Laser radar device

1. A laser radar device comprising:

a light source array having a single reference light source configured to emit a reference laser beam, an optical splitting element configured to split the reference laser beam into a plurality of laser light beams, and a plurality of light emitting ends, the light source array being configured to simultaneously emit the plurality of laser light beams from the plurality of light emitting ends, respectively;

an optical splitter configured to separate a plurality of transmission light components from the plurality of laser light beams, respectively, and configured to separate a plurality of local light components from the plurality of laser light beams, respectively;

an optical modulator configured to modulate one of the transmission light components to generate modulated transmission light;

a transmission/reception optical system configured to receive, as received light, the modulated transmission light reflected by a target existing in external space, while scanning the external space with the modulated transmission light;

an optical combiner configured to generate a plurality of interference light components by combining the received light and the plurality of local light components;

an optical receiver array including a plurality of optical receivers arranged at respective positions that optically correspond to different receiving fields of view of the transmission/reception optical system, and configured to generate a plurality of detection signals by detecting the plurality of interference light components;

a switching circuit configured to select a detection signal from among the plurality of detection signals corresponding to the different receiving fields of view, in accordance with a scanning speed of the transmission/reception optical system with respect to the external space; and

a signal processor configured to calculate a signal spectrum of the selected detection signal, and calculate an observation quantity including a velocity vector of the target on a basis of the signal spectrum,

wherein the signal processor includes:

a signal divider configured to divide the detection signal selected by the switching circuit into a plurality of time domain signals indicating respective signal waveforms of a plurality of gate time domains;

a domain converter configured to convert the plurality of time domain signals into a plurality of frequency domain signals, respectively;

an integrator configured to calculate a plurality of spectra of the plurality of the time domain signals from the plurality of frequency domain signals, and calculate the signal spectrum by integrating the plurality of spectra; and

an observation quantity calculator configured to calculate the observation quantity on a basis of the signal spectrum.

2. A laser radar device comprising:

a light source array having a single reference light source configured to emit a reference laser beam, an optical splitting element configured to split the reference laser beam into a plurality of laser light beams, and a plurality of light emitting ends, the light source array being configured to simultaneously emit the plurality of laser light beams from the plurality of light emitting ends, respectively;

an optical splitter configured to separate a plurality of transmission light components from the plurality of laser light beams, respectively, and configured to separate a plurality of local light components from the plurality of laser light beams, respectively;

an optical modulator configured to modulate one of the transmission light components to generate modulated transmission light;

a transmission/reception optical system configured to receive, as received light, the modulated transmission light reflected by a target existing in external space, while scanning the external space with the modulated transmission light;

an optical combiner configured to generate a plurality of interference light components by combining the received light and the plurality of local light components;

an optical receiver array including a plurality of optical receivers arranged at respective positions that optically correspond to a plurality of different receiving fields of view of the transmission/reception optical system, and configured to generate a plurality of detection signals by detecting the plurality of interference light components;

a signal processor configured to calculate a plurality of signal spectra of the plurality of detection signals, and calculate a plurality of signal-to-noise power ratios of the plurality of detection signals,

wherein the signal processor includes:

a signal divider configured to divide each of the plurality of detection signals into a plurality of time domain signals indicating signal waveforms of a plurality of gate time domains;

a domain converter configured to, for each of the plurality of detection signals, convert the plurality of time domain signals into a plurality of frequency domain signals, respectively;

an integrator configured to, for each of the plurality of detection signals, calculate a plurality of spectra of the plurality of time domain signals from the plurality of frequency domain signals, and calculate, as the plurality of signal spectra, a plurality of integration spectra corresponding to the plurality of detection signals by integrating the calculated plurality of spectra;

an SNR calculator configured to calculate the plurality of signal-to-noise power ratios from the plurality of integration spectra, respectively;

a selector configured to select at least two integration spectra from among the plurality of integration spectra by using the plurality of signal-to-noise power ratios, and calculate a noise reduction spectrum by adding or averaging the at least two signal spectra; and

an observation quantity calculator configured to calculate observation quantities including a line-of-sight velocity and a velocity vector of the target on a basis of the noise reduction spectrum that is calculated by the selector.