This optical pulse compression divergence angle after launch telescope

 Another type of laser pointer will be demonstrated in the next passage.
The following were introduced in accordance with the latter classification ranging pulse ranging and phase. Ranging laser pulse. The laser pulse ranging principle. Because the speed of light is constant, the light propagation along the straight line, by measuring the beam round-trip propagation time in the test distance can be calculated straight-line distance between two points. Laser pulse ranging principle is controlled by a laser pulse timer to open the door to receive the returned laser pulse control timer closed, measure the round-trip propagation time of the laser beam in the test distance to complete the distance measurement. The formula is: where d is the test distance; c is the velocity of propagation of the laser in the atmosphere; t is the round-trip propagation time of the laser in the test distance. It is the concept of laser pointer .
The laser pulse structure of the rangefinder. Pulse laser rangefinder to simplify the structure shown in Figure (6-18) as shown. It's working process is as follows: When the rangefinder at the target, the laser on the issue of a strong very narrow pulses of light. This optical pulse compression divergence angle after launch telescope. Ruby laser, for example, its beam divergence is generally a few milliradians, after the launch telescope, compressed to zero a few milliradians. The light pulses reach all parts of the 10 km far away, only a few meters diameter spot. Out in the light pulse emission, which has a very small part of light immediately by two reflector into the receiving telescope, after the filter to reach the photoelectric converter into electrical signals, ie, light pulses into electrical pulses. Two types of laser pointer will be introduced.Means that the cumulative count can be measured to measure the amount of displacement of the mirror. The Doppler shift measurement of the movement of the mirror can be expressed as where is the speed of light, the wavelength of light. If measuring the time for measuring the displacement of the mirror can be recorded the following formula where the cumulative number of pulses. Laser interferometer, the measured signal is added on top of the carrier frequency as the frequency modulation, should generally be less than one-third of the carrier frequency, corresponding to the Doppler shift can not exceed the maximum allowable measurement speed of about a. As a result, the operating frequency of the processing circuit can be set between, in order to filter out less than the noise. How to perform the sampling inspection of laser pointer ?laser pointer should be protected well
The laser interferometer length measuring applications for example. Laser interferometer length measuring in addition to the measurement of length can be measured can be converted to physical quantities of the measured length, such as the length of the measurement point of view, another example, pressure, temperature, refractive index. This section angle and refractive index measurements as an example to illustrate the laser interferometer length measuring applications. Laser angle measurement. Laser angle measurement principle of the small-angle interferometer similar, and are based on the trigonometric sine of the principle.