紫外三元复合消色差相位延迟器优化设计的分析

为了设计在紫外波段消色差性能优良的三元复合λ／4波片，根据复合波片理论，利用同一波长（300nm）的2个λ0／4波片和1个λ0／2波片组合成复合波片，研究了复合波片的相位延迟量随波长的变化，得出复合波片在250-350nm的光谱范围内是消色差的；在此基础上对三元复合消色差λ／4波片进行了优化设计，即通过改变中间波片的相位延迟量和精确调整复合角，使消色差范围拓宽到200-400nm，相位延迟计算偏差在5％左右．通过改变中间波片的材料，即氟化镁晶体代替石英晶体，用上述同样方法设计出UVC波段消色差λ／4波片，其相位延迟计算偏差在2％以内．这种优化设计对拓宽紫外波段消色差范围，提高延迟量精度具有实用价值．

Analysis on Optimization Design of an Ultraviolet Three-in-one Composite Achromatic λ/4 Wave-Plate

In order to design a high-quality ultraviolet composite achromatic λ/4 wave-plate, the composite wave-plate theory was applied to make a composite achromatic λ/4 wave-plate constituted by two λ0/4 wave-plates and a λ0/2 wave-plate with the same wavelength of 300 nm. By studying the theoretical curve between the composite wave-plate＇s phase retardation and the wavelength, this composite wave-plate was proved to be achromatic within the spectrum scope of 250-350 nm. Then an optimization design of the above composite achromatic wave-plate was put forward, which was clone by changing the phase retardation of the middle wave-plate and adjusting the composite angle, the achromatic scope was enlarged to 200-400 nm, and the phase retardation variation was decreased to be about 5%. Moreover, with the same method an UVC super achromatic λ/4 wave-plate was designed, while changing the material of the middle wave-plate： quartz replaced by MgF2. And its phase retardation variation was found to be within 2%. This kind of optimization design was proved to be quite valuable in enlarging the ultraviolet achromatic scope and exacting the phase retardation.