Abstract: A heterodyne two-dimensional grating measuring device and measuring method thereof includes a light source, a reading head, a photoelectric receiving module, and a processor. The light source is configured to generate two beams of linearly polarized light having characteristics of overlapping, polarization orthogonal, and fixed frequency difference. The reading head is configured to receive the two beams of the linearly polarized light, the two beams of the linearly polarized light are respectively incident on a surface of a moving two-dimensional measuring grating to generate ±1-order diffracted lights of two dimensions, and the ±1-order diffracted lights are respectively incident to the photoelectric receiving module through the reading head.

Abstract: A heterodyne one-dimensional grating measuring device and measuring method thereof, including a light source, a reading head, a photoelectric receiving module, and a signal processing system. The light source is configured to generate two linearly polarized lights having characteristics of overlapping, polarization orthogonal, and fixed frequency difference. The reading head is configured to receive two beams of polarized lights and be respectively incident on a surface of a moving measuring grating to generate a +1-order diffracted light and a ?1-order diffracted light. The photoelectric receiving module is configured to receive the +1-order diffracted light and the ?1-order diffracted light to form two paths of beat frequency signals. The signal processing system is configured to perform differential calculation on the two paths of the beat frequency signals to realize a displacement measurement of single diffraction of the measuring grating for four-fold optical subdivision.

Abstract: An interferometer has a first input configured to provide a first measurement beam at a first frequency, and a second measurement signal at the first frequency. The interferometer has a second input configured to provide a reference beam at a second frequency that is different than the first frequency; an optical element comprising a first portion comprising a polarization beam splitter; and a diffraction grating disposed over the optical element configured to diffract the first measurement beam and the second measurement beam.

Abstract: A lithographic method for measuring a position of a target grating with a mask sensor apparatus which comprises a plurality of detector modules each comprising a diffraction grating located at a mask side of a projection system of a lithographic apparatus and an associated detector, the method comprising a first step of measuring first intensities of a combination of diffraction orders diffracted from the target grating while the mask sensor apparatus is moved relatively to the target grating along a first direction; a second step of displacing the mask sensor apparatus relative to the target grating in a second direction, wherein a size of the relative displacement is proportional to a spatial frequency of a potential error; and a third step of measuring second intensities of the combination of diffraction orders diffracted from the target grating while the mask sensor apparatus is moved relatively to the target grating along the first direction.

Abstract: A method, involving illuminating at least a first periodic structure of a metrology target with a first radiation beam having a first polarization, illuminating at least a second periodic structure of the metrology target with a second radiation beam having a second different polarization, combining radiation diffracted from the first periodic structure with radiation diffracted from the second periodic structure to cause interference, detecting the combined radiation using a detector, and determining a parameter of interest from the detected combined radiation.

Abstract: A number of variations may include a cable movement detector for determining a movement of a cable. A light source may be directed at the cable. A light detector may receive a reflection of the light source from the cable.

Abstract: Provided is a chromatic confocal sensor including: a light source section that emits a plurality of light beams having different wavelengths; an optical head that includes an objective lens that converges the plurality of light beams at different focal positions and selects, as measurement light, light reflected by an object to be measured at the focal position out of the plurality of light beams; a spectroscope including diffraction gratings that split the selected measurement light into a plurality of diffracted light beams and a sensor that receives two or more of the plurality of diffracted light beams; and a signal processing/control section that calculates a position of the object to be measured based on a difference between light reception positions of the two or more diffracted light beams received by the sensor.

Abstract: A displacement measurement system comprising at least one retro reflector and a diffraction grating. Said displacement measurement system is constructed and arranged to measure a displacement by providing a first beam of radiation to the measurement system, wherein the diffraction grating is arranged to diffract the first beam of radiation a first time to form diffracted beams. The at least one retro reflector is arranged to subsequently redirect the diffracted beams to diffract a second time on the diffraction grating. The at least one retro reflector is arranged to redirect the diffraction beams to diffract at least a third time on the diffraction grating before the diffracted beams are being recombined to form a second beam. And the displacement system is provided with a sensor configured to receive the second beam and determine the displacement from an intensity of the second beam.

Abstract: A displacement detecting device includes an irradiation optical system, an interference optical system, a light-receiving section, and a displacement detecting section. The irradiation optical system causes two light-beams to be incident on a diffraction grating respectively at different angles with respect to a plane perpendicular to the X-direction along which grating structures of the diffraction grating are periodically arranged. The interference optical system causes two Mth-order diffracted lights of respective light-beams incident on the diffraction grating to interfere with each other, so as to generate an interference light. The light-receiving section receives the interference light and detects an interference signal. The displacement detecting section detects a vertical displacement of a surface having the diffraction grating arranged thereon based on the change of the interference signal.

Abstract: A method for displaying the movement state of a memory card slot is disclosed. Detection is performed to determine whether a slot button has been touched for activating. A light intensity signal is received and transformed into an electrical signal when the slot button has been activated, in which the light intensity signal represents the movement of the memory card slot. Next, the electrical signal is processed through a processor for deriving a position of the memory card slot, and the movement state is displayed according to the position of the memory card slot.

Abstract: Fringe patterns at first and second spatial frequencies are projected onto a work piece surface and a reference surface, respectively. An image of the projected fringe patterns is obtained and a measurement signal associated with work piece displacements and a reference signal are obtained based on the first and second spatial frequencies. The image of the projected fringe patterns can exhibit substantial or complete overlap of the fringe patterns at the first and second spatial frequencies, and the overlapping patterns can be separated based on the spatial frequencies. Fringe pattern shifts at one or both of the first and second spatial frequencies can be used to adjust a pattern transfer system to permit accurate pattern transfer.

Abstract: An encoder interferometry system includes an interferometer positioned to receive first and second beams having different frequencies, in which the interferometer has at least one polarizing beam splitting element for directing the first beam along a measurement path to define a measurement beam and the second beam along a reference path to define a reference beam. The encoder interferometry system further includes a encoder scale positioned to diffract the measurement beam at least once, a detector positioned to receive the measurement and reference beams after the measurement beam diffracts from the encoder scale, and an output component positioned to receive the measurement and reference beams before they reach the detector and deflect spurious portions of the first and second beam away from the detector.

Abstract: An optical encoder includes a light source 10, a scale 20 disposed so as to face the light source, a light receiving element 31 configured to receive luminous flux from the light source through the scale, and a signal processing circuit 39 configured to process an output signal of the light receiving element. A light emitting window 11 of the light source is constituted of a collection of a plurality of point light sources and has a shape which meets a predetermined expression.

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: A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase.

Abstract: A method of detecting the velocity of a moving object comprising the steps of: passing a beam of coherent light through an optical mask having a pattern of alternating opaque and non-opaque regions formed thereon, whereby an image of alternating light and dark fringes is projected along the length of the light beam; causing the moving object to pass through the projected image such that a portion of the light beam is reflected from the moving object as a series of pulses; detecting the reflected light pulses and the frequency of the pulses; and calculating the velocity of the object as a function of the pulse frequency and the known separation of the fringes of the image.

Abstract: A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase.

Abstract: A displacement measurement system configured to provide measurement of the relative displacement of two components in six degrees of freedom with improved consistency and without requiring excessive space.

Abstract: The invention relates to a system (1) for detecting a translation (T) of a body (2) with a diffraction pattern (3) applied to said body. The system comprises means (4) for providing an incident light beam (I) to said diffraction pattern and to obtain a diffracted light beam (D) from said diffraction pattern; means (4) for measuring a phase difference by interference between said incident light beam and said diffracted beam an means (4) for detecting said translation on the basis of said measured phase difference. The invention further relates to a method for detecting a translation of a body (2); a redirection arrangement 6 and a frequency multiplexing system.

Abstract: A measuring instrument, in particular for transmission measurement with transparent substrates, comprises a measuring head with a light emitting element for emitting a light beam and a light receiver element for recording an incident light beam, and a retro-reflector for reflection of the emitted light beam. The measuring instrument allows transmission measurements to be carried out on transparent substrates with only one reflection measuring head. The measuring instrument also allows reflection measurements to be carried out, for example on non-transparent substrates or by tilting the measuring head and covering the retro-reflector. The measuring instrument only requires one measuring head and can therefore be produced more cost-effectively. It does not require calibration, as the retro-reflector also reflects the light in the original direction in the case of oblique incidence and in the event of positional changes caused by process or operational factors (vibrations etc.).

Abstract: A position measuring arrangement for determining a relative position between a first object and a second object. The arrangement includes a light source having a single-mode laser light source that generates radiation and a signal generator that receives the radiation and generates displacement-dependent output signals that determine a relative position between a first object and a second object. A feedback device, wherein the laser light source interacts with the feedback device in such a way that an excitation of several modes takes place in the single-mode laser light source, and a multi-mode operation of the single-mode laser light source results.

Abstract: A diffraction laser encoder apparatus for positional and movement information measurement of a target made with a diffraction grating. The diffraction laser encoder has a laser light source for generating a source beam. A polarization beam splitter assembly comprises a polarization beam splitter for receiving the source beam for splitting a P-polarization component and an S-polarization component of the source beam into parallel and offset beams. A focusing lens focuses the P-polarization component and the S-polarization component beams onto the target diffraction grating and returning diffracted P-polarization and diffracted S-polarization beams back into the polarization beam splitter for generating a detector beam coaxially containing the diffracted P-polarization and the diffracted S-polarization beams. A detector assembly receives the detector beam for electrical processing and analysis for resolving the positional and movement information.

Abstract: An adaptive optics system configured as an optical phase front measurement system which provides for relatively high resolution sampling as in holographic techniques but without the need for a reference beam. The optical phase front measurement system includes one or more lenses and a spatial light modulator positioned at the focal plane of the lenses and a camera which enables the phase front to be determined from intensity snapshots. The phase front measurement system allows for relatively long range applications with relatively relaxed criteria for the coherence length of the laser beam and the Doppler shift. As such, the system is suitable for a wide variety of applications including astronomy, long range imaging, imaging through a turbulent medium, space communications, distant target illumination and laser pointing stabilization.

Abstract: A light wave measuring instrument has a small optical system. Beams from a laser light source illuminate a grating scale and plus-first-order-diffracted and minusfirst-order-diffracted and minus-first-order-diffracted beams from the grating scale are diffracted and reflected so as to travel through their original optical paths. The beams are returned to a non-polarization beam splitter, transmitted through a quarter wavelength plate and converted into one straight polarized beam having a polarization direction varying with the phase difference between the two beams. The straight beam is then separated. The separate beams are separated into P and S polarized beams. The S polarized beams are reflected by a polarization film, while the P polarized beams are reflected by a parallel glass plate. These beams are transmitted through the polarization film again to become coherence signal beams having reverse phases of fringes, which are then emitted in the same direction.

Abstract: A lithography system for exposing a photosensitive member includes a photosensitive member placement unit, and an interference optical system. The interference optical system produces interference fringes on the photosensitive member so that the interference fringes will be transferred to the photosensitive member. The interference fringes are aligned based on detected light that has passed through the interference optical system.

Abstract: The invention features methods and systems for optical correlation of ultrashort optical waveforms, e.g., pulses. The optical waveform passes through a diffractive optic, e.g., a mask or grating, to generate multiple sub-beams corresponding to different diffractive orders. At least two of the sub-beams are then imaged onto the sample to produce a desired crossing pattern. To perform the correlation, the diffracted sub-beams are variably delayed relative to one another prior to overlapping on the sample. The sample generates a signal beam in response to the overlapping sub-beams, the signal beam providing a correlation between the sub-beams for each of the variable delays.