菱体型消色差延迟器的新设计

New design of rhomb-type achromatic retarders

为了改善菱体型延迟器件的消色差性能,扩大材料的选择显得非常必要。根据光在介质表面全反射时发生相变这一原理,分析了菱体型消色差延迟器件,得出折射率设计点n与对应的结构角θ两者关系的规律,随着折射率设计点n的增大,虽然dn/dλ增大,但是dδ/dn却迅速减小,因此高折射率的材料可能有更好的消色差性能。结果表明,低折射率的材料熔石英相位延迟在350nm～1240nm的光谱区域内的最大延迟误差小于1.32°,而高折射率的材料LaK2玻璃相位延迟在此区域内的最大延迟误差却小于0.95°。高折射率的材料比低折射率的材料有更好的消色差性能。

In order to improve achromatism of rhomb-type retarders,it is necessary to expand selection of materials.According to the principle that the light arising total reflection has a phase transformation in the medium surface,rhomb-type achromatism retarders were analyzed,and relation between the refractive index n and structural angle θ was deduced.Although dn/dλ increases with enlargement of the refractive index n,dδ/dn decreases rapidly,so high refractive index materials probably have better achromatism.It was shown that the maximal delay errors of low refractive index materials were smaller than 1.32°,and the maximal delay errors of high refractive index materials were smaller than 0.95° within the range of 350nm^1240nm.Comparing with low refractive index materials,high refractive index materials have better achromatism.