Tunable Retarder Research Articles

In-line variable-phase reflection retarder using a coated deformable three-mirror system

The locus of the ratio of net complex-amplitude external-reflection coefficients for the p and s polarizations of a symmetric three-mirror system as a function of the angle of incidence follows very closely the unit circle in the complex plane when ZnS-coated Ag mirrors are used with a ZnS film thickness d=985.2 nm at 10.6 mu m wavelength. Consequently, such a system performs as an in-line, variable-phase retarder with the quarterwave and halfwave retardations attainable at incidence angles of (51.117 degrees , 72.863 degrees ) and 79.360 degrees , respectively. The associated amplitude diattenuation is negligible (<0.01 dB), and the system performance as a tunable retarder for incident collimated laser radiation is virtually unaffected by film thickness errors of +or-20 nm.

Si02 -Si Film-Substrate Single-Reflection Retarders For Different Mercury Spectral Lines

Design parameters for Si02-Si film-substrate single reflection retarders for several mercury spectral lines are presented. An example of an angle-of-incidence tunable retarder (AITR) capable of multiple wavelength operation (MWO) is reported. Simple, approximate formulae for calculating film-substrate retarder design parameters (least film thickness d' and incidence angle are presented.

An angle-of-incidence tunable, SiO 2-Si (film-substrate) reflection retarder for the UV mercury line λ=2537Å

We present an optimum design of a SiO 2-Si film-substrate single-reflection, angle-of-incidence tunable retarder for the UV spectral line λ=2537 Å. Small changes in film thickness around the optimum value do not significantly affect the device performance. The same applies to small shifts of the wavelength of operation, neglecting the effect of dispersion.

High-precision Tunable Retardation Plate for Use with Visible and Ultra-violet Polarized Light

A variable retardation plate suitable for polarizing optics in the visible and ultra-violet has been developed. It is based on the photoelastic effect induced by lateral compression of a rectangular plate of fused silica. A special pressure frame employing hydraulic pressure gives very even compression, and the stress pattern induced is uniform to within 1 per cent over most of the plate area. A pneumatic ballast system has also been developed to stabilize the pressure, which maintains the retardation constant to within ½ per cent over a period of hours. Possible applications of the retardation plate in optical instrumentation and in the accurate measurement of pressure are discussed.