Abstract: An absolute distance meter for measuring a distance to a target may include a synthesizer including a first quadrature modulator and structured to receive a reference signal having a reference frequency and output a first signal having a first frequency and a second signal having a second frequency, a laser structured to output a laser beam, wherein the laser beam is modulated by the second signal, an optical system for directing the laser beam toward the target, a reference phase calculating system structured to calculate a reference phase based on signals having the first frequency and the second frequency, a target optical detector structured to receive at least a portion of the laser beam returned from the target and structured to output a measured electrical signal having the second frequency based on the at least a portion of the laser beam, and a measure phase calculating system structured to calculate a measure phase based on the measured electrical signal and the first signal.

Abstract: Scannerless loss modulated flash color range imaging methods and apparatus are disclosed for producing three dimensional (3D) images of a target within a scene. Apparatus and methods according to the present invention comprise a light source providing at least three wavelengths (passbands) of illumination that are each loss modulated, phase delayed and simultaneously directed to illuminate the target. Phase delayed light backscattered from the target is spectrally filtered, demodulated and imaged by a planar detector array. Images of the intensity distributions for the selected wavelengths are obtained under modulated and unmodulated (dc) illumination of the target, and the information contained in the images combined to produce a 3D image of the target.

Abstract: A method (200) and system (220) for range detection is provided. The system can include a sensing unit (110) for detecting a location and movement of a first object (401), and a processor (107) for providing a measure of the movement. The processor can convert the measure to a coordinate signal for moving a second object (124) in accordance with a location and movement of the first object. The system can include a pulse shaper (109) for producing a pulse shaped signal (167) and a phase detector (101) for identifying a movement from a reflected signal (166). A portion of the pulse shaped signal can be a frequency modulated region (312), a constant frequency region (316), or a chirp region (324). In one arrangement, the pulse shaper can be a cascade of all-pass filters (515) for providing phase dispersion.

Abstract: A micro-mirror optical tracking and ranging system comprises an optical transceiver having a Micro-Electro-Optical Mechanical System (MEOMS) micro-mirror beam steering system and an electronic control and operating system for processing electronic signals. An optical transceiver and MEOMS micro-mirror beam steering system comprises two oppositely installed micro-mirrors controlled so that they spin and tilt synchronously and project a laser beam out in a wide solid angle and interval in a substantially conically shaped scanning pattern. Such an optical transmitter system provides a steered frequency-modulated continuous-wave (FMCW) laser beam. When a laser beam waveform reflects off of an object within the scanned patter it is detected by the optical receiver an electronic control and operating system processes the detected laser beam waveform by mixing it with the original transmitted laser beam waveform and calculates the precise distance and location of the object.

Abstract: The invention relates to a solid-state range sensing system. As with previous solid-state range sensing systems, an energy source is activated and deactivated in a cyclic pattern with a selected source frequency. A receiver is adapted to sense the reflection of emitted energy from the target. The receiver includes a shielding system to block the sensing of the reflected energy from the target in a cyclic pattern with a selected receiver frequency. Unlike the prior art, the frequency of the source and receiver are offset by a small frequency. The resulting output signal of the receiver is a further cyclic pattern beat signal of frequency equal to the difference between the source activation and receiver shielding modulation frequencies. The best signal is effectively a down-converted version of the source modulation frequency and, unlike the prior art, is compared with a reference beat signal whereby the phase difference between the two beat signals is used to determine a range value.

Abstract: A distance measuring device is provided that reduces the time required for a distance measurement without degrading accuracy of the measured value.

Abstract: The present invention provides a method and apparatus for comparing device and non-device structures. The method includes determining at least one characteristic parameter associated with at least one non-device structure on at least one workpiece and determining at least one characteristic parameter associated with at least one device structure on the at least one workpiece. The method also includes comparing the at least one characteristic parameter associated with the at least one non-device structure and the at least one characteristic parameter associated with at least one device structure.

Abstract: A spectrometer and spectrometry method comprising modulating a light source with a carrier waveform multiplied by an envelope function, directing light from the light source through a sample region and to a photodetector, and demodulating current from the photodetector at a reference frequency. Also a method for computing a modulation waveform comprising specifying a target detection efficiency in a Fourier space, computing a response of a waveform that comprises a carrier wave multiplied by an envelope function, and modifying the envelope function using nonlinear optimization means to minimize a difference between the computed response and a predetermined target detection efficiency.

Abstract: General method for extracting source distance information from any kind of received radiation, including electromagnetic and acoustic, without involving round-trip time or phase in any form, and thus more truly passive than existing passive radars. The method exploits the facts that radiation from a real source must comprise wavepackets of nonzero bandwidth, that the individual frequency components of a wavepacket must have consistent phase at the source, and that their instantaneous phases must increase linearly along the path in proportion to the respective frequencies, so that the phase gradient across the components must be proportional to the distance travelled. The invention simplifies over naïve phase gradient measurement by scanning the phase gradient at a controlled rate, thereby converting the gradient into normalized frequency shifts proportional to the scanning rate and the source distance.

Abstract: A reference electrical signal oscillated by the main oscillator (11) has two kinds of frequencies (f1, f2) which are different from each other and any one of which is alternatively selected, a sampling signal is synchronized with the reference electrical signal once every n times, and a frequency (fs) of the sampling signal is an average value of the two kinds of frequencies (f1, f2) of the reference electrical signal, and the A/D conversion portion carries out at least one A/D conversion per period of the reference electrical signal and the received electrical signal based on the sampling signal.

Abstract: The invention is based on a laser range finder that has a transmitter unit (10) with at least one laser, a receiver unit (12), and a single sideband modulation unit (14) that can use a first single sideband modulation frequency (ZF1) generated by an oscillator unit (16) and a carrier frequency (T1) to generate a modulation frequency (S1) of the transmitter unit (10). According to the invention, the oscillator unit (16) can generate at least one additional frequency (ZF2) and the single sideband modulation unit (14) can use the additional frequency (ZF2) to generate a demodulation frequency (S2) of the receiver unit (12).

Abstract: The invention relates to a system for measuring velocity. In one embodiment, the system includes a laser assembly having a laser diode and a power detection diode. The laser diode emits a plurality of laser signals which are frequency-modulated, wherein a selected one of the frequency-modulated signals is directed to and reflected from a target, and wherein another selected one of the frequency-modulated laser signals transmitted via one signal path is combined with the reflected laser signal transmitted via another delayed signal path in the interior of the laser assembly. The power detection diode detects the combined signal. The system also includes a signal processor configured to obtain velocity information from the detected signal by use of the harmonic frequencies associated with the modulation frequency.

Abstract: A spectrometer and spectrometry method comprising modulating a light source with a carrier waveform multiplied by an envelope function, directing light from the light source through a sample region and to a photodetector, and demodulating current from the photodetector at a reference frequency. Also a method for computing a modulation waveform comprising specifying a target detection efficiency in a Fourier space, computing a response of a waveform that comprises a carrier wave multiplied by an envelope function, and modifying the envelope function using nonlinear optimization means to minimize a difference between the computed response and a predetermined target gain spectrum.

Abstract: A light wave distance-measuring system, comprising a projection optical system having an optical axis of outgoing light and for projecting a measuring light, and a photodetection optical system having an optical axis of a returning light and for receiving a reflection light, wherein the photodetection optical system comprises a light receiving lens for receiving and for converging the reflection light, a light receiving surface where the reflection light enters, and a ring-like perforated multi-focal optical member arranged between the light receiving surface and the light receiving lens and for converging the light to the light receiving surface.

Abstract: The invention relates to a system for measuring velocity. In one aspect of the invention, the system comprises a laser emitting device, an optics assembly, a combiner and a signal processor. The laser emitting device generates a frequency-modulated laser signal. The optics assembly splits the frequency modulated signal into a plurality of laser signals, and directs the split signals to a target and receives at least one signal reflected from the target. The combiner receives one of the split signals transmitted via one signal path and the at least one reflected signal transmitted via another signal path, and multiplies the received signals. The signal processor extracts velocity information from the multiplied signal.

Abstract: Apparatus and method are provided for distance measurement to a remote surface using high frequency modulated transmitted and reflected laser beams and phase-shift calculations. To improve phase-shift resolution, the reflected bean is further modulated, before detection, at a high frequency similar yet different from that of the transmitted beam so as create a resulting detector signal having at least a lower frequency signal which is easily detected by a response limited detector. The lower frequency signal retains the phase-shift information and thus enables determination of the phase-shift information with stable, inexpensive low-frequency optical detectors. Three-dimensional mapping can performed wherein one or more apparatus employ a plurality of detectors or a scanner producing a plurality of sequential reflected beams, each of which results in a plurality of phase-shift information for an area on the surface.

Abstract: A synthetic aperture ladar system using a mode locked laser transmitter. The inventive system (12) includes a mode locked laser transmitter (22), a receiver (40) adapted to detect signals transmitted by said laser (22) and reflected by an object (32) and a signal processor (50) for analyzing the signals. The laser (22) is particularly novel as a synthetic aperture ladar transmitter inasmuch as it includes a mode locking mechanism (180). The mode locking mechanism (180) causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of coherent pulses which may be used for synthetic aperture ladar applications. In a particular embodiment, the present teachings are implemented in a multifunctional laser which, in its operational mode, outputs a mode locked beam for synthetic aperture ladar.

Abstract: A high range resolution ladar includes a chirp generator for producing a chirp signal waveform that is used by a laser diode to propagate a divergent laser light waveform. The reflected light signals from the target are directed to a self mixing detector that is coupled to the chirp generator where the responsivity of the detector varies in accordance with the chirp waveform for converting reflected light signals from the target to electrical signals and for mixing the converted electrical signal with the chirp waveform to produce an output electrical signal whose frequency is proportional to the range to the target. The self-mixing detector includes at least one detector having a semiconductor substrate and first and second electrodes deposited on the substrate and spaced from each other, wherein the first set of electrodes is connected to the chirp generator and the second set of electrodes is connected to a memory for storing a plurality of frames of image data.

Abstract: Methods of measuring widths of illumination spots and distances between two points, and predicting detected signal widths are provided. Systems, software, and kits for performing the methods of the invention are also provided.

Abstract: An object of the invention is to obtain a coherent laser radar device that provides one system of a photo detector and eliminates a blind zone, including a pulsed laser that oscillates at a frequency which is identical with or close to an output light of a local light source as a single frequency; a transmission/reception optical system that irradiates a pulsed laser beam from the pulsed laser toward a target as a transmission light and receives a scattered light from the target as a reception light; a light coupling means that couples the output light from the local light source and the reception light; a photo detecting portion that conducts light coherent detection on a coupled light; and a signal processing device that calculates a speed and a distance of a target in accordance with an output of the detection, in which the photo detecting portion comprises: a photo detecting element that conducts the light coherent detection; a microwave switch that changes over a propagation path of an output from the ph

Abstract: A method and system for automatic recognition and classification of a vibrating target among members of a plurality of objects having their vibration spectra stored in a database. In deciding as to which member of an alleged couple of vibrating objects the target should be assigned, the method uses an algorithm of signal processing which is based on wavelet packet analysis to predict a-priory a bandwidth in which the differences between the vibration of the spectrum is mostly pronounced, and the resolution within the bandwidth which is adequate to enable the decision.

Abstract: A system for signal acquisition in a distance meter includes at least one photoelectric receiver that detects electromagnetic radiation that is high-frequency modulated via a modulation frequency and converts the same to high-frequency electrical signals (HF). A device is provided for transforming the high-frequency electrical signals (HF) supplied by the photoelectric receiver into low-frequency measuring signals (NF) that can be passed on to a signal-processing unit mounted downstream of the device. The device for transforming the high-frequency electrical signals (HF) supplied by the photoelectric receiver into low-frequency measuring signals (NF) can include at least one switch whose switching frequency is controlled by a control frequency (F) whose frequency is higher or lower than the modulation frequency by the amount of the low-frequency measuring signal.

Abstract: An apparatus and method of dynamically optimizing an acquisition range of a radar system, including modulating a CW radar signal with a PN code that has an adjustable code frequency of modulation and an adjustable chip length. The method includes transmitting the modulated radar signal and receiving a return radar signal, based on the transmitted radar signal. The method continuously measures a SNR of the received return radar signal, and adaptively tunes the adjustable code frequency of modulation, and adaptively tunes the adjustable chip length, based on the continuously measured SNR. In this manner, the acquisition range of the radar system is optimized.

Abstract: A laser radar system is disclosed. The laser radar system includes a transmitting means that transmits a signal. The transmitted signal is formed by an optical signal that is amplitude modulated with a source signal thereby forming a transmitted signal having light packets at a repetition rate of the source signal. A receiving means that receives the transmitted signal after it is reflected from an object. A Doppler processor determines the Doppler frequency shift of the source signal from signals derived from the reflected signal.

Abstract: The present invention provides an oscillation measuring method comprising: a laser beam emission step S1 for emitting a laser beam to an object to be measured; a return beam reception step S2 for receiving a return beam reflected by the object and having an object Doppler frequency according to a velocity of the object; a self-mixing step S3 for mixing the return beam having the Doppler frequency with another beam emitted upon reception of the return beam and generating a self-frequency according to a resonator change during a time from the emission to the reception of the return beam, so as to generate a beat wave containing the object Doppler frequency superposed with the self-frequency; and an oscillation information output step S4 for outputting the beat wave or information obtained from signal processing of the beat wave as the object oscillation information. This enables to measure a fine oscillation of an object to be measured.

Abstract: The present invention is an improved distance measuring interferometer that includes high speed phase modulators and additional phase meters to generate and analyze multiple heterodyne signal pairs with distinct frequencies. Modulation sidebands with large frequency separation are generated by the high speed electro-optic phase modulators, requiring only a single frequency stable laser source and eliminating the need for a first laser to be tuned or stabilized relative to a second laser. The combination of signals produced by the modulated sidebands is separated and processed to give the target distance. The resulting metrology apparatus enables a sensor with submicron accuracy or better over a multi-kilometer ambiguity range.

Abstract: A method and apparatus of a plurality of detecting elements for detecting and producing an image of an object includes a signal generator for generating a waveform signal, a laser for producing a light signal modulated by the waveform signal, and a mixing and detecting device coupled to and driven by the signal generator for converting reflected light signals received from the target into electrical signals and for mixing the converted electrical signals with the waveform signal to produce an output electrical signal. A read-out is connected to the mixing and detecting device for removing the output electrical signals from the mixing and detecting, and a signal processor is connected to the read-out for processing the output electrical signals from the read-out to detect and produce and image of the object.

Abstract: A method of generating in-quadrature signals is disclosed. The method comprises phase shifting a Doppler frequency-shifted signal; phase shifting a local oscillator signal; mixing the phase shifted Doppler frequency-shifted signal and the phase-shifted local oscillator signal generating thereby a signal which includes the phase-shifted Doppler frequency-shifted signal and a further phase-shifted local oscillator signal; and mixing the unphase-shifted Doppler frequency-shifted signal and the unphase-shifted local oscillator signal generating thereby a signal which includes the unphase-shifted local oscillator signal and a further phase-shifted Doppler frequency-shifted signal. A method of determining the velocity of an object is also disclosed.

Abstract: One aspect of the invention relates to an optical signal processing device including a Mach-Zehnder interferometer which includes a reference arm comprising a first Fabry Perot interferometer and a sample arm comprising a second Fabry Perot interferometer including at least two mirrors forming a Fabry-Perot cavity therebetween, and an adsorbing material disposed within the cavity. The Fabry-Perot interferometer in the sample arm permits a first portion of an input signal to pass multiple times through the sample while a second portion of the input signal passes through the reference arm, and the first and second signal portions are combined at an output to result in constructive or destructive interference between the signal portions.

Abstract: An optical correlator is used to detect the presence of a target in a laser detection and ranging (LADAR) system by analyzing the return signal, and to provide initial estimates of the targets range and velocity to the LADAR receiver. The optical correlator includes an acoustic optical Bragg cell that deflects an input laser signal using the received and down-converted LADAR signal. An integrating optical detector is disposed to receive the optical outputs of the acoustic optical Bragg cell and an optical processor analyzes and processes the integrating optical detector data. The integrating optical detector integrates the optical outputs of the Bragg cell over time and the integrating optical detector output is sampled over a sampling period so that target detection is uncorrelated to noise.

Abstract: A three-dimensional time-of-flight (TOF) system includes a low power optical emitter whose idealized output S1=cos(&ohgr;·t) is reflected by a target distance z away as S2=A·cos(&ohgr;·t+&PHgr;), for detection by a two-dimensional array of pixel detectors and associated narrow bandwidth detector electronics and processing circuitry preferably fabricated on a common CMOS IC. Phase shift &PHgr; is proportional to TOF or z, z=&PHgr;·C/2·&ohgr;=&PHgr;·C/{2·(2·&pgr;·f)}, and A is brightness. &PHgr;, z, and A are determined by homodyne-mixing S2 with an internally generated phase-delayed version of S1, whose phase is dynamically forced to match the phase of S2 by closed-loop feedback. Idealized mixer output per each pixel detector is 0.5·A·{cos(2&ohgr;·t+&PHgr;)+cos(&PHgr;)}.

Abstract: A method and system are provided for measuring water current direction and magnitude. A plurality of beams of radiation are transmitted radially outward from a location above a body of water. Each beam is incident on the water's surface at an angle with respect thereto. Each beam experiences a Doppler shift as a result of being incident on the water's surface such that a plurality of Doppler shifts are generated. Each Doppler shift is measured with the largest one thereof being indicative of water current direction and magnitude.

Abstract: An incoherent ladar transmitter (12) adapted for use with synthetic aperture processing. The system (12) includes a first mechanism (44, 48, 50) for generating a laser beam (18). A second mechanism (44, 68) records phase information pertaining to the laser beam (18) and subsequently transmits the laser beam (18) from the system in response thereto. A third mechanism (40) receives a reflected version (20) of the laser beam and provides a received signal in response thereto. A fourth mechanism (72) corrects the received signal based on the phase information recorded by the second mechanism (44, 68). In a more specific embodiment, the ladar system (12) includes a synthetic aperture processor (46) for correcting the received signal based on the phase information and providing a corrected laser signal in response thereto.

Abstract: A high range resolution ladar includes a chirp generator for producing a chirp signal waveform that is used by a laser diode to propagate a divergent laser light waveform. The reflected light signals from the target are directed to a self mixing detector that is coupled to the chirp generator where the responsivity of the detector varies in accordance with the chirp waveform for converting reflected light signals from the target to electrical signals and for mixing the converted electrical signal with the chirp waveform to produce an output electrical signal whose frequency is proportional to the range to the target. The self-mixing detector includes at least one detector having a semiconductor substrate and first and second electrodes deposited on the substrate and spaced from each other, wherein the first set of electrodes is connected to the chirp generator and the second set of electrodes is connected to a memory for storing a plurality of frames of image data.

Abstract: A coherent laser radar system includes a pulsed laser oscillating a pulsed laser beam which is split into two parts by an optical divider. A first part of the two is transmitted as a transmitted beam via a beam splitter. A second part is supplied to a delay line via a coupling optics and others to be delayed by a predetermined time as a local beam, and is incident onto an optical coupler. The received beam from the target is incident onto the optical coupler via a scanning optics and so on. A photodetector carries out the coherent detection of the light beam coupled by the optical coupler. A signal processor computes a target velocity and the like from a signal generated by the detection and converted into a digital signal by an A/D converter. This makes it possible to solve a problem of a conventional system in that the system configuration is complicated and expensive.

Abstract: A method and system for determining range by correlating a relationship between one or more distances of a diffraction grating from an illuminated target surface with variations in the respective wavelengths of high order diffraction spectra. The high order diffraction spectra are observed through the diffraction grating. The high order diffraction spectra are derived from broadband radiation transmitted from the illuminated target surface.

Abstract: A three-dimensional image capturing device performs sensing operations of a first reflected light beam component and a second reflected light beam component. In the sensing operation of the first reflected light beam component, the pulse shape of a distance measuring light beam is triangular. The electric charge accumulating period starts at the same time as the disappearance of a pulse of the distance measuring light beam, and ends after the disappearance of a pulse of the reflected light beam. In the sensing operation of the second reflected light beam component, the pulse shape of a correction light beam is rectangular. The electric charge accumulating period starts at the same time as the disappearance of a pulse of the correction light beam, and ends after the disappearance of a pulse of the reflected light beam. A signal charge obtained by the first reflected light beam component sensing operation is divided by a signal charge obtained by the second reflected light beam component sensing operation.

Abstract: A radar system which is used for determining optical range includes a frequency analyzer for the analysis of differential frequency signals, which originate from a mixture of the transmitted signal with the received signals, for example reflected from a fog bank. The frequency spectrum images the distance profile of the fog bank.

Abstract: A self-referencing microdoppler ladar receiver is provided for detecting the vibration of a target based upon an analysis of backscattered signals without a local reference derived from the transmitter. The self-referencing microdoppler ladar receiver includes a frequency shifter for receiving a backscattered signal from the target and for controllably shifting the frequency of the backscattered signal. The self-referencing microdoppler ladar receiver also includes an interferometer, such as a Mach Zender interferometer, for directing portions of the frequency shifted signals along first and second paths of unequal length and for combining the portions of the frequency shifted signals to produce first and second output signals. The self-referencing microdoppler ladar receiver also includes a signal processor for providing a feedback signal to control the frequency shifter based upon differences in the respective power levels of the first and second output signals.

Abstract: The photosensitive device implements charge coupling and accumulation for analyzing a light signal. A sensor has an image zone M rows and N columns of photosensitive sites for receiving a light signal during successive acquisition periods, a transfer zone of P rows and N columns of non-photosensitive sites for receiving, in each site of a first row, the sum of the charges in a respective column of the image zone at the end of each successive sampling period. It also has a storage zone of P rows an N columns in which each column is adjacent to a respective column of the transfer zone and each site is arranged to receive charges contained in an adjacent site of the transfer zone and to accumulate it. The sensor is clocked for a sequence.

Abstract: A method and apparatus of a plurality of detecting elements for detecting and producing an image of an object includes a signal generator for generating a waveform signal, a laser for producing a light signal modulated by the waveform signal, and a mixing and detecting device coupled to and driven by the signal generator for converting reflected light signals received from the target into electrical signals and for mixing the converted electrical signals with the waveform signal to produce an output electrical signal. A read-out is connected to the mixing and detecting device for removing the output electrical signals from the mixing and detecting, and a signal processor is connected to the read-out for processing the output electrical signals from the read-out to detect and produce and image of the object.

Abstract: A radar system which is used for determining optical range includes a frequency analyzer for the analysis of differential frequency signals, which originate from a mixture of the transmitted signal with the received signals, for example reflected from a fog bank. The frequency spectrum images the distance profile of the fog bank.

Abstract: A system and method for determining at least one physical quantity by means of a relation between a transmission signal and a reception signal, wherein a transmitter emits the transmission signal having a predetermined frequency through a signal path for reception as the reception signal by a receiver. A reference signal generator generates a reference signal having a frequency which has a predetermined fixed relation to the frequency of the transmission signal. The reception signal is mixed with the reference signal to produce an intermediate frequency signal, which is filtered to isolate a difference signal, converted to a digital signal and then processed digitally to determine a phase and/or amplitude relation of the respective physical quantity to be determined. The transmission signal, the reference signal and the digital signal are generated in phase-locked relation using a clock signal derived from a main clock pulse of a master oscillator.

Abstract: A coherent laser radar system includes a pulsed laser oscillating a pulsed laser beam which is split into two parts by an optical divider. A first part of the two is transmitted as a transmitted beam via a beam splitter. A second part is supplied to a delay line via a coupling optics and others to be delayed by a predetermined time as a local beam, and is incident onto an optical coupler. The received beam from the target is incident onto the optical coupler via a scanning optics and so on. A photodetector carries out the coherent detection of the light beam coupled by the optical coupler. A signal processor computes a target velocity and the like from a signal generated by the detection and converted into a digital signal by an A/D converter. This makes it possible to solve a problem of a conventional system in that the system configuration is complicated and expensive.

Abstract: The photosensitive device implements charge coupling and accumulation for analyzing a light signal A sensor has an image zone M rows and N columns of photosensitive sites for receiving a light signal during successive acquisition periods, a transfer zone of P rows and N columns of non-photosensitive sites for receiving, in each site of a first row, the sum of the charges in a respective column of the image zone at the end of each successive sampling period. It also has a storage zone of P rows an N columns in which each column is adjacent to a respective column of the transfer zone and each site is arranged to receive charges contained in an adjacent site of the transfer zone and to accumulate it. The sensor is clocked for a sequence.

Abstract: An apparatus for determining various physical quantities such as temperature, pressure, stress, strain, distance and the like in a manner such that a change in the physical quantity of interest results in a measurable change in the frequency of oscillation of a signal generated within the apparatus.

Abstract: The present invention provides several apparatus, methods, and computer program products for phase shifts in an optical signal generated by an optical device. The present invention includes a optical phase modulator for altering the phase of the optical signals output by an optical device. The present invention also includes a detector assembly that receives an interference signal generated by an optical interference of a power signal and a reference signal. The detector assembly generates a lockin signal representing the optical phase difference between the power signal and the reference signal. Connected to both the detector assembly and the optical phase detector is a processor. The processor receives the lockin signal from the detector assembly and compares the lockin signal to at least one predetermined set point value. The predetermined set point value represents either a desired maximum lockin signal value or a range of acceptable lockin values.