JPH01100491A - Laser radar image former - Google Patents

Abstract

PURPOSE:To shorten a one-screen formation time while obtaining a desired zooming function, by controlling the time for fetching a signal from a detector as desired with a fast laser light scanning. CONSTITUTION:A laser light from a laser oscillator 1 is made to scan an object 5 in a scanning range 51 through a light modulator 2, a beam splitter 6, an X-axis scanner 3 and a Y-axis scanner 4. The X-axis scanner 3 is arranged, for example, in rotary mirror fashion to perform a fast scanning and the Y-axis scanner 4, for example, in galvanomirror fashion. A laser light reflected on the object 5 is condensed to a detector 8 with a lens 7 via the Y-axis scanner 4, the X-axis scanner 3 and a beam splitter 6. An image former 9 forms an image based on an output of an image fetching signal generator 18. In the formation of the image, an output signal of the image fetching signal generator 18 is controlled to a desired value thereby enabling the zooming of an image.

Description

[Detailed description of the invention] Industrial applications The present invention uses a laser beam that scans two-dimensionally.

The present invention relates to a laser radar image forming apparatus that measures the shape and distance of an object.

BACKGROUND OF THE INVENTION Laser radar image forming devices that measure the distance to an object using laser light have come to be widely used as a visual information source for remote control of mobile robots.

This laser radar image forming device is, for example, an applied
Optics Vol. 23, p. 2565, 1984 (Ap
p! , 0ptics.

Vol. 23, P2565.1984), the structure was as shown in Fig. 6.

That is, the laser beam emitted from the laser oscillator 1 is intensity-modulated by the optical modulator 2, the laser beam is two-dimensionally irradiated onto the object 5 by the scanner 20, and the laser beam reflected from the object 5 is detected by the detector 8. To detect. Image formation is performed by an image capture device 21 synchronized with the scanning light.

Generally, when scanning with a laser beam, a single galvano mirror type, a resonant type, a rotating mirror type, a hologram type, etc. are used.

According to the conventional example, a galvanometer mirror is used in the scanner 20 to perform raster scanning, and an image with a viewing angle of 12.times.12.degree. is obtained in a frame time of 9 minutes using 512 scanning lines.

Problems to be Solved by the Invention However, in a galvano-mirror type scanner, even if the mirror is downsized, a scanning speed of only about 100 to 300 Hz can be obtained, and it takes several seconds to several tens of seconds to form one screen.

Of course, the galvano mirror type allows the scanning angle of view to be changed arbitrarily, and a zoom function can be added to the laser radar image forming apparatus by controlling the scanning angle of view.

On the other hand, resonant type, rotating mirror type, and hologram type scanners are capable of high-speed scanning of several hundred to several thousand Hz, but cannot add a zoom function because the scanning angle of view cannot be controlled arbitrarily.

SUMMARY OF THE INVENTION In view of the above problems of the prior art, an object of the present invention is to provide a laser radar image forming apparatus that scans laser light at high speed, shortens the time required to form one screen, and has an optional zoom function. It is something to do.

Means for Solving the Problems The laser radar image forming apparatus of the present invention is directed to a laser oscillator, a light modulation means for intensity modulating the laser light output from the laser oscillator, and the intensity modulated laser light. a laser beam scanning means for two-dimensionally irradiating an object;
It includes a detector that detects reflected laser light from an object, an image capture signal generator for forming an image, and an image forming means that forms an image from the output of the detector based on the output of the image capture signal generator. It is something.

Effects of the Invention With the above configuration, the present invention realizes high-speed laser beam scanning, and also adds an arbitrary zoom function by arbitrarily controlling the signal acquisition time from the detector.

That is, the laser beam is scanned at high speed by the laser beam scanning means and irradiated onto the object. The reflected laser light from the object is detected by a detector, and this detection signal is captured based on the output of the image capture signal generator and an image is formed by the image forming means. By controlling the output signal of the image capturing signal generator to an arbitrary value during image formation, the image can be zoomed without changing the scanning angle and scanning speed of the laser beam scanning means.

EXAMPLES Hereinafter, the present invention will be explained with reference to drawings showing examples thereof.

FIG. 1 shows a perspective view of an embodiment of an optical system of a laser radar image forming apparatus according to the present invention.

A laser oscillator 1 is a means for outputting laser light, and an optical modulator 2
is means for modulating the intensity of the light, and the X-axis scanner 3 and Y-axis scanner 4 are means for two-dimensionally scanning the object 5 in a scanning range 51 with laser light. In order to perform high-speed scanning, the X-axis scanner 3 is, for example, a rotating mirror type, and the Y-axis scanner 4 is, for example, a galvano-mirror type. The scanning speed sy of the Y-axis scanner 4 is the scanning speed `1tSx of the X-axis scanner 3, and the number of scanning lines is N, then Sy = + Sx / N (1
). Here, the scanning speed of the X axis is 6000Hz
, if the number of scanning lines is 256, the scanning speed of the Y axis is 23.
4 Hz, which can be tracked sufficiently with a galvano-mirror type scanner.

The laser beam reflected from the object 5 is transmitted to the Y-axis scanner 4,
The light passes through an axial scanner 3 and a beam splitter 6, and is focused onto a detector 8 by a lens 7.

The detector 8 is a means for detecting reflected laser light.

Image forming device 9 creates an image based on the output of image capture signal generator 18 . In this embodiment, the distance to the object 5 is determined from the phase difference between the output of the detector 8 and the reference signal of the optical modulator 20 of the laser beam, and this distance data is converted into an 8-bit signal, and a distance image is stored in the frame memory. It is recorded as. The images recorded in the frame memory are displayed on the monitor TVIO in real time.

Next, the present invention will be described in detail, focusing on the operation of the image capture signal generator 18.

Since a detection signal is always output from the detector 8, when forming a zoom image, the image capture signal generator 1
It is necessary to select and capture the detection signal based on the output of 8.

Further, the X-axis scanner 3 and the Y-axis scanner 4 must be completely synchronized so that there is no deviation between the scanning lines of the image.

The relationship between the laser beam scanning line and the image capture signal is shown in Figure 2 (
Shown in a), '(b), (C), (d), and (e).

As shown in FIG. 2(e), the laser beam is scanned two-dimensionally along the Y-axis, but only the X-axis scanner 3 is shown. The laser beam 11 incident on the Y-axis is scanned, for example, from left to right by the X-axis scanner 3, and is
A scan line 12 of the book is obtained. In order to match images between each scanning line, a scanning reference position is detected. In this embodiment, the other surface of the rotating mirror is used as a scanning reference position detector 15 that combines a semiconductor laser 13 and a photodiode 14.
to determine the scanning line reference. With respect to the scanning line 12, the scanning reference position signal (a) is generated with a delay of time to (FIG. 2(a)). There is a time delay t from this scanning reference position signal (a)
d, the image capture signal (b) at the time interval m is generated from the image capture signal generator 18, and the detection signal (C) is generated.
e Import into the image forming device 9 (Fig. 2 (b), (C))
. The captured image data (d) is recorded in the frame memory according to the specified address (Fig. 2 (d))
.

FIGS. 3(a), (b), and (C) show the relationship between the scanning range of the X and Y axes and the image forming range.

The laser beam is scanned and irradiated onto the object 5. Since the Y-axis scanning angle is determined by the selection of the X-axis scanner 3, the Y-axis width of the scanning range 51 is constant. When zooming an image, the image forming range 52 that occupies within the scanning range 51 is changed by changing the generation frequency (f=l/tot) of the capture signal of the image capture signal generator 18. Since the number of pixels of the image in the image forming range 52 (number of image capture signals n×number of scanning lines N) is constant, the image on the monitor TV will be zoomed.

On the other hand, since the scanning angle of the Y axis is proportional to the voltage applied to the galvanometer mirror, the g
Change it as a/%/gc. Since the number N of scanning lines 12 is constant, the scanning of the object 5 is ga
, it becomes dense, and gc becomes sparse.

In order to set the image forming position at the center of the scanning range 51, the time delay td from the reference position signal is changed according to the image forming range 52. The time delay from the reference position signal is t, where one scanning time on the Y axis is T, the time delay to in generating the reference position signal, the image capture signal interval Δt, and the number of captured pixels of the scanning line n.
d is given by the following equation.

ta = 1 / 2 ((T -2t o -n
The widest-angle image is obtained when Δt ) ) (21td is set to zero. It is also possible to intentionally change the zoom ratio of the Y-axis and the Y-axis to obtain an image with different vertical and horizontal magnifications.

FIG. 4 is a block diagram of an embodiment of the present invention centering on the zoom control system.

The zoom magnification is input from the control circuit 16. ”The CPU (Central Processing Unit) 17 adjusts the image capture signal frequency f (=1/Δ) according to the zoom magnification.
t), the time delay td from the reference position signal, and the scanning voltage of the Y-axis scanner 4 are calculated.

Now, when an image capture start is input to the control circuit 16, a signal is sent from the 0PU 17 to the drivers 31 and 41 of each of the X-axis scanner 3 and Y-axis scanner 4.
The scanner works. When the X-axis scanner 3 rotates, a reference position detection signal is sent from the reference position detector 15 to the CPU 1.
7 is input. When the CPU 17 receives the reference position signal, it outputs n signals to the image capture signal generator 18 at intervals of Δt after a time td, and the image forming device 9 outputs n signals to the image capture signal generator 18 based on the generated signals. Import image data. The image taken into the image forming device 9 is
It is displayed on the monitor TV 10 in real time.

Next, as a second embodiment of the present invention, a case will be described in which X-axis scanning is performed using a resonant method.

FIG. 5 shows the relationship between the scanning angle and image capture of a resonant scanner. Since a resonant scanner uses resonance to realize a high-speed scanner, the scanning is sinusoidal. For use as a scanner for image capture, a portion of the sine wave that has some degree of linearity is used. Therefore, the time delay to in generating the reference position signal with respect to the scanning angle needs to be longer than that in the one-type rotary mirror. The settings of the time delay td from the reference position signal and the image capture time interval Δt are the same as those described in the first embodiment.

As mentioned above, for example, a high-speed scanner is used for X-axis scanning, and zooming can be performed without changing the scanning angle or scanning speed, so instantaneous zoom switching is possible regardless of the time response of the scanner. Furthermore, Y-axis scanning uses a single galvano mirror system, and the scanning angle can be controlled according to the zoom magnification, so the time required to form an image for one screen remains constant regardless of the zoom magnification.

In addition, when the zoom magnification is changed, the CPU calculates a time delay according to the zoom magnification using the reference position signal, so that the center position of the screen does not change. Does not make you feel uncomfortable.

Furthermore, by changing the zoom magnification of the X and Y axes, images with different aspect ratios can be obtained.

Effects of the Invention The present invention uses the above-described configuration to scan laser light at high speed, shorten the scanning time for one screen, control the signal acquisition time from the detector, and provide an arbitrary zoom function. It is something that can be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an optical system of a laser radar image forming apparatus according to an embodiment of the present invention, and FIGS. 2(a), (b), (C), (
d) and (e) are diagrams for explaining the relationship between the scanning line of the laser beam of the same laser radar image forming apparatus and the image capture signal, and Figures 3 (a), (b), and (C) are diagrams for explaining the relationship between the scanning line of the laser beam of the same laser radar image forming apparatus and the image capture signal. A diagram showing the relationship between the scanning range of the X and Y axes and the image forming range of the radar image forming apparatus. Figure 4 is a block diagram of the zoom control system of the laser radar image forming apparatus. Figure 5 is a diagram showing the relationship between the scanning range of the X and Y axes and the image forming range of the radar image forming apparatus. FIG. 6 is a graph showing the relationship between scanning angle and image capture in another embodiment of the present invention, and FIG. 6 is a block diagram of a conventional laser radar image forming apparatus. 1...Laser oscillator, 2...Light modulation type, 3...
X-axis scanner, 4... Y-axis scanner, 5... Target, 6... Beam splitter, 7... Lens, 8...
・Detector, 9... Image forming means, 10... Monitor T
V, 11...Laser light, 12...Scanning line, 13...
・Semiconductor laser, 14... Photodiode, 15・
...Scanning reference position detector, 16...Control DO
17...CPU, 18...Image capture signal generator, 20...Scanner, 21...Image capture device,
31...X-axis scanner driver, 41...Y-axis scanner driver, 51...scanning range, 52...
・Name of image formation agent: Patent attorney Toshio Nakao and 1 other person No. 3
Diagram ゛kari I'! Figure 25Figure 6

Claims (3)

[Claims] (1) A laser oscillator, a light modulation means for intensity modulating the laser light output from the laser oscillator, and a laser light scanning means for two-dimensionally irradiating the target object with the intensity-modulated laser light. , a detector for detecting reflected laser light from the object, an image capture signal generator for forming an image, and an image forming means for forming an image from the output of the detector based on the output of the image capture signal generator. A laser radar image forming apparatus comprising: (2) The laser radar image forming apparatus according to claim 1, wherein the image capture signal generator for image formation has a function of controlling an arbitrary frequency. (3) Equipped with means for detecting the scanning reference position of the laser beam,
2. The laser radar image forming apparatus according to claim 1, wherein the image capturing signal generator captures an image by setting an arbitrary time delay from the detection signal.