| 摘要 |
The final condensing lens element, commonly used in a system for concentrating light at an aperture, is replaced by light restricting path means forming a transversely unobstructed, open ended light path. Spaced, opposed front surface mirrors define a portion of the path along which light is reflected back and forth between the mirror surfaces to emerge at the open end as a uniform flood of light. The absence of transverse surfaces avoids any collecting of dirt which would cause streaks to be printed on film printed with the concentrated light.
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