摘要
针对波片常规设计中存在的零级波片厚度过小而不易制作、多级片的相位延迟量受温度影响较大的现状,给出了一种设计厚单元零级波片的思路与方法。根据单轴双折射晶体的光学性质,给出了厚单元零级波片设计的原理公式,据此使用任意单轴双折射晶体设计出可选择厚度的零级波片。分析了波片的厚度精度和温度变化对厚单元零级波片相位延迟量的影响,并与常规设计波片进行了比较。分析结果表明:1μm的厚度偏差对厚单元零级波片相位延迟量的影响小于0.3°,仅为相同厚度偏差下常规设计零级波片和多级波片的近6%;温度的变化对厚单元零级波片相位延迟量的影响与其对常规设计零级波片的影响相近,而温度的变化对厚单元零级波片相位延迟量的影响仅为相同厚度常规设计多级片的近1/30。针对三个波长波片设计制作了实验样品并进行了实验测试,验证了厚单元零级波片设计和制作的可行性。所设计的厚单元零级波片具有综合相位延迟性能和厚度可以灵活设计的特点,且便于制作,较常规设计波片具有明显的优势。
Objective Phase retarders are vital optical devices used in various optical polarization applications.Phase retarders are c onstructed using uniaxial birefringent crystals called wave plates.In theory,all birefringent crystals can be used to manufacture wave plates.However,the corresponding thickness of a zero-order 1/4 wave plate in the visible spectrum is only a dozen microns,even if it is constructed from a quartz crystal with low birefringence,making manufacturing difficult.Therefore,the plates are often manufactured with a thickness exceeding 300μm,called multi-order wave plates.The retardation of a multi-order wave plate is significantly influenced by the temperature of the application environment,which is unfavorable in the natural environment.The design principle and structure of a thick-unit zeroorder wave plate that overcome the difficulty in manufacturing zero-order wave plates and the adverse effects of ambient temperature on the retardation of multi-order wave plates are proposed in this study.The design principle and performance parameters of thick-unit zero-order wave plates are analyzed to realize the production of multi-order wave plates,with a retardation accuracy higher than those of the existing zero-order wave plates,whose retardation is less sensitive to temperature than those for multi-order wave plates with the same thickness.Methods First,the relationship between the optical axis angle and the thickness of the thick-unit zero-order wave plate w as determined based on the optical properties of uniaxial birefringent crystals after obtaining the required retardation for the designed wavelength using equations of refraction and the refractive index of the e-ray[Eqs.(9)and(10)].Second,the effects of the wave plate thickness accuracy and temperature variation on the phase retardation of thick-unit zero-order wave plates were analyzed.The proposed design was compared with a conventional design in an actual design case.Third,experimental samples were fabricated using optical quartz crystals in the proposed design,and their phase retardation was examined using normalized polarization measurements(Fig.5).Results and Discussions The fundamental design equations[Eqs.(9)and(10)]of a thick-unit zero-order wave plate c an be used to design zero-order wave plates with a selectable thickness for any uniaxial birefringent crystal(Fig.3).Furthermore,the effects of the thickness accuracy and temperature variation on the phase retardation are investigated based on a design case using optical quartz crystals.The results are as follows:1)A thickness difference of 1μm has an influence of less than 0.3°on the phase retardation of the thick-unit zero-order wave plate,which is less than 6%of that o f the conventionally designed zero-order wave plate or the multi-order wave plate with the same thickness difference(Fig.4).This indicates that,by using the same manufacturing technology,the thick-unit zero-order wave plate design can achieve higher precision of phase retardation.2)The effect of temperature variations on the phase retardation of the thick-unit zero-order wave plate is similar to that for the conventional zero-order wave plate and is only 1/30 of that for a conventional multi-order wave plate(Table 1).3)Tests on the samples verified the feasibility of designing and manufacturing thick-unit zero-order wave plates.When the ambient temperature is varied within a range of±5°C,the variation in the phase retardation is within 0.15°(Table 2).Conclusions In this study,a design principle and method for thick-unit wave plates are proposed and any uniaxial b irefringent crystal can be used to manufacture a zero-order wave plate with a selectable thickness.This overcomes the manufacturing difficulty in conventionally designed zero-order wave plates owing to the minimal thickness and adverse effects of temperature variations on the phase retardation of multi-order wave plates.Given the significant advantages of highly precise retardation,stable temperature,flexible thickness,and ease of manufacturing,the proposed design provides a novel approach for designing and fabricating high-performance zero-order wave plates.
作者
吴闻迪
Wu Wendi(Shandong provincial Key Laboratory of Laser Polarization and Information Technology,School of Physical Engineering,Qufu Normal University,Qufu 273165,Shandong,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第23期58-63,共6页
Chinese Journal of Lasers
关键词
激光光学
偏振光学
零级波片
相位延迟量精度
温度效应
laser optics
polarization optics
zero-order wave plate
accuracy of phase retardation
temperature effect
