Abstract: An method for measuring an optical thickness of a test object, the method includes: interfering a first optical wave front from the test object and a second optical wave front from a reference surface to produce an interference signal; for a selected location on the test object, obtaining an interference pattern of the test object at a first wavelength &lgr;1; for the selected location, calculating a first estimate of the optical thickness from the interference pattern recorded at wavelength &lgr;1; for the selected location obtaining an interference pattern of the test object at a second wavelength &lgr;2; for the selected location, calculating a second estimate of the optical thickness from the interference pattern recorded at wavelength &lgr;2; and for the selected location, calculating a third estimate of the optical thickness by combining the first and second estimates of optical thickness.

Abstract: Process for measuring distances by optical means on a specular or quasi-specular strip (1) of bright metal, characterised by the following steps:

Abstract: A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1−n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

Abstract: A wavelength determining apparatus for thin film thickness monitoring light so as to determine the wavelength of the monitoring light which is projected to an optical thin film under deposition and transmitted through or reflecting from the optical thin film, comprising a means, related to optical intensity change of the monitoring light, to calculate a first stopping index value to stop deposition of said optical thin film whose thin film thickness reaches desired thin film thickness in each nominated wavelength of the plural monitoring light, and a means to determine the nominated wavelength of the monitoring light in the plural monitoring light based on the first stopping index value of each calculated nominated wavelength.

Abstract: The present invention is to a method for measuring the thickness of a layer on an object during a layer-depositing process, and a device by which the method can be realized. In the method, a diffraction object having at least two opposing diffracting limits at a known spacing, is positioned in such a way that a layer is deposited or absorbed at the diffracting limits of the diffraction object, whose thickness of layer has a known relationship with the thickness of the layer on the object. The diffracting limits of the diffraction object are projected by a coherent light pencil on a detection surface. The local intensity distribution, which is induced by diffraction on the detection surface, is detected and computed from the intensity distribution of the thickness of the layer. The method permits the detection of the thickness of thin layers during the layer-depositing process independently of the parameters of the material and with a high precision.

Abstract: An anodizing system for forming a anodized coating on at least a portion of a substrate thereby creating an anodized substrate is disclosed. The anodizing system includes a bath, a coating thickness monitor, at least one probe and at least one controller. The coating thickness monitor includes at least one radiation source directed at at least a portion of the anodized substrate; at least one probe for capturing at least a portion of the radiation reflected and refracted by the anodized coating on the anodized substrate, the captured radiation being at least a portion of the radiation directed the anodized substrate from the radiation source; and at least one detector in communication with the at least one probe, the at least one detector capable of processing the captured radiation to allow a determination of at least the thickness.

Abstract: A system and method for testing a physical attribute of a manufactured object that includes a laser generator and pulse generator that generate a plurality of Dirac-like pulses. The pulses, directed at an object, cause a sonic signal to be initiated indicative of the physical attribute of the manufactured object, and are detected. The system also controls the width of the Dirac-like pulses and time separation between pulses. A display may also be used to present the detected signal or physical attribute. The Dirac-like pulses are structured to produce a particular output in the manufactured object. The Dirac-like pulses may be altered dynamically in the presence of deviations from the expected output. One embodiment of the Dirac-like pulses is a series of pulses with pulse widths less than 20% a time separation between successive pulses.

Abstract: The present invention relates to a method of determining a thickness of at least one layer on at least one semiconductor wafer (12), comprising the steps of: projecting a first laser pulse (14) on a surface (16) of the at least one layer (10), thereby generating an acoustical wave due to heating of the surface of the at least one layer (10); after a propagation time of the acoustical wave, projecting a series of second laser pulses (18) on the surface (16) of the at least one layer (10); measuring reflected laser pulses (20) of the second laser pulses (18), thereby sensing the times of reflection property changes of the surface (16) of the at least one layer (10); and determining the thickness of the at least one layer (10) by analyzing the times of reflection property changes. The present invention further relates to a system for determining a thickness of a layer (10) on a semiconductor wafer (12).

Abstract: A method of determining thickness and refractive index of an optical thin film is described. The method includes generating a diagnostic light beam having a first and a second wavelength. The method also includes measuring unattenuated light intensities at the first and the second wavelength of the diagnostic light beam. The method also includes measuring attenuated light intensities at the first and the second wavelength of the diagnostic light beam after transmission through the optical thin film. A null light intensity for the diagnostic light beam at the first and second wavelength is also determined. A first and second normalized intensity function is determined using the measured unattenuated light intensities, the measured attenuated light intensities, and the measured null light intensities. The thickness and refractive index of the optical thin film is then determined by solving the first and second normalized intensity function for thickness and refractive index.

Abstract: One aspect of the present invention relates to a method to facilitate formation of an oxide portion of an anti-reflective layer on a substrate. The method involves the steps of forming an oxidized portion of an anti-reflective coating over an anti-reflective layer disposed on the substrate; reflecting a beam of x-ray radiation at the oxidized portion; generating a measurement signal based on the reflected portion of the light beam; and determining a thickness of the oxidized portion based on the measurement signal while the oxidized portion is being formed at the substrate.

Abstract: The invention refers to an optical measurement arrangement, in particular for layer thickness measurement and for ascertaining optical material properties such as refractive index, extinction factor, etc. of a specimen (P), having an illumination device (1) for emitting a measurement light beam (6), a beam splitter (8) for dividing the measurement light beam (6) into a specimen light beam (10) and a reference light beam (9), a measurement objective for directing the specimen light beam (10) onto a measurement location (M) on the surface of the specimen (P) and for acquiring the light reflected from the measurement location (M), and an analysis device (11) into which the reference light beam (9) and the specimen light beam (10) reflected from the specimen (P) are coupled in order to obtain information about the specimen (P), in particular about layer thicknesses present thereon.

Abstract: A method of simultaneously measuring the thickness, group index of refraction, and top and bottom surface profiles of a sample, includes the steps of locating the sample between a surface of a transparent optical flat and a parallel reflective surface such that the respective optical distances between any two of the surface of the optical flat, the top surface of the sample, the bottom surface of the sample, and the reflective surface are distinct and in a known relative optical distance relationship, the distance between the surface of the transparent optical flat and the parallel reflective surface being known.

Abstract: A method and an apparatus to determine characteristics of a film on a substrate in a processing chamber. An example of a method in accordance with one embodiment of the present invention includes impinging optical radiation upon the film, sensing optical radiation reflected from the film to form spectral signals containing information concerning interference fringes, and obtaining thickness information of the film as a function of a periodicity of the interference fringes. The apparatus includes a detector in optical communication with the processing chamber to sense optical radiation generated by the plasma, and a spectrum analyzer in electrical communication with the optical detector. The spectrum analyzer resolves the spectral bands and produces information corresponding thereto. A processor is in electrical communication with the spectrum analyzer, and a memory is in electrical communication with the processor.

Abstract: The present invention provides a method for monitoring a modifying-process taking place in a thin-film sample and thereby characterizing the sample thus modified, wherein the modifying-process is performed for purpose of improving physical properties of the sample. The present invention further provides a monitoring tool for characterizing various thin-film processes. Advantages of the method of the present invention are manifest in its non-intrusive nature, fast (or real-time) response, robust sensitivity, and versatility in a variety of thin-film processes. Another inherent advantage of the present invention is that an assortment of the “n&k” parameters can be obtained by using only measurement tool, in contrast to two (or more) simultaneous measurement tools used in the prior art.

Abstract: An optical system includes a spectrometer and a multipass optical probe. The multipass optical probe includes a retroreflective element such that light propagating, in a first direction, from the probe to a sample under test and passing through or reflecting from the sample under test, is reflected back in a second direction opposite the first direction, so as to pass through the sample under test a total of at least two times.

Abstract: Thickness of a film in a sample may be detected by directing pump laser pulses to the surface of a sample to generate an acoustic pulse in a sample. The acoustic pulse propagates downwards until it reaches an interface between the bottom of the film and a substrate and is reflected back to the top surface of the film as a first echo. A reflection of the first echo propagates downwards and is again reflected back towards the surface as a second echo. Heterodyne interferometry is used to measure the lapse of time between the first and second echos from which the thickness of the film may be determined.

Abstract: A method and a recording medium for measuring three-dimensional thickness profile and refractive index of transparent dielectric thin-film with some patterns or not, which is fabricated in the semiconductor and related industrial field, using white-light scanning interferometry is provided. A method for measuring a thickness profile using white-light scanning interferometry in optical system includes the following steps. A first step is to extracting a phase graph by acquiring an interference signal and performing Fourier transform. A second step is to extracting a mathematical phase graph through modeling of a measurement object. And a third step is to measuring a profile value and a thickness value by applying an optimization technique to an error function determined by using phase values which is acquired from said first step and said second step.

Abstract: A method of processing interferometric data relating to a sample having multiple reflective surfaces, includes the steps of: specifying a set of acceptance ranges for peaks of interest in the interferogram, based on a knowledge of the sample; determining which peaks in the interferogram fall within the acceptance ranges; identifying which peaks within the acceptance ranges represent multiple reflections and eliminating these peaks from the interferometric data; identifying acceptance ranges which do not contain peaks; and employing other peaks in the interferogram to calculate the locations of peaks in the acceptance ranges that do not contain peaks.

Abstract: The measuring device comprises at least one measuring head having a reference part, which comprises a reference surface against which the moving web is supported. The reference surface comprises a measuring area in the inside of which the property of the web is measured. The reference part is arranged in connection with the measuring head in such a way that below the reference part, there is a substantially open air space. The measuring head comprises means for generating negative pressure in the air space below the reference part, and the reference part comprises holes formed through it, in such a way that the negative pressure generated in the air space affects through the reference part the space between the reference surface and the moving web in such a way that the web is supported against the reference surface substantially over the whole area of the measuring area.

Abstract: A method for high-precision measurement of film thickness and the distribution of film thickness of a transparent film is disclosed. The method is performed during a CMP process, without being affected by the film thickness distribution among the LSI regions or on the semiconductor wafer surface. The film thickness is measured by specifying relatively level measurement regions, according to a characteristic quantity of the spectral waveform of the reflected light from the transparent film, such as the reflection intensity, frequency spectrum intensity. This permits highly accurate control of film thickness. The leveling process in CMP processing can be optimized on the basis of the film thickness distribution.

Abstract: The invention is directed to a method for contactless determination of product characteristics, particularly in continuous or discontinuous fabrication of layer systems formed of a plurality of layers with different optical characteristics.

Abstract: A laser-based technique to determine glass thickness employs a pulsed laser to induce an ultrasonic wave between the surfaces of a region of glass, causing the surfaces to move in and out at a characteristic frequency. The surface motion is monitored to determine the characteristic frequency, which is proportional to the thickness of the glass in the region of the ultrasonic wave. The pulsed laser produces a short duration pulse that illuminates a surface of the glass, which is absorbed within the glass to cause a rapid thermal expansion that generates the ultrasonic wave. The surface motion induced by the ultrasonic wave is preferably detected with a laser interferometer system, the output of which is analyzed to determine the surface motion's characteristic frequency.

Abstract: A method of calibrating an interferometer system and a multilayer thin film used for calibrating the interferometer system. The method including measuring the step height of a gold step with the interferometer system, the multilayer thin film comprising a gold layer that defines the gold step. The multilayer thin film having an optical flat, a first layer on the surface of the optical flat, a second layer on the first layer, a test layer on a part of the second layer, and a gold layer on the test layer and on a part of the second layer uncovered by the test layer. The test layer having a test layer step, and the gold layer having a gold step over the test layer step. Also, a reference standard and a method of making the reference standard for a thin film sample with one or more component thin film layers, the reference standard having a gold layer over the surface of the thin film sample.

Abstract: Apparatus for producing an indication of a material property of a sheet-like material according to the present invention may comprise an excitation source for vibrating the sheet-like material to produce at least one traveling wave therein. A light source configured to produce an object wavefront and a reference wavefront directs the object wavefront toward the sheet-like material to produce a modulated object wavefront. A modulator operatively associated with the reference wavefront modulates the reference wavefront in synchronization with the traveling wave on the sheet-like material to produce a modulated reference wavefront. A sensing medium positioned to receive the modulated object wavefront and the modulated reference wavefront produces an image of the traveling wave in the sheet-like material, the image of the anti-symmetric traveling wave being related to a displacement amplitude of the anti-symmetric traveling wave over a two-dimensional area of the vibrating sheet-like material.

Abstract: The invention is directed to a system and method for implementing process control for tubing thickness using sonic NDE techniques. The system may, for example, generate ultrasound waves in a test object during the manufacturing process. A detector such as an interferometer may be used to detect the ultrasound waves. An interpreter or analyzer may determine the tubing or sheet thickness from the waves. Then, a control system may determine and implement an appropriate control action on the process.

Abstract: A system is provided for automatically measuring paint film thickness of painted bodies for closed loop control of a paint process for painting the bodies in a paint booth. The system includes a cell for receiving painted bodies from the paint booth and a conveyor control system for controlling the movement of painted bodies between the paint booth and the cell. The system also includes an AutoPelt system communicating with the conveyor control system for measuring paint film thickness of the painted bodies in the cells. The system includes an integrated paint quality control (IPQC) monitoring system communicating with the AutoPelt system for receiving data of paint film thickness information and combining the paint film thickness information with automation parameters on a vehicle identification number (VIN) basis of the painted bodies to control paint automation equipment of the paint booth.

Abstract: A method for the production of multi-layer systems with N layers having predetermined thickness, especially for the production of multi-layer systems for wavelength ranges in the extreme ultraviolet and soft X-ray wavelength range is described, in which N layers are deposited and if need be one or more layers are partially removed after deposited and in wich at the same time as deposition and/or removal of layers, the layers' reflectivity dependent on layer thickness is measured. The method includes the following steps: Calculation of a reflectivity-time curve of the multi-layer system to be produced Determination of points in time ti (i=1, 2, . . . , N), at which the deposition of the i-th layer is to be stopped; and if need be determination of points in time ti′ (i=1, 2, . . .

Abstract: Optical displacement gauges 20 are respectively arranged on both sides of a thin sheet material w, and displacement of surface position of the thin sheet material w is measured by irradiating measurement light L1 to the surface of the thin sheet material w. Thickness variation of the thin sheet material w is obtained from the measurement results of displacement of the surface position of the thin sheet material w.

Abstract: The present invention relates to a film thickness measuring method measuring a film thickness of an element formation layer formed on a substrate and its object is to provide a film thickness measuring method which can measure a residual film thickness of a polishing object film in a polishing process at a high accuracy. In a fabrication method of a thin film magnetic head, alumina is coated over a dummy layer 54 and a bottom shielding layer 16 after forming the dummy layer 54 along with the bottom shielding layer 16 and a planarized layer 24 is formed by polishing the surface thereof using a CMP. Next, after forming a top shielding layer 32 over the bottom shielding layer 16, a planarized layer 38 is form by embedding alumina. A film thickness of an embedded 38 on the dummy layer 54 is measured by a non-contact optical film thickness measuring equipment and a film thickness of the top shielding layer 32 is measured based on the film thickness.

Abstract: An method for measuring an optical thickness of a test object, the method includes: interfering a first optical wave front from the test object and a second optical wave front from a reference surface to produce an interference signal; for a selected location on the test object, obtaining an interference pattern of the test object at a first wavelength &lgr;1; for the selected location, calculating a first estimate of the optical thickness from the interference pattern recorded at wavelength &lgr;1; for the selected location obtaining an interference pattern of the test object at a second wavelength &lgr;2; for the selected location, calculating a second estimate of the optical thickness from the interference pattern recorded at wavelength &lgr;2; and for the selected location, calculating a third estimate of the optical thickness by combining the first and second estimates of optical thickness.

Abstract: The invention relates to a method and device for simultaneously measuring multiple properties of a sample composed of multiple layers of films. The measurement features several steps. First, at least one source of excitation radiation irradiates the sample's surface to excite an acoustic mode. A probe source of radiation irradiates the acoustic mode and is diffracted off the surface of the sample to form a signal beam. A detector detects the acoustic mode to generate a signal beam, which is then analyzed to determine an acoustic frequency and an amplitude, a depth of modulation, or a decay constant. These properties are then further analyzed to determine of at least two properties (e.g., a thickness of two layers) of the sample.

Abstract: A monitoring tool for monitoring an article in a wet environment, the monitoring tool including a monitoring station having an optical unit, a liquid holding unit for receiving the article, and a window, through which at least a portion of the article is viewable by the optical unit, a buffer station associated with the monitoring station having a plurality of supporting assemblies for receiving the article before and after being monitored, wherein at least one of the supporting assemblies includes a liquid receptacle for holding the article therein, and a gripping unit operating in conjunction with the monitoring station for moving the article from the buffer station to the liquid holding unit of the monitoring station.

Abstract: In a wafer thickness measuring apparatus and a method thereof, detection values are obtained from a sample piece (for example, a wafer chip) at a plurality of measurement points thereon by first and second detectors for absolute measurement of distances, and at the same time, measurement values of the fluctuations, for relative measurement of distances, are obtained by the optical heterodyne interferometer, and those measurement values are memorized as a plurality of measurement data being related with those measurement values. When measuring the thickness of a wafer, the measurements are performed at measurement points on the wafer which has a front surface and a reverse surface in height lying within the height of the sample piece, on which such a correspondence is obtained, thereby obtaining the detection values of the first and second detectors.

Abstract: A method for determining the thickness of a thin sample is described. The method includes the step of exciting time-dependent acoustic waveguide modes in the sample with an excitation radiation field. The acoustic waveguide modes are detected by diffracting probe radiation off a ripple morphology induced on the sample's surface by the acoustic waveguide modes. The diffracted probe radiation is then analyzed to measure phase velocities or frequencies of the acoustic waveguide modes. A thickness of the thin sample is determined by comparing the measured phase velocities or frequencies to the phase velocities or frequencies calculated from a mathematical model.

Abstract: A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined.

Abstract: The invention relates to a process and to a device for measuring the thickness of transparent materials. More particularly, but not exclusively, the invention concerns the thickness measurement of glass materials and, even more precisely, the thickness measurement of flat glass, in particular float glass. According to the invention, a light beam with modulated frequency is focused, two light beams or rays reflected by each of the surfaces of the transparent material are received, interference is created between them, the number of oscillations per modulation period of the interference signal is determined, the path difference (&dgr;) between the two beams and the thickness (e) of the transparent material are deduced and the phase shift (&phgr;) of the said interference signal is determined. This determination of the phase-shift between the two signals each coming from one of the surfaces of the transparent material can then be used to deduce other characteristics of the said material.

Abstract: The present invention is an endpoint detector and a method for quickly and accurately measuring the change in thickness of a wafer in chemical-mechanical polishing processes. The endpoint detector has a reference platform, a measuring face, and a distance measuring device. The reference platform is positioned proximate to the wafer carrier, and the reference platform and measuring device are positioned apart from one another by a known, constant distance. The measuring face is fixedly positioned with respect to the wafer carrier at a location that allows the measuring device to engage the measuring face when the wafer is positioned on the reference platform. Each time the measuring device engages the measuring surface, it measures the displacement of the measuring face with respect to the measuring device. The displacement of the measuring face is proportional to the change in thickness of the wafer between measurements.

Abstract: A method and apparatus for detecting the endpoint of CMP processing on semiconductor wafer in which a lower layer of material with a first reflectivity is positioned under an upper layer of material with a second reflectivity. Initially an endpoint site is selected on the wafer in a critical area where a boundary between the upper and lower layers defines the desired endpoint of the CMP process. The critical area on the wafer is generally determined by analyzing in the circuit design and the polishing characteristics of previously polished test wafers to denote the last points on the wafer from which the upper layer is desirably removed by CMP processing. After an endpoint site is selected, a light beam impinges the polished surface of the wafer and reflects off of the surface of the wafer to a photo-sensor. The photosensor senses the actual intensity of the reflected light beam.

Abstract: The invention provides an apparatus for measuring a property of a sample (using, e.g., ISTS) that includes: 1) an excitation laser that generates an excitation laser beam; 2) an optical system aligned along an optical axis that separates the excitation laser beam into at least three sub-beams; 3) an imaging system aligned along the optical axis that collects the sub-beams and focuses them onto the sample to form an optical interference pattern that generates a time-dependent response in the sample; 4) a probe laser that generates a probe laser beam that diffracts off the time-dependent response to form a signal beam; 5) a detector that detects the signal beam and in response generates a radiation-induced electronic response; and 6) a processor that processes the radiation-induced electronic response to determine the property of the sample.

Abstract: An optical system is fabricated in the form of one device, so that the simplified optical system is realized. A displacement is measured with a high resolving power utilizing an interference fringe. An interference measurement probe 2 receives a coherent light from a light source section 1, and divides the coherent light into a plurality of luminous fluxes. The interference measurement probe 2 emits a plurality of irradiation luminous fluxes at different angles. The plurality of irradiation luminous fluxes form an interference fringe and the interference fringe is irradiated onto an objective 8. A light receiving section 3 is disposed at a position where a reflection luminous flux from the objective 8 interferes, and receives an interference light reflected from the objective 8, thereby outputting a light receiving signal which is converted to an electric signal.

Abstract: The apparatus for measuring the thickness of transparent objects (1) has a radiation source (3) of short coherence length and a Michelson interferometer (5), wherein the object (1) to be measured can be arranged in its measuring arm (11), and path length variation element (15), which has an optical path length that changes periodically due to its own rotation, is arranged in the reference arm (13). The cross-sectional surface (34) of the element (15) wherein the reference beam comes to rest has at least four corners so that the reference radiation path in the element (15) has at least two reflections on the inner surfaces of the element. The reference beam (41e) coming out of the element (15) is reflected back by means of a fixed reflector (30) into the element (15), preferably into itself.

Abstract: The invention relates to a method and device for measuring distances through the atmosphere against a target through propagation time measuring. Measuring light signals are transmitted towards a target and light pulses reflected by the target are received. The distance measuring includes a coarse measuring procedure and a fine measuring procedure. During the coarse measuring procedure at least one time point is fixed after which the measuring signal from the target can be expected to appear. During the fine measuring procedure a number of measurements are performed. The signal information collection during the fine measuring procedure takes place in a matching time space after the time point fixed during the coarse measuring. Preferably, the measuring during the coarse measuring procedure takes place with one or a few measuring pulses and measuring during the fine measuring procedure with a number of measuring light pulses.

Abstract: A laser range finder includes a circular in-sight field of view which incorporates within it a magnified "TV view" of the target area with the TV view roughly approximating the rectangular shape of a standard television picture. Also within the circular field, over and under the TV view, are a target quality indicator, a range distance display, and other indicators. Within the TV view is a targeting reticle which indicates roughly the footprint of ranging laser pulses such that a target can be selected. The target quality indicator is a bar graph which displays the number of identifiable received reflected laser pulses from a series of such pulses emitted by the range finder. By aiming the range finder at various targets via the footprint reticle, repeatedly firing the range finder and monitoring the target quality graph for each firing, a user can move the range finder to find a surface proximate the target with a reflective quality sufficient to yield an accurate target range reading.

Abstract: The present invention provides a laser radar (ladar) imaging system in which both the range of an object being imaged and the velocity of the object can be measured simultaneously and accurately with superior range resolution and with minimal ambiguity. Use is made of a ladar system based on matched-filter cross-correlation of light pulse waveforms that have multiple, simultaneous frequency components with phase variation and incommensurate spectral frequency spacing between frequency components.

Abstract: A distance measurement device is provided which determines the measurement zone of an object and also determines the direction of movement of the object within the measurement zone.

Abstract: A "laser tape measure" for measuring distance which includes a transmitter such as a laser diode which transmits a sequence of electromagnetic pulses in response to a transmit timing signal. A receiver samples reflections from objects within the field of the sequence of visible electromagnetic pulses with controlled timing, in response to a receive timing signal. The receiver generates a sample signal in response to the samples which indicates distance to the object causing the reflections. The timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the reflection such that the time between transmission of pulses in the sequence in sampling by the receiver sweeps over a range of delays.

Abstract: A laser rangefinding system (12) that utilizes multiple pulse, multiple return, modal range processing for clutter rejection. A laser source (16) emits a series of laser beam pulses (42), and each reflected return from objects (46) in a scene for each of the pulses is recorded. Each return signal above a predetermined threshold is added as a count to a count table within a selected bin representing the range of the return signal. After all of the analog return signals are recorded, the range bin with the most counts is selected as the range of a target.

Abstract: A distance measurement device comprises at least one switch for generating a start signal, a distance measurement device for measuring the distance to an object in response to the start signal, a memory device for storing distance data measured by the distance measurement device, the stored data defining a plurality of measurement zones within the full range of distance measurement of the distance measurement device, and a judgement circuit for judging which measurement zone the result of the distance measurement performed by the distance measurement means belongs to from the plurality of measurement zones defined by the distance data stored in the memory device. In accordance with this configuration, division points can be set if an object is placed at an actual division point desired and a switch is pressed. Accordingly, when an operator sets the division point, it is unnecessary to depend on memory, perception, or calculation, and the setting of the division points becomes easier.

Abstract: The present invention relates to an apparatus and a method for detecting pulses of light energy from at least two fields of view. A first detector having a first bias detects a pulse received at a first point in time. A second detector having a second bias, different from the first bias, detects a pulse received at a second point in time. A processor compares an output of the first detector with a first threshold to produce a signal representing receipt of a pulse from a first field of view. The processor also compares an output of the second detector with a second threshold, different from the first threshold, to produce a signal representing receipt of a pulse from a second field of view. Because the detectors are biased with different biases, the detected pulses are easily distinguished. Thus, multiple fields of view can be detected without complex hardware. The detectors can be biased with opposite polarities so that background noise is cancelled out.

Abstract: An active imaging system for viewing targets with a high degree of range resolution of approximately one foot. The imaging system utilizes a laser pulse which passes through an electro-optical pulse slicer which creates a sharp leading edge and/or a sharp falling edge on the laser pulse. The laser pulse travels to the target under observation, illuminates and reflects off of the target and returns to a camera. A target is viewed only during the time all or a portion of the returning laser pulse overlaps the time the camera shutter gate is open. The imaging system is particularly suited for determining depth information about a target by varying the time relationship when the returning laser pulse is received by the camera.