Scanning system for viewfinder image field - has two angled mirrors each with two reflective faces set at right angles

摘要

The scanning system, e.g. for the image field of an infrared viewfinder, uses two scanning elements(3, 4), reflecting the incident light. Each element(3, 4) has two reflective faces at 90 degrees to one another, with the output face of the first element(3) lying in parallel opposition to the input face of the second element(4). The spacings between the input lens(2) and the first scanning element(3) and between the two scanning elements(3, 4) are selected so that an intermediate image(5) is obtained between the latter, e.g. with a field lens(10) at this point. A focussing lens(6) is positioned between the output face of the second scanning element(4) and the photodetector(8).