JPH05264719A - Laser rader apparatus - Google Patents

Abstract

PURPOSE:To perform a distance measuring operation accurately by preventing that a detector is saturated by the strong intensity of reflected light when a short distance is measured by means of a laser radar apparatus. CONSTITUTION:A control part 2 which controls a laser output is installed between a laser oscillation part 1 and a signal processing part 6. Whether the distance-measuring state of all frames which are input through a lens 4 and a photodetection circuit 5 is saturated or not is judged by the signal processing part 6. In a saturated state, the laser output of a next frame is controlled so as to prevent a detector from being saturated, and the accuracy of the title apparatus is kept.

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.

[0002]

2. Description of the Related Art In a conventional laser radar apparatus, when a received light level is saturated corresponding to the saturation of a detector in short-distance measurement, a received waveform shows a waveform rising earlier than an actual timing.

FIG. 4 is a detection characteristic diagram (a) for long-distance measurement and a detection characteristic diagram (b) for long-distance measurement of a conventional laser radar device.

As shown in FIG. 4 (a), the detector for detecting the laser beam is saturated in the short distance measurement, and the output waveform is saturated as compared with the case of FIG. 4 (b). It is captured as a waveform of the rising timing that has advanced ahead of time.

[0005]

The above-mentioned conventional laser radar device is a detector for detecting a received laser beam when performing distance measurement within a certain short distance, which is determined by the performance of the device. Since the output waveform is saturated due to saturation and is captured at a timing earlier than the actual time, there is a drawback that accurate distance measurement cannot be performed.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a laser radar device capable of accurately measuring a distance even at a short distance.

[0007]

The laser radar device of the present invention captures the reflected light of the target of the transmitted laser light at a short distance and saturates the short-distance received light level in correspondence with the received light level of the reflected light. It has a configuration for reducing the transmission level of the transmission laser light so as to suppress it.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

The embodiment shown in FIG. 1 includes a laser oscillator 1 for outputting a pulse laser, a control circuit 2 for controlling the output of the laser oscillator 1, and a scanner 3 for scanning a pulse laser beam over a predetermined range. A lens 4 for receiving the reflected light from the target 7, a light receiving circuit 5 for photoelectrically converting the light receiving input, and a signal processing unit 6 for processing the output signal of the light receiving circuit 5 and performing signal processing such as distance measurement. Consists of

Next, the operation of this embodiment will be described.
The laser oscillating unit 1 generates and outputs a pulse laser, and the scanner unit 6 scans the pulse laser to irradiate a target as scan laser light.

The reflected light from the target 7 travels backward, passes through the lens 4 as a light receiving optical system, and is guided to the light receiving circuit.

The light receiving circuit 5 converts the reflected light into an electric signal and sends the electric signal to the signal processing unit 3, where the signal processing unit 3 performs distance measurement calculation.

FIG. 2 is a plan view showing the target irradiation of scan laser light by the laser scanner.

In FIG. 3, the scanning laser beam scanned by the scanner unit 3 is applied over a predetermined scanning range.

Assuming that the target 7 exists at such a short distance that the light receiving detector of the laser radar device is saturated, the relationship between the distance measurement and the scan angle in this case is as shown in FIG. 3 (a). . In this case, the detector of the light receiving circuit is saturated, so that the rising timing of the received waveform is ahead of the actual timing.

This state is detected by the signal processing unit 6, and the output level of the pulse laser in the next frame is controlled by the control circuit 2 so that the light receiving level is not saturated, as shown in FIG.
Suppress as shown in.

The laser oscillating unit 1 constantly supplies the signal processing unit 6 with information on the oscillation level.

In this way, it is possible to perform distance measurement while avoiding saturation at short distances.

[0020]

As described above, the present invention controls the level of the sending pulse laser so that the detector of the light receiving circuit does not saturate when the target is at a short distance. Has the effect of being able to secure.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a plan view showing target irradiation of scan laser light in the embodiment of FIG.

3A is a diagram showing a relationship between a distance measurement distance and a scan angle in an initial frame of short-distance distance measurement in the embodiment of FIG. 1, and FIG. 3 is a view showing a relationship between a pulse laser output and a scan angle in a next frame. It is (b).

4A and 4B are a detection characteristic diagram of a short-distance measurement and a detection characteristic diagram of a long-distance measurement by a conventional laser radar device.
Is.

[Explanation of symbols]

 1 Laser Oscillator 2 Control Circuit 3 Scanner 4 Lens 5 Light Receiving Circuit 6 Signal Processor 7 Target

Claims (1)

[Claims] 1. A transmission level of the transmission laser light is captured so that reflection light of the transmission laser light at a short distance from a target is captured and saturation of the short-distance light reception level is suppressed corresponding to the light reception level of the reflected light. A laser radar device characterized by reduction.