| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared lens which is small in size, can be composed at a low cost, has a back focus much longer than a focal distance, and has satisfactory imaging performance. SOLUTION: The infrared lens used in a wavelength band of 3μm to 12μm is composed of a single lens L1 of positive meniscus shape, the concave face of which is oriented on the object side. The object side face of the lens has an aspherical shape which increases curvature as it extends from its central part to its peripheral part. The image side face of it has an aspherical shape which increases curvature from its central part to its peripheral part. COPYRIGHT: (C)2011,JPO&INPIT
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