Abstract: A method is provided that involves mounting a transmit block and a receive block in a LIDAR device to provide a relative position between the transmit block and the receive block. The method also involves locating a camera at a given position at which the camera can image light beams emitted by the transmit block and can image the receive block. The method also involves obtaining, using the camera, a first image indicative of light source positions of one or more light sources in the transmit block and a second image indicative of detector positions of one or more detectors in the receive block. The method also involves determining at least one offset based on the first image and the second image. The method also involves adjusting the relative position between the transmit block and the receive block based at least in part on the at least one offset.

Abstract: A time of flight (ToF) sensor includes: a first pixel including a first photogate to receive light reflected by an object and generate a first phase signal, and a second photogate to generate a second phase signal having a phase difference of 180 degrees with respect to the first phase signal; a second pixel including a third photogate to receive the reflected light and generate a third phase signal different from the first phase signal and a fourth photogate to generate a fourth phase signal having a phase difference of 180 degrees with respect to the third phase signal; a first signal output unit to output the first and second phase signals; and a second signal output unit to output the third and fourth phase signals, wherein the first, second, third and fourth photogates output the first to fourth phase signals during a frame period.

Abstract: A LIDAR system includes a reference light source configured to generate an outgoing light signal that includes multiple reference channels that each has a different frequency. The system also includes a comparative light source configured to generate an outgoing light signal that includes multiple comparative channels. Each of the comparative channels has a different frequency. The comparative channels are each associated with one of the reference channels in that LIDAR data is generated for a sample region on a field of view using a comparative channel and the associated reference channel. The comparative channel and the associated reference channel have different frequencies.

Abstract: A cascaded interferometric system for Fourier domain optical coherence tomography (OCT) in which the output of one sub-system interferometer is directed through a second sub-system interferometer for performing the Fourier transform in hardware.

Abstract: In a method for time-of-flight (ToF) based measurement, a scene is illuminated using a ToF light source modulated at a first modulation frequency FMOD(1). While the light is modulated using FMOD(1), depths are measured to respective surface points within the scene, where the surface points are represented by a plurality of respective pixels. At least one statistical distribution parameter is computed for the depths. A second modulation frequency FMOD(2) higher than FMOD(1) is determined based on the at least one statistical distribution parameter. The depths are then re-measured using FMOD(2) to achieve a higher depth accuracy.

Abstract: A three dimensional time of flight (TOF) camera includes a transmitter and a receiver. The transmitter is configured to generate an electrical transmit signal at a plurality of frequencies over an integration time period and generate a transmit optical waveform corresponding with the electrical transmit signal. The receiver is configured to receive a reflected optical waveform that is the transmit optical waveform reflected off of an object, integrate the reflected optical waveform over the integration time period, and determine a distance to the target object based on a TOF of the optical waveform. The integration time period includes exposure time periods. A length of each of the exposure time periods corresponds to one of the frequencies. The TOF is determined based on a correlation of the electrical transmit signal and the return optical waveform utilizing a correlation function with respect to the integration time period.

Abstract: A system for measuring velocity of particles such as particles in air is a Light Detection and Ranging (LIDAR) system, having a micro-electro-mechanical-system (MEMS).

Abstract: Methods and systems for performing three dimensional LIDAR measurements with an integrated LIDAR measurement device are described herein. In one aspect, a return signal receiver generates a pulse trigger signal that triggers the generation of a pulse of illumination light and data acquisition of a return signal, and also triggers the time of flight calculation by time to digital conversion. In addition, the return signal receiver also estimates the width and peak amplitude of each return pulse, and samples each return pulse waveform individually over a sampling window that includes the peak amplitude of each return pulse waveform. In a further aspect, the time of flight associated with each return pulse is estimated based on a coarse timing estimate and a fine timing estimate. In another aspect, the time of flight is measured from the measured pulse due to internal optical crosstalk and a valid return pulse.

Abstract: A measuring apparatus comprising a tunable laser diode for generating a mono mode measurement radiation, said laser diode being designed as a laser beam source in such a way that an emission wavelength of the measurement radiation is variable within a wavelength range by means of the variation of a tuning parameter, comprising an absorption medium defining absorption lines within the wavelength range, comprising a memory having a line atlas for the absorption medium, comprising a detector for determining an absorptivity and comprising a control and evaluation unit for regulating the emission wavelength by means of the at least one tuning parameter in a manner dependent on the absorptivity determined in such a way that the emission wavelength remains stable.

Abstract: An apparatus is described having an image signal processor. The image signal processor has a plurality of depth calculation units to calculate a respective time of flight depth value for different pixel array locations. Each of the plurality of depth calculation units is to receive a response signal from a same pixel in a pixel array so that the plurality of depth calculation units are able to calculate multiple depth values for the different locations of the pixel array from respective response signals from different groups of pixels in the pixel array of which the pixel is a member. Each of the groups include pixels of different receive clock phases sufficient to calculate a respective depth value. Another apparatus is also described where multiple depth values are similarly calculated from different groups of pixels that each include a same pixel but where a depth calculation unit calculates each of the multiple depth values.

Abstract: A multi-mode frequency sweeping interferometer has a single measurement light producing device configured to produce a coherent light source consisting of a single light beam. The single measurement light producing device transitions the single light beam between a fixed light beam and a scanning wavelength light beam. A primary beam splitter produces a first reference beam and a first measurement beam from said single light beam. The first reference beam is configured to travel a fixed path length to a primary reference reflector and the first measurement beam is configured to travel to and from a moveable reflective target over an unknown path length. A first interferometer is created by interfering the first reference beam with the first measurement beam and one or more optoelectronic devices may be configured to determine a measured distance to the movable reflective target.

Abstract: A compact, balanced, up to three degrees of freedom measuring interferometer having dual beam splitters rotated ninety degrees with respect to each other and a measurement detector including a quadrant detector or multi-core fiber with four detectors which enables fiber delivery of an optical source without periodic error, an interferometer system, and method for using is disclosed.

Abstract: Systems and methods for measuring a distance to an object. An exemplary method includes directing light beams from three or more continuous-wave lasers onto a target to generate an interference beam, and also frequency shifting the light beams split off from the lasers to generate local oscillator beams. When the interference beam and the local oscillator beams are combined, the method further includes determining optical phases of heterodynes produced by combining the light beams and the local oscillator beams, and determining synthetic phases by taking the difference between the optical phases of the heterodynes. The method further includes determining synthetic wavelengths based on the differences between the frequencies of the lasers. The method further includes determining a distance to the target based on the synthetic phases and the synthetic wavelengths.

Abstract: A laser radar device includes: a pulse laser that outputs transmission light to a target; an transmission optical system that makes the transmission light at a predetermined beam spread angle; a light-receiving element array that receives scattered light from the target and converts the light to an electric signal; an electric circuit array that detects a reception intensity and a reception time from the electric signal; a range/three-dimensional shape output unit that measures a range to the target or a three-dimensional shape of the target on the basis of the reception time; a determination unit that determines whether the beam spread angle is changed or not on the basis of the reception intensity and the reception time; and a control unit that changes the beam spread angle on the basis of a determination result.

Abstract: Techniques for using small parallax angles in remote sensing to determine cloud feature height include exploiting two identical medium-resolution SWIR bands with parallax to estimate cloud edge feature heights well enough to enable assessments of the impacts of shadows and proximate cloud scattering on ground illumination, and hence, on reflectance calculations. The bands are intentionally designed to have a suitable parallax angle, in one embodiment approximately 1.5 degrees. With this parallax, one band will see more ground pixels than the other band as they encounter a leading edge of a cloud and the other band will see more ground pixels than the one band as they encounter the lagging edge of the cloud. From these numbers of pixels, the height of the leading and lagging edges of the cloud can be determined.

Abstract: A laser radar device mounted on a vehicle includes a first laser emission part configured to generate a measuring laser beam by using a laser beam emitted from a laser source and to illuminate a predetermined area in a front traveling direction and a second laser emission part configured to generate a measuring laser beam by using the laser beam emitted from the laser source. A beam spread angle, viewed from a side of the vehicle, of the measuring laser beam generated by the second laser emission part is larger than a beam spread angle, viewed from a side of the vehicle, of the measuring laser beam generated by the first laser emission part.

Abstract: A measuring device for the measurement of a distance to a target object has a beam source which is designed as an electrical-optical component and which emits a transmission beam. A detector, which is designed as a further electrical-optical component, receives a reception beam that is reflected and/or scattered by the target object. A beam splitting lens is configured to deflect the transmission and/or reception beam. Alternatively or additionally, the measuring device includes a beam shaping lens is configured for shaping the transmission and/or reception beam. A lens support is configured to accommodate the electrical-optical components. The lens support also accommodates the beam splitting lens and/or the beam shaping lens. The lens support has a first wafer for accommodating the electrical-optical components and a second wafer for accommodating the beam splitting lens, and/or the beam shaping lens.

Abstract: A distance measuring system and method employing a laser distance sensor may have utility in various applications. In accordance with one aspect of the present invention, a laser distance sensor may acquire accurate distance measurements with a short baseline.

Abstract: An optical sensor includes a driver, light detector and echo canceller. The driver is adapted to selectively drive a light source. The light detector is adapted to produce a detection signal indicative of an intensity of light detected by the light detector. The echo canceller is adapted to produce an echo cancellation signal that is combined with the detection signal produced by the light detector to produce an echo cancelled detection signal having a predetermined target magnitude (e.g., zero). The echo canceller includes a coefficient generator that is adapted to produce echo cancellation coefficients indicative of distance(s) to one or more objects, if any, within the sense region of the optical sensor. The optical sensor can also include a proximity detector adapted to detect distance(s) to one or more objects within the sense region of the optical sensor based on the echo cancellation coefficients generated by the coefficient generator.

Abstract: The present invention relates to a method and system for detecting and mapping three-dimensional information pertaining to one or more target objects. More particularly, the invention consists of selecting one or more target objects, illuminating the one or more target objects using a first light source and capturing an image of the one or more target objects, then, illuminating the same one or more target objects using a second light source and capturing an image of the one or more target objects and lastly calculating the distance at the midpoint between the two light sources and the one or more target objects based on the decay of intensities of light over distance by analyzing the ratio of the image intensities on a pixel by pixel basis.

Abstract: A photogate electrode has a planar shape of a rectangular shape having first and second long sides opposed to each other and first and second short sides opposed to each other. First and second semiconductor regions are arranged opposite to each other with the photogate electrode in between in a direction in which the first and second long sides are opposed. Third semiconductor regions are arranged opposite to each other with the photogate electrode in between in a direction in which the first and second short sides are opposed. The third semiconductor regions make a potential on the sides of the first and second short sides higher than a potential in a region located between the first and second semiconductor regions in a region immediately below the photogate electrode.

Abstract: A rangefinder for measuring a distance of an object includes a case, in which a refractor, a measuring light source, a light receiver, a receiving lens, a reference light source, and a reflector are provided. The measuring light source emits measuring light to the refractor, and the refractor refracts the measuring light to the object. The measuring light reflected by the object emits to the light receiver through the receiving lens. The reference light emits reference light to the reflector, and the reflector reflects the reference light to the light receiver. The refractor and the reflector may be turned for calibration.

Abstract: A detection system for detecting an object includes a transmitter including a light source configured to emit a first light beam having a first frequency towards the object. The detection system also includes a receiver configured to receive a second light beam reflected from the object, and a detector positioned within the receiver. The second light beam has a second frequency as a result of a non-linear optical response of a surface of the object to the first light beam. The detector is configured to detect the object based on the second frequency of the second light beam.

Abstract: Separate reception/transmission apertures enhance pointing: reception is more efficient than transmission (kept smaller for MEMS steering). Apparatus aspects of the invention include lidar transmitters emitting laser beams, and scan mirrors (or assemblies) angularly adjustable to deflect the beams in orthogonal directions. In one aspect, afocal optics magnify deflection; a transmitter aperture transmits the beam; a lidar receiver doesn't share the transmitter aperture. In another aspect, auxiliary optics calibrate the deflection. A method aspect of the invention notices and responds to a remote source—using a similar local laser, adjustable scan mirror or assembly, afocal deflection magnifier, transmission aperture and separate receiver. Method steps include operating the receiver to notice and determine location of the remote source; and controlling the transmitter to direct laser light back toward that location.

Abstract: A CMOS detector with pairs of interdigitated elongated finger-like collection gates includes p+ implanted regions that create charge barrier regions that can intentionally be overcome. These regions steer charge to a desired collection gate pair for collection. The p+ implanted regions may be formed before and/or after formation of the collection gates. These regions form charge barrier regions when an associated collection gate is biased low. The barriers are overcome when an associated collection gate is high. These barrier regions steer substantially all charge to collection gates that are biased high, enhancing modulation contrast. Advantageously, the resultant structure has reduced power requirements in that inter-gate capacitance is reduced in that inter-gate spacing can be increased over prior art gate spacing and lower swing voltages may be used. Also higher modulation contrast is achieved in that the charge collection area of the low gate(s) is significantly reduced.

Abstract: In one aspect, a method includes transmitting a tone waveform from a laser detection and ranging (LADAR) sensor, detecting a target using an echo of the tone waveform reflected from the target, determining a radial velocity of the target using the echo of the monotone waveform from the target, transmitting, from the LADAR sensor, linear frequency modulation (FM) chirp signals and determining a range to target using echoes from the linear FM chirp signals.

Abstract: Techniques are disclosed for providing a multi-zone sensing array configured for use in a dual-mode active/passive sensor system. In some embodiments, the techniques can be used to minimize or otherwise reduce power dissipation in sensor arrays, while further providing the ability to readout the active returns rapidly. The techniques can be implemented, for example, by using the full N×M array format for target acquisition in a passive imaging mode, and then, with the aid of a gimbal for instance, place the region-of-interest in a subset of the array configured with dual-mode active/passive pixel receivers to provide three-dimensional imaging. Such techniques are capable of, for example, supporting both active and passive operating modes of a countermeasure system.

Abstract: A method for operating a chromatic range sensor (CRS) system to identify abnormal spectral profiles arising from light reflected from more than one portion of a workpiece surface is provided. The method comprises: providing a CRS system comprising: an optical element, a light source, and CRS electronics comprising a CRS wavelength detector; operating the CRS system to receive an output spectral profile from a measurement point on a workpiece surface and provide corresponding output spectral profile data; analyzing the output spectral profile data to provide a peak region asymmetry characterization; and providing a corresponding abnormality indicator if the peak region asymmetry characterization indicates that the peak region is abnormally asymmetric.

Abstract: A method of establishing the location of a pair construction points for a stud in a building interior at a construction site and for determining the length of the stud needed to extend between the pair of construction points uses a robotic total station. The points are defined by x and y coordinates and anticipated z coordinates on upper and lower surfaces. The robotic total station establishes the points by directing a beam of laser light toward anticipated points and, through an iterative process, determining the actual location of the points on upper and lower surfaces that have the same x and y coordinates.

Abstract: Determination of a sensor device location in a sensor network is described. A system can include rotating optical beams having a known location. Detectors can be located with each of the rotating optical beams. The system can include a sensor device placeable as part of the sensor network. A reflector can be near the sensor device and can reflect at least two optical beams back to the detectors associated with each of the respective optical beams. A triangulation module can triangulate a position of the reflector, and thus the sensor, based on the reflected optical beams.

Abstract: An electro-optical distance measuring device having a photodetection unit comprising a plurality of pixels arranged in a predetermined arrangement is disclosed. A signal processing unit has a storage unit for storing the detection result in correspondence with each of the pixels, wherein the signal processing control unit sequentially changes a position of the division for every cycle wave at which the photodetection amount is detected and continues detections until a detected range becomes at least one cycle or more. The arithmetic processing unit calculates a waveform for at least one cycle stored in the storage unit for each pixel, obtains a phase difference of the waveform with respect to the irradiated distance measuring light, and calculates the distance based on the phase difference.

Abstract: A method for determining a distance to a target point located approximately at ground level includes aiming a measurement device at the target point, determining a tilt of the measurement device using tilt sensors, and determining a height of the measurement device above the ground. A position of the target point may be determined using the tilt and height of the measurement device, a position of the measurement device, and a bearing to the target point.

Abstract: An optical ranging device has a light emitting element, a light receiving element, a light emitting lens, and a light receiving lens. Provided between the light receiving lens and the light receiving element are a first reflection surface and a second reflection surface for changing a direction of an optical axis of a light beam condensed by the light receiving lens and guiding the light beam to the light receiving element. A single medium exists between the first reflection surface and the second reflection surface.

Abstract: Methods and systems for using spectrally separated light pulses to collect more LIDAR information are presented. In one embodiment, a monochromatic pulse is transmitted to collect range information and a white pulse is transmitted a short time afterwards to collect spectral responsivity information or color of the target. In another embodiment, the white light pulse is used to collect both range and spectral responsivity information of the target. In another embodiment, the spectral separated laser is spatially spread in order to collect range information over more than one point at a time.

Abstract: In a device for optically scanning and measuring an environment, where the device is a laser scanner having a light emitter which, by a rotary mirror, emits an emission light beam, with a light receiver which receives a reception light beam, which, after passing the rotary mirror and a receiver lens which has an optical axis, is reflected from an object in the environment of the laser scanner. The laser scanner also includes a control and evaluation unit which, for a multitude of measuring points, determines the distance to the object. Also, a rear mirror is provided on the optical axis behind the receiver lens, where the rear mirror reflects towards the receiver lens the reception light beam which is refracted by the receiver lens.

Abstract: A method for adjusting the modulating frequency and the intensity of the IR illumination of a Time of Flight measurement system proportionally to the speed of movement and the ambient light level of the TOF system, thus adjusting the range of vision of the system dependent on speed. In an alternate embodiment the modulating frequency of a TOF measurement system is periodically adjusted to cover a larger range of vision of the TOF.

Abstract: Example methods, apparatuses, or articles of manufacture are disclosed herein that may be utilized, in whole or in part, to facilitate or support one or more operations or techniques for proximity sensor distance detection ambiguity removal.

Abstract: A laser rangefinder includes a scanning laser emitter emitting a narrow laser beam, a controller in communication with the scanning laser emitter and configured to control the scanning laser emitter to emit the laser beam to scan a preset range in a preset manner, a laser detector positioned adjacent to the scanning laser emitter and configured to capture an image of a spot formed by the laser beam reflected off an object; and a processor in communication with the controller and the laser detector. The processor is configured to obtain an angle that the laser beam is tilted and process the image to obtain position coordinates of the spot in the image. The processor is further configured to calculate a distance from the laser rangefinder to the object based upon the angle and the position coordinates of the spot.

Abstract: A method and system for 3D surface mapping system using a plurality of image sensors, each image sensor associated with an optical flow processor, each image sensor sharing a substantially coaxial optical path from the scene to a beam splitter and having substantially non-coaxial optical paths between the beam splitter and the image sensor such that the optical magnification of each optical path varies differently with the distance between the system and the surface of interest. The ratio of detected optical flows combined with the parameters of the two optical paths and the baseline between the image sensors is used to compute the Z-distance from the optical center of the image sensors to the surface.

Abstract: A scanning beam laser range finder and a method are provided for detecting an intrusion into a protected area by enhancing the capability of detecting an intruded attempting to blend with the area background. The laser range finder and method include an Emitter/Receiver configured to emit laser pulses towards each point out of the plurality of points and to receive therefrom reflected laser pulses. Further included is a processor coupled to the Emitter/Receiver and configured to derive an initial distance separating the laser range finder away from each point, the initial distance having an initial measurement error. At least one amplitude comparator is coupled to the Emitter/Receiver and to the processor, which is configured to derive a corrected distance to each point, the corrected distance having a corrected measurement error smaller than the initial measurement error.

Abstract: A light source transmits detecting light toward an object. The object reflects the detecting light and forms a reflected light. A sensor is used for sensing the reflected light. Then, an exposure control unit coupled to the sensor performs luminance convergence on the reflected light according to luminance of the reflected light sensed by the sensor. And a distance measurement device coupled to the sensor detects a distance between the object and the light source and/or the sensor according to an image position of the reflected light on the sensor.

Abstract: A structure of an optical path for laser range finding includes a main body and a light-emitting unit assembled in the main body. The main body has a transmitting channel, a receiving channel and a calibration channel. The light-emitting unit is assembled in the transmitting channel. The light-emitting unit emits an external optical beam and an internal optical beam. The external optical beam is emitted through the transmitting channel. The internal optical beam is emitted to the receiving channel via the calibration channel. An included angle is defined between the external optical beam and the internal optical beam. A receiver is mounted in the receiving channel. Under this arrangement, the external optical beam and the internal optical beam do not interfere with each other.

Abstract: Methods, systems, and apparatuses are provided for estimating a location on an object in a three-dimensional scene. Multiple radiation patterns are produced by spatially modulating each of multiple first radiations with a distinct combination of one or more modulating structures, each first radiation having at least one of a distinct radiation path, a distinct source, a distinct source spectrum, or a distinct source polarization with respect to the other first radiations. The location on the object is illuminated with a portion of each of two or more of the radiation patterns, the location producing multiple object radiations, each object radiation produced in response to one of the multiple radiation patterns. Multiple measured values are produced by detecting the object radiations from the location on the object due to each pattern separately using one or more detector elements. The location on the object is estimated based on the multiple measured values.

Abstract: Systems, methods, and other embodiments associated with distance based position measurement are described. In one embodiment, an apparatus is configured to be positioned proximate a feature of interest. The apparatus includes a laser distance meter (LDM) configured to emit a laser beam and to determine first and second distances between the LDM and first and second targets. The first and second targets have known positions in three dimensions with respect to a reference plane from which the LDM is located. The apparatus also includes a trilateration unit configured to compute a two dimensional position of the LDM relative to the targets based, at least in part, on the first and second distances.

Abstract: An optical pen for use in a chromatic range sensor (CRS) may be used in a probe system for a coordinate measuring machine (CMM). The optical pen includes a confocal optical path, an interchangeable optics element, an optical pen base member, and a repeatable fast exchange mount. The confocal optical path includes a confocal aperture and a chromatically dispersive optics portion. The interchangeable optics element includes the chromatically dispersive optics portion. The optical pen base member includes an external mounting surface for mounting to an external reference frame. The repeatable fast exchange mount includes a first mating half located on the base member and a second mating half located on the interchangeable optics element. The repeatable fast exchange mount is configured to allow the base member to receive and hold the interchangeable optics element in a fixed relationship relative to the base member and the external reference frame.

Abstract: An optical sensor for measuring at least one of a range, a position, and a profile of an object that is to be measured, the measured object emitting electromagnetic radiation due to the temperature of the object to be measured, and the sensor having a light source for illuminating the surface of the measured object and a detector for detecting the illuminating light reflected at the object to be measured, wherein with respect to the measurability even on the bodies that emit electromagnetic radiation, the light generated by the light source has a wavelength below the peak of the Planck radiation spectrum of the object that is to be measured. A corresponding method is specified.

Abstract: Systems, methods, and articles of manufacture for automatic target recognition. A hypothesis about a target's classification, position and orientation relative to a LADAR sensor that generates range image data of a scene including the target is simulated and a synthetic range image is generated. The range image and synthetic range image are then electronically processed to determine whether the hypothesized model and position and orientation are correct. If the score is sufficiently high then the hypothesis is declared correct, otherwise a new hypothesis is formed according to a search strategy.

Abstract: In a distance measuring system, photoelectrons are generated depending on light energy received in a light-receiving period predetermined for the emission timing of pulsed light emitted to a target object and are cumulatively stored, and a distance to the target object is determined according to a time-of-flight process. A solid-state image sensing device cumulatively stores therein photoelectrons generated depending on the light energy received in each of the first and second light-receiving periods. The first light-receiving period is part of a rise period of the reflected light intensity received by the image sensing device, and the second light-receiving period includes a peak of the reflected light intensity and a fall period thereof.

Abstract: A distance-measuring device for contactless measurement of a distance to an object, including a housing; a contactless measuring apparatus utilizing an optical measuring beam arranged in the housing and having a radiation unit, an optical unit with optical elements encompassing at least a transmitting and receiving lens system, an optical transmitting path with an optical axis for emitting a measuring beam onto the target object, an optical receiving path with an optical axis for receiving a measuring beam that is reflected and/or scattered by the target object. At least one optical element is movable relative to an initial position; a motion sensor detects a movement of the object, the optical element movable out of the initial position into a variable compensation position so that the transmitting path can be stabilized at a spatially fixed position.

Abstract: The present application provides a distance measuring apparatus that can measure a distance with accuracy even when a light receiving level of a reflected light becomes saturated. A light emitting section of the distance measuring apparatus emits a measuring light toward an object to be measured. A light receiving section receives the reflected light being reflected from the object to be measured. A distance calculating section obtains a distance to the object to be measured based on an elapsed time which is from a point the measuring light is emitted until a point a light receiving level of the reflected light indicates a peak thereof. A distance correcting section corrects a value of the distance to the object to be measured depending on a length of saturation time of the light receiving level when the light receiving level becomes saturated and the peak is impossible to identify.