Abstract: A combination of hindle shell and hindle sphere test bodies are employed to test optical surface quality or optical figure of a test optic having a convex hyperboloid reflective surface. A hindle sphere or array of hindle spheres is used to test an outer portion of the reflective surface. A subaperture hindle shell is used simultaneously with the hindle spheres to test the central portion of the reflective surface that is untested by the hindle spheres alone. The test optic may be coupled to a rotator to facilitate testing of the outer portion of the reflective surface where the hindle sphere is a segment of a full hindle sphere. A single hindle shell can test the reflective surface without the aid of a hindle sphere by employing a translator. The translator is used to decenter the test optic from the hindle shell. The translation results in non-null test results, which are analytically predictable and correctable by testing apparatus.

Abstract: A footwear, in particular a mocassin, provided with an attachment to prevent longitudinal and transverse relative displacement between the snowshoe and the footwear and to provide simple and rapid attachment of the latter to the snowshoe. A footwear or moccasin including a strap secured against the exterior face of each of the two opposite lateral walls of the front portion of the footwear, and forming upright strap passages against the opposite sides of the footwear and in transverse alignment with the articulation of the toes, and tying straps projecting through the upright strap passages and attaching a snowshoe to the footwear.