Abstract: This invention provides a phase detector with more than two detector units on a printed circuit layer. A detector set includes a pair of detector units or one detector unit, and a detector row includes a plurality of detector sets in one line. The phase detector includes a plurality of detector rows and each row has a detector set in one period, wherein all detector units are interleaved to have the same interval between any two adjacent detector units, which is defined as a pitch and the pitch is equal to one period dividing the detector pair number, which is the half sum of the number of one detector set for all rows.

Abstract: A patterning device, including alignment targets having alignment features formed from a plurality of diffractive elements, each diffractive element including an absorber stack and a multi-layered reflector stack is provided. The diffractive elements are configured to enhance a pre-determined diffraction order used for pre-alignment and to diffract light in a pre-determined direction of a pre-alignment system when illuminated with light of a wavelength used for the pre-alignment. The diffractive elements may occupy at least half of an area of each alignment feature. The diffractive elements may be configured to enhance first or higher order diffractions, while substantially reducing zeroth diffraction orders and specular reflection when illuminated with a wavelength used for reticle prealignment. The dimensions of each diffractive element may be a function of a diffraction grating period of each alignment feature.

Abstract: A motor may be configured to drive a drive shaft and an engagement member supported on the drive shaft. A detectable feature comprising a rotary member may be supported on the drive shaft such that movement of the drive shaft by the motor changes a state of the detectable feature. At least one sensor may be arranged to detect the state of the detectable feature. Circuitry may be configured to provide a signal in response to a change in the state of the detectable feature detected by the at least one sensor.

Abstract: A photoelectric encoder includes a scale; a detector; alight application section; a pair of origin signal reception sections; and a signal processing section adapted to provide the maximum value of the signal level output from the origin signal reception sections by side lobe light occurring as reflected on the origin mark as a stipulated value, provide an effective area of origin detection between the first position at which output of one of the origin signal reception sections for outputting a larger signal level than the stipulated value earlier than the relative displacement becomes a larger signal level than the stipulated value and the first position at which output of the other origin signal reception section exceeds the stipulated value and then becomes a smaller signal level than the stipulated value, and configured to generate the origin detection signal in the effective area.

Abstract: On the +X and ?X sides of a projection unit, a plurality of Y heads are arranged in parallel to the X-axis by a distance half or less than half the effective width of the scale, so that two heads each constantly form a pair and face a pair of Y scales. Similarly, on the +Y and ?Y sides of the projection unit, a plurality of X heads are arranged in parallel to the Y-axis by the distance, so that two heads each constantly form a pair and face a pair of X scales. Of the pair of heads consisting of two heads which simultaneously face the scaler measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to dust and the like adhering on the scale surface, measurement values of the other head is used. By using the two pairs of Y heads and the pair of X heads, a position of a stage within a two-dimensional plane is measured in a stable manner and with high precision.

Abstract: A method for detecting the position of a conveyor, comprising the steps of: providing on the conveyor belt an irregular marking, constituted by marks and the like that are detectable optically; by means of a vision device, detecting portions of the marking at preset time intervals; comparing a detection performed by the vision device with a previously performed detection, in order to determine the extent and direction of the movement.

Abstract: An optical displacement detection apparatus includes a scale and a sensor head. The scale has a first and second pattern. The head includes a first photodetector that detects a beam through the first pattern and generates a first signal, and a second photodetector that detects the beam through the second pattern and generates a second signal. The first and second signals include a first component, and a second component that corresponds to an absolute displacement of the scale. The first pattern, the second pattern, the first photodetector, the second photodetector, and a beam source are disposed such that the detection of the first photodetector and the detection of the second photodetector are performed correlatively.

Abstract: An optical encoder comprising a set of light sources configured to emit light rays in a serial manner, an encoded scale configured to reflect at least a portion of the emitted light rays, and a photodetector, where the photodetector is configured to detect at least a portion of the reflected light rays and to generate signals based on the detected light rays for each of the light sources.

Abstract: A measurement device for determining an installation position for a fire sprinkler head is provided. The measurement device includes a body adapted for positioning across and proximate to the center of a tile grid cell. The measurement device also includes a light source mounted to the body. The light source is adapted to project a beam of light onto a surface positioned above the tile grid cell. When the measurement device is positioned across the tile grid cell, the light source is proximate to the center of the tile grid cell.

Abstract: An exemplary method involves, in a system comprising a tool that performs a task on a workpiece, a method for determining displacement of the workpiece relative to the tool. Respective displacements of loci of at least a region of the workpiece are mapped using a Goos-Hänchen-insensitive (GH-insensitive) displacement sensor to produce a first set of physical displacement data for the region. Also mapped are respective displacements, from the tool, of the loci using a GH sensitive sensor to produce a second set of optical displacement data for the region. Goodness of fit (GOF) is determined of the second set of data with the first set. According to the GOF, respective GH-correction (GHC) coefficients are determined for at least one locus of the region. When measuring displacement of the at least one locus in the region relative to the tool, the respective GHC coefficient is applied to the measured displacement to reduce an error that otherwise would be present in the measured displacement due to a GH effect.

Abstract: A position measuring device including a reflective scale and a scanning unit. The scanning unit includes a retroreflector and a signal unit wherein the signal unit includes a light source and a detector arrangement. The scanning unit and the signal unit are structurally separate from one another and are disposed in planes parallel to one another, and wherein the scanning unit is movable relative to the reflective scale in a measuring direction. The light source emits a beam that propagates freely in a direction to the scanning unit, wherein from the scanning unit along the direction to the signal unit a pair of interfering partial beams propagate freely and wherein between the signal unit and the scanning unit the partial beams propagate freely in a propagation direction that is oriented perpendicular to the planes.

Abstract: The invention provides a method for automatic calibration of slides and a method for automatic calibration of slide frames and a slide for performing the method. To this end, slide frames (4; 210) with at least one slide seat and slide (212a-212h; 300) are provided with a calibration marking (304). In particular the inventive slide (212a-212h; 300) includes a slide substrate (302) and a calibration marking (304), the calibration marking (304) being connected to the slide substrate (302).

Abstract: Movements of a lithographic apparatus include dynamic positioning errors on one or more axes which cause corresponding errors which can be measured in the applied pattern. A test method includes operating the apparatus several times while deliberately imposing a relatively large dynamic positioning error at different specific frequencies and axes. Variations in the error in the applied pattern are measured for different frequencies and amplitudes of the injected error across a frequency band of interest for a given axis or axes. Calculation using said measurements and knowledge of the frequencies injected allows analysis of dynamic positioning error variations in frequency bands correlated with each injected error frequency.

Abstract: A fine movement stage is driven by a controller, based on positional information of the fine movement stage in a measurement direction measured by a measurement system and correction information of a measurement error caused by a tilt of the fine movement stage included in the positional information. Accordingly, driving the fine movement stage with high precision becomes possible, which is not affected by a measurement error included in the positional information in a measurement direction of the measurement system that occurs due to a tilt of the fine movement stage.

Abstract: A method and device for calibrating a distance determining device for determining a distance between an optical system and an object. The method includes providing a detecting system having marking elements and a measuring camera. Using the distance determining device, a light structure is projected onto a carrier that provides a calibration pattern. The measuring camera detects the marking elements or the calibration pattern to determine the spatial position of the optical system. Coordinates of a calibration pattern in a coordinate system associated with the measuring camera are determined. An image of the calibration pattern and the light structure is created using a camera of the optical system. Coordinates of an image of a calibration pattern and the light structure in a coordinate system associated with the camera image plane are determined. The distance determining device is calibrated using the determined coordinates and the determined spatial position of the optical system.

Abstract: In an absolute position encoder, a multi-spectral light source illuminates a position on a topographic surface at an angle of incidence determined from a vector normal to the surface. A target on, and positionally-registered to, the topographic surface comprises a variable grating that diffracts the incident light to form a multi-spectral diffraction pattern in which the angular dispersion of the diffraction pattern varies with the absolute position of the incident light along the grating. A chromatically responsive sensor detects a narrow band of the diffraction pattern through an entrance aperture positioned at an angle of detection determined from the vector normal to the topographic surface and outputs a signal responsive to the change in the angular dispersion of the detected narrow band of the diffraction pattern. The source/sensor unit maintains (within an acceptable noise tolerance) its geometric relationship to the vector normal to the topographic surface at the position of illumination.

Abstract: A measuring device for detecting a relative position, the measuring device including a measurement graduation movable in at least one measurement direction and a scanning unit for determining a relative position of the measurement graduation with respect to the scanning unit. The scanning unit includes a light source, a scanning grating disposed on a first side of a transparent carrier element that is positioned in a scanning beam path and a detector arrangement. The scanning unit further includes an attenuation structure that adjusts a light intensity on the detector arrangement in a defined manner, wherein either 1) the attenuation structure is disposed on a second side, opposite the first side, of the transparent carrier element or 2) the attenuation structure has a permeability that varies as a function of location at least along one direction so that a light intensity which is uniform at least in that one direction results on the detector arrangement.

Abstract: A laser beam emitted by an encoder main body enters a wafer table via a PBS from the outside, and reaches a grating at a point that is located right under exposure area, and is diffracted by the grating. Then, by receiving interference light of a first polarized component that has returned from the grating and a second polarized component reflected by the PBS, positional information of the wafer table is measured. Accordingly, because the first polarized component, which has passed through PBS passes through the wafer table until it is synthesized with the second polarized component again, does not proceed through the atmosphere outside, position measurement of the wafer table can be performed with high precision without the measurement beam being affected by the fluctuation of the atmosphere around the wafer table.

Abstract: In a system for detecting the position of an object in relation to a reference system, the object is arranged so as to be movable in relation to the reference system along at least two orthogonal first and second main movement axes. To record the position of the object in relation to the reference system, a position measuring device includes at least two two-dimensional measuring standards situated along the first main movement axis, and four scanning units for an optical scanning of these measuring standards. In addition, at least four additional supplementary scanning units are provided, which are situated between the four scanning units along the first main movement axis.

Abstract: An encoder configuration comprises an illumination portion, a scale comprising a scale track, and a signal processing electronics. The signal processing electronics may include a detector comprising a first set of three detector sub-portions that provide a first set of signals comprising three respective sub-portion signal subsets that have nominally the same signal characteristics when the scale track is not contaminated or defective. The processing electronics analyze the first set of signals and identify a least-similar sub-portion signal subset that has a corresponding signal characteristic value that is least similar to comparable signal characteristic values associated with more-similar sub-portion signal subsets of the first set of signals. Position measurements are based on valid signals including a plurality of the more-similar sub-portion signal subsets and not including the least-similar sub-portion signal subset if it is significantly different.

Abstract: A method and apparatus for suppressing loss of scale image contrast due to interference effects from optical path length differences, including lens profile aberrations, are provided in a displacement sensing optical encoder that uses a telecentric imaging configuration. According to the invention, the encoder is configured such that the image light that reaches the detector comprises symmetric ray bundles concentrated symmetrically on opposite sides of the optical axis center at the limiting aperture of the telecentric imaging configuration. Central ray bundles, and/or other ray bundles that have an optical path lengths significantly different than the operational symmetric ray bundles are prevented or blocked. As a result destructive interference is prevented and image contrast is improved.

Abstract: A scale for a displacement detection apparatus includes a base, and reflection layers formed on the base in a lattice structure, wherein the scale is used as a member displaceable relative to a light-emitting element whose emission wavelength is approximately 1000 nm or less and a light-receiving element receiving the light that is emitted from the light-emitting element and is reflected by the reflection layers, and wherein the base is made of silicon.

Abstract: A relocating device for locating and relocating a first object relative to a second object is for use in association with a means for defining a location point on the second object. The relocating device includes at least one light source, a power source. The at least one light source is producing at least two beams of light wherein each beam of light is capable of defining a beam location point on the second object. The at least one light source is operably connected to the first object. The power is source operably connected to the at least one light source. The means for defining a location point on the second object defines each beam location point on the second object.

Abstract: On the +X and ?X sides of a projection unit, a plurality of Z heads are arranged in parallel to the X-axis, by a distance half or less than half the effective width of the Y scale so that two Z heads each constantly form a pair and face a pair of Y scales. Of the pair of heads consisting of two Z heads which simultaneously face the scale, measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to dust and the like adhering on the scale surface, measurement values of the other head is used, and the positional information of the stage in at least the Z-axis direction is measured in a stable manner and with high precision.

Abstract: A distance measuring measurement instrument and a method for such a station for scanning a surface or volume of an object are disclosed. The measurement instrument includes a position calculating circuit adapted to calculate position data including at least horizontal and vertical angle and distance between the measurement instrument and the object. A plurality of points in each of a number of subsets of a scanning area of the object during a measurement session and, at detection of a new point in the new subset, information related to at least one point having a corresponding location in at least one preceding subset is used, wherein the preceding subset being adjacent to the new subset.

Abstract: A method for adjusting an object distance for focusing upon a face of an item, including a data carrying graphical that is placed within a field-of-view of a fixed focal length imaging device. The method employs using parallax focusing techniques to produce a laser spot indicator, and further calls for providing a fixed on-screen focusing target to indicate a location to which the laser spot indicator must be moved and positioned before in-focus imaging activities can be realized. This abstract is provided to comply with rules requiring abstracts, and is submitted with the intention that it will not be used to interpret or limit the scope and meaning of the claims.

Abstract: A position detecting sensor includes a grid structure composed of plural electrodes extending in a first direction and plural electrodes extending in a second direction perpendicular to the first direction. The electrodes have light permeability. In a rectangular area defined by four cross-points, where two adjacent electrodes extending in the first direction and two adjacent electrodes extending in the second direction cross each other, a dummy pattern is disposed so as to provide uniform optical characteristics for the sensor. At least some of the electrodes extending in the first direction are shaped to include inclinations relative to the first direction, so as to minimize the Moire effect that may develop between the electrodes and an array of pixels in an overlaid display device. Also, at least some of the electrodes extending in the first direction are shaped to be line-symmetric about a straight line extending in the first direction.

Abstract: A method of measuring shot shape includes sequentially exposing a substrate with main scale marks (32) in compliance with a predetermined map, and forming a reference grid including a plurality of the main scale marks (32) arranged in the predetermined map in at least one shot region, exposing a shot for measuring, via a projection optical system, that includes a plurality of auxiliary scale marks (34) arranged in the predetermined map in the shot region, measuring a relative positional relationship between adjacent main scale marks (32), measuring an amount of deviation between the main scale marks (32) and the auxiliary scale marks (34), and correcting the reference grid based on the relative positional relationship, and calculating a shot shape of the shot for measuring based on the corrected reference grid and the amount of deviation.

Abstract: In an absolute position encoder, a multi-spectral light source illuminates a position on a topographic surface at an angle of incidence determined from a vector normal to the surface. A target on, and positionally-registered to, the topographic surface comprises a variable grating that diffracts the incident light to form a multi-spectral diffraction pattern in which the angular dispersion of the diffraction pattern varies with the absolute position of the incident light along the grating. A chromatically responsive sensor detects a narrow band of the diffraction pattern through an entrance aperture positioned at an angle of detection determined from the vector normal to the topographic surface and outputs a signal responsive to the change in the angular dispersion of the detected narrow band of the diffraction pattern. The source/sensor unit maintains (within an acceptable noise tolerance) its geometric relationship to the vector normal to the topographic surface at the position of illumination.

Abstract: An encoder includes a scale, a detector array that includes a plurality of detectors, and a signal processor configured to process and convert into positional information, an output signal from the detector array. The signal processor includes a first phase acquirer, a second phase acquirer, and a positional information acquirer configured to acquire Sv as a position signal that represents a position of the scale. Sv satisfies Sv=A·?1?B·?2 where A and B are coefficients that satisfy A/B=n/m using integers m and n that satisfy |(m·P1?n·P2)|<|(P1?P2)|. ?1 is a first phase acquired by the first phase acquirer, ?2 is a second phase acquired by the second phase acquirer, P1 is the first modulation period, and P2 is the second modulation period.

Abstract: An optical encoder device is provided, in which first light transmissive slits are formed in a movable slit plate and second light transmissive slits are formed in a stationary slit plate. The number of the second light transmissive slits is defined as S. The second light transmissive slits are formed in the stationary slit plate such that when one of the second light transmissive slits is optically coincident with one of the first light transmissive slits, the remaining S-1 second light transmissive slits are shifted in position from other first light transmissive slits corresponding to the remaining second light transmissive slits by S-1 phase differences.

Abstract: A position detector includes a first planar encoder including a first encoder head unit mounted on a test object that is a movable member, and a first grating unit mounted on a fixed member, the first planar encoder being configured to detect a position of the test object in two directions by measuring a position of the first grating unit using the first encoder head unit, and a second planar encoder including a second encoder head unit mounted on the fixed member, and a second grating unit mounted on the movable member, the second planar encoder being used to generate data for calibrating the position of the first grating unit measured by the first encoder head unit.

Abstract: A stage device is equipped with: a wafer stage that has a coarse movement stage that moves along an XY plane and a table that is finely movable in at least a direction parallel to the XY plane; and an encoder system. A plurality of encoder heads are arranged on the coarse movement stage. Each of the heads irradiates a first grating section placed parallel to the XY plane and a second grating section arranged on the table with measurement beams, respectively, and receives diffracted lights from each of the first and second grating sections. The encoder system measures positional information of the table (wafer stage) within the XY plane based on an output of at least one encoder head that faces the first and second grating sections.

Abstract: The invention relates to an optoelectronic angle sensor for determining a rotational angle about an axis, comprising a code carrier (2) provided with a flat coding (3) and a photosensitive detector. The code carrier (2) and the detector can be displaced about the axis in relation to each other. Said angle sensor also comprises a device for producing an evaluable image of at least one part of the coding on the detector such that the image contains information relating to a rotational position of the code carrier (2) in relation to the detector, in addition to an evaluation unit for determining the rotational angle from the image. The coding (3) is self-luminous and it also comprises at least part of the device for producing an evaluable image.

Abstract: Systems and methods for calibrating a solid-imaging system (10) are disclosed. A calibration plate (110) having a non-scattering surface (140) with a plurality (150) of light-scattering fiducial marks (156) in a periodic array is disposed in the solid-imaging system. The actinic laser beam (26) is scanned over the fiducial marks, and the scattered light (26S) is detected by a detector (130) residing above the calibration plate. A computer control system (30) is configured to control the steering of the light beam and to process the detector signals (SD) so as to measure actual center positions (xA, yA) of the fiducial marks and perform an interpolation that establishes a calibrated relationship between the angular positions of the mirrors and (x,y) locations at the build plane (23). The calibrated relationship is then used to steer the laser beam in forming a three-dimensional object (50).

Abstract: The disclosure relates to a remote displacement sensor, such as an optical strain gauge, which uses an optical amplifier implemented by patterns, such as, but not limited to, moiré patterns, to calculate changes in position or gauge length. In the embodiment implemented as a strain gauge with moiré patterns, two foil layers are provided, a lower foil layer with a reference or static moiré pattern generated by the overlaying of a first pattern with parallel lines at a first fundamental frequency and a second pattern with parallel lines at a second fundamental frequency. The lower foil layer further includes a first section with a first pattern with parallel lines at the first fundamental frequency while the upper layer provides a second section with a second pattern with parallel lines at the second fundamental frequency. The overlaying of the foils causes an overlying of the first and second sections thereby causing a moiré pattern of the same wavelength as the reference pattern.

Abstract: A measurement device for determining an installation position for a fire sprinkler head is provided. The measurement device includes a body adapted for positioning across and proximate to the center of a tile grid cell. The measurement device also includes a light source mounted to the body. The light source is adapted to project a beam of light onto a surface positioned above the tile grid cell. When the measurement device is positioned across the tile grid cell, the light source is proximate to the center of the tile grid cell.

Abstract: A control system controls a support structure of a lithographic apparatus. A first measurement system measures the position of a substrate supported by the support structure, in a first coordinate system. A second measurement system measures the position of the support structure in a second coordinate system, the first measurement system having a presumed position in the second coordinate system. A controller controls the position of the support structure based on measurements by the second measurement system, to convert the measured position of the substrate into a converted position of the support structure in the second coordinate system, to position the support structure based on the converted position, to receive a position error signal indicative of a difference between the presumed position and an actual position of the first measurement system in the second coordinate system, and to position the support structure dependent upon the position error signal.

Abstract: By irradiating a detection beam from an irradiation system of a detection device to a scale used for measuring the position of a wafer stage, and detecting the detection beam via the scale by a photodetection system, a surface state (an existence state of foreign substance) of the scale is detected. With this operation, detection of the surface state can be performed contactlessly with respect to the scale. Moreover, movement control of the wafer stage can be performed with high precision by taking the surface state into consideration.

Abstract: In an apparatus for measuring a quasi-static error of a rotation driving shaft, a positional error and an angular error in each of X, Y, and Z axis directions during rotation of a driving shaft is measured by means of a single measurement apparatus. In the apparatus, a first splitter, a second splitter, and a reflector spectrally output or reflect a laser beam, which is output from a laser driving device, to a first position sensor and a second position sensor, so that it is possible to obtain every error information on positional errors and angular errors in X, Y, and Z axis directions of a rotation driving shaft through input position change data of the inputted laser beam.

Abstract: A measurement system configured to measure a position dependent signal of an object table, the measurement system including at least one sensor mountable on the object table and a sensor target object mountable on a substantially stationary frame, and a mounting device configured to mount the sensor target object on the substantially stationary frame, wherein the measurement system further includes a compensator configured to compensate movements and/or deformations of the sensor target object with respect to the substantially stationary frame. The compensator may include a passive or an active damper and/or a feedback position controller. In an alternative embodiment, the compensator includes a gripping device which fixes the position of the sensor target object during a high accuracy movement of the movable object.

Abstract: In one example embodiment, position of the alignment unit is acquired using a fiducial mark formed on a moving table, and the moving table is moved such that an alignment mark formed on the workpiece is located within a field of view of the alignment unit to measure the position of the alignment mark. Subsequently, the position and posture of the workpiece are accurately measured based on the position of the alignment unit and the position of the alignment mark measured by the alignment unit.

Abstract: A position detecting device for detecting a position of an object, includes a light emitting portion that emits light, a light receiving portion that receives the light from the light emitting portion, and a scale that is arranged between the light emitting portion and the light receiving portion, and includes a position detecting pattern and a smear detecting pattern. The position detecting pattern has a first light transmitting portion for transmitting the light from the light emitting portion and a first light interception portion for intercepting the light from the light emitting portion which are alternately arranged in a detection range of the object. The smear detecting pattern for detecting smear of the scale has a second light transmitting portion for transmitting the light from the light emitting portion and a second light interception portion for intercepting the light from the light emitting portion which are alternately arranged.

Abstract: New and useful concepts for an autofocus system and method are provided. A basic concept uses fringe projection in an autofocus system and method. A further aspect provides spatial filtering concepts for the fringe projection concept. In yet another aspect, the fringe projection autofocus system and method is provided with temporal phase shifting using no moving parts. In a still further aspect, the fringe projection autofocus system and method is provided with unambiguous height measurement concepts.

Abstract: A position sensing optical encoder includes an illumination source that operates by providing primary radiation having a first level of intensity uniformity to saturate at least a portion of a relatively broad phosphor area including uniformly distributed phosphor. The phosphor area absorbs the primary radiation and emits phosphor radiation to illuminate the encoder scale pattern. The scale pattern spatially modulates the phosphor light, and the spatially modulated pattern of phosphor light is sensed by a photodetector arrangement. Due at least partially to saturation of the phosphor, the phosphor light has a second level of phosphor light intensity uniformity that is more uniform than the first level of primary light intensity uniformity, which enhances the encoder accuracy. The uniform phosphor illumination intensity is economically provided over a broad area with few components and minimized optical path length, particularly for path length perpendicular to the scale.

Abstract: A scanning unit, by which a scale, which is movable in relation to the scanning unit in a measuring direction, can be optically scanned. The scanning unit including a detector arrangement and a transparent support having a first surface and a second surface, wherein the detector arrangement is arranged on the second surface. The scanning unit further including a transparent cover plate, which is fastened on the first surface of the transparent support and includes a shielding device for shielding the detector arrangement against electromagnetic fields.

Abstract: A drive unit drives a wafer stage in a Y-axis direction based on a measurement value of an encoder that measures position information of the wafer stage in the Y-axis direction and based on information on the flatness of a scale that is measured by the encoder. In this case, the drive unit can drive the wafer stage in a predetermined direction based on a measurement value after correction in which a measurement error caused by the flatness of the scale included in the measurement value of the encoder is corrected based on the information on the flatness of the scale. Accordingly, the wafer stage can be driven with high accuracy in a predetermined direction using the encoder, without being affected by the unevenness of the scale.

Abstract: An encoder configuration comprises an illumination portion, a scale comprising a scale track, and a signal processing electronics. The signal processing electronics may include a detector comprising a first set of three detector sub-portions that provide a first set of signals comprising three respective sub-portion signal subsets that have nominally the same signal characteristics when the scale track is not contaminated or defective. The processing electronics analyze the first set of signals and identify a least-similar sub-portion signal subset that has a corresponding signal characteristic value that is least similar to comparable signal characteristic values associated with more-similar sub-portion signal subsets of the first set of signals. Position measurements are based on valid signals including a plurality of the more-similar sub-portion signal subsets and not including the least-similar sub-portion signal subset if it is significantly different.

Abstract: Systems and methods for calibrating a solid-imaging system (10) are disclosed. A calibration plate (110) having a non-scattering surface (140) with a plurality (150) of light-scattering fiducial marks (156) in a periodic array is disposed in the solid-imaging system. The actinic laser beam (26) is scanned over the fiducial marks, and the scattered light (26S) is detected by a detector (130) residing above the calibration plate. A computer control system (30) is configured to control the steering of the light beam and to process the detector signals (SD) so as to measure actual center positions (xA, yA) of the fiducial marks and perform an interpolation that establishes a calibrated relationship between the angular positions of the mirrors and (x,y) locations at the build plane (23). The calibrated relationship is then used to steer the laser beam in forming a three-dimensional object (50).

Abstract: A drive unit drives a wafer stage in a Y-axis direction based on a measurement value of an encoder that measures position information of the wafer stage in the Y-axis direction and based on information on the flatness of a scale that is measured by the encoder. In this case, the drive unit can drive the wafer stage in a predetermined direction based on a measurement value after correction in which a measurement error caused by the flatness of the scale included in the measurement value of the encoder is corrected based on the information on the flatness of the scale. Accordingly, the wafer stage can be driven with high accuracy in a predetermined direction using the encoder, without being affected by the unevenness of the scale.