Achromatic Phase Retarder Testing And Performance Optimization Design

Phase retarders are important optical components that introduce a phase shift between orthogonal and linearly polarized components of light transmitted through them. Fitted with other polarimetric elements, they can realize modifying of light and controlling of polarization states. Conventional phase retarders are mostly applied to a single wavelength, however achromatic phase retarders can be applied to broader optical spectrum which weaken the dependence of retardation on wavelength largely and operate at an irreplacable action in modern laser technology. Achromatic phase retarders can be divided into two classes: birefringence and total internal reflection. In this paper, we studied total internal reflection(TIR) achromatic phase retarders.In the first section, we mainly introduce the development general situation of the achromatic phase retarders and the important significance of this topic research. The second section, firstly, we introduce the theory of total reflection phase change; then we have a summary to structure and principle of the Fresnel rhombs Mooney rhombs achromatic device 1 (AD-1) and achromatic device2(AD-2)srectangle prisms compound rhomb and all kinds of oblique-incidence rhomb phase retarders.Comparing all kinds of ways to measure the phase retardation, they aren't suit to measure the phase retardations of achromatic phase retarders because the basic parameters of devices relate to the wavelength majoritily. In view of this situation, in the third section , according to the theory of polarization modulation, we substitute the ordinary analyzer with Wollaston prism and build a suit of new measurement system, Moreover, we introduce a normalization parameter to attribute retardation that will be measured from Jones matrix . In the same time, we discuss all kinds of error sources existing in the system, the result indicate this system's relative error can be controlled less than 0.5 percent. Then use this system, from two aspects which involve the spectrum characteristic of retarder and sensibility of retardation to the incidence angle, we test the practical performance of several kinds of achromatic retarders separately, the results are congruous to the theory analyses basically.Both the measurement and theory analysis show that it is difficult to have comparative comprehensive good performance for the majority achromatic retarders. In the forth section, we optimized the routinedesign scheme. We analyze the theory of total reflection phase change for thin-film-coated systematically, applying the relations for thin-film-coated on total reflection interface, we extract one design-scheme of achromatic phase retarder that is not sensitive to the change of incidence angle. We design the examples of Fresnel rhomb coated with film on the two total reflection interfaces or on one single interface. The theory analysis show that the no-sensibility to incidence angle of the coated Fresnel rhomb retarder is improved largely and the character of achromatic is also improved greatly. Besides, we give a concrete design of the oblique incidence retarder which isn't sensitive to the incidence angle. We supply the principle and design basis to the later research on further study of total reflecting thin-film-coated achromatic phase retarders and development effort of better achromatic phase retarders.