In this paper, the impact of factors on frequency conversion efficiency has analyzed departing from the theoretical
formula of frequency doubling frequency efficiency. The results of analyzing show that the frequency multiplication
efficiency closely to be not only related to the fundamental frequency laser parameter, but also influenced by several
factors such as crystal type, crystal length and so forth. Because of the needs of high conversion efficiency of doubling
frequency, the fundamental frequency laser parameter, the crystal type and the crystal length must be determined
reasonably to achieve the optimum parameter between fundamental wave peak power density and phase mismatch factor.
To compare with the conclusion mentioned above, an experimental device was established on 266nm quadrupler UV
laser and 10mJ UV laser which quadruple conversion efficiency 15.5% was achieved in the condition of fundamental
frequency single pulse energy 60mJ, the divergence angle under the beam quality M <sup>2</sup>=2, pulse width 10ns.
Based on the development of infrared thermometry all over the world, a problem has been pointed out. Whenever
infrared thermometer has been used in measuring temperature, the field of full vision of target must be considered. Or
else there will be a mistake. In the thesis, base on the theory of infrared thermometer, we analyze the reasons of the error.
And we also deduce the theory equation of partial vision temperature measurement about infrared thermometry. In the
process of deduction, because of the other influences are not considered; so we get the approximate equation of partial
vision temperature measurement, based on measurement value we draw a compensatory curve to compensate the
equation of infrared thermometry. The curve has reflected the compensating effect well. In the end, we analyze the
reasons of error. We draw a conclusion that this method of partial vision temperature measurement is feasible. We
discuss the error which caused by distance and get a feasible method to correct the error.