a first aperture and a second aperture, wherein a parameter of the first aperture differs from that of the second aperture. The unit cell repeats with a periodicity on the order of or less than said predetermined wavelength, The structure parameters are configured to preferentially support cavity modes for coupling to and enhancing transmission of a predetermined polarization state at the predetermined wavelength. By structuring the unit cell with apertures that differ by appropriate degrees in at least one of dimension, height, dielectric constant of material filling the apertures, shape, and orientation, the devices can be adapted for polarization and/or wavelength filtering- and/or light circulating, weaving, or channeling.

Abstract: A wavefront sensing technique using Polarization Rotation INTerferometry (PRINT) provides a self-referencing, high-resolution, direct measurement of the spatially dependent phase profile of a given optical beam. A self-referencing technique is used to create a reference beam in the orthogonal polarization and a polarization measurement to measure the spatial-dependent polarization parameters to directly determine the absolute phase profile of the beam under test. A high-resolution direct measurement of the spatially-resolved phase profile of one or more optical beams is realized.

Abstract: An apparatus and method for imaging a section of a medium are disclosed. The section of medium has features (“Polarization Sensitive Features”) which return light according to the polarization of the received light. The disclosed apparatus and method may be configured to measure the irradiance of light returned from the object across the lateral (with respect to the optical axis) dimension.

Abstract: A linearly polarized light reaches a sample S through a polarizer and receives a retardation from the sample S. Then, the light reaches a movable mirror unit and a fixed mirror unit of a phase shifter through a first polarizing plate and a second polarizing plate. Then, the reflected measurement lights pass through an analyzer, and are caused by an imaging lens to form an interference image on the light-receiving surface of a detector. At this time, an optical path length difference between a beam reflected on the movable mirror unit and a beam reflected on the fixed mirror unit is continuously changed the movable mirror unit. Hence, the imaging intensity of the interference image detected by the detector continuously changes producing a synthetic waveform similar to an interferogram. The synthetic waveform is Fourier-transformed, to obtain an amplitude per wavelength and a birefringent phase difference per wavelength.

Abstract: Measuring polarization profile along an input optical beam cross-section using an optical system includes a polarization beam splitting assembly for splitting the input beam into a predetermined number of beam components with a predetermined polarization relation between them, and including a polarization beam splitter in an optical path of the input beam splitting it into beam components having a polarization relationship and a birefringent element in an optical path of the beam components for splitting each of them into a pair of beams having ordinary and extraordinary polarizations, thereby producing the predetermined number of output beam components. The pixel matrix is located in substantially non-intersecting optical paths of the output beam components and generates a number of output data pieces indicative of intensity distribution within the output beam components and data contained therein being indicative of the polarization profile along the input beam cross-section.

Abstract: In one embodiment, an apparatus comprises an optical system with multiple detectors and a processor. The optical system is configured to produce images of an optical source in a first dimension and a second dimension substantially orthogonal to the first dimension at each detector at a given time. Each image from the images is based on an interference of an emission from the optical source in a first direction and an emission from the optical source in a second direction different from the first direction. The processor is configured to calculate a position in a third dimension based on the images. The third dimension is substantially orthogonal to the first dimension and the second dimension.

Abstract: A system for sensing the position of a movable object includes a polarization maintaining fiber configured to receive light from a light source; an optical system configured to rotate an angle of polarization of the light by a first predetermined angle; a low birefringence fiber connected to the optical system at a first end and having a mirror connected to a second end configured to reflect the light and rotate the angle of polarization at a second predetermined angle, the second end being configured to overlap a magnetic field of the a magnet attached to the object. The angle of polarization is rotated to a third predetermined angle proportional to at least one of the strength of the magnetic field and an amount of the overlap. The optical system is configured to decompose the third predetermined angle into a first component and a second component. A detector is configured to detect a differential between the first and second components indicative of the amount of the overlap.

Abstract: A method of controlling a light beam in an optical system includes a light source that directs a collimated light beam along a path, through a sample, and toward the active area of a stationary detector. The method includes the step selectively moving a lens into the path of the light beam for spreading the beam in instances where the path of the beam is altered by the sample between the source and the stationary detector. The detector, therefore, is held stationary. Adjustment means are provided for increasing the intensity characteristic of the light that reaches the detector to account for a decrease in intensity that occurs when the lens is in the path of the light beam to spread the beam.

Abstract: A birefringent filter includes an EM directing element in optical alignment with a first surface of the birefringent plate. A polarimetric imager includes a birefringent filter including a birefringent plate formed of a birefringent material and an EM directing element in optical alignment with a first surface of the birefringent plate. The imager further includes a detector in optical alignment with a second surface of the birefringent plate. A projection system includes an EM directing element and a birefringent filter. The filter includes (1) a birefringent plate formed of a birefringent material and having a first surface in optical alignment with the emissions source, and (2) an EM directing element in optical alignment with a second surface of the birefringent plate.

Abstract: A Fiber-optic current sensor for sensing electric current carried in an electric conductor (18). Its optical section comprises: a light source (1); a directional coupler (2) with two ports (2A, 2B) of two arms each; a radiation polarizer (3); a polarization modulator (4); a fiber line (17) coupled to a current-sensing fiber loop (11); a mirror (10); and a photodetector (22). The first port of the coupler (2) is coupled to the light source (1) and to the photodetector (22). Its second port is coupled via the radiation polarizer (3) to the polarization modulator (4). The polarization modulator comprises a magneto-sensitive element (5), around which a solenoid (6) is wound. The fiber loop (11) comprises a magneto-sensitive optical fiber with embedded linear birefringence. An electronic section comprises a signal generator (21) which drives the solenoid (6); and a signal processing unit which receives the optical signal from the photodetector (22).

Abstract: Provided is a particle characterization device that can ensure measurement accuracy even though light detecting means has a single configuration, and enables the number of optical elements to be decreased as much as possible to suppress cost increase and reduce the number of adjustment places, and the particle characterization device has an incident side polarizer and an incident side ¼ wavelength plate as an illumination optical system mechanism and, as a light receiving optical system mechanism, an exit side ¼ wavelength plate and an exit side polarizer that can be rotated to a plurality of angle positions around a cell, wherein light attenuating means that prevents a polarization state from being changed is provided on a light path, and a light attenuation rate by the light attenuating means is controlled such that a detected light intensity at each measurement position falls within a measurement range of light detecting means.

Abstract: A linearly polarized light reaches a sample S through a polarizer and receives a retardation from the sample S. Then, the light reaches a movable mirror unit and a fixed mirror unit of a phase shifter through a first polarizing plate and a second polarizing plate. Then, the reflected measurement lights pass through an analyzer, and are caused by an imaging lens to form an interference image on the light-receiving surface of a detector. At this time, an optical path length difference between a beam reflected on the movable mirror unit and a beam reflected on the fixed mirror unit is continuously changed the movable mirror unit. Hence, the imaging intensity of the interference image detected by the detector continuously changes producing a synthetic waveform similar to an interferogram. The synthetic waveform is Fourier-transformed, to obtain an amplitude per wavelength and a birefringent phase difference per wavelength.

Abstract: Techniques and devices for measuring polarization crosstalk in birefringence optical media including polarization maintaining fiber.

Abstract: An optical system configured to visually inspect a target having a variable position with respect to the optical system is provided. The optical system includes a polarizer configured to convert an incident light reflected or diffused from the target into linearly polarized light; a light modulating element configured to modulate a polarization state of the linearly polarized light in response to control signals; and a lens group comprising at least one birefringent element, the birefringent element configured to refract or reflect the modulated linearly polarized light with a first polarization state under a first refraction index to enable inspection of the target at a first object position, and the birefringent element further configured to refract or reflect the modulated linearly polarized light with a second polarization state under a second refraction index to enable inspection of the target at a second object position.

Abstract: A detection apparatus includes an optical system including a polarization beam splitter and a quarter-wave plate. The optical system illuminates a mark via the polarization beam splitter and the quarter-wave plate in sequence, and directs light reflected from the mark via the quarter-wave plate and the polarization beam splitter in sequence towards a light-receiving element An airtight container configured to enclose therein at least part of the optical system includes, as a partition wall thereof, a light transmitting member arranged in an optical path between the polarization beam splitter and the quarter-wave plate.

Abstract: 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 ?, 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 ?. 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.

Abstract: A system for controlling a light beam in an optical setup includes a light source that directs a collimated light beam along a path, through a sample, and toward the active area of a stationary detector. A lens is selectively movable into the path of the light beam for spreading the beam in instances where the path of the beam is altered by the sample between the source and the stationary detector. The detector, therefore, is held stationary. Adjustment mechanisms are provided for increasing the intensity characteristic of the light that reaches the detector to account for a decrease in intensity that occurs when the lens is in the path of the light beam to spread the beam.

Abstract: A system, method of configuring, and application a system for introducing a relative phase retardation into orthogonally polarized components of an electromagnetic beam entered thereinto, wherein the system involves a substantially achromatic multiple element retarder system for use in wide spectral range (for example, 190-1700 nm) rotating compensator spectroscopic ellipsometer and/or polarimeter systems.

Abstract: The invention relates to a differential polarizing laser-scanning microscope (DP LSM) for determining differential polarization quantities of a material, comprising a laser light source (L) for scanning the sample and illuminating it with a coherent and monochromatic light, a microscope unit (ME) with a sample holder for providing a preselected optical magnification and imaging and a polarization state setting unit (PAA) positioned in the illuminating beam path (between the light source and the sample holder). The microscope is further provided with detectors (D1, D2) in the observing beam path, at least one filter holder in front of the detectors and a signal-processing unit (VE) for processing the electrical signals of the detectors. In the DP-LSM microscope an optical element (DP) is located in the common beam path comprising the illuminating and the observing beams, for separating the orthogonal polarization components.

Abstract: A apparatus for use in a borehole in an earth formation. The apparatus may include: an electromagnetic source; an anisotropic permittivity material, either natural or manufactured, receiving electromagnetic radiation from the electromagnetic source; and a detector for estimating the electromagnetic radiation transmitted through the anisotropic permittivity material as an indication of a parameter of interest. Also, a method of estimating a parameter of interest using the aforementioned apparatus.

Abstract: The invention is directed to find a false defect from defect candidates and obtain a threshold with which the false defect can be eliminated by the smallest number of review times. Defect candidates are reviewed and selected as a defect or a false defect. By deleting a defect candidate having a characteristic quantity equal to or less than that of the false defect from a map or displaying it in another sign, the false defect can be determined visually. Since the defect candidate having the characteristic quantity equal to or less than that of the selected false defect is deleted from the map or displayed in another sign, the defect candidates unnecessary to set a threshold are not reviewed. The number of defect candidates to be reviewed can be largely reduced as compared with that in the conventional technique. Further, by repeating the above work, the threshold is automatically calculated, and an inspection result map with the threshold is displayed, so that a re-inspection is unnecessary.

Abstract: A fiber rotator mechanism for rotating a portion of an optical waveguide, specifically an optical fiber, about a longitudinal axis thereof comprises a motor having a tubular rotor through which the fiber extends, in use, and to which the fiber is secured, directly or indirectly. An optical fiber may be secured by means of a device which also compresses the optical fiber to induce a required birefringence, conveniently by means of a spring-loaded clamping device or a ferrule of shape memory material.

Abstract: An arrangement for and a method of characterising the polarisation properties of an optical system, in particular an optical system of a microlithographic projection exposure apparatus. The arrangement includes at least one polarisation state generator (130, 230, 330) which sets a defined polarisation state of radiation incident on the optical system, and a polarisation state detector (140, 240, 340) adapted to measure the exit polarisation state of radiation issuing from the optical system, wherein the optical system is designed for a working wavelength of less than 15 nm, and wherein the polarisation state generator and/or the polarisation state detector are so designed that their polarisation-optical action on an incident light beam is substantially constant over an angle spectrum of the light beam of at least 10°.

Abstract: An apparatus, for measuring an applied electrical field and for reducing perturbation to the electrical field being measured, includes a laser integrated into an electro optic crystal sensor head prior to the output fiber. A probe beam is passed along the crystal direction of low birefringence of nearly circular optical indicatrix, rather than one of high EO modulation. The EO crystal is placed between two crossed polarizers and oriented such that a small tilt angle is subtended between its optic axis and the path of the probe beam. Improved optical coupling is achieved by using a large core multimode fiber at the output, to reduce optical insertion losses. A collimating lens emits the intensity modulated laser beam back to a photodetector, where the intensity modulated laser beam is converted to an electrical signal representing both field strength and phase of the electrical field applied to the sensor head.

Abstract: A apparatus for use in a borehole in an earth formation. The apparatus may include: an electromagnetic source; an anisotropic permittivity material, either natural or manufactured, receiving electromagnetic radiation from the electromagnetic source; and a detector for estimating the electromagnetic radiation transmitted through the anisotropic permittivity material as an indication of a parameter of interest. Also, a method of estimating a parameter of interest using the aforementioned apparatus.