M. A. Sadovnikov, V. D. Shargorodsky, A. L. Sokolov
Retroreflectors are widely used in satellite laser ranging for the precise determination of coordinates of navigation and gedetic satel-lites.
The specificity of the application of cube corner retroreflectors in laser ranging systems is that the reflected laser beam deviates from the direction to the detector due to the so-called speed aberration. Therefore, in order for a ranging system to operate, the energe of the reflected laser beam must be distributed over a sufficiently larg area and concentrated on the beam periphery rather than on optical axis. An important role in the formation of the diffraction pattern is played by the polarization state of radiation. In connection with this, retroreflectors with non-metallized or part- metallized are of significant interest. The aim of this paper is to present results of porization-wave analysis of retroreflectors with different coated surfaces. As is shown, retroreflectors are diffractive polarization-optical elements, which form a polarization-ingomogeneous beam whose polarization changes in both the transverse and longitudinal directions. The radiation intensity distribution in the far field of a retroreflector significally depends on the phas shift of the E vector components upon reflection. The porization-wave analysis is presented for cube corner retroreflectors of 3 types: A – uncoated prisms (using total internal reflection); B – prisms with 3 metal-coated reflective surfaces; C – prisms with a single metal-coated surface. The spatial polarization pattern as well as the retroreflector cross-section has been calculated using a set of Hermite-Gaussian modes to represent the optical field spatial distribution.
Owing to the energy redistribution from the center to the periphery, retroreflectors with non-metallized surfaces form a beter intensity distributin in the far field. So a retroreflector array composed of uncoated prisms is preferable for use on board of GLONASS spacecraft, while an array composed of prisms with a single metal-coated surface may be used on board of a geostationary spacecraft.