Abstract: A wind measurement lidar includes: an output unit to output a laser beam; a transmitter-receiver to emit the laser beam produced by the output unit into the air, and to receive a scattered beam of the laser beam; a received signal acquiring unit to obtain a received signal through heterodyne detection of the laser beam and the beam acquired via the transmitter-receiver; a controller to control the transmitter-receiver; a storage to store as a noise signal the received signal obtained when the laser beam is controlled so as to be produced, but not to be emitted into the air; a frequency difference unit to subtract the noise signal from the received signal obtained when the laser beam is controlled so as to be emitted into the air; and a wind speed measurer to measure a wind speed from the subtraction result.

Abstract: A laser radar device includes a searchable distance calculation device 2 to calculate an amount of attenuation at a time of propagation of a light wave from a temporal change in scattered light intensity measured by a marine snow measurement device 1, and calculate a searchable distance in a target search device 4 from the amount of attenuation.

Abstract: A speed calculator 16 selects a speed calculation method corresponding to a peak value of an SNR which is detected by a peak SNR detector 15 from among a plurality of speed calculation methods of calculating the speed (wind speed) of an aerosol to calculate the speed (wind speed) of the aerosol according to the speed calculation method. As a result, there is provided an advantage of being able to calculate the speed (wind speed) of the aerosol in a short time with a high degree of accuracy.

Abstract: A device includes a light source (1) for generating light with a single wavelength; a modulator (3) for modulating the light generated into transmission light; a beam scanner (7) for carrying out beam scanning by which the transmission light modulated is radiated, and the light reflected is received; a beam scanning controller (8) for controlling the radiation direction; a signal processing unit (12) for performing wind measurement through heterodyne detection using the light generated and the corresponding received light; and an optical axis corrector (9) for correcting the optical axis angular shift between the transmission light and the received light, which accompanies the beam scanning, with respect to the received light used by the signal processing unit (12) or the transmission light used by the beam scanner (7), on the basis of the radiation direction of the beam scanner (7), the angular speed of the beam scanning and the wind measurement distance.

Abstract: An optimal position analysis unit 24 specifies an optimal installation position for a photodetector 6 by using spectra which by a spectrum and wind speed computing unit 23 calculated by analyzing output data of a photodetector 6 installed at different installation positions, controls a position adjustment made by an optical unit adjustment driving unit 7, and optimizes the installation position of the photodetector 6.

Abstract: A laser radar device includes a multi-wavelength light oscillator to generate a plurality of light beams with different wavelengths, a plurality of modulation units to modulate each of the plurality of light beams with a modulation frequency altered according to a corresponding line of sight of emission, a transmitting/receiving optical system to emit each of the light beams modulated by the modulation units in a corresponding line of sight, and receive reflected light beams, an optical receiver to perform heterodyne detection by using the generated light beams and the received light beams corresponding to the generated light beams, and detect beat signals in the respective lines of sight, and a signal analyzing unit to calculate a value of Doppler wind speed in the respective lines of sight from the respective beat signals, and calculate a value of three-dimensional wind speed using the values of Doppler wind speed.

Abstract: An S/N calculation circuit 12 to calculate the S/N ratio of a received signal, and an S/N comparison circuit 13 to compare the S/N calculated by the S/N calculation circuit 12 with a threshold Th are disposed, and a parameter setting circuit 14 controls the radiation state of a beam radiated from a transmission optical system 5 according to the result of the comparison performed by the S/N comparison circuit 13. As a result, even if the state of the propagation environment gets worse, degradation in the communication quality can be prevented and communicative stabilization can be achieved.

Abstract: There is provided a coherence length measurement device (10) that calculates a coherence length Lc based on a spectrum v calculated by an FFT device (9) and performs, in case where the coherence length Lc is shorter than an FFT gate width Gw, a setting change to shorten the FFT gate width Gw and a pulse width Pw, and the FFT device (9) performs frequency analysis on a received signal outputted from an A/D converter (8) by a unit of an FFT gate following the setting change to calculate the spectrum v of the received signal.

Abstract: A noise spectral differential unit records a noise spectrum in a state without any received signal, and subtracts the noise spectrum from a received signal spectrum. An offset corrector performs offset correction of the signal spectrum obtained by subtracting the noise spectrum by the noise spectral differential unit with respect to the noise level at a frequency separated from the frequency peak position of the received signal by a prescribed value. A frequency shift analyzer executes signal processing of the signal spectrum resulting after the offset correction and measures a frequency shift. A wind velocity converter makes wind velocity detection from the frequency shift measured by the frequency shift analyzer.

Abstract: An optical transmitter 1 includes an optical phase modulator 131 that performs phase modulation on a continuously oscillating light, a light intensity modulator 132 that performs pulse modulation on the light on which the phase modulation is performed, to output the light as a transmission light, a first signal generator 133 that generates a pulse modulation driving signal in which on and off time intervals are repeated periodically, to drive the optical intensity modulator 132, and a second signal generator 134 that generates a saw tooth wave driving signal having an amplitude equal to an integral multiple of a driving voltage needed to acquire a modulation phase of 2? of the optical phase modulator 131, and having a constant period, to drive the optical phase modulator 131.

Abstract: A wind measurement lidar includes: an output unit to output a laser beam; a transmitter-receiver to emit the laser beam produced by the output unit into the air, and to receive a scattered beam of the laser beam; a received signal acquiring unit to obtain a received signal through heterodyne detection of the laser beam and the beam acquired via the transmitter-receiver; a controller to control the transmitter-receiver; a storage to store as a noise signal the received signal obtained when the laser beam is controlled so as to be produced, but not to be emitted into the air; a frequency difference unit to subtract the noise signal from the received signal obtained when the laser beam is controlled so as to be emitted into the air; and a wind speed measurer to measure a wind speed from the subtraction result.

Abstract: A system controller 16 determines whether the quality of either a distance image or a light intensity image satisfies reference quality, and, when the quality of either the distance image or the light intensity image dos not satisfy the reference quality, outputs a speed change command to lower a speed, an altitude change command to change a submarine altitude (depth), or the like to a navigation control unit 2, thereby changing a physical relative relation between a measurement plane 3 and a device in question. As an alternative, the system controller changes a beam scanning rate f, a beam divergence ?, or the like within limits at which the amount of variation in a spatial resolution does not exceed a permissible amount.

Abstract: A lidar includes CW laser light sources that oscillate CW laser light rays with wavelengths different from each other; an optical multiplexing coupler that mixes the CW laser light rays oscillated by the CW laser light sources; an optical branching coupler that splits the CW laser light passing through the mixing by the optical multiplexing coupler; a light modulator that modulates first CW laser light split by the optical branching coupler; and an optical fiber amplifier that amplifies the laser light modulated by the light modulator, in which a transmit-receive optical system irradiates a target with the laser light amplified by the optical fiber amplifier, and receives scattered light of the laser light by the target.

Abstract: An S/N calculation circuit 12 to calculate the S/N ratio of a received signal, and an S/N comparison circuit 13 to compare the S/N calculated by the S/N calculation circuit 12 with a threshold Th are disposed, and a parameter setting circuit 14 controls the radiation state of a beam radiated from a transmission optical system 5 according to the result of the comparison performed by the S/N comparison circuit 13. As a result, even if the state of the propagation environment gets worse, degradation in the communication quality can be prevented and communicative stabilization can be achieved.

Abstract: A laser radar device includes a searchable distance calculation device 2 to calculate an amount of attenuation at a time of propagation of a light wave from a temporal change in scattered light intensity measured by a marine snow measurement device 1, and calculate a searchable distance in a target search device 4 from the amount of attenuation.

Abstract: A noise spectral differential unit records a noise spectrum in a state without any received signal, and subtracts the noise spectrum from a received signal spectrum. An offset corrector performs offset correction of the signal spectrum obtained by subtracting the noise spectrum by the noise spectral differential unit with respect to the noise level at a frequency separated from the frequency peak position of the received signal by a prescribed value. A frequency shift analyzer executes signal processing of the signal spectrum resulting after the offset correction and measures a frequency shift. A wind velocity converter makes wind velocity detection from the frequency shift measured by the frequency shift analyzer.

Abstract: There is provided a coherence length measurement device (10) that calculates a coherence length Lc based on a spectrum v calculated by an FFT device (9) and performs, in case where the coherence length Lc is shorter than an FFT gate width Gw, a setting change to shorten the FFT gate width Gw and a pulse width Pw, and the FFT device (9) performs frequency analysis on a received signal outputted from an A/D converter (8) by a unit of an FFT gate following the setting change to calculate the spectrum v of the received signal.

Abstract: A speed calculator 16 selects a speed calculation method corresponding to a peak value of an SNR which is detected by a peak SNR detector 15 from among a plurality of speed calculation methods of calculating the speed (wind speed) of an aerosol to calculate the speed (wind speed) of the aerosol according to the speed calculation method. As a result, there is provided an advantage of being able to calculate the speed (wind speed) of the aerosol in a short time with a high degree of accuracy.

Abstract: An optimal position analysis unit 24 specifies an optimal installation position for a photodetector 6 by using spectra which by a spectrum and wind speed computing unit 23 calculated by analyzing output data of a photodetector 6 installed at different installation positions, controls a position adjustment made by an optical unit adjustment driving unit 7, and optimizes the installation position of the photodetector 6.

Abstract: A laser radar system includes: a scanner for transmitting a pulse toward a target while two-dimensionally scanning a transmitting beam, and outputting scan angle information; a lens of the receiver for receiving received light; a high aspect photo detector array for converting the received light into a received signal; a transimpedance amplifier array for amplifying the received signal; an adder circuit for adding the received signal from each element of the transimpedance amplifier array; a distance detecting circuit for measuring a light round-trip time to the target of an output signal from the adder circuit; and a signal processing unit for causing the scanner to perform a two-dimensional scanning operation in association with the scan angle information, to determine distances to multiple points on the target based on the light round-trip time and a speed of light and measure a three-dimensional shape of the target.