CONDENSER LENS FOR INFRARED-RAY TYPE DETECTOR

摘要

PURPOSE:To obtain a compact, thin and efficient condenser lens by crossing slantingly the rotation axis shared by respective hyperboloids of a Fresnel's face of the 2nd face obtained by combining a 1st face shaped in plane and the 2nd face shaped in hyperboloid. CONSTITUTION:The condenser lens is constituted of the Fresnel's face obtained by combining the 1st face shaped in plane and the 2nd face 20 shaped in hyperboloid and the rotation axis C shared by respective hyperboloids of the Fresnel's face of the 2nd face 20 is crossed slantingly the plane constituting the 1st face 10. Since an angle can be formed between parallel beams converged upon a focus without generating aberration and the normal H of the plane 10 in accordance with the angle formed between the rotation axis C shared by respective hyperboloids of the Fresnel's face and the plane 10, infrared rays obtained from a necessary direction can be efficiently converged without directing the lens to the necessary direction. Thus, the compact infrared-ray type condenser lens for a detector having high converging efficiency can be obtained.