CN1329742C - Laser radar control method based on image intensifier - Google Patents

Abstract

The invention discloses a laser radar control method based on an image intensifier. The image intensifier is used as a detector to obtain laser echo images for reversing atmospheric information. The video signal is collected by the CCD camera coupled to the image intensifier, and the laser is triggered to emit light after processing through synchronous separation. The photodiode detects the light time and triggers the delayer. The delayed signal generates a pulse signal through the pulse width generator to trigger image enhancement. machine work. The laser radar control method based on the image intensifier can be competent for the control of most laser radars using image sensors with door opening time control, the control accuracy is high, and it has practical value.

Description

LiDAR control method based on image intensifier

technical field

The invention relates to the fields of optical environment monitoring and electronics, in particular to a laser radar control method based on an image intensifier.

Background technique

Lidar is an important means of measuring atmospheric parameters. In order to obtain atmospheric information at different heights, it is necessary to detect laser echoes at different distances. Traditional Lidar is based on photomultiplier tubes or photon counters as detectors. Therefore, the control system only needs to The light emission time is detected, and then delayed for an appropriate time (no special accuracy is required), and the multiplier tube or photon counter is turned on to obtain the required information. However, the information obtained by this radar cannot fully meet the needs.

Contents of the invention

In order to solve the problems of the above-mentioned schemes, precise time delay is adopted, the desired distance is obtained by the product of the laser transmission speed and time, and the desired beam length is obtained by the product of the precise opening time of the image intensifier and the speed of light, through a series of precise control Delay time and door opening time, conduct several layered profile observations on the atmosphere, and then obtain atmospheric profile information through data analysis. In order to achieve the above-mentioned purpose, the delay time and door opening time accuracy must reach at least 10 nanoseconds (the corresponding distance or air column length accuracy is 1.5 meters). The image intensifier must be equipped with a CCD camera, so there is a synchronization problem, that is, the image cannot appear at the blanking moment of the CCD camera, otherwise the image cannot be obtained, so the working timing of the entire system must be controlled by the CCD synchronization signal.

Technical scheme of the present invention is as follows:

Based on the laser radar control method of image intensifier, it is characterized in that:

Place the image intensifier at the focal point of the receiving telescope, and couple the image intensifier with the CCD camera through the relay lens coupling method. The video signal collected and output by the CCD device is divided into two channels: one is sent to the computer for collection, and the other is input synchronously The splitter performs synchronous separation and outputs the odd-even field synchronous signal. The odd-even field synchronous signal is input into the monostable circuit and outputs a narrow pulse signal. The narrow pulse signal is input into the buffer and then outputs a buffer signal. The buffer signal is sent to the external trigger of the laser. The laser is triggered to emit light; at the exit of the laser, the PIN photodiode detects the moment of light emission, and outputs the light signal, which is input to the emitter follower for buffering, outputs standard TTL level, triggers the programmable delayer, and the programmable delayer The output trigger signal triggers the programmable pulse width generator, and the programmable pulse width generator generates a pulse signal. After the pulse signal is input to the power drive part, the output drive signal triggers the image intensifier to work.

The chip used in the synchronous separator is LM1881; the laser is an externally triggered YAG pulse laser with a repetition rate of 25 Hz; the chip used in the monostable circuit is 74ls123; the PIN photodiode is a high-speed silicon PIN photodiode.

After the monostable circuit outputs a narrow pulse signal, the pulse width is 9-11 microseconds.

Effect of the present invention

The laser radar control method based on the image intensifier can be competent for the control of most laser radars using image sensors with door opening time control, the control accuracy is high, and it has practical value.

Description of drawings

Fig. 1 is a schematic block diagram of the control method of the present invention.

Fig. 2 is a block diagram of the control system of the present invention.

Fig. 3 is a block diagram of the timing generator module of the present invention.

Fig. 4 is a schematic diagram of a part of the circuit of the single-chip microcomputer of the present invention.

Fig. 5 is a circuit schematic diagram of the delay part of the present invention.

Detailed ways

Refer to Figure 1-5, place the image intensifier at the focal point of the receiving telescope, couple the image intensifier with the CCD camera through the relay lens coupling method, the video signal collected and output by the CCD device is divided into two channels: one is sent to Computer acquisition, one input synchronous separator LM1881 for synchronous separation, output odd and even field synchronous signal, this odd and even field synchronous signal is input into the monostable circuit 74ls123 and then output a narrow pulse signal with a pulse width of 9-11 microseconds, this narrow pulse signal is input into the buffer The buffered signal is output after the laser, and the buffered signal is sent to the external trigger of the laser, and the laser is triggered to emit light; the laser is a YAG pulse laser that can be triggered externally, and the repetition frequency is 25Hz; at the exit of the laser, the high-speed silicon PIN photodiode detects the moment of light output, and outputs The optical signal, the optical signal is input to the emitter follower for buffering, the output standard TTL level, triggers the programmable delayer, the programmable delayer outputs the trigger signal to trigger the programmable pulse width generator, and the programmable pulse width generator generates Pulse signal, after the pulse signal is input to the power drive part, the output drive signal triggers the work of the image intensifier.

The image intensifier is directly connected to the receiving telescope through the cylinder, so that the photosensitive surface of the image intensifier is in the focal plane of the image intensifier. The relay optical path includes two mirrors to adjust the beam direction and a diverging system. The laser beam is directly incident on the secondary mirror of the telescope through a diverging system. Diverging systems can be either negative or positive lenses.

The computer and the single-chip microcomputer carry out data communication through the parallel port. The single-chip microcomputer converts the instructions transmitted by the computer into the driving signals of each actuator, and the latch stores the data in the preset end of the preset counter. During the scanning process of the focal length of the system from far to near or from near to far, the computer sends data to the single-chip microcomputer according to the pre-set data, and the pulse signal of the stepping motor is formed after processing by the single-chip microcomputer, which is provided to the stepping motor driver to control the adjustment. The coke motor works.

Both the transmitting and receiving telescopes are card-type astronomical telescopes with an aperture of 350mm. The image intensifier is a high-speed gate image intensifier produced by Japan Hamamatsu Company, the model is C7609. The CCD camera uses a common high-resolution black and white CCD. The single-chip microcomputer adopts PIC16C74 of microchip company, the latch adopts three pieces of 74LS373, and the basic counting unit of the delayer and pulse generator adopts two pieces of 74F163 and five pieces of 74ls191 high-speed preset counters, the counting clock is 100MHz, and the time accuracy reaches 5nS . The delay range is 0.5μS-200μS, the pulse width adjustment range is 100nS-10μS delay and pulse width generator (timing generator).

Claims (3)

1, based on the laser radar control method of image intensifier, it is characterized in that:

Image intensifier is placed on receiving telescope focus place, by the relay lens coupling scheme image intensifier and CCD camera are coupled, the vision signal that the CCD camera is gathered and exported, be divided into two-way: the one tunnel gives computer acquisition, one tunnel input sync separator carries out separated in synchronization, output parity field synchronizing signal, export narrow pulse signal after this parity field synchronizing signal input monostable circuit, export buffering signals behind this narrow pulse signal input buffer, buffering signals is sent into the external trigger of laser instrument, and laser instrument is triggered bright dipping; Export at laser instrument, detect quarter light time by PIN photodiode, export out light signal, go out the light signal emitter follower input and cushion, the outputting standard Transistor-Transistor Logic level triggers programmable delayer, trigger pulse width generator able to programme by programmable delayer output trigger pip, pulse width generator able to programme produces pulse signal, and after this pulse signal inputed to the power drive part, output drive signal triggered image intensifier work.

2, the laser radar control method based on image intensifier according to claim 1 is characterized in that image intensifier adopts high speed gate image intensifier; Sync separator is chip used to be LM1881; But laser instrument is the YAG pulsed laser of external trigger, repetition frequency 25Hz; Monostable circuit is chip used to be 741s123; PIN photodiode is the high-speed silicon PIN photodiode.

3, the laser radar control method based on image intensifier according to claim 1 is characterized in that the video field sync signal is exported the narrow pulse signal pulsewidth after monostable circuit be the 9-11 microsecond.

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