JPS5896267A - Laser radar - Google Patents

Abstract

PURPOSE:To enable the detection of a target in a wide range of distance, by using a multielement array as a detector, and thereby increasing the width of a range gate proportional to the number of elements in comparison with the case wherein a detector with a single element is used. CONSTITUTION:In a laser radar detecting a target by scanning a visual field, raster scanning is made by transmission laser beams 10 generated from a transmission laser generator 1, and reflected beams from a target are detected by a multielement array. After an output of each detecting element is amplified by each of amplifiers 6A1, 6A2...6An, each output is delayed by each of delay units 12A1, 12A2...12An-1 in accordance with the difference in a scanning time among the detecting elements, and is synthesized by an adder 13, and thereby a signal output of reflection signals from a wide range of distance is obtained. By processing this output by a signal processor 7, the detection of the target is performed, and the result thereof is displayed on a display unit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning laser radar that scans a field of view in a raster pattern and detects a target.

First, referring to FIG. 1, a conventionally used scanning laser radar will be explained.

In FIG. 1, (l) μ transmission laser generator, (2) beam splitter, 131HX-Y scanner, (41 telescope, (51 detector, 161H amplifier, (7) signal processor, (8 ) is the display, and Q (Ii is the transmitting laser source. Note that here, the transmitting and receiving source system (9) is a common reference for convenience of explanation. Also, the laser transmission direction of the transmitting laser generator 11+ and the receiving source system are shown here. installed in the same direction as the instantaneous field of view of the system.
It is assumed that

In this simple configuration, the laser beam emitted from the transmitting laser generator (1) is completely transmitted through the beam splitter 12+, scans the field of view in a raster pattern by the x-y scanner (3), and is transmitted through the telescope (4). nru. In this way, the emitted transmitting laser beam is reflected by a target within its field of view and received by the telescope (4). After passing through the receiving source μX-Y scanner (3), the beam splitter (2
) and then enters the detector +51 VC. The output signal of the detector (51) is amplified by an amplifier 161, processed by a signal processor (7), and displayed as an image on a display (8), for example, to detect the target.

By the way, now the beam spread angle of the transmitting laser source αG is θ
t, and the instantaneous receiving field of view is θr. From the S/N point of view, θt is set to be approximately equal to θr.

If the dwell time per pixel corresponding to −1 reception instantaneous field of view is τd, and the transit time from when the source of the transmitting ray is reflected by the target to when it is received again is τt, then the reflected light is transmitted to the detector (51 In order to detect n, there is a constraint that τt≦τd.

.tau.d and .tau.t have n-order relationships with the number of pixels N in the 17th frame, the 7th frame rate, and the distance to the target IllRt.

τd =−→r...mark...
... illF However, the speed of light is O. Then the 111th. +21
The following conditions are determined from the formula and the above constraints.

From the above equation, it is clear that the data rate can be increased or the number of pixels in the 17 beam can be increased in a conventional scanning laser radar in which the transmitting direction of the transmitting laser source αa and the direction of the receiving instantaneous field of view are set to be the same. However, if the scanning field of view is widened and the angular resolution is improved, the detection distance of the target becomes shorter.

Therefore, this invention aims to solve this drawback.

We will use a multi-element array as a detector! 5, and will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which a deflector 12 is installed on il+.
is a delay device and an asH adder.

Figure 8 is a diagram for explaining the operation of Figure 2. (14
1μ scanning field of view, AI, A4... An instantaneous reception field of view corresponding to each element of the multi-element array of the Anμ detector 15), and B shows the laser transmission direction.

Now, the multi-element array is a linear array along the scanning direction
It is assumed that the line is offset by an angle Oo1 along the line.

At this time, since the scanning angular velocity in the X direction is given by θr -n, the output of each detection element AI + A2...A, is given by the following distance 11Rti in relation to the transit time of the transmitting laser tie. -B4i (i=L2-n) Only the reflected light from the target in the O range becomes a signal output.

However, θoi = θo ten (i −1) X (θr+ to θr
)−161θt〉△θr and the distance covered by the output of each detection element is $11i! Rtt ~R411Rt* ~
Ra = &n ~ &nt's overlap each other. Therefore, the output of each detection element is connected to an amplifier (6AI
), (6As) - (6An), and then a delay device (12
At), (12Az) - (12An-t) to delay each output, and adder (1:Hc) to synthesize the output, the output of adder a3 is finally the distance ll! range Rtn -
The signal output of the reflected signal from the target at R41 is obtained.
Ru. This output is processed by a signal processor (7) to detect the target, and the result is displayed on, for example, a display (8).

Using this method, the width of the range gate becomes larger in proportion to the number of elements compared to the case of using a single-element detector, making it possible to perform detection over a wide distance. becomes. Further, there is an advantage that the number of pixels N and the frame rate N5 can be increased by increasing the width of the range gate by just a foot.

Note that 2 and above showed a method of delaying and combining all outputs from n detection elements, but 2, for example, l.

2. Combine each output of k and (K+1), ...n into two parts, and display the combined output of (Jn in different colors on a color display etc.). There is also the advantage that it can be easily determined whether it exists within a distance range.

In another embodiment of the present invention, the output of each detection element is
Signal processor (71) and switch sequentially to display, for example, display (
8) It is also possible to detect the target by displaying it on the top.
This method makes it possible to precisely discriminate the distance of a target, and if the offset angle θok in the transmitting and receiving directions can be varied, target detection can be performed over a wider distance range.

Above we have discussed the case where the sending and receiving raw silk is the same.
This invention can also be applied to the case where the sending and receiving school threads are separate. Further, although the case where the direct detection method is used to detect the receiving 1g source has been described, it goes without saying that the present invention can be similarly applied to the case where the heterodyne detection method is used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional laser radar, FIG. 2 μ is a diagram showing an embodiment of the present invention, and FIG. 8 μ is a diagram showing scanning of a field of view according to the present invention. In the figure, (1) is the transmitting laser generator, +21i beam splitter, (3; is the X-Y scanner, 141t'X telescope. (51μ detector, (61μ amplifier), (7) is the signal processor, (8 ) is the display, +91fi sending, receiving source raw silk, +
IGμ transmitting laser, Qll is a deflector, Q3 is a delay device, and 03μ adder. airz scanning field of view, Aμ reception instantaneous field of view, Be-ff
The laser transmission number is the same. In FIG. 9, the same reference numerals are given to the same parts or parts corresponding to μ. Agent Shin Kuzuno - 111Figure 31

Claims (1)

[Claims] (!: A laser radar that detects an eye by scanning a field of view, comprising: a transmitting laser generator; a means for scanning a beam-shaped transmitting laser in a rusk-like manner;
a detection means consisting of a multi-element array for detecting reflected light from a target, and configured to detect a target within a field of view by delaying outputs from each element of the multi-element array and then combining them. It has all the features of laser radar. (2) The eyes are designed to scan the field of view! A laser radar for full detection includes a transmitting laser generator, means for scanning the transmitting laser source in the form of a beam in a raster pattern, and a detecting means consisting of a multi-element array for detecting reflection t'f from the target; A laser radar characterized in that it is configured to detect all targets by sequentially switching outputs from each element of the multi-element array.