Arrangement for test mark positioning in spheric perimeters

Claim 1

Arrangement for test mark positioning in spherical perimeters comprising a semi-spherical screen having a concave and a convex face, said screen having a light-transmissive central rear projection portion, a plurality of test markings being arranged on said concave face, a light detecting means, a substantially plane mounting means, said light detecting means being provided on said mounting means in opposition to said convex face, a double-projector for producing a first light beam and a second light beam substantially about an optical axis x--x, and directing said first and said second light beam to said central portion and to said light detecting means, respectively, said double-projector being arranged between said central portion and said light detecting means, said double-projector, said central portion and said light detecting means being in optical alignment, first means for moving said double-projector substantially at right angles to said optical axis x--x, second means for displacing said plane mounting means in its plane, a projector for producing a third light beam secured to said mounting means, said third light beam being substantially at right angles relative to said plane of said mounting means, an image plane being optically aligned relative to said projector, said projector being for directing said third light beam to said image plane, and a plurality of a light cables, the number of said light cables corresponding to the number of said test markings, each of said light cables having a light entrance face in said image plane, and a light exit face in said test markings, said light entrance faces having the same mutual spaced relation as said test markings on said screen.