负折射率材料透镜的消色差

Achromatism about Negative Refractive Index Lens

以工作在近红外波段0.848μm^1.114μm,焦距100mm,入瞳直径20mm,具有负阿贝数的负折射率平凹透镜为例,介绍了两种对该类负折射率透镜的消色差设计方法,即利用正折射率材料透镜与负折射率材料透镜组合消色差和负折射率透镜中引入衍射光学元件实现折衍射混合透镜消色差方法.结果表明,正负折射率材料透镜组合消色差方法中正折射率材料透镜承担几乎全部光焦度,进而引入大量额外单色像差,但利用衍射光学元件可以在不引入额外像差的同时实现负折射率透镜的消色差.根据负折射率材料在介质与空气分界面的特殊折射特性,推导了以负折射率为基底的衍射光学元件的衍射效率公式,得到衍射微结构高度公式,求出不同波长处的衍射效率值.负折射率二元衍射光学元件在设计波长0.912μm处衍射效率为40.53%,在波长0.848μm处的衍射效率为35.06%,在波长1.114μm处的衍射效率值为39.83%.

An example of achromatic designs for a negative-refractive-index plane-concave lens with 100 mm focal length, 20 mm the pupil diameter and negative abbe number in near infrared wave band from 0. 848 μm to 1. 114μm was given to explain two achromatic methods about the negative-refractive- index lens. The two methods are combing positive-refractive-index lens with negative-refractive-index lens and introducing the diffractive optical elements into the negative-refractive-index lens. The analysis results show that the positive-refractive-index lens undertakes almost all the power in the method of combing positive-refractive-index lens with negative-refractive-index lens, so a large number of additional monochromatic aberrations are introduced. However, the diffraction optical element can correct the chromatic-aberration of the negative-refractive index lens without introducing additional aberrations. The diffraction efficiency of the negative-refractive-index diffractive optical elements is deduced based on the special propagating laws and imaging properties of negative-index lenses, the expression for microstructure height is given,and the diffraction efficiencies are calculated. The diffraction efficiency for the negative-index binary diffractive optical element in the design wavelength 0. 912 μm is 40. 53%, in wavelength 0. 848μm is 35.06 % ,and in wavelength 1. 114μm is 39.83%.