Patent ID: 7564633

Claim:
A catadioptric imaging system comprising: a double-reflecting Mangin mirror having: an optically transmissive body, a partially reflective surface at a first side of the optically transmissive body for admitting light into the optically transmissive body and for partially reflecting the light within the optically transmissive body, a concave reflective surface at a second side of the optically transmissive body for returning the light to the partially reflective surface, an aperture within the concave reflective surface, and a concave refractive surface at the second side of the optically transmissive body within the aperture of the concave reflective surface, the concave reflective surface and the concave refractive surface at the second side of the optically transmissive body having nominal centers of curvature located in opposite directions along a common optical axis for reducing refraction angles at which the light exits the optically transmissive body through the aperture, the partially reflective surface and the concave reflective surface being arranged with respect to one another so that marginal rays of light approaching the partially reflective surface from the concave reflective surface strike the partially reflective surface at an angle of incidence that is less than an angle of total internal reflection; and the partially reflective surface being treated for enhancing a radially symmetric polarizing effect of the partially reflective surface favoring a reflection of one direction of the radially symmetric polarization with respect to an orthogonal direction of the radially symmetric polarization.