Guarantee of High Accuracy of Range Finder

Optical velocity measurement has the following characteristics: because the laser beam is ray-based, the estimated velocity measurement distance is far from the useful distance of radar velocity measurement, the accuracy of velocity measurement beyond 1000M is high, and the fault is less than 1 km. in view of the principle of laser velocity measurement, the laser beam must be aimed at the plane reflection point perpendicular to the laser beam, and because the measured vehicle is too far away and in a moving condition, perhaps the plane of the vehicle body is not large, which leads to the work intensity of the police on duty is very large and it is easy to be tired. Now American laser technology company has produced a laser velocimeter with continuous automatic velocimetry function, which is specially used to deal with this problem. The Dongcheng Brigade of the Dongguan Traffic Police Detachment has used this improved speedometer to capture speeding vehicles and has achieved remarkable results. In view of the principle of laser speedometer, laser speedometer may not be used in sports, but can only be used intermittently. Therefore, the general traffic police put the instruments on the patrol cars, and the laser velocimeter used in most countries now uses a type of safety laser, which is safe for human eyes.

The laser velocimeter is in close contact with the laser rangefinder. Its principle is primarily through laser ranging. Laser ranging (i.e. electromagnetic wave with a speed of 300,000 km/s) determines the distance between the measured object and the inspection point by emitting a laser beam to the measured object, receiving the reflected wave of the laser beam, and recording the time difference. Then the laser velocimeter carries out laser ranging for the measured object twice with a specific time distance to obtain a distance change difference value of the measured object in the period of time, and then obtains that the moving speed of the measured object and the power consumption of the laser velocimeter are relatively low, and two No.5 batteries can be continuously used for 20 hours. There are many kinds of optical range finders and their functions vary greatly, but there are only two kinds of optical range finders in terms of working methods (or working principles), namely, pulse laser ranging and continuous wave laser ranging. The principle of pulse laser ranging is to use a pulse laser to emit a series of very narrow light pulses (the pulse width is less than 50ns) to the policy, the light is partially reflected after reaching the policy surface, and the distance between the range finder and the policy can be calculated by measuring the time from the light pulse emission to the receiver.

Assuming that the measured distance is h, the reciprocating time of light pulse is t, and the propagation speed of light in the air is c, the laser ranging function declares a strong laser. the ranging ability is strong, and even for non-cooperative policies, the maximum ranging can reach more than 30000m m. Its ranging accuracy is generally 5 meters, and the highest can reach 0.15m m. Pulsed laser rangefinder can be used in military ranging for various uncooperative policies, as well as in climate to measure visibility and cloud height. It can also be used in precision distance measurement for artificial satellites and other fields.