We have elaborated and evaluated a new high-precision method of automated establishment of the position of an object. Unlike the method using laser theodolites, the desire object is defined not by a specular reflector, but a laser beam directed upwards (laser spotlight). In so doing, the photodetectores register the laser radiation scattered by the aerosol component of the atmosphere and propagating perpendicularly to the beam axis (side scattering). The intensities of the side scattering registered by the photodetectors have been estimated in terms of the current concepts as a function of the distance, laser radiation parameters, and the state of the atmosphere. The calculations have shown that despite the relatively small value of the side scattering intensity, it is possible to reliably register light signal from large distances with the use of sufficiently powerful lasers and high-sensitivity photodetectores. To evaluate the proposed method, we developed and tested under real conditions an operative model of a laser-optical system based on a small-size "dry" neodymium laser (peak power of 0.5 MW, pulse repetition rate up to 5 Hz). The model is able to automatically establish the position of an object at a distance of up to 0.5 km to an accuracy no worse than 20 cm in a locality blocked from direct observation.
With the aim of a parameters control of multiwave lasers the influence of the competition of CO2 molecule rotational- vibrational transitions on the original two-channel technique has been investigated experimentally. The strong competition of transitions is observed only at two-wave generation on lines of one band, for example, 000a- 1000. At the two-wave lasing on lines of various bands the competition of transitions can be essential weak.
Several original schemes for intracavity frequency doubling of CO2 laser radiation (TEA and cw systems) in AgGaSe2 nonlinear crystals have been proposed and studied experimentally. Computer modeling was used for optimization of the optical schemes and cavity parameters. The enhancement by several fold in conversion efficiency was achieved for intracavity SHG in comparison with traditional schemes. A 60% peak power efficiency and 15% energy conversion efficiency has been obtained with a TEA CO2 laser. More than 100 mW at 5 micrometers was generated in the crystal with L equals 17 mm, which is a record output for SHG of a cw CO2 laser. This output is more than 10 times higher than 5 micrometers power measured with standard focusing the CO2 laser beam.
The lidar complex of equipment based on TEA CO2 laser specially designed for atmospheric sensing, with automatic tuning on generation lines in the spectral ranges 9 - 11.3 and 4.5 - 5.6 micrometers has been described. Besides regular transitions 0001 - 1010 (0200), the laser is able to generate powerful (megawatt) pulses on hot band (011 - 1110) lines. Considerable extension of the spectral range to the short-wave region is attained due to effective TEA CO2 laser second harmonic generation in nonlinear crystals. Taking into the real potentialities of the lidar complex in hand, using a package of spectroscopic data HITRAN, computer simulation of atmospheric transmission has been made. On this bases, by the method of differential absorption a method has been elaborated for measuring small concentrations of a large number of gases, including especially dangerous atmospheric pollutants CO, C2H4, etc. This method was tried out on medium paths (approximately 1 km) in the real conditions of Minsk. Small (background) concentrations of a number of atmospheric gases have been measured.
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