TeO_2晶体旋光性对其分光特性的影响分析

Impact of the rotatory property of TeO_2 crystal on its spectral characteristics

TeO2是声光可调滤波器主要成像晶体,由于晶体本身在分光成像时会产生色差,漂移等问题,文中从基础理论出发,研究了TeO2晶体的旋光性对其作为声光可调滤波器时分光特性的影响,进而对其基本参数作了优化。首次对比分析了I.C.Chang理论体系与P.A.Gass修正理论体系,通过对比分析方法,得出在红外波段,两种理论体系对于超声波频率协调关系的计算结果差异较大,作者认为是I.C.Chang理论忽略晶体旋光特性所引起,因此,以P.A.Gass理论作为基础的声光可调滤波器设计方法适用于红外波段,当入射光极角小于30°时,其旋光特性对分光性能的影响较小。通过对比分析可知,设计的入射光极角应小于54.7°,这样可以保持较高的声光优值和较低水平的超声波频率;在红外波段,设计的入射光极角应小于39.2°,两频率协调关系偏差Δf较小。

TeO2 is the main imaging crystal of acousto-optic tunable filter. There are chromatic aberration and drift in the crystal itself while the spectroscopic imaging. In this paper, based on the fundamental theory, the impact of TeO2 crystal optical activity to dichroism as the acousto-optic tunable filter was researched and its basic parameters were optimized. The I.C.Chang theoretical system and the P.A.Gass modified theoretical system were compared and analyzed. The results show that the two theoretical systems are quite different when the relationship of ultrasonic frequency coordination is calculated results in the infrared. Assuming that it was caused by the ignored the rotatory property of crystal of I.C.Chang theory, the design method of acousto-optic tunable filter based on P.A.Gass theory is applicable to infrared. The influence of rotatory property on the spectroradiometric property was smaller when the incident polar angle less than 30°. Through comparative analysis research, incident polar angle of design should be less than 54.7°, which can maintain higher figure of merit of sound and light and a lower level of the ultrasonic frequency; in the infrared, the incident polar angle of the design should be less than 39.2°, between two frequency coordination deviation Af is smaller.