Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Japan Aerospace Exploration Agency

Kimio Asaka

Yoshihito Hirano

Shumpei Kameyama

Shusou Wadaka

Takayuki Yanagisawa

Toshiyuki Ando

Atsushi Okamura

Masaharu Imaki

Takahiko Fujisaka

Akihito Hirai

Toshio Wakayama

Hiroshi Sakamaki

Tomoya Matsuda

Yasuisa Ooga

Masahiro Hagio

Masashi Furuta

Yoshinori Okuno

Etsuo Sugimoto

Naoki Matayoshi

Hidetaka Kiyosue

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.

Laser radar system

A measurement system for an aircraft having the three-axis components of the airspeed of the aircraft, the three-axis components of the wind speed currently encountered by the aircraft, and the wind speed distribution ahead of the aircraft simultaneously in real time. It comprises a Doppler anemometer measuring the airflow speeds at a plurality of points separated by a prescribed distance in the beam irradiation direction that changes in a time series, and an inertial data measurement device measuring the movement information and positional information of the aircraft. Moreover, the display system of the aircraft includes the horizontal two-axis airspeed of the aircraft, the three-axis components of the wind speed currently encountered by the aircraft, and information on the wind speed distribution ahead of the aircraft are displayed simultaneously in real time.

Airspeed / wind speed measurement device for aircraft, and display device for same

A laser radar apparatus includes a mixerfor converting the frequency of an electric signal outputted from a photodetectorinto a baseband frequency by using a modulating signal generated by an oscillator. The laser radar apparatus carries out a coherent integral of the electric signal whose frequency has been converted by the mixer, and measures the quality of scatterers which exist in the atmosphere from a result of the integral. As a result, even when the S/N ratio of the light signal received by a receiving optical unitis low, the laser radar apparatus can detect the quality of the scatterers.

Laser radar apparatus

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 photo detecting element; a microwave amplifier; and a switch control means that changes over the microwave switch so as to transmit a signal before a reference time as a monitor signal and transmit a signal after the reference time as a reception signal with a time at which the pulse light from the pulsed laser has completely passed through the transmission/reception optical system as the reference time.

Coherent laser radar device

In a coherent CW laser radar apparatus, a soft target such as rain, fog, and air turbulence can be detected by using a CW laser. The coherent CW laser radar apparatus is arbandd by comprising: as an optical component, a CW laser oscillating a laser radiation having a single wavelength; a dividing means for dividing laser radiation derived from the CW laser; an optical modulator for modulating one of the laser radiation divided by the dividing means; an optical antenna for projecting the modulated laser radiation as transmitted radiation toward a target, and also for receiving scattered radiation from the target as received radiation; combining means for combining the other of the laser radiation divided by the dividing means as local radiation with the received radiation received from the optical antenna; and a photodetector for optical-heterodyne-detecting the combined radiation. Also, this coherent CW laser radar apparatus is further arbandd by employing: as an electric component, a pseudo-random modulation signal generator for supplying a pseudo-random modulation signal to the optical modulator; a variable delay device for time-delaying a portion of the pseudo-random modulation signal generated from the pseudo-random modulation signal generator; a correlating device for multiplying the output signal of the photodetector by the pseudo-random modulation signal time-delayed by the variable delay device; and signal processing means for acquiring physical information such as a distance of the target and a velocity of the target based upon a intensity and a frequency of the output signal from the correlating device, and also the delay time set by the variable delay device. In this radar apparatus, an optical path between the optical components is constituted by an optical fiber.

Coherent laser radar apparatus and radar/optical communication system

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.

Coherent laser radar system and target measurement method

Disclosed is a radar system capable of obviating a problem that a sufficient improvement of an S/N ratio could not be obtained in the prior art, and comprising a transmitter/receiver for detecting a phase of a receiving signal reflected from an observation target, an A/D converter for converting the receiving signal into a digital signal, a range gate for extracting the receiving signal having a time corresponding to the predetermined pulse width, a data dividing unit for dividing the receiving signals in to two groups of data, an FFT unit for fast-Fourier-transforming one group of data of the two groups of data, an FFT unit for fast-Fourier-transforming the other group of data, a complex conjugating unit for taking a complex conjugate of an output of the FFT unit, a complex multiplying unit for performing a complex multiplication for the every same Doppler frequency component with respect to an output of the former FFT unit and an output of the complex conjugating unit, and a complex adder for executing a coherent addition of a result of the complex multiplication the same number of times as the repetitions with respect to the same Doppler frequency component. The receiving signals can be coherently integrated both in the pulse and between the pulses, and the S/N ratio can be improved.

Radar system and coherent integrating method thereof

Growing community of inventors

Tokyo, Japan

Kimio Asaka