| 摘要 |
PCT No. PCT/GB95/02184 Sec. 371 Date Jun. 12, 1998 Sec. 102(e) Date Jun. 12, 1998 PCT Filed Sep. 15, 1995 PCT Pub. No. WO97/10523 PCT Pub. Date Mar. 20, 1997A projection system incorporating a screen (2, 14) with a substantially achromatic response in a direction substantially perpendicular to the plane of the screen. The screen (2, 14) comprises a diffraction grating (4), means (5) for attenuating zero order and a diffuse holographic optical element (6). The system further comprises a focusing element with positive optical power. The aggregate optical power of the grating and the holographic optical element is substantially less than that of the focusing element. |
