| 摘要 |
PROBLEM TO BE SOLVED: To precisely measure the transmission decentration of a lens to be inspected, irrespective of whether the focal length of the lens to be inspected is positive or negative, by a method wherein inspection light is transmitted back and forth through the lens to be inspected, and the transmission decentration is measured at a set image-formation magnification irrespective of the kind of the lens to be inspected. SOLUTION: A laser beam 12 radiates diffused light from a pinhole 13 via a convex lens. A collimating lens 2 converts the diffused light into parallel light via a mirror 8a and a mirror 8b in the forward route, and it converts the diffused light into convergent light in the backward route. Light which is passed through the collimating lens 2 is incident on a lens 1 to be inspected as parallel light. Inspection light which is transmitted through the lens 1 to be inspected is reflected by a concave mirror 15, it is passed through its original optical path, it is transmitted through the lens 1 to be inspected again, the it is image-formed on a TV camera 9 via the mirror 8a, the lens 2, the mirror 8b and a semitransparent mirror 14. The formed image of the pinhole 13 displays on a display 16 a deflection according to the decentration amount due to the rotation of the lens 1 to be inspected. Since the inspection light is transmitted back and forth through the lens 1 to be inspected, it is subjected to the influence of twice the intrinsic transmission decentration of the lens 1 to be inspected, and its inspection capability is increased.
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