successful, techniques for the additional beam deflection were tested and some interesting results were achieved. One of the most important results consists in the fact that the possibility has been confirmed in full scale and real atmosphere to a direct output laser beam in the other direction, to that which the PCM defines. These experiments showed that for a large deflection the conjugated part of the output laser beam decreases, i.e. the quality of the phase conjugation decreases. The main parameter, which defines the limit of laser beam deflection, is the correlation radius of the atmosphere. Results of such experiments are useful for a more exact choice of regions for laser stations. For example, a deflection of 2-4 arc seconds for very turbulent atmosphere is near the upper limit of acceptable values. One of the possible laser station schemes includes two principal systems: a multi-channel laser and a multi- channel optical system. It is absolutely necessary to have the phase-conjugating system, since this can simultaneously coordinate all channels of the laser and all channels of the optical system in order to provide overall diffraction-limited phase conjugation. The preliminary estimation of parameters of the laser could be based on known specific parameters of present solid-state lasers. Using an output power of 400 kW3 power per unit volume equal to 50 W * cm3 one has the total volume of 8 cell of the laser’s active medium. Common power from the unit area of output surface of the active medium is equal to 1 kW * cm2. This defines the approximate sum of the length of 20 cm of amplifying medium along the beam (at least for the majority of the crystal in the output states of the laser). The total area of output amplifying stages of about 400 cm2 could be divided into different versions to define a number of channels, but it should be done for concrete design. It can only be noted that the most probable number of channels is 50-100. Let us consider a separate laser channel. The output power is about 3-5kW, the volume of active medium in several amplifying stages is about 50-100 cm3. For the first experimental laser station, the present devices and facility could be used: discharge lamp pumping, standard cooling systems, standard laser crystals. But for the future commercial laser system one needs new techniques. At the present time, significant progress has been made regarding new generation solid-state lasers —with pumping by radiation of semiconductor lasers (diode pumped lasers). It allows us to have a greater efficiency (it is quite possible to achieve an efficiency of about 15-20%). But the main advantage of this technique is the increase in the life time of the laser by a factor of ten. Also, the free-electron laser is promising. It has some well-known possible advantages in comparison with other lasers. It is difficult to estimate at the moment the real potential of this laser for commercial projects, because we are only in the initial stages of free-electron laser development. It is necessary to confirm the advantages in integrating experiments of a large-scale facility and at a high average output power in an acceptable time.
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