| 摘要 |
1,067,731. Optical apparatus. ALOS A. G. May 19, 1964 [May 28, 1963], No. 20498/64. Heading G2J. A projection system comprises a projection screen, an objective and an illuminating apparatus which includes a light source, a condenser and a concave reflector, the reflector having a reflection capability that progressively decreases from the outer periphery to the centre of the reflector in order to provide a uniformly illuminated screen. As shown in Fig. 3, the reflector comprises a part spherical glass base 30 provided with a reflecting coating 31 on the convex rear face and, at the centre of its concave surface, with two layers 32, 33 of light absorbing material, each layer having a thickness which decreases from the centre of the reflector. The variation in reflection capability may be provided by a reflecting coating of a thickness which decreases towards the centre or by a reflective metal coating which is matted or dulled towards the centre of the reflector. |
