JPH07311268A - Surveying laser radar - Google Patents

Abstract

PURPOSE:To provide a surveying laser radar which can survey via an optimum wavelength which can permeate sea water in a sea area and effectively survey a target of a deeper depth. CONSTITUTION:A laser radar surveys a target position by emitting a laser light 12 and inputting an echo to be reflected by a target 17 in the sea 16, and comprises a controller 21 for outputting a scan command of a variable band wavelength for a variable wavelength laser 11, and a wavelength selecting signal processor 20 for selecting a wavelength by obtaining the emitting strength and the reflecting strength of a certain wavelength and selecting the wavelength in which reflecting the strength/emitting strengths become maximum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser radar device for exploration.

[0002]

2. Description of the Related Art Conventionally, a laser radar device mounted on an aircraft or the like for irradiating a laser beam and inputting an echo reflected by a target such as a submerged ship in the sea to search a target position is shown in a schematic view of FIG. Is known,
That is, in FIG. 2, the laser beam 32 emitted from the YAG laser 31 passes through the hole of the perforated concave mirror 33, and is irradiated to the underwater 36 via the mirror 34. At this time, the mirror 34 is vibrated and the laser beam 32 is emitted in the scanning direction 35. When the beam is scanned and the target 37 existing in the sea 36 is searched,
The laser light that hits the target 37 is reflected, and a part of it travels in the direction opposite to the incident light, passes through the mirror 34, is condensed by the concave mirror 33 on the photoelectric converter 38, and the laser reflected light that enters the photoelectric converter 33 is reflected. It is converted into an electric signal and processed by the signal processor 39, and the presence or absence of the target 37 is determined.

However, the wavelength of the laser beam 32 is in the wavelength range of 400 to 600 nm where the transmittance of seawater is good, the output is high, and it can be mounted on an aircraft or the like with good maintainability.
The second harmonic 523 nm of the AG laser 31 is adopted and fixed. However, the degree of attenuation of laser light in seawater differs depending on the amount of scattering by suspended matter in the sea, and as shown in the diagram of FIG. 3, the minimum attenuation wavelength of laser light, that is, the maximum transmission wavelength, differs depending on the sea area.
Therefore, as described above, the wavelength of the laser beam 32 is 523 nm.
Since it is not possible to search at the optimum wavelength depending on the sea area if it is fixed at, it is not possible to perform deep exploration according to the sea area. In addition, in order to search the target 37 located deeper against the increase of the attenuation coefficient, the laser intensity must be increased. For example, in the sea area with the attenuation coefficient α = 0.12, even if the laser intensity is doubled, the maximum search is possible. The depth is only 2.9 m, which is a disadvantage.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and it is possible to perform exploration at an optimum wavelength that allows seawater to be transmitted well depending on the sea area, and a target with a deeper depth can be effectively used. It is an object of the present invention to provide a laser radar device for exploration capable of exploring.

[0005]

To this end, the present invention provides a laser radar device for irradiating a variable wavelength laser beam in a laser radar device for irradiating a laser beam and inputting an echo reflected by an underwater target to search a target position. And a controller for issuing a scan command of a variable band wavelength to the laser device, and means for selecting an irradiation intensity / reflection intensity at a certain wavelength and selecting a reflection intensity / a wavelength at which the irradiation intensity is maximized. To do.

[0006]

In the laser radar device for exploration of the present invention, the wavelength of the laser device is scanned over a variable band by the signal from the controller, and the irradiation intensity and the reflection intensity at a certain wavelength are obtained by the wavelength selection means to obtain the maximum reflection intensity / irradiation intensity. The wavelength to be used is selected, the wavelength of the laser device is fixed at that wavelength, and the underwater target is searched.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the laser radar device for exploration of the present invention will be described with reference to the schematic view of FIG. 1. The wavelength tunable laser 11 is a wavelength tunable laser using the optical parametric oscillation principle capable of oscillating in the band of 400 to 600 nm. There is a perforated concave mirror 13 in front of the laser light 12 emitted from the wavelength tunable laser 11, and a mirror 14 is installed in front of the concave mirror 13 for scanning direction 1.
Scan the laser beam to 5 and target 16 underwater
Exploring 7. Further, a photoelectric converter 18 is arranged at a position where the reflected light from the concave mirror 13 is received, and a search signal processor 19 and a wavelength selection signal processor 20 are connected to the photoelectric converter 18 for wavelength selection. The signal processor 20 and the wavelength tunable laser 11 are connected to a controller 21 which issues a scan command of an appropriate wavelength in a variable band.

In such an apparatus, the laser light 12 emitted from the wavelength tunable laser 11 passes through the hole of the perforated concave mirror 13, and the underwater 16 is scanned by the mirror 14 vibrated in the scanning direction 15 to search the target 17. The laser light that hits the target 17 is reflected, and a part of it is focused on the photoelectric converter 18 via the mirror 14 and the concave mirror 13, and the laser reflected light that has entered the photoelectric converter 18 is converted into an electrical signal 22 for exploration. Is processed by the signal processor 19 for
The presence or absence of the target 17 is determined. Then, when irradiating the laser light 12 from the wavelength tunable laser 11, the signal 23 from the controller 21 scans the wavelength of the wavelength tunable laser 11 to 400 to 600 nm, and the wavelength selection signal processor 20 performs photoelectric conversion at this time. The intensity ratio between the signal 24 from the device 18 and the power monitor signal 25 of the wavelength tunable laser 11 is calculated, and the signal and the signal 23 from the controller 21 are temporarily recorded. When the scan is completed, the wavelength at which the intensity ratio becomes maximum is determined from the relationship between the intensity ratio and the wavelength, and the wavelength signal is sent to the controller 21. The controller 21 fixes the wavelength of the wavelength tunable laser 11 with the wavelength signal and switches to the search mode to perform the search.

Thus, according to this apparatus, the wavelength selecting signal processor 20 selects the wavelength at which the reflection intensity / irradiation intensity of the laser beam 12 is maximum, so that the wavelength of the seawater which is most permeated in the exploration sea area is selected. The target 17 can be probed with the laser beam 12, and a deeper depth can be effectively probed. For example, in the conventional wavelength of 532 nm, the attenuation coefficient α = 0.12, but 480
If the wavelength of nm is α = 0.08, 532 nm
If the maximum penetration depth at 50 m is 50 m, the maximum penetration depth at 480 nm is about 69 m, and a depth of 19 m can be explored.

[0010]

In summary, according to the present invention, in a laser radar device for irradiating a laser beam and inputting an echo reflected by an underwater target to search a target position, a laser device for irradiating a variable wavelength laser beam,
By providing a controller for issuing a scan command of a variable band wavelength to the above laser device and a means for selecting the irradiation intensity and the reflection intensity at a certain wavelength and selecting the wavelength at which the reflection intensity / irradiation intensity is the maximum, the INDUSTRIAL APPLICABILITY The present invention is extremely useful industrially because it provides a laser radar device for exploration that can perform exploration at an optimum wavelength that can penetrate seawater and can effectively probe a target at a deeper depth.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a laser radar device for exploration of the present invention.

FIG. 2 is a schematic diagram of a conventional laser radar device for exploration.

FIG. 3 is a diagram showing a relationship between a laser light wavelength and an attenuation coefficient in a sea area.

[Explanation of symbols]

 11 Tunable laser 12 Laser light 13 Concave mirror 14 Mirror 15 Scanning direction 16 Undersea 17 Target 19 Signal processor for exploration 20 Signal processor for wavelength selection 21 Controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Tatsuo 1-1, Atsunoura-machi, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Shipyard (72) Inventor Seiji Ryu 1-1, Atsunoura-machi, Nagasaki City Mitsubishi Heavy Industries Ltd. In-house

Claims (1)

[Claims] 1. A laser radar device for irradiating a laser beam and inputting an echo reflected by an underwater target to search a target position, and a laser device for irradiating a variable wavelength laser beam and a variable band wavelength for the laser device. A laser radar device for exploration, comprising a controller for issuing a scan command of, and means for determining the irradiation intensity and the reflection intensity at a certain wavelength and selecting the wavelength at which the reflection intensity / irradiation intensity is maximum.