| 摘要 |
PURPOSE:To prevent effectively the burn, etc. of a light guide by irradiation of light by using a liquid crystal lens of which the focal length changes with temp. to a condenser lens system for irradiating the light on the incident end face of the light guide. CONSTITUTION:The liquid crystal lens 4 is formed with a pair of focal length variable lenses 10a, 10b by sealing liquid crystals 9a, 9b having the same characteristic within the two cells formed of transparent plates 8a, 8b having convex faces positioned to face both faces of a transparent plate 6. A connector 5A of the light guide of an endoscope is mounted to a light source device 1 and the light is condensed by the lens 4 constituting the condenser lens and is irradiated in the spot shape on the incident end ace of the connector 5A. The temp. of the lens 4 increases considerably uppon attainment of such a temp. at which the adhesive agent, etc. of the fiber bundle are deteriorated. Then the focal length of the lens converged to the focused state increases and the spot-shaped area to be riradiated is larger than the incident end face. The quantity of the light irradiated on the incident end face decreases consequently and the deterioration and burn of the fiber bundle by the heat are automatically prevented.
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