Abstract: Apparatus (1) for additively manufacturing three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of at least one energy beam (4), which apparatus (1) comprises an irradiation device (5) with at least one beam guiding element (7) on which the energy beam (4) is partially reflected, wherein a first beam part (10) extends between the beam guiding element (7) and a build plane (18) of the apparatus (1) and a second beam part (11) is transmitted through or scattered at the beam guiding element (7), wherein a determination device (12) is provided that is adapted to determine at least one parameter of the second beam part (11).

Abstract: An optical position measuring device for recording a relative position of two scales includes the scales. The longitudinal extents of the scales are oriented parallel to a first and second measuring direction. A horizontal plane of movement is spanned by these measuring directions. A light source is configured to emit an illumination beam that is split into at least two sub-beam bundles at the first scale. The sub-beam bundles subsequently impinge on the second scale, which is tilted about the direction of the longitudinal extent thereof relative to the horizontal plane of movement, and are back-reflected to impinge again on the first scale and are recombined there such that a resulting signal beam is subsequently propagated toward a detection unit, via which phase-shifted scanning signals are generatable with respect to a relative movement of the scales along a third perpendicular measuring direction and the first or second measuring direction.

Abstract: An electron beam apparatus is provided. The apparatus comprises an e-beam source configured to generate an electron beam, a first part configured to support a substrate, the first part comprising an object table for supporting the substrate, the first part further comprising a short stroke actuator system for actuating the object table relative to the e-beam source, the short stroke actuator system comprising a short stroke forcer. The apparatus further comprises a second part configured to movably support the first part and a long stroke actuator system configured to actuate movement of the first part with respect to the second part, the long stroke actuator system comprising a long stroke forcer, wherein the short stroke forcer and/or the long stroke forcer is configured to be switched off while the electron beam is projected onto the substrate.

Abstract: According to some aspects, calibration techniques are provided that allow an optics module of an additive fabrication device to be installed and operated in a stereolithography device by a user. In particular, the calibration techniques enable the optics module to be calibrated in a way that only depends on the characteristics of the optics module, and not upon any other components of the stereolithography device. As a result, the techniques enable a user of a stereolithography device to remove one optics module and replace it with another, without it being necessary to repair or replace the whole device. In some cases, the calibration techniques may include directing light onto one or more fiducial targets within the stereolithography device and measuring light scattered from said targets.

Abstract: Aspects of the present disclosure provide a method of aligning a wafer pattern. For example, the method can include providing a wafer having a reference pattern located below a front side of the wafer, and directing a light beam to the wafer. The method can further include identifying at least one of power and a wavelength of the light beam such that the light beam is capable of passing through the wafer and reaching the reference pattern, or identifying at least one of power and a wavelength of the light beam based on at least one of a material of the wafer and a depth of the reference pattern below the front side of the wafer. The method can further include using the light beam to image the reference pattern.

Abstract: The method can include measuring the tridimensional positions of a reference feature for a first at least three different angular positions of the reference feature around the first rotation axis and a same first reference angular position around the second rotation axis, the reference feature being fixed relative to the component; and measuring the tridimensional positions of the reference feature for a second at least three different angular positions of the reference feature around the first rotation axis and a same second reference angular position around the second rotation axis.

Abstract: A coordinate measuring machine and a method for operating a coordinate measuring machine, and a rotary table module for a coordinate measuring machine with a rotary table for receiving a workpiece and a rotary table block are provided. The rotary table is supported on a rotary table side rotatably about a rotary table axis. The rotary table block has, opposite the rotary table side of the rotary table block, a bottom side with which the rotary table module can be supported on a measurement table of the coordinate measuring machine. The rotary table block has a further supporting side with which the rotary table block is supportable on the measurement table of the coordinate measuring machine and which differs from the bottom side in its alignment. The rotary table module includes a pose capturing device for the determination of whether the rotary table block is supported on the bottom side.

Abstract: The disclosure provides for a method of calibrating a detection system that is mounted on a vehicle. The method includes detecting characteristics of the mirror and characteristics of a vehicle portion using the detection system. The mirror reflects the vehicle portion to be detected using the detection system. The method also includes determining a first transform based on the detected one or more of mirror characteristics, determining a second transform based on the one or more vehicle portion characteristics, and determining a third transform based on a known position of the vehicle portion in relation to the vehicle. Further, the method includes determining a position of the detection system relative to the vehicle based on the first, second, and third transforms and then calibrating the detection system using the determined position of the detection system relative to the vehicle.

Abstract: An additive manufacturing apparatus includes a platform, a dispenser configured to deliver a plurality of successive layers of feed material on a platform, a light source configured to generate a light beam, an auxiliary polygon mirror scanner configured to receive the light beam from the light source and reflect the light beam, and a primary mirror scanner to receive the light beam reflected by the auxiliary polygon mirror scanner and direct the light beam to impinge on an exposed layer of feed material.

Abstract: A rotary encoder includes: a rotary disk with an angle code; a light source; a detector reading the angle code; and a processing unit acquiring a reading value. The light source includes at least two light-emitting elements spaced from each other. Every time the rotary disk is rotated by a predetermined angle, where an arbitrary angle from a rotation angle ? within a reading range on the detector is provided as ?, the processing unit acquires reading values fI(?+?) and fI(?) with a first light-emitting element and a reading value fII(?+?) with a second light-emitting element, to calculate a reading value error due to deflection at an angle ?+? based on the difference between the reading values fII(?+?) and fI(?+?), to obtain a difference gI(?,?) between the reading values fI(?+?) and fI(?) such that the error is reflected, and to self-calibrate based on a change in the difference gI(?,?).

Abstract: A touch display device includes a display panel including a plurality of first pixels and a plurality of second pixels alternately disposed along a first direction, and a touch screen layer disposed on the display panel, the touch screen layer including a plurality of first touch electrodes having a zigzag shape and disposed between one of the first and second pixels along a second direction crossing the first direction, in which a first pixel of the first pixels and a second pixel of the second pixels have different sizes from each other, and a first distance from a first touch electrode of the first touch electrodes to the first pixel is different from a second distance from the first touch electrode to the second pixel.

Abstract: An optical measurement apparatus includes a main body base, an optical base movably combined with the main body base, a measurement optical system fixed to the optical base, and an optical base moving mechanism which moves the optical base relative to the main body base. The optical base moving mechanism moves the optical base relative to the main body base between an internal measurement position and an external measurement position. A measurement object position of the measurement optical system coincides with an internal measurement object position within the main body base. The measurement object position of the measurement optical system coincides with an external measurement object position outside the main body base.

Abstract: Multiple cameras are used for tool positioning, as-built documentation, and/or personnel monitoring in construction site. A camera unit comprises one or more imaging devices, a processing computer, and a communication device. The camera units are placed at multiple locations in a construction site to cover an area. The camera units are self-positioned by detecting a calibration target that moves within a working volume. The camera units can detect and calculate positions of objects, including measurement sticks, tools, personnel, etc., in the area.

Abstract: A display apparatus uses an LED array having an LED pixel pitch, having LED pixels emitting light with viewing angles ?. A transmissive diffuser panel is mounted with the LED array, having a directly-lit, diffuser panel surface spaced away from the LED array by an adjustable distance D. The distance D and the viewing angles ? being are effective to merge illumination from multiple LED pixels in the LED array on the directly-lit diffuser panel surface. A controller is connected to the LED array having circuitry to control the LED array in response to image data to induce display via the diffuser panel of a time varying image with spatially varying colors and intensities.

Abstract: Disclosed is a 3D scanner comprising at least one scanning module for acquiring three-dimensional coordinates of a surface of an object and a positioning device on which the object is placeable or fixable, whereby the positioning device is movable relative to the at least one scanning module, and the 3D scanner further comprising at least one accelerometer, which is configured to measure a change of the position of the positioning device relative to the scanning module, and a first processing unit which is connected to the at least one scanning module and to the positioning device for receiving data. Also disclosed is a method for scanning a surface of an object to acquire three dimensional (3D) coordinates of the surface.

Abstract: A scale includes a grating pattern arranged in a measurement direction. A detection head can be moved relative to the scale in the measurement direction and outputs an electric signal indicating a result of detection of the pattern. An operation unit calculates a relative displacement of the detection head relative to the scale. The detection head irradiates the scale with light. A light-receiving unit includes a light-receiving element array arranged in the measurement direction and outputs a result of detection of the irradiation light applied to the light-receiving element array as the electric signal. An optical system forms light from the scale into interference fringes on a light-receiving surface of the light-receiving unit by using lens arrays arranged in the measurement direction. A lens array pitch between neighboring lenses of the lens arrays is not equal to an integral multiple of a pitch of the grating pattern.

Abstract: A positioning system, in particular, six-dimensions positioning system of a shadow sensor with respect to a constellation of light sources is provided. The sensor can be a shadow sensor and has a mask and a 2D imager. By recording the shadow of the mask cast by each light source on the imager, and by properly multiplexing the light sources, the system can compute the 6D position of the shadow sensor with respect to the constellation of light sources. This computation is based, in part, on treating the shadow of the mask cast on the imager as the equivalent of the projection of light in a pinhole or projective camera. In one embodiment, the system is applied in a surgical domain. In another embodiment, the system is rapidly deployed.

Abstract: The encoder includes a scale provided with first and second periodic patterns, a sensor movable relatively with respect to the scale and including a detection element array to detect the first and second periodic patterns, a periodic signal producer to produce, by using output from the detection element array, a first periodic signal changing corresponding to a first period of the first periodic pattern and a second periodic signal changing corresponding to a second period of the second periodic pattern, and a correction signal producer to produce, by using the second periodic signal, a correction signal for reducing in the first periodic signal a signal component changing corresponding to the second period. A position calculator produces, by using the first periodic signal and the correction signal, information indicating position.

Abstract: In an exposure apparatus exposes a substrate with an energy beam via a projection optical system, a substrate stage system has a movable body that holds the substrate and is driven to move the substrate. An encoder system measures positional information of the movable body by irradiating each of four areas of a grating section with a beam via each of four heads. A controller controls driving of the movable body based on the positional information measured by the encoder system. As the movable body moves, a relationship between the grating section and the heads changes between a first state, in which the four heads respectively face the four areas, and a second state, in which only three of the heads respectively face three areas of the four areas. At least three areas of the four areas are always faced by three of the heads at least during substrate exposure.

Abstract: A position-measuring device, as well as a system having such a position-measuring device, is used for determining the position of a first object relative to a second object, the first and the second object being movable relative to one another along at least two measuring directions. The position-measuring device has an optical unit that is linked to one of the two objects and includes at least one light source, a detector system, as well as further optical elements in a defined configuration. In addition, the position-measuring device includes a measuring standard-reflector unit, which is provided on the other object, and has at least two differently formed regions in one track that are optically scannable by the optical unit for position sensing.

Abstract: In an exposure method of exposing a substrate with an energy beam via a projection optical system, a movable body that holds the substrate is driven to move the substrate. Positional information of the movable body is measured with an encoder system by irradiating each of four areas of a grating section with a beam via each of four heads. Driving of the movable body is controlled based on the positional information measured by the encoder system. As the movable body moves, a relationship between the grating section and the heads changes between a first state, in which the four heads respectively face the four areas, and a second state, in which only three of the heads respectively face three areas of the four areas. At least three areas of the four areas are always faced by three of the heads at least during substrate exposure.

Abstract: A reflector device comprising a reflector (106), having an inner surface (120, 122), and at least one solid state light emitting element (114). The inner surface of the reflector comprises first and second surface portions (120, 122), which are flat and which extend in planes intersecting at an angle. The at least one solid state light emitting element (114) is mounted at at least one of said first and second surface portions (120,122) such that a major part of the light emitted from said at least one solid state light emitting element (114) illuminates the other one of said first and second surface portions (120,122).

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 predetermined 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 malfunction of the head, measurement values of the other head is used, and the positional information of the stage in at least the Z-axis direction can be measured in a stable manner and with high precision.

Abstract: The optical encoder includes a scale provided with a periodic pattern in which an optical portion is periodically formed with a first period in a first direction, and a light receiver movable relatively with the scale in the first direction and photoelectrically converts a detection light from a light source and then passing through the optical portions. The optical portion periodically has a pattern, which is formed by pattern portions mutually adjacent in a second direction orthogonal to the first direction and mutually shifted in the first direction, in the second direction with a second period of t. A width w of the light source in the second direction satisfies w=(a+b)/b·nt where n represents a natural number, and a:b represents a ratio of a distance from the light source to the periodic pattern and a distance from the periodic pattern to the light receiver.

Abstract: The invention provides a positioning device for locating a planar light beam emitted by an optical triangulation sensor across a diameter of a hole formed in a surface of an object. The positioning device has an adjustable guiding element which is capable of locating an optical triangulation sensor at the same distance away from holes have a range of diameters. The guiding element is movably mounted relative to a platform that is fixed to the optical triangulation sensor. The guiding element comprises a body which is insertable into the hole, the body having a pair of contact surfaces for contacting diametrically opposed portions of the hole, the pair of contact surfaces being opposed to each other in a direction orthogonal to the plane of the planar light beam.

Abstract: An optical position-measuring device for detecting the relative position of two objects includes a measuring standard connected to one object, and a scanning unit connected to the other object and including a light source, one or more grating(s), and a detector system. The detector system includes a plurality of detector element groups arranged in a detection plane, via which a plurality of position-dependent, phase-shifted scanning signals is able to be generated by scanning a periodic fringe pattern that results in the detection plane, the detector elements that have in-phase scanning signals forming a group in each case. The sum of the areas and the centroid of the detector elements of a group is identical to the sum of the areas and the centroid, respectively, of the detector elements of each other group. Periodic diaphragm structures are arranged in front of the light-sensitive areas of the detector elements.

Abstract: A three-dimensional measurement apparatus includes a projection unit configured to project a plurality of types of stripe pattern light. The projection unit projects stripe pattern light, which can be obtained by shifting stripe pattern light whose reliability calculated by the calculation unit is equal to or greater than a threshold value by a predetermined cycle, on the object.

Abstract: A measuring graduation includes a phase grating for a photoelectric position measuring device for measuring positions in a first direction and in a second direction extending orthogonally to the first direction. The phase grating has a periodic array of grating elements in the first direction and in the second direction. The grating elements each have an outer contour that is formed by a continuous line which includes two mutually opposing first straight edges, two mutually opposing second straight edges extending perpendicularly to the first straight edges, and connecting lines extending between the first straight edges and the second straight edges. The connecting lines form an obtuse angle with the first straight edges and with the second straight edges.

Abstract: An optical position measuring instrument including a scanning plate and a scale, wherein the scale and the scanning plate are movable relative to one another. The optical position measuring instrument including a grating and a light source that emits a beam toward the grating, wherein the grating receives the beam and splits the beam into two partial beams with orthogonal polarization states. The optical position measuring instrument including a polarizer being arranged in beam paths of the two partial beams, wherein the polarizer has a structure to generate polarization effects on the two partial beam striking the polarizer that are periodically variable, wherein a polarization period of the periodically variable polarization effects is greater than a graduation period of the grating. The two partial beams being reunified into a resultant beam. A detection unit that receives the resultant beam and generates a plurality of displacement-dependent scanning signals.

Abstract: The encoder includes a scale including first and second periodic patterns, and a detector relatively movable with respect to the scale and whose detection state is switchable between a first detection state to read the first periodic pattern and output a first signal and a second detection state to read the second periodic pattern and output a second signal. A processor performs a first process to detect a first absolute position by using the first and second signals and then performs a second process to calculate a relative movement amount by using a specific signal that is one of the first and second signals and detect a second absolute position by using the relative movement amount and the first absolute position. The specific signal is obtained from the detector set in a same detection state as that set last in the first process.

Abstract: Methods for performing a scheme that results in a refined measurement pattern within an optical grid are provided. Physically adjusting spacing of elements within an optical grid to achieve enhanced resolution is historically unfeasible, as reduction of the spacing causes light sensors of the optical grid to pick up false signals when reading light beams. Technology introduced by the present invention generates a virtual reduced spacing of the elements within the optical grid by using two signals that are slightly different. These slightly different signals can accomplish, at least, quarter-grid spacing resolution within the optical grid. Additionally, the enhanced resolution derived from the virtual reduced spacing is employed to govern movement of a motor. The motor movement is in response to one or more changes of direction such that the motor is operating in its linear range.

Abstract: In a lithographic apparatus, a slip of a patterning device relative to a support, the support constructed to support the patterning device, may be provided by measuring a position of the support relative to a first structure of the lithographic apparatus; measuring a position of the patterning device relative to a second structure of the lithographic apparatus; determining a correlation between the position of the patterning device and the position of the support from the measured position of the support, the measured position of the patterning device, and the mutual positions of the first and second structures; and deriving from the correlation a slip of the patterning device relative to the support. The structure may include a projection system to project a radiation beam patterned by the patterning device. The projection system may be connected to a frame, such as a metrology frame of the lithographic apparatus.

Abstract: The present invention provides a measurement apparatus which measures a position of a second object relative to a first object, the apparatus including a first measurement unit which includes a diffraction grating provided on the first object, and a first head and a second head provided on the second object, and is configured to measure the position of the second object relative to the first object by the first head or the second head, and a processing unit configured to perform a process of obtaining the position of the second object relative to the first object.

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 an overlay includes generating an original signal using first and second overlay measurement keys that are spaced apart from each other, generating a first spectrum signal by performing Fourier transform of the original signal, generating a second spectrum signal by filtering the first spectrum signal, and generating a corrected signal by performing inverse Fourier transform of the second spectrum signal.

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 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: An optical encoder includes: an optical scale having periodical optical patterns and can be relatively and angularly displaced; a projector for irradiating the optical scale with light; a light receiver for receiving light from the optical scale; and a calculator for calculating an absolute rotation angle ? of the optical scale in accordance with a signal from the light receiver. The optical patterns include a plurality of light shielding portions and a plurality of light transmitting portions, each of the portions being located alternately.

Abstract: Method for determining the position and/or displacement of a mobile element with respect to a fixed frame, includes using a fixed light source emitting a light beam, arranging the source with respect to the mobile element and a sensor to induce an interaction between the beam and sensor, using a concave mirror, integral in movement with the mobile element, for reflecting the beam in direction to the sensor, arranging on the path of the beam a fixed optical mask which presents a two dimensional regular pattern interlaced with an absolute code, detecting and processing the image casted by the mask on the sensor, computing the displacement value of the image on the sensor and using the computed displacement value for computing and providing the position and/or the displacement in at least one direction of the mobile element in dependence of the image's displacement.

Abstract: While an exposure processing is performed to a wafer held by a fine movement stage supported by a coarse movement stage in an exposure station, at least a part of a measurement processing to a wafer held by another fine movement stage supported by another coarse movement stage and an exchange of a wafer held by yet another fine movement stage on a center table is concurrently performed. Because of this, exposure with a higher throughput becomes possible, even when compared with a conventional exposure apparatus which concurrently performs an exposure processing to a wafer on a wafer stage, and processing such as wafer exchange and alignment on another stage.

Abstract: An x linear encoder, which is configured of a pickup placed on a measurement mount and facing an x scale fixed on the lower surface of a barrel that houses a projection optical system, measures the displacement of the barrel with the measurement mount serving as a reference. With the configuration of the x linear encoder, a path of a measurement light that propagates back and forth between the pickup and the scale is significantly shortened, compared with the case of using an interferometer.

Abstract: A three dimensional shape measurement apparatus includes an illumination section and a grating transfer unit. The illumination section includes a light source unit generating a light and a grating unit changing the light generated by the light source unit into a grating pattern light having a grating pattern. The illumination section illuminates the grating pattern light onto a measurement target in a predetermined direction. The grating transfer unit transfers the grating unit in a predetermined inclination direction with respect to an extension direction of the grating pattern and an arrangement direction of the grating pattern. Thus, manufacturing cost may be reduced, and the three dimensional shape measurement apparatus may be easily managed.

Abstract: Described is a system and method for in situ sample preparation and imaging. The system includes a multi-axis stage 100 having a bulk stage 110 and a grid stage 150 with various degrees of freedom to allow for sample preparation. In some embodiments, a focused ion beam system is used to prepare a lamella on the bulk stage 110. The lamella can then be transferred to the grid stage 150 from the bulk stage 110 without needing to move the multi-axis stage 100 from the focused ion beam system.

Abstract: An origin location detection circuit in an encoder. The encoder includes a scale on which an origin pattern indicating an origin is provided and a detection head relatively displaceable with respect to the scale. The origin location detection circuit includes a comparator for generating an origin signal indicating a location of the origin from an output voltage signal, which is output from a detector of the detection head and has been affected by involvement of the origin pattern; a DC voltage detection circuit smoothing the output voltage signal; and a differential amplifier circuit performing differential amplification of the output voltage signal and a DC voltage signal output from the DC voltage detection circuit. A differential amplifier signal of the differential amplifier circuit is input to the comparator.

Abstract: The laminated diffractive optical element includes plural diffraction gratings (21, 22 and 23) laminated with each other, the respective diffraction gratings being formed of a same light-transmissive material. In the element, reflective films are formed on grating surfaces (11 and 12) of the respective diffraction gratings, each of the reflective films being disposed between the diffraction gratings. Each of the reflective films reflects light in a specific wavelength range and transmits light in a wavelength range different from the specific wavelength range, the specific wavelength ranges of the respective reflective films being different from each other. The grating surfaces of the respective diffraction gratings are formed in shapes different from each other according to the specific wavelength ranges corresponding to the respective reflective films.

Abstract: An optical position-measuring device includes a measuring standard having a first grating in a form of a periodic incremental graduation and an absolute mark. A scanning unit is displaceable relative to the measuring standard in a measuring direction. The scanning unit has at least one second grating disposed at a scanning distance from the first grating. A first detector array is configured to obtain a first scanning signal for purposes of position determination in which the gratings are illuminated with light of a first wavelength. A second detector array is configured to obtain a second scanning signal for purposes of position determination in which the absolute mark is illuminated with light of a second wavelength. The first wavelength is shorter than the second wavelength.

Abstract: A position measurements system to measure a position of a movable object with respect to another object includes two or more one dimensional (1D) encoder heads mounted on one of the movable object and the other object and each capable of emitting a measurement beam along a measurement direction, one or more reference targets mounted on the other of the movable object and the other object, each reference target including a planar surface with a grid or grating to cooperate with the two or more one dimensional (1D) encoder heads, and a processor to calculate a position of the object on the basis of outputs of the two or more 1D encoder heads, wherein the measurement direction of each of the two or more 1D encoder heads is non-perpendicular to the planar surface of the respective reference target.

Abstract: The invention relates to a method and an apparatus for measuring masks for photolithography. In this case, structures to be measured on the mask on a movable mask carrier are illuminated and imaged as an aerial image onto a detector, the illumination being set in a manner corresponding to the illumination in a photolithography scanner during a wafer exposure. A selection of positions at which the structures to be measured are situated on the mask is predetermined, and the positions on the mask in the selection are successively brought to the focus of an imaging optical system, where they are illuminated and in each case imaged as a magnified aerial image onto a detector, and the aerial images are subsequently stored. The structure properties of the structures are then analyzed by means of predetermined evaluation algorithms. The accuracy of the setting of the positions and of the determination of structure properties is increased in this case.

Abstract: An optical position measuring instrument including a first scale having a first graduation, wherein the first scale is disposed movable in a first measuring direction, and at a first defined position in the first measuring direction, the first scale includes a spatially limited first marking that differs from the first graduation. The optical position measuring instrument further including a second scale having a second graduation, wherein the second scale is disposed movable in a second measuring direction, and at a second defined position, the second scale includes a second reference marking that is usable for generating at least one reference signal at a reference position of the second scale only if the first scale is located in the first defined position.

Abstract: An encoder emits modulated light from a light source section and lets a first light and a second light separated from the modulated light interfere with each other in a moving grating. In the encoder, the light emitted from the light source section is electrically modulated, and the first light and the second light have different light path lengths.