Elementary optics and applications to fire control instruments (1922)
United States. Army. Ordnance Dept · Washington, Govt. Print. Off. · leaf 28
ng faces and two at the lowerpair of faces, which are inclined to each other atan angle of 90° and which form a roof. This prismis subject to the same difficulty in production asthe roof angle prism, previously described, as theangle between the two lower faces must be accu-rately 90°. In figure 24… … t =. p? > -M U V ^ —1 \y , ••?-/ yi^ Fig. 23.—Brashear-Hastings erecting prism. in one piece and is of such shape that it can be held very rigidly inan instrument. The last two reflecting surfaces form a roof angle.This is designated as the Sprenger prism. 25 The erecting prism used in (he…
Optics · Optical instruments · Fire control (Gunnery) -- Optical equipment
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