Screenless portable microfilm reader - gives parallel beams via prism system with transparent, semi-reflective and reflective common faces

The optical system is intended for a compact and portable microfilm reader. It permits direct reading of a microfilm without a screen using an objective and eyepiece and a system consisting of two sets of prisms (Q1,U1,P1 and Q2,U2,P2). The common faces (B and G) between prisms (U1,P1 and U2,P2) are semi-reflective, the face (C,H) between (U1,U2) fully reflective, and the faces between (Q1,U1 and Q2,U2) fully transparent. The arrangement is such that incident liqht (at A and F) in (Q1 and Q2) passes (a and b) into (U1 and U2) where it is split (at B and G) into (a1,2 and b1,2). The beams (a1,b1) are reflected (at C,H) back into (Q1,Q2) from which it emerges (at D and I) parallel to its original entry. The beams (a2,b2) pass through (P1,P2) into (Q2 and Q1) to emerge (at E and J) parallel to its original entry and to the beams emerging (at D and I).