For a 100 kW laser beam this means a mirror at least 140 m in diameter. [Beverly, 1980c] [Taussig, 1979][Walbridge, 1980] Figure 7.33 Examples of Optical Pumping Lines in Solar Energy. [Taussig, 1979] Figure 7.34 Indirect Solar Pumped Laser. [Walbridge, 1980] An indirect solar pumped laser is one possible way to avoid the inefficient use of solar energy. Solar energy is stored to a black body and the laser is pumped by blackbody radiation shown in Figure 7.34. Walls of the black body emit radiation in spectral distribution depending on the temperature of the black body. Temperature range required for wavelengths used for lasant pumping is 2000-3000 K. The lasant absorbs much of pumping wavelength from radiation passed through lasant. Rest of the radiation spectra is then absorbed by other wall of the black body shown in Figure 7.35. [Beverly, 1980c][Taussig, 1979][Walbridge, 1980] The efficiency of an indirect solar pumped laser can rise very close to the theoretical value of the lasant. The factors to decrease the efficiency are the energy required for cooling and the leak emission of the black body.
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