Abstract: Provided is a method for focusing a workpiece in the Z-axis for optical metrology. The auto focusing subsystem includes a focus detector having a tilt angle, a capture range, and a plurality of sensors. A processor coupled to the focus detector is configured to utilize the plurality of focus signals measured using the focus detector to determine two or more focus parameters. The two or more focus parameters and calibration data are used to determine an initial position of the workpiece and to generate instructions to move the workpiece to a best focus position.

Abstract: Optical apparatus includes a device package, with a radiation source contained in the package and configured to emit a beam of coherent radiation. A diffractive optical element (DOE) is mounted in the package so as to receive and diffract the radiation from the radiation source into a predefined pattern comprising multiple diffraction orders. An optical detector is positioned in the package so as to receive and sense an intensity of a selected diffraction order of the DOE.

Abstract: A laser self-mixing measuring device is provided, comprising a laser with a laser cavity and a surface arranged along the optical path of the laser beam which redirects incident laser light back into the laser cavity. The surface comprises a periodic structure which diffracts the laser light into partial beams.

Abstract: The invention discloses an optical interferometer which can be used to provide simultaneous measurements over multiple path lengths and methods to employ such an interferometer as to achieve a variety of functions covering simultaneous measurements at different depths separated by an increment of a multiple differential delay matched in the interferometer as well as imaging. Optical sensors, optical coherence tomography (OCT) set-ups, optical sensing methods and OCT methods are disclosed which can provide: (i) multiple en-face images at several depths with dynamic dispersion compensation, (ii) fast acquisition of cross sections, (iii) fast acquisition of 3D volumes of a scattering object while maintaining dynamic focus; (iv) fast acquisition of long axial measurement profiles, non mechanical, with dynamic focus, range scalable, with applications in tracking and OTDR.

Abstract: System and method for estimating and correcting an aberration of an optical system. The method includes capturing a first plurality of images on a first plurality of planes. The first plurality of images is formed by at least the optical system. Additionally, the method includes processing at least information associated with the first plurality of images, and determining a first auxiliary function based upon at least the information associated with the first plurality of images. The first auxiliary function represents a first aberration of the optical system. Moreover, the method includes adjusting the optical system based upon at least information associated with the first auxiliary function.

Abstract: Phase differences associated with a defocused wavefront can be determined from a single color image. The color image, which is a measurement of intensity as a function of wavelength, is used to calculate the change in intensity with respect to wavelength over the image plane. The change in intensity can then be used to estimate a phase difference associated with the defocused wavefront using two-dimensional fast Fourier transform solvers. The phase difference can be used to infer information about objects in the path of the defocused wavefront. For example, it can be used to determine an object's shape, surface profile, or refractive index profile. It can also be used to calculate path length differences for actuating adaptive optical systems. Compared to other techniques, deriving phase from defocused color images is faster, simpler, and can be implemented using standard color filters.

Abstract: A measurement displacement system and method are described. The measurement displacement system comprises a sensor head configured to transmit input optical beams and to receive measurement beams. The system comprises a transmission grating configured to diffract the input optical beams into sub-beams comprising more than one diffraction order. The transmission grating is adapted move in a direction. The measurement displacement system comprises a reflective element configured to diffract the sub-beams from the transmission grating and to return the sub-beams to the transmission grating. The reflective element is substantially stationary relative to the sensor head and the transmission grating selectively recombines the sub-beams to form the measurement beams and returns the measurement beams to the sensor head.

Abstract: High-resolution, common-path interferometric imaging systems and methods are described, wherein a light source generates and directs light toward a sample. An optical imaging system collects the resultant substantially scattered component and substantially unscattered component. A variable phase shifting system is used to adjust the relative phase of the scattered and unscattered light components. The interfered components are sensed by an image sensing system. The process is repeated multiple times with different phase shifts to form corresponding multiple electronic signals representative of raw sample images. The raw sample images are then processed by a signal processor to form a processed image, where each image pixel has an amplitude and a phase. This picture can be displayed directly using some combination of brightness and color to represent amplitude and phase.

Abstract: A differential interference contrast (DIC) determination device and method utilizes an illumination source, a layer having a pair of two apertures that receive illumination from the illumination source, and a photodetector to receive Young's interference from the illumination passing through the pair of two apertures. In addition, a surface wave assisted optofluidic microscope and method utilize an illumination source, a fluid channel having a layer with at least one aperture as a surface, and a photodetector that receives a signal based on the illumination passing through the aperture. The layer is corrugated (e.g., via fabrication) and parameters of the corrugation optimize the signal received on the photodetector.

Abstract: The present invention provides a method including measuring a wavefront aberration of the optical system to be measured on a measurement surface, measuring a pupil transmittance distribution of the optical system determining a pupil function of the optical system based on the wavefront aberration and the pupil transmittance distribution, and performing imaging computation using the pupil function to obtain a light intensity distribution formed on an image plane of the optical system, and calculating a flare, generated in the optical system, from the light intensity distribution.

Abstract: A Micro Electro-Mechanical System (MEMS) spectrometer architecture compensates for verticality and dispersion problems using balancing interfaces. A MEMS spectrometer/interferometer includes a beam splitter formed on a first surface of a first medium at an interface between the first medium and a second medium, a first mirror formed on a second surface of the first medium, a second mirror formed on a third surface of the first medium and balancing interfaces designed to minimize both a difference in tilt angles between the surfaces and a difference in phase errors between beams reflected from the first and second mirrors.

Abstract: A reflective metrological scale has a metal tape substrate and a scale pattern of elongated side-by-side marks surrounded by reflective surface areas of the substrate. Each mark has a furrowed cross section and may have a depth in the range of 0.5 to 2 microns. The central region of each mark may be rippled and darkened to provide an enhanced optical reflection ratio with respect to surrounding surface areas. A manufacturing method includes the repeated steps of (1) creating a scale mark by irradiating the substrate surface at a mark location with overlapped pulses from a laser, each pulse having an energy density of less than about 1 joule per cm2, and (2) changing the relative position of the laser and the substrate by a displacement amount defining a next mark location on the substrate at which a next mark of the scale is to be created.

Abstract: A multi-directional projection type moiré interferometer includes a stage, an image formation part, rotating mirrors, fixed mirrors, and a pattern illumination generating part. The stage moves a target object. The image formation part is provided above the stage to take a pattern image reflected from the target object placed on the stage. The rotating mirrors are vertically arranged and inclined at an angle different from each other to receive a pattern illumination, change the optical path of the pattern illumination, and emit the pattern illumination. The fixed mirrors emit the pattern illumination, emitted from the rotating mirrors, toward the target object. The pattern illumination generating part emits the pattern illumination toward the rotating mirrors. The pattern illumination generating part includes a grating board, and grating elements are formed at the grating board to emit the pattern illumination toward the rotating mirrors.

Abstract: Methods include simultaneously diffracting a beam in a first direction and a second direction orthogonal to the first direction to form a once-diffracted beam, where the beam comprises a wavefront shaped by a test object, simultaneously diffracting the once-diffracted beam in orthogonal directions to form a twice-diffracted beam, overlapping at least two orders of the twice-diffracted beam in each direction to form an interference pattern at a detector, the interference pattern being formed by multiple copies of the wavefront laterally sheared in the first direction and multiple copies of the wavefront laterally sheared in the second direction; and determining information about the wavefront based on the interference pattern.

Abstract: An arrangement for generating phase-shifted incremental signals characterizing relative positions of two objects moving with respect to each other along a measuring direction. The measuring arrangement includes a light source emitting bundles of beams, a measurement grating, a plurality of optional gratings and a scanning unit. The scanning unit includes a grating in a scanning plane, wherein the grating includes a plurality of blocks arranged periodically along the measuring direction with a grating periodicity equaling a fringe pattern periodicity, and each block includes n grating sections arranged along the measuring direction, each of the n grating sections having a periodic grating structure, deflecting the bundles of beams propagated through each of the n grating sections in several different spatial directions.

Abstract: The method comprises positioning a diffraction grating with a two-dimensional meshing on the path of the beam to be analyzed and processing at least two interferograms of at least two different colors, each interferogram being obtained in a plane from two sub-beams with different diffraction orders. The invention can be used to analyze and correct divided wavefronts.

Abstract: A method of imaging at least a part of an object. The method comprises splitting electro-magnetic radiation to first and second portions, propagating the first and second portions, spectrally dispersing the first portion toward the part and the second portion toward a reference element, combining between reflections of the spectrally dispersed first and second portions to produce an interference signal, capturing an image of the part from the interference, and adjusting at least one of a tilt of said image plane and a curvature of the image by changing a deviation between the phase of at least one spectral component of the first portion and the phase of at least one spectral component of the second portion.

Abstract: A non-periodic reflection beamsplitter or reflector for use in an interferometer. The interferometer employs non-periodic reflectors or a non-periodic beamsplitter in order to produce interference patterns to analyze. The non-periodic reflectors or beamsplitters may be concentrically arranged reflectors having equal area. The beamsplitter consists of two adjacent non-periodic structures having complementary reflection and transmission patterns.

Abstract: An approach to challenging the absolute nature attributed to the Heisenberg uncertainty principal in the context of data obtained from a double slit system, wherein the double slit system is applied at least once with a multiplicity of photons or particles to produce a reference interference pattern on a first screen, and applied a second time to determine where a single photon or particle impacts a second screen. Comparison of projections from each slit through the point of impact of the single photon or particle on the second screen, to the reference interference pattern on the first screen, provides insight to which slit the single photon or particle passed.

Abstract: Methods and apparatus (1100) for trapping fluid-borne object(s) (212) using one or more Fresnel zone plates (202) located in proximity to a fluid medium (208). Optical tweezers based on one or more Fresnel zone plates may be integrated with a microfluidic structure (e.g., chambers, channels) (1104) of various geometries so as to form one or more optical traps (215) within a fluid medium contained by the microfluidic structure(s). Three-dimensional trapping of objects can be obtained with stiffness comparable to that of conventional optical tweezers based on a microscope objective. In one example, a single Fresnel zone plate is particularly configured to form multiple optical traps upon irradiation, so as to trap multiple objects simultaneously. Exemplary applications of the methods and apparatus disclosed herein include determination of various fluid medium properties (e.g., velocity, refractive index, viscosity, temperature, pH) and object sorting.

Abstract: A method and a system for analyzing the wavefront of a light beam, wherein a diffraction grating is arranged in a plane perpendicular to the light beam to be analyzed and optically conjugated to the analysis plane. Different emerging beams of the grating interfere to generate an image having deformations linked to the gradients of the wavefront to be analyzed. The method is characterized in that the grating carries out the multiplication of an intensity function which is implemented by a two-dimensional grating with hexagonal meshing of surface S transmitting the light of the beam to be analyzed into plural emerging beams arranged in a hexagonal meshing, by an phase function which is implemented by a two-dimensional grating with hexagonal meshing of surface 3S which introduces a phase shift close to 2?/3 (modulo 2?) between two adjacent secondary beams.

Abstract: An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

Abstract: A Talbot interferometer includes a diffraction grating, an image pickup device, a moving unit configured to move at least one of the diffraction grating and the image pickup device in an optical axis direction of the test object, and a computer configured to adjust a position of the at least one of the diffraction grating and the image pickup device using the moving unit so that a Talbot condition can be met, based on a spatial frequency spectrum obtained from a plurality of interference fringes captured by the image pickup device while moving the at least one of the diffraction grating and the image pickup device using the moving unit.

Abstract: A sensor platform for use in sample analysis comprises a substrate (30) of refractive index (n1) and a thin, optically transparent layer (32) of refractive index (n2) on the substrate, (n2) is greater than (n1). The platform incorporates one or multiple corrugated structures in the form of periodic grooves (31), (33), which defines one or more sensing areas each for one or more capture elements. The grooves are so profiled, dimensioned and oriented that when coherent light is incident on the platform it is diffracted into individual beams or diffraction order resulting in reduction of the transmitted beam and an abnormal high reflection of the incident light thereby creates an enhanced evanescent field at the surface of the or each sensing area. The amplitude of this field at the resonant condition is greater by an order of approximately 100 than the field of prior art platforms so that the luminescence intensity created from samples on the platform is also increased by a factor of 100.

Abstract: A probe is presented that includes a light source, a coherent fiber bundle, and a pattern selector. The pattern selector is disposed between the light source and the proximal end of the coherent fiber bundle. The pattern selector includes at least one patterned zone through which light from the light source passes to project at least one fringe set onto a surface. Each of the at least one fringe sets has a structured-light pattern. The probe further includes an imager for obtaining at least one image of the surface and a processing unit that is configured to perform phase-shift analysis on the at least one image. A method for projecting a plurality of fringe sets suitable for phase-shift analysis on a surface using a probe is presented.

Abstract: A transmitted wavefront measuring method comprises the steps of emitting light 101 from a light source 100 onto an object to be measured 120 to receive interfering light transmitted through the object and a diffraction grating 130 on a light receiving portion 140 disposed at a predetermined distance from the diffraction grating to measure an intensity distribution of the interfering light T10, performing a Fourier transform of the intensity distribution to calculate a frequency distribution T20, and obtaining a transmitted wavefront of the object based on a primary frequency spectrum in the frequency distribution T30 to T90. The step of obtaining the transmitted wavefront comprises the steps of performing an inverse Fourier transform of the primary frequency spectrum with reference to a grating frequency of the diffraction grating to calculate a complex amplitude of the interfering light T60, and obtaining the transmitted wavefront based on the complex amplitude T90.

Abstract: A method of applying a double slit system to the end that both knowledge of an interference pattern formed on a screen located at one distance from the slits, and knowledge of improved probability as to which slit a particular particle or photon passed in the act of forming said interference pattern on that screen, wherein the method uses a remormalization interference pattern preliminarily provided on a screen located at a different distance from the slits, as a reference.

Abstract: Disclosed is a Rotation sensor with a light source, a light detector, an internal part having a first lateral surface, which is globally cylindrical and convex, and an external part having a second lateral surface which is globally cylindrical and concave. The first and second lateral surfaces both have a same central axis defining a rotation axis for a relative rotation between the internal part and the external part the angle of which this rotation sensor can measure. A first grating is arranged at the first lateral surface with its grating lines parallel to the rotation axis, and a second grating is arranged at the second lateral surface with its grating lines parallel to said rotation axis.

Abstract: Characterization of an optical system is quickly and easily obtained in a single acquisition step by obtaining image data within a volume of image space. A reticle and image plane are positioned obliquely with respect to each other such that a reticle having a plurality of feature sets thereon, including periodic patterns or gratings, is imaged in a volume of space, including the depth of focus. Metrology tools are used to analyze the detected or recorded image in the volume of space through the depth of focus in a single step or exposure to determine the imaging characteristics of an optical system. Focus, field curvature, astigmatism, spherical, coma, and/or focal plane deviations can be determined. The present invention is particularly applicable to semiconductor manufacturing and photolithographic techniques used therein, and is able to quickly characterize an optical system in a single exposure with dramatically increased data quality and continuous coverage of the full parameter space.

Abstract: The present disclosure relates to an improved device and methods for adapting to a laser diffraction apparatus used for measuring particle size distribution and density of the plume of a powder composition emitted from a dry powder inhaler.

Abstract: The invention relates to a device (10, 20) for detecting a phase difference between two light beams (8A, 8B), said device including: a diffraction grating (2) which can generate an interference field between the two light beams; and a photodiode (1,5) which is arranged to receive the interference field, said diffraction grating being integrated into the photodiode. The invention is characterized in that the diffraction grating is an amplitude grating (2).

Abstract: A measurement apparatus comprises: a light source; a first optical system configured to reflect a certain component of a light beam emitted by the light source by a final surface thereof and transmit a remaining component of the light beam; a reflecting surface configured to reflect the remaining component; an optical member configured to generate a first shearing interference fringe formed by the certain component, and a second shearing interference fringe formed by the remaining component; an image sensing unit configured to simultaneously sense the first and second shearing interference fringes generated by the optical member; and an arithmetic unit configured to calculate, a wavefront aberration of the first optical system and a wavefront aberration of the first optical system and an optical system to be measured, using data on the first and second shearing interference fringes, thereby calculating a wavefront aberration of the optical system to be measured.

Abstract: An apparatus and method to determine a property of a substrate by measuring, in the pupil plane of a high numerical aperture lens, an angle-resolved spectrum as a result of radiation being reflected off the substrate. The property may be angle and wavelength dependent and may include the intensity of TM- and TE-polarized light and their relative phase difference.

Abstract: Electromagnetic illumination radiation is produced and provided as an input wave. The input wave passes through a diffractive optical element and leaves as an incoming measuring wave, the wave front of the input wave being transformed such that the wave front of the incoming measuring wave is adapted to the desired shape of the effective reflection surface. Furthermore, the test object is disposed in a test position in which the incoming measuring wave is reflected back to the diffractive optical element as a reflected measuring wave, the reflected measuring wave passing through the diffractive optical element and leaving as an outgoing measuring wave, the propagation direction of the outgoing measuring wave being deviated in relation to the opposite propagation direction of the input wave. A reference wave branched off from the illumination radiation interferes with the outgoing measuring wave this interference being recorded by detector.

Abstract: A method for measuring the heights of patterns of an object, including: a light emission, the light includes a propagation mode of interest for at least one wavelength of interest, an illumination of the surface of the object by the light, a reflection of the light by the surface of the object, a collection of the reflected light, a division of the wavefront of the reflected light into division components, by at least one pattern of the illuminated surface, a filtering of the collected light, including a modal filtering removing all modes other than the propagation mode of interest, for the wavelengths of interest, and from the filtered light, and for the wavelengths of interest, an extraction of information about phase differences between the division components.

Abstract: A method for measuring the optical properties of multifocal ophthalmic lenses. Collimated light is passed through an ophthalmic lens and onto an array of lenslets. Light exiting the array of lenslets is detected by a sensor. Blurred spots and/or double spots may represent diffractive zones of the wavefront. A centroid of the spot or a brighter of two spots may be used to determine the lateral position of the spot. Theoretical calculations, laboratory measurements, clinical measurements and experimental image spots may be generated, compared and cross-checked to determine a monofocal equivalent lens. A Modulation Transfer Function (MTF) may be used to evaluate and compare a diffractive lens and a monofocal equivalent lens.

Abstract: A phase-difference sensor measures the spatially resolved difference in phase between orthogonally polarized reference and test wavefronts. The sensor is constructed as a linear-carrier phase-mask aligned to and imaged on a linear-carrier detector array. Each adjacent element of the phase-mask measures a predetermined relative phase shift between the orthogonally polarized reference and test beams. Thus, multiple phase-shifted interferograms can be synthesized at the same time by combining pixels with identical phase-shifts. The multiple phase-shifted interferograms can be combined to calculate standard parameters such as modulation index or average phase step. Any configuration of interferometer that produces orthogonally polarized reference and object beams may be combined with the phase-difference sensor of the invention to provide single-shot, simultaneous phase-shifting measurements.

Abstract: An improved condition testing system and method includes a structure including a semiconductor material with a target portion and a second portion. The target portion has a first feature when at least one of the following occurs: an external force is received by the second portion of the structure and an internal condition occurs in the target portion. The system and method further has a interferogram shaped and located to produce a first optical interference pattern when the target portion and the interferogram are exposed to non-invasive illumination and when the target portion has the first feature. Further implementations use a second test interferogram spaced apart from the first test interferogram.

Abstract: A differential interference contrast (DIC) determination device and method utilizes an illumination source, a layer having a pair of two apertures that receive illumination from the illumination source, and a photodetector to receive Young's interference from the illumination passing through the pair of two apertures. In addition, a surface plasmon assisted optofluidic microscope and method utilize an illumination source, a fluid channel having a layer with at least one aperture as a surface, and a photodetector that receives a signal based on the illumination passing through the aperture. The layer is corrugated (e.g., via fabrication) and parameters of the corrugation optimize the signal received on the photodetector.

Abstract: A measuring system for the optical measurement of an optical imaging system, which is provided to image a pattern arranged in an object surface of the imaging system in an image surface of the imaging system, comprises an object-side structure carrier having an object-side measuring structure, to be arranged on the object side of the imaging system; an image-side structure carrier having an image-side measuring structure, to be arranged on the image side of the imaging system; the object-side measuring structure and the image-side measuring structure being matched to each other in such a way that, when the object-side measuring structure is imaged onto the image-side measuring structure with the aid of the imaging system, a superposition pattern is produced; and a detector for the locally resolving acquisition of the superposition pattern. The imaging system is designed as an immersion system for imaging with the aid of an immersion liquid.

Abstract: A wavefront-aberration-measuring device measures wavefront aberration of a to-be-tested optical system and includes a diffraction grating that splits light transmitted through the optical system, a detecting unit that detects interference fringes produced by beams of the split light, an arithmetic unit that calculates the wavefront aberration from the detected interference fringes, an image-side mask insertable into and retractable from an image plane of the optical system, and an illuminating unit that incoherently illuminates the image-side mask. The image-side mask has an aperture with a diameter larger than ?/2NA, where ? denotes a wavelength of the illuminating unit and NA denotes a numerical aperture of the to-be-tested optical system. The arithmetic unit calculates the wavefront aberration of the optical system from the interference fringes detected with the image-side mask being retracted from the image plane and the interference fringes detected with the image-side mask being in the image plane.

Abstract: Described is a multiple channel interferometric surface contour measurement system. The measurement system includes a multiple channel interferometer projector, a digital camera and a processor. The projector includes two or more interferometer channels. Each channel has an optical axis spatially separate from the optical axes of the other channels. Each channel projects a fringe pattern onto the surface of an object to be measured. Image data for the fringe patterns projected on the object surface are acquired by the digital camera. The processor controls the projection of the fringe patterns of different spatial frequencies, adjusts the phase of each fringe pattern and generates surface contour data in response to the camera image data. The multiple channel interferometric surface contour measurement system provides numerous advantages over conventional single channel interferometric systems, including reduced sensitivity to optical noise, improved stability and increased measurement accuracy.

Abstract: Optical rotation counter associated with a rotary disc of an angle sensor provided with means for coding the angular position of the disc, including at least one fixed source of coherent light emitting a light beam, a diaphragm and a support moved by the rotation of the coding disc. On its face facing the incident beam, the support includes at least one cell for coding its displacement orientated in the direction of the said displacement and generates an optical code by interference with the incident light beam, the said optical code being readable after interference on at least one photodetector.

Abstract: A wavefront aberration measuring apparatus which measures an wavefront aberration of an optical system to be inspected includes a point light source which supplies a measuring light; a photodetector which has a detection surface arranged at a position optically conjugate with the point light source; a wavefront change applying section which is arranged in an optical path between the point light source and the photodetector and which applies a wavefront change to the light outcome from the optical system; and a measuring section which measures the wavefront aberration of the optical system based on an output of the photodetector and the wavefront change applied by the wavefront change applying section. It is possible to measure the wavefront aberration of the optical system with a relatively simple construction, without using the interference method.

Abstract: Methods include simultaneously diffracting a beam in a first direction and a second direction orthogonal to the first direction to form a once-diffracted beam, where the beam comprises a wavefront shaped by a test object, simultaneously diffracting the once-diffracted beam in orthogonal directions to form a twice-diffracted beam, overlapping at least two orders of the twice-diffracted beam in each direction to form an interference pattern at a detector, the interference pattern being formed by multiple copies of the wavefront laterally sheared in the first direction and multiple copies of the wavefront laterally sheared in the second direction; and determining information about the wavefront based on the interference pattern.

Abstract: An improved condition testing system and method includes a structure including a semiconductor material with a target portion and a second portion. The target portion has a first feature when at least one of the following occurs: an external force is received by the second portion of the structure and an internal condition occurs in the target portion. The system and method further has a grating shaped and located to produce a first optical interference pattern when the target portion and the grating are exposed to non-invasive illumination and when the target portion has the first feature. Further implementations use a second grating spaced apart from the first grating.

Abstract: Diffraction grating based fiber optic interferometric systems for use in optical coherence tomography, wherein sample and reference light beams are formed by a first beam splitter and the sample light beam received from a sample and a reference light beam are combined on a second beam splitter. In one embodiment, the first beam splitter is an approximately 50/50 beam splitter, and the second beam splitter is a non 50/50 beam splitter. More than half of the energy of the sample light beam is directed into the combined beam and less than half of the energy of the reference light beam are directed into the combined beam by the second beam splitter. In another embodiment, the first beam splitter is a non 50/50 beam splitter and the second beam splitter is an approximately 50/50 beam splitter. An optical circulator is provided to enable the sample light beam to bypass the first beam splitter after interaction with a sample.

Abstract: A method for measuring a saturated photorefractive index and a recording time constant to correct the precision includes measuring the diffraction efficiency as a function of time for both phase matching and phase mismatching. The saturated photorefractive index and the recording time constant are verified by substitution into a theoretical formula derived from the Coupled Wave Theory. Thus, the method allows a precise determination of the dynamic range of volume holographic memories and thus their storage capacities. The same procedure can also apply to photopolymers.

Abstract: A measuring device configured to measure a wave aberration of an optical system to be measured includes a reflection optical element for reflecting light, having passed through a mask and the optical system to be measured, into the optical system to be measured, and a detector for detecting an interference fringe of light having passed through pinholes and openings. The mask has at least three pinhole-opening pairs, each including one pinhole and one opening having a larger diameter than the pinhole that are arranged point-symmetrically, the three pinhole-opening pairs having the common center of symmetry. The light to be measured formed in two of the three pairs is made to interfere with the reference light formed in the remaining pair, or, the light to be measured formed in one of the three pairs is made to interfere with the reference light formed in the other two pairs.

Abstract: A wavelength shift measuring apparatus of the present invention is a wavelength shift detection sensor (WLCD1) which measures a shift of a wavelength of a light beam emitted from a light source, and includes a beam splitter (BS2) splitting the light beam emitted from the light source into a plurality of light beams and to synthesize two light beams among the plurality of light beams to generate an interference light, a spacer member (SP) provided so that an optical path length difference of the two light beams split by the beam splitter (PBS2) is constant, and a plurality of photoelectric sensors (PD) detecting the interference light generated by the beam splitter (BS2). The plurality of photoelectric sensors (PD) output a plurality of interference signals having phases shifted from one another based on the interference light to calculate a wavelength shift using the plurality of interference signals.