| 摘要 |
909,431. Focusing devices. HENSOLDT & SOHNE, OPTISCHE WERKE A.G., M. July 25, 1960 [Aug. 12, 1959], No. 25741/60. Classes 97 (1) and 98 (1). To eliminate stray light reaching an observer's eye by reflection from a ground-glass focusing screen or the like, a curved coloured disc is placed between the screen and the observer's eye with its concave side towards the observer's eye which is placed substantially at the centre of curvature so that it is imaged on itself. Light incident on the disc 5 will necessarily originate from points such as 6 other than the region of centre of curvature so that no reflected light can enter the eye. Stray light passing through the disc and reflected from the screen 1, or a magnifier 2 in front of it, will pass twice through the disc, and will thus be greatly attenuated, before reaching the observer's eye. Preferably, also, the magnifier has an anti-reflection coating giving maximum suppression for the wavelength region where the disc transmits. |
