| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared zoom lens consisting merely of germanium, capable of configuring a bright optical system with reduced variation in brightness during varying a magnification rate, and capable of forming a clear and vivid image by facilitating correction of aberration, especially spherical aberration that is generally hard to be corrected. SOLUTION: The infrared zoom lens includes first to fourth groups of lens pieces arranged in series from the foremost position closest to an object, each of the lens groups having all the lens pieces made of germanium, and at least one of the lens groups consisting of a single lens piece. COPYRIGHT: (C)2011,JPO&INPIT
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