| 摘要 |
The light trap, designed for a parallel light beam (2), comprises a cylindrical chamber (1A) with a side wall (3) which has an absorbent inner surface (4), and an inlet member (5) at one end of the chamber with inner (7) and outer (8) surfaces and a truncated conical aperture (9) between them. The aperture is located coaxially with the chamber and a conical body (12) located inside it and fixed to its base (10). The truncated conical aperture (9) converges from the outer face of the inlet member to its inner face, and its diameter on the outer face is equal to the diameter (D) of the light beam (2). The thickness (E) of the inlet member is determined from the equation E = D/(tg2A + tgA), where A is half the angle of the aperture. The inner conical body (12) is coated with a material which reflects light equally in all directions, e.g. barium sulphate with visible light and gold for infrared light. In addition, the outer wall is designed to dissipate heat, and is made from copper. |
