| CPC G02B 7/02 (2013.01) [G01J 5/08 (2013.01); G02B 3/04 (2013.01)] | 10 Claims |
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1. An infrared lens unit comprising:
a lens barrel including
a tubular part extending along a central axis extending in upward and downward directions, the tubular part having an inner circumferential surface surrounding the central axis, the tubular part having a through-hole therein demarcated by the inner circumferential surface, and
a protruding part disposed on the inner circumferential surface of the tubular part, the protruding part having an annular shape extending in a circumferential direction about the central axis; and
an infrared lens supported on the lens barrel such that the infrared lens is supported by the tubular part via the protruding part, wherein
the infrared lens is made of chalcogenide glass,
the protruding part includes, in a cross section of the protruding part on a plane on which the central axis extends:
a linear portion including an upper end and a lower and extending in an upward direction from the lower end to the upper end; and
a first sloping portion including an upper end and a lower end located at the upper end of the linear portion, the first sloping portion being inclined with respect to the linear portion such that the first sloping portion is away from the central axis as extending from the lower end of the first sloping portion to the upper end of the first sloping portion, and
the infrared lens contacts the linear portion and the sloping portion of the protruding part.
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