Abstract: Disclosed is a changing device for optical components in a microscope. The changing device includes an optical component having a flat surface. The changing device further includes a carrier for inserting and/or holding the optical component. The changing device further includes a receptacle for holding the carrier in an optical path of the microscope. The carrier has bearing surfaces for the flat surface of the optical component and positioning surfaces located in the same plane, which are not covered by the optical component, when inserting the latter. The receptacle has bearing surfaces for contact with the positioning surfaces and first attachment means for attaching the carrier positioned on the receptacle in order for the positioning surfaces to act upon the bearing surfaces.

Abstract: A dual-optical displacement sensor system includes a scanner including a first and second scanner head including optical displacement sensors providing a first and second beam having a first optical axis (OA) and a second OA. A computing device or programmed circuit is coupled to receive time versus position data from measurements involving alignment target(s) including at least one knife edge pair including a first and second knife edge oriented in a first plane of the alignment target that is essentially perpendicular to the OAs positioned between the scanner heads for interacting with the beams, and implement at least one equation to analyze the data for determining a degree of alignment of the first and second OA. Using the degree of alignment, an algorithm is for automatic alignment of the OAs or assist instructions for a user alignment of the OAs that provides guiding steps for the user for the alignment.

Abstract: A process tool for processing production substrates, the process tool including: a movable stage configured to perform long-stroke movements in an X-Y plane; an imaging device mounted to a fixed part of the tool and having an optical axis substantially parallel to the X-Y plane; and a mirror mounted on the movable stage and oriented at a predetermined angle of inclination to the X-Y plane so that by moving the movable stage to a predetermined position a part of a component to be inspected can be imaged by the imaging device.

Abstract: The invention provides a stage system comprising a stage (ST) which is movable in respect of a reference structure. One of the stage and the reference structure comprises a reflective surface (REFS). An optical position sensor (IF1) is arranged at the other one of the stage and the reference structure and is configured to determine a position of the reflective surface relative to the optical position sensor. An optical shape sensor (IF2) is configured to determine a shape of the reflective surface. The stage system further comprises a position measurement controller configured to derive a stage position of the stage from the position of the reflective surface relative to the optical position sensor and from the shape of the reflective surface as determined by the optical shape sensor.

Abstract: A focusing device comprises a base unit and a mirror unit which is translatable relative to the base unit parallel to an optical axis of the focusing device. The mirror unit is configured to receive incident light along the optical axis in a first direction and to reflect the incident light parallel with the optical axis in said first direction. The mirror unit comprises at least four mirrors, at least one of the mirrors being curved.

Abstract: A light source measurement apparatus includes an objective lens that collects light emitted from a light source having a plurality of light emission points, a first reflection attenuation filter, a second reflection attenuation filter, a condensing lens, a space filter, and a movable stage, in which the first reflection attenuation filter and the second reflection attenuation filter are disposed such that polarization directions are orthogonal to each other, in which the space filter has an opening through which light emitted from a measurement target light emission point among the plurality of light emission points is transmitted, and in which the opening has a shape in which a dimension of the measurement target light emission point in a fast direction is larger than a dimension of the measurement target light emission point in a slow direction.

Abstract: An optical apparatus includes a beam splitter that transmits a part of an incidence ray and reflects another part of the incidence ray, a mirror member that includes a mirror surface arranged at a position at which light transmitted through the beam splitter is incident, and a retroreflective member that is arranged at a position at which light specularly reflected on the mirror surface, to be incident on the beam splitter and specularly reflected by the beam splitter is incident.

Abstract: In an alignment apparatus, a measurement device includes an illuminator that illuminates a first original-side mark and a second original-side mark arranged in an original and a first substrate-side mark and second substrate-side mark arranged in a substrate. The measurement device performs coarse measurement based on light beams from the first original-side mark and the first substrate-side mark by causing the illuminator to illuminate the first original-side mark and the first substrate-side mark under a first condition, and performs fine measurement based on light beams from the second original-side mark and the second substrate-side mark by causing the illuminator to illuminate the second original-side mark and the second substrate-side mark under a second condition.

Abstract: A module accommodates multiple superluminescent light emitting diodes, SLEDs, 12r, 12g and 12b. The SLEDs are arranged in an enclosure and output respective light beams to propagate into free space within the enclosure. The individual light beams from the SLED sources are combined into a single beam path within the enclosure using beam combiners 40r-g, 40rg-b. Each beam combiner is realized as a planar optical element, the back side of which is arranged to receive a SLED beam and route it through the optical element to the front side where it is combined with another SLED beam that is incident on and reflected by the front side. The free-space propagating combined beam is output from the module via an optical fiber 42 (or through a window).

Abstract: According to one embodiment, a prism system is provided. The prism system includes a polarizing beam splitter (PBS) surface. The PBS surface is configured to generate first and second sub-beams having corresponding first and second polarization information from a received beam, the second polarization information being different than the first polarization information. A first optical path of the first sub-beam within the prism system has substantially same length as a second optical path of the second sub-beam within the prism system. Additionally or alternatively, the first sub-beam achieves a predetermined polarization extinction ratio.

Abstract: An optical interferometer includes a beam splitter module and an optical sensor. The beam splitter module includes a lens assembly and a splitter cube. A light incident surface of the splitter cube is substantially orthogonal to an optical axis of the lens assembly. An acute angle is between the light incident surface and a light splitting surface of the splitter cube. A sampling surface of the splitter cube is substantially parallel to the light incident surface. A light reflecting surface of the splitter cube is substantially orthogonal to the light incident surface. The light incident surface is closer to the lens assembly than the sampling surface. A reference arm is defined between a splitter position on the light splitting surface and the light reflecting surface, a sample arm is defined between the splitter position and the sampling surface, and the reference arm is longer than the sample arm.

Abstract: The invention relates to a method for capturing and compensating the influence of ambient conditions on an imaging scale (S) in a measuring microscope. Here, a modification of the optical properties in the measuring microscope that is caused by a change in the ambient conditions is measured by use of a reference measurement system, in particular an etalon, and, at the same time, an image of a reference structure with at least one reference length (L0) that is situated on a calibration mask is produced by use of a detector of the measuring microscope and a change (?L) of the reference length (L0) that is caused by the change in the ambient conditions is determined in the image of the reference structure. Subsequently, a correlation is established between the modification of the optical properties of the reference measurement system and the length change (?L) in the image, produced in the detector, of the reference structure of the calibration mask.

Abstract: A metrology system includes a radiation source that generates light, an optical modulation unit, a reflector, an interferometer, and a detector. The optical modulating unit temporally separates a first polarization mode of the light from a second polarization mode of the light. The reflector directs the light towards a substrate. The interferometer interferes the diffracted light from a pattern on the substrate, or reflected light from the substrate, and produces output light from the interference. The detector receives the output light from the interferometer. The first and second polarization modes of the output light are temporally separated at the detector.

Abstract: The invention provides a method and apparatus for applying spatial filtering the optical beam of a free space optical coherence tomography (OCT) system substantially without problematic reflections back to the optical source. The invention teaches spatially filtering the reference beam of the OCT system which is typically designed to provide isolation of the optical source from undesirable optical feed-back, thereby achieving spatial filtering without generating undesirable reflections back to the optical source. Various embodiments are taught.

Abstract: A laser measurement system for measuring up to 21 geometric errors, in which a six-degree-of-freedom geometric error simultaneous measurement unit and a beam-turning unit are mounted on either the clamping workpiece or the clamping tool, while an error-sensitive unit is mounted on the remaining one, the beam-turning unit has several switchable working postures and multi-component combinations in its installation state, it can split or turn the laser beam from the six-degree-of-freedom geometric error simultaneous measurement unit to the X, Y, and Z directions in a proper order, or the beam-turning unit can split or turn a beam from the error-sensitive unit to the six-degree-of-freedom geometric error simultaneous measurement unit. The present invention is of simple configuration and convenient operation. Up to 21 geometric errors of three mutual perpendicular linear motion guides are obtained by a single installation and step-by-step measurement.

Abstract: The present disclosure provides a method for improving capability of resisting image noise of a co-phasing system of a dispersed fringe sensor. The method comprises the following steps: carrying out a coarse co-phasing adjustment by utilizing the dispersed fringe sensor until the coarse co-phasing is stabilized in a closed loop; collecting a two dimensional dispersed fringe image by the dispersed fringe sensor; superposing the dispersed fringe image along a dispersed direction so as to convert the two dimensional dispersed fringe image to a one dimensional image along an interferential direction; extracting peak values of the main peak, a left side lobe and a right side lobe of the one dimensional image along the interferential direction, and calculating corresponding piston error value of the image by carrying out a Left-subtracting-right LSR algorithm on these peak values.

Abstract: An optical assembly for a system for inspecting or measuring of an object is provided that is configured to move as a unit with a system, as the system is pointed at a target, and eliminates the need for a large scanning (pointing) mirror that is moveable relative to other parts of the system. The optical assembly comprises catadioptric optics configured to fold the optical path of the pointing beam and measurement beam that are being directed through the outlet of the system, to compress the size of the optical assembly.

Abstract: A method for measuring errors in the linear feed shafts of a multi-spindle machine tool having two or more rotating feed shafts in addition to three linear feed shafts, wherein: at least first through third reflecting mirrors are attached to a table of the machine tool; a laser length-measuring machine is attached to the tip of a principal shaft of the machine tool; the linear feed shafts are driven, and the laser length-measuring machine is moved to prescribed measuring points; the two or more rotating feed shafts are driven at each of the measuring points; the coordinates at each measuring point are calculated by measuring the distances between the first through third reflecting mirrors and the laser length-measuring machine; and errors in the linear feed shafts of the machine tool are obtained by comparing the machine coordinates of the machine tool.

Abstract: System and method for correcting a topography of an object being imaged by a multi-array microscope system. The object is forced to conform to a surface of the substrate supporting the object with a suction force and the topography of the chosen object surface is determined. The supporting substrate is bent with the use of force applied to the substrate with at least one actuator such as to reduce the deviations of the determined topography of the object's surface from a pre-determined reference surface by transferring the changes in the curvature of the supporting substrate to the object. In particular, the chosen surface of the object can be substantially flattened for ease of simultaneous imaging of this surface with multiple objectives of the multi-array microscope.

Abstract: Disclosed is a device manufacturing method, and accompanying inspection and lithographic apparatuses. The method comprises measuring on the substrate a property such as asymmetry of a first overlay marker and measuring on the substrate a property such as asymmetry of an alignment marker. In both cases the asymmetry is determined. The position of the alignment marker on the substrate is then determined using an alignment system and the asymmetry information of the alignment marker and the substrate aligned using this measured position. A second overlay marker is then printed on the substrate; and a lateral overlay measured on the substrate of the second overlay marker with respect to the first overlay marker using the determined asymmetry information of the first overlay marker.

Abstract: A projection exposure apparatus for microlithography includes: an illumination system configured to illuminate a mask in an object field with exposure light; and a projection objective comprising multiple optical elements configured to image the exposure light from the mask in the object field to a wafer in an image field. The projection exposure apparatus is a wafer scanner configured to move the wafer relative to the mask during an exposure of the wafer with the exposure light. The projection objective further includes at least one manipulator configured to manipulate at least one of the optical elements and a control unit configured to control the manipulator. The control unit is configured to manipulate the optical element with the manipulator during the exposure of the wafer with the exposure light.

Abstract: An apparatus (AS) measures positions of marks (202) on a lithographic substrate (W). An illumination arrangement (940, 962, 964) provides off-axis radiation from at least first and second regions. The first and second source regions are diametrically opposite one another with respect to an optical axis (O) and are limited in angular extent. The regions may be small spots selected according to a direction of periodicity of a mark being measured, or larger segments. Radiation at a selected pair of source regions can be generated by supplying radiation at a single source feed position to a self-referencing interferometer. A modified half wave plate is positioned downstream of the interferometer, which can be used in the position measuring apparatus. The modified half wave plate has its fast axis in one part arranged at 45° to the fast axis in another part diametrically opposite.

Abstract: A system for positioning a tool relative to a workpiece includes a movable table for accommodating a workpiece, the table executing movements in two main moving directions during the processing of the workpiece, one or more planar measuring standards provided in stationary fashion about the tool and extend in the plane of the main moving directions, and scanning heads, mounted in at least three corners of the table, for detecting the position of the table relative to the measuring standards. The position of the table is determinable by the scanning heads in six degrees of freedom. In at least one of the corners, one or more scanning heads having a total of at least three measuring axes is/are provided for 3-D position detection in three independent spatial directions. The sensitivity vectors of the measuring axes for the 3-D position detection are neither parallel to the X-Z plane nor parallel to the Y-Z plane.

Abstract: The present invention provides a measurement apparatus which obtains a measurement value with respect to a measurement surface based on an interference signal obtained by causing measurement light reflected from the measurement surface and reference light reflected from a reference surface to interfere with each other, the apparatus including a measurement head including an interference optical system configured to generate the interference signal, and a processor configured to obtain a position of an alignment target on the measurement surface based on the interference signal, and obtain the measurement value based on the position of the alignment target and the interference signal.

Abstract: A stage apparatus includes: a first blowing unit configured to blow out temperature-controlled gas to a measurement optical path of the first interferometer and a measurement optical path of a second interferometer; and a second blowing unit configured to blow out temperature-controlled gas to the measurement optical path of the second interferometer, wherein the first blowing unit blows out gas in a direction along an X-direction, and the second blowing unit blows out the gas obliquely with respect to a Y-direction from an upstream side to a downstream side of the gas blown out from the first blowing unit.

Abstract: The present disclosure provides a telecentric optical assembly comprising a first portion of a telecentric optical link including a first kinematic mount having alignment structures, where the first kinematic mount can be attached to a first substrate having a first array of active optical elements; and a second portion of the telecentric optical link including a second kinematic mount having recesses configured to mate with the alignment structures, where the second kinematic mount can be attached to a second substrate having a second array of active optical elements. Additionally, the first and second kinematic mounts, when mated, can align optical beams between the first array of active optical elements and the second array of active optical elements.

Abstract: A novel means of provided a hybrid flexure mounted moving mirror component in an interferometer is introduced herein. In particular, a linear bearing in combination with a novel flexure mounting having novel tilt and velocity control of the moving optical component is provided. Such an arrangement enables correction of the errors at the mirror itself while also solving the problem of isolating vibration and noise caused by the imperfections in the bearing surfaces used in many conventional interferometers. Using such a coupled flexure mounting of the present invention, in addition to the above benefits, also enhances velocity control because the resultant low mass of the moving mirror assembly enables the systems disclosed herein to respond faster than conventional mirror velocity controlled interferometer instruments and with a lower velocity error so as to provide a more stable and lower noise spectra from the analytical instrument.

Abstract: Localization and tracking system. The system includes at least one laser mounted for pointing its beam at arbitrary locations within a three-dimensional space. An object within the three-dimensional space supports a screen at its top for receiving the laser beam to create a shaped image on the screen. The shaped image on the screen is observed by a camera and computing apparatus determines the location of the object in the three-dimensional space from pointing parameters of the laser and from shape and center points of the shaped image on the screen.

Abstract: A volumetric error compensation measurement system and method are disclosed wherein a laser tracker tracks an active target as the reference point. The active target has an optical retroreflector mounted at the center of two motorized gimbals to provide full 360 degree azimuth rotation of the retroreflector. A position sensitive detector is placed behind an aperture provided at the apex of the retroreflector to detect the relative orientation between the tracker laser beam and the retroreflector by measuring a small portion of the laser beam transmitted through the aperture. The detector's output is used as the feedback for the servo motors to drive the gimbals to maintain the retroreflector facing the tracker laser beam at all times. The gimbals are designed and the position of the retroreflector controlled such that the laser tracker always tracks to a pre-defined single point in the active target, which does not move in space when the gimbals and/or the retroreflector makes pure rotations.

Abstract: Provided is an interferometer system that irradiates an object to be measured with measuring light to thereby measure the position of the object to be measured. The interferometer system includes a laser light source; an interferometer configured to separate laser light emitted from an emission opening of the laser light source into the measuring light and reference light; and an optical path protecting member configured to surround an optical axis such that the laser light passes through the inside thereof and of which one opening is in contact with the emission opening.

Abstract: Position detector for determining the rotation angle position of a rotatably supported object, comprising a light source for producing a light beam, a diffraction grating, a mirror which is connected with the object in a co-rotating manner in such a way that the light beam is reflected therefrom onto the diffraction grating and passes over the diffraction grating during a rotation of the mirror, thereby producing diffraction light, an interference device which is configured such as to be able to bring different diffraction orders of the diffraction light to interference, thereby producing an interference pattern, a light detector by means of which a brightness course, caused by the passing over of the diffraction grating with the reflected light beam, of the interference pattern can be detected, and an evaluation unit by which the rotation angle position of the object can be determined based on the brightness course.

Abstract: A stage metrology suitable for REBL includes an interferometer stage metrology system configured to measure the position and rotation of a short-stroke wafer scanning stage, wherein the interferometer metrology system includes two or more interferometers for each axis of measurement, wherein a first interferometer mirror is disposed on a first surface of the short-stroke wafer scanning stage and a second interferometer mirror is disposed on a second surface of the short-stroke wafer scanning stage, and a control system configured to determine a shape error for the first interferometer mirror using two or more interferometer measurements from the two or more interferometers associated with the first interferometer mirror and a shape error for the second interferometer mirror using two or more interferometer measurements from the two or more interferometers associated with the second interferometer mirror.

Abstract: A method for machine measurement for an NC processing machine is provided. The processing machine has a machine head, for example, a fork head and an associated mechanical and electrical spindle changing interface for holding a motor spindle. A laser interferometer with a beam generator and a beam detector is also provided and at least one measurement optic which interacts with the laser interferometer, for example, in the form of a reflector, and laser interference measurements, which are directed at a measurement optic, in particular distance measurements, carried out for machine measurement. The laser interferometer has an interface which corresponds to the spindle changing interface, and the laser interferometer is substituted for the motor spindle via the spindle changing interface for machine measurement, and is aligned by means of the machine axes for the laser interference measurements.

Abstract: Methods and apparatus are provided for the alignment of an interferometric system. A spatial filter comprising a reflective pinhole is provided at the output of the interferometer, and tilt is measured by a tilt detection subsystem positioned to reimage the pinhole. A shear detection subsystem is positioned to image an offset of the interferometer beams. Tilt and shear offsets are determined by comparing measurements obtained from the tilt and shear subsystems with pre-recorded measurements obtained for an aligned state. The tilt and shear offsets are employed to realign the system using positioning controls corresponding a reduced number of dominant degrees of freedom of the system.

Abstract: A method for correction of the measured values of optical alignment systems with at least two measurement planes which are located in succession in the beam path. From each measurement plane, the beam path to the light source is transformed back in order to compute new incidence points using a beam which has been corrected by taking into consideration imaging errors.

Abstract: A projection exposure tool for microlithography for imaging mask structures of an image-providing substrate onto a substrate to be structured includes a measuring apparatus configured to determine a relative position of measurement structures disposed on a surface of one of the substrates in relation to one another in at least one lateral direction with respect to the substrate surface and to thereby simultaneously measure a number of measurement structures disposed laterally offset in relation to one another.

Abstract: A method for determining an offset between a center of a substrate and a center of a depression in a chuck includes providing a test substrate to the depression, the test substrate having a dimension smaller than a dimension of the depression, measuring a position of an alignment mark of the test substrate while in the depression, and determining the offset between the center of the substrate and the center of the depression from the position of the alignment mark.

Abstract: A system for performing alignment of two wafers is disclosed. The system comprises an optical coherence tomography system and a wafer alignment system. The wafer alignment system is configured and disposed to control the relative position of a first wafer and a second wafer. The optical coherence tomography system is configured and disposed to compute coordinate data for a plurality of alignment marks on the first wafer and second wafer, and send that coordinate data to the wafer alignment system.

Abstract: An image sensor for fringe images of interference fringes and the like in which the optical system has a simpler configuration than that of the conventional line image sensor, and faster detection becomes possible includes a light receiving plane on which two or more straight rows of pixels are disposed, and captures images of regular fringes generated from light reflected from an irradiated body in accordance with the amount of light received by each pixel; among the rows of pixels, at least two rows of pixels are disposed at right angles to each other, and acquires images of linear fringes crossing almost at right angles in two directions among the fringe projected onto the light receiving plane.

Abstract: A position detection apparatus that illuminates diffraction gratings formed on two objects with light from a light source and receives diffracted light from the diffraction gratings to acquire relative positions of the two objects includes: an optical system configured to cause plus n-th order diffracted light and minus n-th order diffracted light from each of the diffraction gratings to interfere with each other, where n is a natural number; a light receiving unit; and a processing unit, wherein the light receiving unit receives a two-beam interference light from each of the diffraction gratings, and wherein the processing unit acquires the relative positions of the two objects by using the two-beam interference light at an area where two-beam interference lights of the diffracted light from the respective diffraction gratings do not overlap each other among the two-beam interference lights of the diffracted light from each of the diffraction gratings.

Abstract: A position measurement apparatus that measures a position of an object using a reference mark includes a first illumination optical system configured to illuminate the object using measurement light from a light source which emits light of a first wavelength band, a second illumination optical system configured to illuminate the reference mark using reference light of a second wavelength band, and a position measurement unit configured to detect light from the object and light from the reference mark and to obtain the position of the object based on the detection result, and the second wavelength band of the reference light is set between an upper limit and a lower limit of the first wavelength band of the measurement light from the light source.

Abstract: The present patent application provides an interference cavity for precisely controlling an optical path including a cavity formed by two equal distance arms, wherein a positive adjusting plate and a negative adjusting plate are disposed in the interference cavity for compensating the change of a cavity length with temperature and thereby ensuring that the interference cavity length is a constant. The present patent application utilizes the matching relationship between the change of the refractive index of the positive adjustment plate with the temperature and the change of the refractive index of the negative adjusting plates with the temperature to make the optical path difference OPL invariant with changes in the environment temperature and thereby to ensure the precision of the optical path.

Abstract: The general field of the invention is that of optical systems for detection of the orientation of mobile objects in space. The main application is helmet posture detection inside of an aircraft cockpit. The system according to the invention operates by interferometry. It comprises a fixed electro-optical device comprising one or more collimated point-like emission sources and a detection assembly comprising one or more point-like photosensitive detectors. Two or more retro-reflecting devices referred to as “cube corner” are disposed on the mobile object. This system can be completed by optical means operating in polarized light mode allowing the direction of variation of the interference fringes to be determined and by other optical devices allowing an initial orientation to be measured.

Abstract: Provided is a semiconductor apparatus. The semiconductor apparatus includes a reference grating and a plurality of detectors. The reference grating diffracts an optical signal generated by being reflected from the alignment grating of a substrate to diffraction beams with different orders. The plurality of detectors measure intensities of a plurality of diffraction beams selected from the diffraction beams, respectively.

Abstract: A method of measuring a phase difference between two regions in an aberration function: Reference structures are produced on a substrate using illumination that minimizes effects of phase aberration. A grating is produced on the substrate using a phase-shift grating reticle to produce, in the exit pupil, a pair of diffracted non-zero orders, while forbidding other diffracted orders and produces interference fringes formed by interference between the pair. The interference contributes to a first grating on the substrate. Overlay error is measured between the grating and the reference structure using diffraction-based or image-based overlay measurements. A phase aberration function for the exit pupil of the lithographic apparatus can then be determined from the measured overlay errors.

Abstract: A detection apparatus determines an amount of relative rotational deviation between two different objects. Each of the objects has a respective grating mark which together form a pair of grating marks. The detection apparatus includes a detector that detects interference fringes produced by an overlap between the pair of grating marks. The detection apparatus also includes a calculation unit that determines the amount of relative rotational deviation between the two different objects from inclination of the interference fringes detected by the detector. The detection apparatus can be applied, for example, in controlling transfer of a pattern formed on a mold to a transfer material applied to a substrate.

Abstract: A mirror (M) of a projection exposure apparatus for microlithography configured for structured exposure of a light-sensitive material and a method for producing a mirror (M). The mirror (M) has a substrate body (B), a first mirror surface (S) and a second mirror surface (S?). The first mirror surface (S) is formed on a first side (VS) of the substrate body (B). The second mirror surface (S?) is formed on a second side (RS) of the substrate body (B), the second side being different from the first side of the substrate body (B). The mirror (M) may be embodied, in particular, such that the substrate body (B) is produced from a glass ceramic material.

Abstract: A correction algorithm may be applied for correcting misalignment of a radially-aligned array of sensors. Due to the tilt, signals from sensors that are further away from the media, may become slightly attenuated, while signals from sensors that are closer to the media are slightly increased. The error appears periodic and largely sinusoidal in nature around the array given the circular nature of the array of sensor elements. The algorithm determines the magnitude and phase of a sinusoidal function that best fits the wavelength data. In one embodiment, a discrete Fourier transform may be performed at the ‘frequency’ equivalent to one period around the array to determine the magnitude and phase estimate thereof. Then, a sinusoidal correction function may be generated using the magnitude and the phase in order to correct the reflectance data.

Abstract: In general, in a first aspect, the invention features a system including an interferometer configured to direct test light to an overlay target and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source, a multi-element detector, one or more optics to image the overlay target on the multi-element detector; and an electronic processor in communication with the multi-element detector. The overlay target includes a first pattern and a second pattern and the electronic processor is configured to determine information about the relative alignment between the first and second patterns.

Abstract: Systems are disclosed that include an interferometer configured to direct test light to an overlay test pad and subsequently combine it with reference light, the test and reference light being derived from a common source, one or more optics configured to direct at least a portion of the combined light to a multi-element detector so that different regions of the detector correspond to different illumination angles of the overlay test pad by the test light, the detector being configured to produce an interference signal based on the combined light, and an electronic processor in communication with the multi-element detector. The overlay test pad comprises a first patterned structure and a second patterned structure and the electronic processor is configured to determine information about the relative alignment between the first and second patterned structures based on the interference signal.