How did they make prisms?
The manufacture of small prisms as used in the telemeter [rangefinder] were by mouldings cemented in fours and then gang-milled by diamond milling tools. They were then taken apart and milled to the other face. Diamond tool milling machines are used for slotting the hypotenuse. Smoothing and polishing was achieved by normal type poker-arm machines. Edging was carried out on small lens in the telemeter by diamond wheels. These wheels are made for Leitz by Jung of Berlin. Question: What was the percentage transmission in the beamsplitters? Answer: The small reflecting mirror in the range finder is very lightly alluminised, the degree of deposit being just sufficient to give an equal degree of brightness to both the directly and indirectly received images when seen through the range finder eyepiece. Comment: This means that if you are really handy, you can buy a 50% aluminized beamsplitter from Edmund Optics and install it yourself…. yeah, right! Question: What were the steps for applyi
