| 摘要 |
PROBLEM TO BE SOLVED: To permit the enlargement of an illumination field and to make an illumination distribution of illumination light uniform over the entire region of a wire field of view. SOLUTION: A lens, which is composed to enclose one concave lens part 20b having a concave surface of a relatively small diameter with four concave lens parts 20a having concave surfaces of a relatively large diameter and is arranged with the concave lens parts 20a and the concave lens part 20b in suitable combinations, is used as the lens 20 for illumination to be disposed at the front end of the insertion part of an endoscope device. As a result, power larger than the concave surface power of the lens for illumination having the one concave surface may be imparted to the individual concave surfaces of the respective concave lens parts 20a and 20b. As a result, the illumination light may be effectively diffused and further, the uniform and bright field of view may be obtained.
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