| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lens meter, with which the transmittance in the ultraviolet region of a lens to be inspected can be measured at low cost and easily by a method, wherein an ultraviolet LED is used as a light-emitting means in an optical system which is used to measure the transmittance and the measurement of the transmittance, is limited to the ultraviolet region. SOLUTION: For example, an ultraviolet LED at a light-emitting wavelength of 350 to 400 nm is used as a light source 50. Its measuring luminous flux 52 is changed into nearly parallel beams of light by a collimating lens 56 and is projected on a lens OL' to be inspected, via a pinhole-like slit plate 57. Then, the measuring luminous flux 52, which is projected on the lens OL' to be inspected, is made to pass through a filter 59 on its optical axis 54. Ultraviolet rays are sorted, and they are guided to a photoelectric conversion element 64 via a condensing lens 60 so as to be detected as an electric signal. The transmittance of the detected ultraviolet rays is displayed on the monitor of a lens meter as a bar graph or the like.
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