Abstract: Described are LiDAR systems comprising a transmission optical system and a collection optical system utilizing a common lens or pieces derived from the same lens to reduce or eliminate image mismatch between the transmission optical system and the collection optical system.

Abstract: An optical detecting device capable of detecting a lift height of an optical navigation apparatus is disclosed. The optical detecting device includes a sensor module and a processor. The sensor module includes a sensor array and at least one detector strip. The sensor array is adapted to acquire navigation information of the optical navigation apparatus moved relative to a working surface by sensing an illumination area, and the detector strip has a detection region across an edge of the illumination area. The processor is electrically connected to the sensor module, and adapted to compute the lift height of the optical navigation apparatus relative to the working surface according to a detection result of the detector strip.

Abstract: A sensor system to provide data for use to control manufacture of an optical fiber in microgravity including a diameter sensor to monitor a diameter of a fiber drawn from a preform material, a tension sensor to monitor tension of the fiber as the fiber is pulled from the preform material to a storage device and a controller in communication with at least one of the diameter sensor and the tension sensor to evaluate sensor data to determine at least one of a speed and rate at which the fiber is pulled from the preform material.

Abstract: An image forming device includes: an image forming unit that forms an image on a transfer medium; and a controller that controls multiple image readers capable of performing image reading for the same surface of the transfer medium, and acquires reading results from the image readers. The controller is capable of performing failure/no-failure determination for the image on the transfer medium based on the reading results, of switching image reading by the multiple image readers between reading by a first number of image readers and reading by a second number of image readers, the second number being smaller than the first number, and of enabling, while the second number of image readers perform reading, at least one of the other image readers to execute a maintenance operation for the at least one of the other image readers.

Abstract: A forming tool detection device includes a reflector module, an image sensor and a backlight module respectively disposed on both sides of the reflector module with a detection space formed between the backlight module and the reflector module for the insertion of a forming tool for detection. The reflector module focuses the light projected by the backlight module and reflects the focused light toward the backlight module and is provided with a hollow portion for the image sensor to capture an image of the forming tool. The reflector module is used to reflect the light emitted by the backlight module so that the tool image captured by the image sensor can detect the length and outer diameter of the forming tool, thereby simplifying the tool detection process.

Abstract: A sensor mounting apparatus and methods for determining level, volume, or both of contaminated cuttings in a cuttings skip includes a collar having a body having a longitudinal axis, a first end, a second end, and a sidewall connecting the first and second ends, the sidewall parallel to the axis, the sidewall having an external surface and an internal surface, the internal surface defining a longitudinal bore through the coupling configured to allow material to flow there through. The apparatus includes a sensor receiver in the sidewall that holds a TOF sensor, the sensor receiver extending from the external surface to the internal surface of the collar, the sensor receiver having an axis skewed at an angle from the sidewall of the body. Fasteners on the first and second ends allow them to be fastened to a fill hose or chute and to a fill opening for the cuttings skip.

Abstract: Described herein are systems and methods that may efficiently detect multi-return light signals. A light detection and ranging system, such as a LIDAR system, may fire a laser beam that may hit multiple objects with a different distance in one line, causing multi-return light signals to be received by the system. Multi-return detectors may be able to analyze the peak magnitude of a plurality of peaks in the return signals and determine a multitude of peaks, such as the first peak, the last peak and the maximum peak. One embodiment to detect the multi-return light signals may be a multi-return recursive matched filter detector. This detector comprises a matched filter, peak detector, centroid calculation and a zeroing out function. Other embodiments may be based on a maximum finder that algorithmically selects the highest magnitude peaks from samples of the return signal and buffers for regions of interests peaks.

Abstract: An image reading apparatus comprises a platen, a support, a reader, an open/close unit, a first obtainer, a mark, a positioning member, and a determiner. A position of the mark on a pressing surface of the cover, is provided at a position at which, in a case where a sheet of a maximum size among standard sizes that can entirely fit in a readable range of the reader is positioned with respect to the positioning member, at least a portion of the mark is not hidden by the sheet as viewed from the reader.

Abstract: Methods and systems for measuring process induced errors in a multiple patterning semiconductor fabrication process based on measurements of a specimen and process information from one or more previous process steps employed to fabricate the specimen are presented herein. A metrology tool is employed after a number of process steps have been executed. The metrology tool measures structural parameters of interest of metrology targets on the wafer based on measured signals and process information, and communicates correctable process parameter values to one or more process tools involved in the previous process steps. When executed by the appropriate process tool, the correctable process parameter values reduce process induced errors in the geometry of the structures fabricated by the process flow. In another aspect, multiple metrology tools are used to control a fabrication process in combination with process information from one or more process steps in the process flow.

Abstract: The present application relates to road traffic monitoring to detect the number, speed and/or type of vehicles travelling on a road. Noise features (104) are deployed on, or formed in, the surface of a road (101). The noise feature (104) is arranged to generate a characteristic acoustic signature when traversed by the wheels of a vehicle (105) travelling within a lane of the road. A distributed acoustic sensor (102, 103) is deployed to detect occurrences of the characteristic acoustic signature. In some embodiments the noise element may comprise at least two distinct elements (104a, 104b), for instance rumble strips arranged transversely to the road, which are a known distance apart along the road. The acoustic signals from a wheel crossing both elements can be detected and used to determine the vehicle speed. The number of vehicle axles and axle separation can also be determined to categorize the type of vehicle.

Abstract: In a case where a user places a document placed on a document positioning glass plate without sufficiently opening an automatic document feeding device, sheet size information will not be reset and an image may be read based on incorrect size information. Therefore, in the present invention, an angle at which the size information is reset is set to an angle between a first angle at which the automatic document feeding device is closed, and a second angle (?1) at which the automatic document feeding device is moved to open automatically after being released from a holding state by a holding unit.

Abstract: There are included a probe that can be arranged in an imaging field of view, a horizontal drive section for causing the probe to contact a side surface of a workpiece on a stage, a display section for displaying a model image, a contact position designation section for receiving designation of contact target position information in the model image, a characteristic amount information setting section for setting characteristic amount information, a measurement setting information storage section for storing a plurality of pieces of contact target position information and the characteristic amount information, and a measurement control section for identifying a position and an attitude of the workpiece from a workpiece image by using the characteristic amount information, for identifying a plurality of contact target positions on the side surface of the workpiece where the probe should contact, based on the identified position and the identified attitude of the workpiece.

Abstract: There are included a display section for displaying a model image, an input receiving section for receiving designation, in the model image, of a measurement element for which measurement is to be performed by the probe, a storage section storing, in advance, an arrangement rule defining a relationship between a shape type or a size of a measurement element and arranged positions of contact target positions of the probe, and a measurement control section for identifying, at a time of measurement execution, contact target positions of the probe based on a position of the measurement element designated by the input receiving section, a shape type or a size of the measurement element, and the arrangement rule that is stored in the storage section, and for controlling a horizontal drive section so that the probe sequentially moves to the plurality of contact target positions identified.

Abstract: Examples disclosed herein relate to classifying paper based on three-dimensional characteristics of the paper. For example, a representation of the three-dimensional characteristics of the paper may be created, and statistical summary information related to the three-dimensional characteristics of the paper may be determined based on the representation. The paper may be classified based on the statistical summary information.

Abstract: The dimensions of an object are measured as it is transported by a forklift within an area of measurement. A first scanner is on a first side of the area of measurement; a second scanner is on an opposite second side and across the first scanner. The first and second scanners provide a dual-head scanner arrangement to capture dimensions of the object. A third scanner is on the first side of the area of measurement, parallel to the first scanner. The first and third scanners are configured to capture speed and direction of the object. Each scanner has a processor to operate it. The first and second scanners are synchronized, and operation of the first and third scanners is correlated. Placement of the first and second scanners establishes a width of the area of measurement and the first and third scanners establish a length thereof.

Abstract: A method to extend the downstream and upstream data carrying capability of an HFC CATV system. At the neighborhood level, the CATV cable (the primary channel) is divided into different segments connected by electrically active junctions. At the junctions, each segment is also connected to a secondary data channel, such as an optical fiber or ultrahigh RF frequency (1 GHz+) secondary channel, which can carry supplemental downstream narrowcast channels and upstream channels between a plurality of such CATV cable segments. At the junctions, some CATV primary channel RF signals such as broadcast channels are passed without interference, while certain primary channel downstream narrowcast RF channels and upstream narrowcast RF channels are precisely suppressed using adaptive cancelling methods. Such adaptive cancellation methods are superior to prior art lowpass, highpass, and bandpass filtering methods because they allow for more efficient use of limited CATV primary channel RF spectrum.

Abstract: A method for determining a distance between two spatial points, thus between a first point and a second point, includes recording a first picture from a first viewing point, wherein the first picture includes a reference object and the first point, recording a second picture for a second viewing point, wherein the second picture includes the reference object and the second point and wherein the second viewing point is different than the first viewing point and finally determining the distance between the first point and the second point from picture data of the first picture and picture data of the second picture using a known dimension of the reference object. Thereby, the first point and/or the second point can be arranged outside a plane encompassing the reference object.

Abstract: An image reading apparatus includes an apparatus body, a document sheet cover, a magnetic force generating portion, and a magnetic force control portion. The apparatus body has a document placement surface. The document sheet cover is supported by the apparatus body so as to be pivotable between an open position where the document placement surface is uncovered and a closed position where the document placement surface is covered with the document sheet cover. The magnetic force generating portion is able to selectively generate a magnetic attraction force and a magnetic repulsion force between a pair of a permanent magnet and an electromagnet provided in the cover portion and the apparatus body, respectively. The magnetic force control portion switches the magnetic force generating portion between a state where the magnetic force generating portion generates the attraction force and a state where the magnetic force generating portion generates the repulsion force.

Abstract: An optical measuring apparatus includes a light emitter, a scanner, a polarizing plate, a photoreceiver, and a CPU. The light emitter emits a laser beam. The scanner uses the laser beam emitted from the light emitter and scans a measurement region where a work piece is placed. The polarizing plate allows passage for only a laser beam, among the laser beams fired by the scanner, directed orthogonally to an emission direction of the laser beam and an axis direction of the work piece. The photoreceiver receives the laser beam that has passed through the measurement region and the polarizing plate. The CPU calculates a dimension of the work piece from a pattern of light and dark in a scan direction, the pattern being obtained by the photoreceiver.

Abstract: A method including providing a device that projects a pattern of coherent radiation. The method further includes capturing a reference image of the pattern using an image sensor by projecting the pattern of the coherent radiation onto a reference surface and engendering a relative motion between the reference surface and the image sensor while capturing the reference image. The method also includes storing the reference image in a memory associated with the device.

Abstract: Described is a technology for measuring ink film thickness by use of differential lighting between two differently positioned light sources. The technology involves an image capture device, a first set of light emitting diodes (LEDs), and a second set of LEDs, where the image capture device is attached to a printer. The first set of LEDs is positioned in parallel to an image capture axis to illuminate a target object evenly from above with a light perpendicular to the target object (e.g., substrate with deposited ink droplets). The second set of LEDs is positioned to illuminate the target object at an angle, thereby casting a shadow. The image capture device takes two snapshots of the target object, utilizing a different light source (of the two sets of LEDs) for each snapshot. The snapshots are compared to determine the shadow's magnitude and the ink film thickness based on the shadow.

Abstract: A wafer crack detection system includes a rotational wafer stage assembly configured to secure a wafer and selectively rotate the wafer, a light source positioned on a first side of the wafer and configured to direct a light beam through the wafer, a sensor positioned on a second side of the wafer and configured to monitor one or more characteristics of light transmitted through the wafer as the wafer is rotated, and a controller communicatively coupled to the sensor and a portion of the rotational wafer stage assembly, the controller configured to: determine the presence of one or more cracks in the wafer based on the monitored one or more characteristics of light transmitted through the wafer, and, responsive to the determination of the presence of one or more cracks in the wafer, direct the rotational stage assembly to adjust the rotational condition of the wafer.

Abstract: Disclosed is a volume sensor having first, second, and third laser sources emitting first, second, and third laser beams; first, second, and third beam splitters splitting the first, second, and third laser beams into first, second, and third beam pairs; first, second, and third optical assemblies expanding the first, second, and third beam pairs into first, second, and third pairs of parallel beam sheets; fourth, fifth, and sixth optical assemblies focusing the first, second, and third beam sheet pairs into fourth, fifth, and sixth beam pairs; and first, second, and third detector pairs receiving the fourth, fifth, and sixth beam pairs and converting a change in intensity of at least one of the beam pairs resulting from an object passing through at least one of the first, second, and third parallel beam sheets into at least one electrical signal proportional to a three-dimensional representation of the object.

Abstract: A two-dimensional light-section method for measuring the profile geometry of cylindrical bodies is disclosed. A fan-shaped laser line forming a light-section line on the surface of the body is imaged with at least one laser, and the laser radiation reflected from the surface of the body is captured by at least one area imaging camera, wherein the laser and the camera are arranged at a triangulation angle in a normal plane aligned with the cylinder axis. The profile geometry is then measured by pivoting the laser out of the normal plane about the cylinder axis. The angle with respect to the normal plane is selected such that the optical axis of the area imaging camera with respect to the surface of the cylinder is located within the glancing angle range of the reflected beams.

Abstract: A paper size detection device includes a central switch, at least two switches disposed to two opposite sides of the central switch at intervals, and at least a sensor corresponding to the two switches located at the two opposite sides of the central switch. The sensor can be designated as a light sensor. One switch triggers the sensor and the other switch is without triggering the sensor under an original no paper condition. So that a detection method of the paper size detection device that uses N light sensors to judge N*2 papers' size can be realized by virtue of the above-mentioned setting structure, N is a positive integer, such as 2, 3, 4 and so on. Thus, the paper size detection device has a simple structure and a lower manufacture cost, and the detection method of the paper size detection device is simplified, accordingly.

Abstract: Apparatus is provided for slitting composite material int1aaaaaaaaaaao tape and for measuring the width of the slit tape as the tape is being reeled onto take up rolls. The tape width is measured by an optical micrometer. The optical micrometer includes a transmitter for directing radiant energy over the tape and, a receiver for receiving radiant energy from the transmitter that passes across an edge of the tape and for producing a signal related to the width of the tape.

Abstract: A method and system for automatically inspecting parts and for automatically generating calibration data for use in inspecting parts are provided. The system includes a support for supporting a part to be inspected and/or a calibration device along a measurement axis. The system further includes a head apparatus including a plurality of radiation plane generators for directing an array of planes of radiation at the part and/or device so that the part and/or device occludes each of the planes of radiation to create a corresponding array of unobstructed planar portions of the planes of radiation. Each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part and/or device. The head apparatus further includes a plurality of radiation plane receivers or cameras such as line scan cameras.

Abstract: The invention relates to a device (1) for measuring the width (B) and/or the position of a metal strip (2) or a slab, which has at least two measuring systems (3, 4), with each located on a side (5, 6) of the metal strip (2) or the slab, wherein each measuring system (3, 4) has a sensor (7) designed to detect the lateral end (8, 9) of the metal strip (2). To make the measuring device robust and to enable dynamic measurement, according to the invention the sensor (7) is located on a moving element (10) with which it can be moved in a straight line in a direction (Q) at right angles to the longitudinal direction (L) of the metal strip (2).

Abstract: In some embodiments, an inspection system for measuring at least a portion of the threaded surface of an internally threaded component includes at least one measuring probe, a component retention device that allows positioning of the internally threaded component relative to the measuring probe and a processing device in signal communication with the measuring probe to receive threaded surface data therefrom.

Abstract: By encoding process-related non-uniformities, such as different height levels, which may be caused by CMP or other processes during the fabrication of complex device levels, such as metallization structures, respective focus parameter settings may be efficiently evaluated on the basis of well-established CD measurement techniques.

Abstract: An apparatus and method for detecting a difference in width of a strip of material from a desired width of material. The apparatus may comprise a light source, a light detector, an alarm, a first fiber optic cable coupled with the light source, a second fiber optic cable coupled with the light detector, and a housing. The housing may comprise a material slot for passing the strip of material therethrough such that edges of the strip of material may at least partially intersect a plurality of light fields directed from the first fiber optic cable to the second fiber optic cable. The amount of light detected by the light detector is dependant on the amount of light blocked by the strip of material. If the amount of light received is outside of a range of tolerance from the desired width of material, the alarm may be actuated.

Abstract: A method of quantifying a shape of a surface includes measuring an elevation (z) of the surface at a plurality of locations in an x-y plane of the surface. The measurement data is fit to a series expansion in terms of one or more base functions that include a series expansion fit. A vector of shape coefficients are calculated from the series expansion fit. A vector of shape coefficients are output.

Abstract: A method of checking the height of a mail item relative to at least one dimensional threshold SH defining a change in postage. The mail items are advanced at a constant speed V along a reference surface. The presence of a mail item is detected relative to a given point of the reference surface. First and second times t1, t2 for which the same mail item is present at the first and second distances d1, d2 relative to the reference surface is detected. The ratio t2/t1 is compared with a value equal to (1??), where ? represents a correction coefficient of less than 1 that depends on the tolerances for detection of the presence of a mail item. The height of a mail item is considered greater than the dimensional threshold SH if, and only if, the relationship t2/t1>1?? is true.

Abstract: A manufacturing process for sheet or shaped work products includes advancing the work product in a direction along a processing path; establishing a reference line with respect to the processing path; capturing visual data related to the work product; converting the visual data into a pixel array; and setting a predetermined line of pixels to correspond with the reference line.

Abstract: A method and inspection head apparatus for optically measuring geometric dimensions of a part are provided. The method optically measures the geometric dimensions of a part having a part axis at an inspection station. The method includes directing an array of spaced planes of radiation at the part so that the part occludes each of the planes of radiation at spaced locations along the part axis to create a corresponding array of unobstructed planar portions of the planes of radiation. Each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part. The method further includes measuring the amount of radiation present in each of the unobstructed planar portions.

Abstract: A method for measuring non-circularity of a core part of an optical fiber base material having the core part and a clad part includes immersing the optical fiber base material in liquid having a refractive index substantially equal to that of the clad part of the optical fiber base material; irradiating parallel light from a side face of the optical fiber base material to measure intensity distribution of transmitted light; measuring a width of a dark space caused by light passing the core part on intensity distribution to obtain a relative value for a core diameter; rotating the optical fiber base material to further obtain the relative value for the core diameter at plural points for a circumferential direction; and obtaining non-circularity of the core part based on the obtained plurality of relative values for the core diameter.

Abstract: A detecting apparatus includes a detecting plate, a controlling box, and an indicator installed on the detecting plate. A region is defined on one face of the detecting plate, for supporting a workpiece thereon, with an edge of the workpiece abutting against one side of the region. A first slot and a second slot are defined in the detecting plate on an opposite side of the region. The controlling box having a circuit board with a processor is installed on an opposite face of the detecting plate. Two light sensors are installed on the circuit board aligning with the first and second slots of the detecting plate respectively. The indicator is electrically connected with the light sensors and controlled by the processor, for showing whether the dimension of the workpiece is eligible, according to detection by the light sensors.

Abstract: Apparatus is provided for slitting composite material into tape and for measuring the width of the slit tape as the tape is being reeled onto take up rolls. The tape width is measured by an optical micrometer. The optical micrometer includes a transmitter for directing radiant energy over the tape and, a receiver for receiving radiant energy from the transmitter that passes across an edge of the tape and for producing a signal related to the width of the tape.

Abstract: One embodiment relates to a method of automated microalignment using off-axis beam tilting. Image data is collected from a region of interest on a substrate at multiple beam tilts. Potential edges of a feature to be identified in the region are determined, and computational analysis of edge-related data is performed to positively identify the feature(s). Another embodiment relates to a method of automated detection of undercut on a feature using off-axis beam tilting. For each beam tilt, a determination is made of difference data between the edge measurement of one side and the edge measurement of the other side. An undercut on the feature is detected from the difference data. Other embodiments are also disclosed.

Abstract: There is provided an edge position detecting apparatus that includes a reflective optical sensor that outputs light to a supporting surface of a supporting member, and receives a reflected light; a moving unit that moves the reflective optical sensor; a reflected light data generating unit that generates reflected light data by obtaining a light-receiving signal; and a detecting unit that detects an edge position of the target detection object. The reflected light data generating unit generates the reflected light data when the target detection object is/is not supported by the supporting member. The detecting unit detects the edge position based on a relative change between a first and a second reflected light data. The first reflected light data is generated when the target detection object is supported by the supporting member. The second reflected light data is generated when the target detection object is not supported by the supporting member.

Abstract: A resolution enhanced optical metrology system to examine a structure formed on a semiconductor wafer includes a source configured to direct an incident beam at the structure through a coupling element. The coupling element is disposed between the source and the structure with a gap having a gap height defined between the coupling element and the structure.

Abstract: Method for measuring the cross-sectional dimension of an elongated profile having rounded or sharp edges, in particular of a flat or sector cable by illuminating the article with light sources and determination of a plurality of shadow borders and calculating the parameter of the circle from the coordinates of the light sources and the shadow borders. The dimensions are determined from the circular parameter.

Abstract: An optical measuring device capable of improving the precision of detection of contamination on a protective glass is disclosed. With threshold values as large as 90%, 50%, 10% of a peak value of a scan signal, measured values Q90, Q50, Q10 of a dimension of a work to be measured are derived, respectively. It is determined whether a difference between the measured value Q90 and the measured value Q50 (or a variation of the measured value) is equal to or larger than a predetermined reference value. (B)-(D) show the presence of contamination on the protective glass, equal to or larger than the reference value. (A) shows the absence of contamination, lower than the reference value. It is then determined whether a difference between the measured value Q50 and the measured value Q10 is equal to or larger than a predetermined reference value. (D) shows the presence of thick contamination on the protective glass, equal to or larger than this reference value.

Abstract: An inspection system and a method for using the inspection system, wherein the inspection system includes a collimated light source defining a source optical path, the collimated light source being operable to cause a collimated light beam to propagate along the source optical path, a sensing device defining a sensor optical path, the sensor optical path being substantially perpendicular to the source optical path, a reflecting device disposed within the source optical path to receive the collimated light beam, the reflecting device causing a reflected collimated light beam to propagate along the sensor optical path to the sensing device and a retention mount, the retention mount being disposed within the sensor optical path such that when a component is retained within the retention mount, the component blocks at least a portion of the reflected collimated light beam.

Abstract: The present invention provides a system and a method to grade a piece of wood and simultaneously to classify this piece of wood by allowing an examination of four longitudinal faces thereof, so as to determine optimal specifications for a subsequent use thereof such as shaving, trimming ends, and other applications. The system comprises a structure, a transversal conveyor, a vision unit and a processing unit. The vision unit is partly located above the conveyor in an inclined plane, collecting data on a lateral and upper longitudinal face of an object as the object moves with the conveyor, and partly located under the conveyor, at an angle therewith, collecting data from a complementary lateral longitudinal face of the object as well as from an inferior longitudinal face thereof, as the object moves with the conveyor. The system allows classification of wooden pieces according to predetermined standards, at a rate of 200 pieces per minute with a margin of error less than or equal to 2%.

Abstract: What is disclosed: is a media width detecting apparatus comprising: a first media detecting section to detect media, a second media detecting section put downward from said first media detecting section, to detect media; wherein said second detecting section decide range to detect media according to result of detection by said first media detecting section.

Abstract: The invention relates to a method and to an apparatus for the detection of objects moved on a segmented conveyor means by means of an optoelectronic sensor, in which in each case the geometric center of the objects is determined via the optoelectronic sensor, whereupon the objects are each associated with that conveyor segment in the region of which the respectively determined geometric center is located. The invention further relates to a method and to an apparatus for the determination of the dimensions of objects moved on a conveyor means by means of an optoelectronic sensor, in which the dimensions of the objects are detected and corresponding.

Abstract: Tracking separation between an object and a surface involves illuminating the surface and reducing the collection angle of light that reflects off of the surface in response to a change in separation between the object and the surface. Reducing the collection angle of light that reflects off of the surface causes the amount of light that is detected to be dependent on the separation distance between the object and the surface. The amount of detected light is then used as an indication of the separation distance.

Abstract: A plurality of microswitches are arranged in a photosensitive material receiving section in a row, in a direction perpendicular to the travel direction of a printing plate. The printing plate is carried while being centered with respect to a center of a transport path. The plurality of microswitches are arranged in an asymmetrical manner with respect to the center of the transport path. Thus the width of a photosensitive material can be precisely calculated with a small number of microswitches. Further, deviation of the photosensitive material from the center of the transport path can be easily detected.

Abstract: A method of analyzing structural characteristics of sidewall spacers fabricated on a wafer is disclosed. A grating bar having a plurality of grating targets is provided. A theoretical optical scatterometry spectrum is generated by subjecting the grating targets to optical scatterometry. An experimental optical scatterometry spectrum is generated by subjecting the sidewall spacers on the wafer to optical scatterometry. The structural characteristics of the sidewall spacers are equated with the structural characteristics of the grating targets when the theoretical optical scatterometry spectrum substantially matches the experimental optical scatterometry spectrum.