초록 ▼

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

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.

대표청구항 ▼

1. A coherent laser radar device comprising:a local light source that oscillates at a single frequency;a pulsed laser that oscillates at a frequency which is identical with or close to the single frequency of said local light source;a transmission/reception optical system that irradiates a pulsed la

1. A coherent laser radar device comprising:a local light source that oscillates at a single frequency;a pulsed laser that oscillates at a frequency which is identical with or close to the single frequency of said local light source;a transmission/reception optical system that irradiates a pulsed laser beam from said 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 said local light source and said reception light;a photo detecting portion that conducts light coherent detection on the light coupled by said light coupling means; anda signal processing device that calculates a speed and a distance of a target in accordance with an output from said photo detecting portion, characterized in that said 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 said photo detecting element;a microwave amplifier; anda switch control means that changes over said microwave switch so as to transmit a signal before a reference time to said signal processing device as a monitor signal and transmit a signal after the reference time to said signal processing device as a reception signal with said reference time being a time at which the pulse light from said pulsed laser has completely passed through said transmission/reception optical system. 2. A coherent laser radar device according to claim 1, characterized in that:said pulsed laser includes an adjusting mechanism that adjusts a cavity length;said device further comprises a control circuit that controls said adjusting mechanism; andsaid control circuit outputs to said adjusting mechanism a control signal that adjusts the cavity length of said pulsed laser on the basis of an error signal from said signal processing device based on a frequency difference between the laser pulse and the local light. 3. A coherent laser radar device according to claim 1, characterized in that:said microwave amplifier is made up of a pre-amplifier that amplifies a signal from said photo detecting element and a post-amplifier that amplifies an output of the pre-amplifier; andsaid microwave switch is disposed between said pre-amplifier and said post-amplifier, outputs a signal that has been amplified by said pre-amplifier as a monitor signal and outputs a signal that has passed through said post-amplifier as a reception signal. 4. A coherent laser radar device according to claim 1, characterized in that:said microwave amplifier is made up of a pre-amplifier that amplifies a signal from said photo detecting element and a post-amplifier that amplifies an output of the pre-amplifier; andsaid microwave switch is disposed between said photo detecting element and said pre-amplifier, outputs a signal from said photo detecting element as a monitor signal and outputs a signal that has passed through said post-amplifier as a reception signal. 5. A coherent laser radar device comprising:a local light source that oscillates at a single frequency;a pulsed laser that oscillates at a frequency which is identical with or close to the single frequency of said local light source;a transmission/reception optical system that irradiates a pulsed laser beam from said pulsed laser toward a target as a transmission light and receives a scattered light from the target as a reception light;a coupling means that couples said reception light and an internal reflection light to an optical path, the internal reflection light comprising a part of the pulsed laser beam from said pulsed laser used for generating a monitor signal;a photo detecting portion that conducts light coherent detection on the light coupled to the optical path by said light coupling means; anda signal processing device that calculates a speed and a distance of a target in accordance with an output from said photo detecting port ion, characterized in that said photo detecting portion comprises:a photo-detecting element that conducts the light coherent detection;a microwave amplifying portion that amplifies an output signal from said photo detecting element; anda gain control means that controls the gain of said microwave amplifying portion so that an amplitude of the output signal from said microwave amplifying portion does not exceed a given threshold value. 6. A coherent laser radar device according to claim 5, characterized in that:said pulsed laser includes an adjusting mechanism that adjusts a cavity length;said device further comprises a control circuit that controls said adjusting mechanism; andsaid control circuit outputs to said adjusting mechanism a control signal that adjusts the cavity length of said pulsed laser on the basis of an error signal from said signal processing device based on a frequency difference between the laser pulse and the local light. 7. A coherent laser radar device according to claim 5, characterized in that:said microwave amplifier is made up of a pre-amplifier that amplifies a signal from said photo detecting element and a gain control amplifier that amplifies an output of the pre-amplifier; andsaid gain control means controls the gain of said gain control amplifier. 8. A coherent laser radar device according to claim 5, characterized in that:said microwave amplifier is made up of a pre-amplifier that amplifies a signal from said photo detecting element and a post-amplifier that amplifies an output of the pre-amplifier; andsaid gain control means comprises a microwave variable attenuator disposed between said pre-amplifier and said post-amplifier, and an attenuation control circuit that controls the attenuation of said microwave variable attenuator. 9. A coherent laser radar device characterized by comprising:a local light source that oscillates at a single frequency;a pulsed laser that oscillates at a frequency which is identical with or close to the single frequency of said local light source;a transmission/reception optical system that irradiates a pulsed laser beam from said pulsed laser toward a target as a transmission light and receives a scattered light from the target as a reception light;a coupling means that couples said reception light and an internal reflection light to an optical path, the internal reflection light comprising a part of the pulsed laser beam from said pulsed laser used for generating a monitor signal;a photo detecting portion that conducts light coherent detection on the light coupled to the optical path by said optical coupler; anda signal processing device that detects a speed and a distance of a target in accordance with an output from said photo detecting portion;a light variable attenuator disposed between said transmission/reception optical system and said photo detecting portion; anda control means that controls the attenuation of said light variable attenuator in such a manner that an amplitude of the output from said photo detecting portion does not exceed a given threshold value. 10. A coherent laser radar device according to claim 9, characterized in that:said pulsed laser includes an adjusting mechanism that adjusts a cavity length;said device further comprises a control circuit that controls said adjusting mechanism; andsaid control circuit outputs to said adjusting mechanism a control signal that adjusts the cavity length of said pulsed laser on the basis of an error signal from said signal processing device based on a frequency difference between the laser pulse and the local light. 11. An apparatus implemented in a laser radar device, the laser radar device being configured to transmit a pulsed laser beam toward a target and process scattered light received from the target in a signal processing unit, the apparatus comprising:light coupling means for coupling the output light of a light source with the received scattered light, the light source being used to generate the pulsed laser beam;photo-detecting means for generating a signal by performing coherent detection on the light coupled by the light coupling means;outputting means for outputting the signal generated by the photo-detecting means to the signal processing unit as a monitor signal before a reference time, and for outputting an amplified version of the signal generated by the photo-detecting means to the signal processing unit as a reception signal after the reference time,wherein the reception signal is used by the signal processing unit to determine at least one of a speed and direction of the target, and the reference time corresponds to a time at which internal reflection signals of the laser radar device are diminished. 12. The apparatus of claim 11, wherein the monitoring signal is used by the laser radar device to adjust a frequency of the pulsed laser beam to be closer to a frequency of a seed light used for generating the pulsed laser beam. 13. The apparatus of claim 11, wherein the photo-detecting means include,a photo-detecting element that performs the coherent detection; anda pre-amplifier operable to generate a first amplified signal by amplifying an output of the photo-detecting element. 14. The apparatus of claim 13, whereinthe photo-detecting means further include a post-amplifier operable to generate a second amplified signal by amplifying the first amplified signal, andthe outputting means includes a microwave switch disposed between the preamplifier and the post amplifier, the microwave switch being operable to:direct the first amplified signal to the signal processing unit as the monitoring signal before the reference time; anddirect the first amplified signal to the post-amplifier after the reference time, thereby allowing the second amplified signal being output to the signal processing unit as the reception signal. 15. The apparatus of claim 11, wherein the outputting means include,a microwave amplifier operably connected to the photo-detecting means, andgain control means for controlling a gain of a signal output by the microwave amplifier. 16. The apparatus of claim 15, wherein the photo-detecting means include,a photo-detecting element that performs the coherent detection; anda pre-amplifier configured to generate an amplified signal by amplifying an output of the photo-detecting element, the amplified signal being sent to the outputting means. 17. The apparatus of claim 16, whereinthe microwave amplifier is a gain control amplifier operably connected to receive the amplified signal output by the pre-amplifier, an output of the microwave amplifier further being directed to the signal processing unit, andthe gain control means controls a gain of the gain control amplifier to increase after the reference time. 18. The apparatus of claim 16, whereinthe gain control means is a microwave variable attenuator operably connected to receive the amplified signal output by the pre-amplifier, the microwave variable attenuator being controlled to attenuate the received amplified signal before the reference time, andthe microwave amplifier is a post amplifier operably connected to receive an output of the microwave variable attenuator, an output of the post amplifier being directed to the signal processing unit. 19. The apparatus of claim 11, further comprising a light variable attenuator operably connected to transfer the received scattered light to the photo-detecting means, light variable attenuator being controlled to attenuate the received scattered light to a given threshold before the reference time. 20. A method in a laser radar device, the laser radar device being configured to transmit a pulsed laser beam toward a target and process scattered light received from the target in a signal processing unit, the method comprising:coupling the output light of a light source with the received scattered light, the light source being used to generate the pulsed laser beam;generating a first signal by performing coheren t detection on the coupled light to generate a first signal;outputting, before a reference time, the first signal to the signal processing unit as a monitor signal; andoutputting, after the reference time, a second signal to the signal processing unit as a reception signal, the second signal being an amplified version of the first signal,wherein the reception signal is used by the signal processing unit to determine at least one of a speed and direction of the target, and the reference time corresponds to a time at which internal reflection signals of the laser radar device are diminished. 21. The method of claim 20, further comprising:utilizing a pre-amplifier to amplify a signal generated by the coherent detection;utilizing a post-amplifier to amplify an output of the pre-amplifier; andutilizing a microwave switch to perform the output steps, the microwave switch being configured to direct the output of the pre-amplifier to the signal processing unit before the reference time, and to direct an output of the post-amplifier to the signal processing unit after the reference time. 22. The method of claim 20, whereinthe outputting steps are performed by a gain control amplifier configured to receive a signal generated as a result of the coherent detection, andthe method further comprises:controlling a gain of the gain control amplifier to increase after the reference time. 23. The method of claim 20, further comprising:utilizing a microwave variable attenuator to attenuate a signal generated as a result of the coherent detection to a given threshold before the reference time, whereinthe outputting steps are performed by a microwave amplifier configured to amplify an output of the microwave variable attenuator. 24. The method of claim 20, further comprising:utilizing a light variable attenuator to attenuate the received scattered light to a given threshold before the reference time, whereinthe coupling step couples an output of the light variable attenuator to the output light of the light source.