Gupta Neelam
U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783-1197, USA.
Appl Opt. 2009 Mar 1;48(7):C151-8. doi: 10.1364/ao.48.00c151.
A number of spectral imagers using acousto-optic tunable filters (AOTFs) operating from the UV to the longwave infrared (LWIR) using KDP, MgF(2), TeO(2), and Tl(3)AsSe(3) crystals to cover different spectral regions have been developed. In the LWIR there is a lack of high quality acousto-optic (AO) materials. Mercurous halide (Hg(2)Cl(2) and Hg(2)Br(2)) crystals are highly anisotropic with a high AO figure of merit due to slow acoustic velocities and high photoelastic constants and are transparent over a wide spectral region from 0.35 to 20 mum for Hg(2)Cl(2) and from 0.4 to 30 mum for Hg(2)Br(2). AO modulators, deflectors, and AOTFs based on these crystals can operate over a wide spectral range. Single crystals of these materials are being grown and some prototype devices have been fabricated. Results are presented from device characterization for an AO cell fabricated in Hg(2)Cl(2) based on longitudinal acoustic mode propagation. This device was very useful in demonstrating the AO interaction as well as soundness of the transducer bonding technique. Acoustic phase velocity is calculated and measured, diffraction efficiency is obtained from experiments, and the AO figure of merit of the sample is evaluated.
已经开发出了许多使用声光可调滤光器（AOTF）的光谱成像仪，这些成像仪利用磷酸二氢钾（KDP）、氟化镁（MgF₂）、二氧化碲（TeO₂）和三硫化二砷铊（Tl₃AsSe₃）晶体，在从紫外到长波红外（LWIR）的波段工作，以覆盖不同的光谱区域。在长波红外波段，缺乏高质量的声光（AO）材料。卤化亚汞（Hg₂Cl₂和Hg₂Br₂）晶体具有高度各向异性，由于声速慢和光弹性常数高，其声光品质因数很高，并且对于Hg₂Cl₂在0.35至20微米的宽光谱区域是透明的，对于Hg₂Br₂在0.4至30微米是透明的。基于这些晶体的声光调制器、偏转器和AOTF可以在很宽的光谱范围内工作。这些材料的单晶正在生长，并且已经制造了一些原型器件。给出了基于纵向声模传播在Hg₂Cl₂中制造的一个声光池的器件表征结果。该器件对于演示声光相互作用以及换能器键合技术的可靠性非常有用。计算并测量了声相速度，通过实验获得了衍射效率，并评估了样品的声光品质因数。
