Please help identify this 4X5 camera back.

[brass-eye]

Hello, I recently purchased this instrument as government surplus. I have not been able to identify the maker or figure out exactly what it purpose is. I studied technical photography and lab technics in the early 90's and worked in 4X5 but never came across something like this. The travel on the axis is approx. 4.625 and 3.450. Two OPL LM54 illuminate and magnify the scales and allow placement of the image to thousands of an inch. The back plate is 4X5 . Any information on maker or ideas for its use would be appreciated. Thanks

[Jim C.]

From my Googling and using Google translate the abbreviation OPL is for - Optics and Precision Levallois
A French company, seems they made optics for the military from 1919 to 1964, just a shot in the dark,
so a guess is that what you have may be the back of a aerial camera ? Metallurgical use ?

Wikipedia French Link for OPL
https://fr.wikipedia.org/wiki/Optique_et_précision_de_Levallois

[brass-eye]

Thanks for your reply Jim. I found the same info on OPL however no mention of this instrument. I believe that the LM54 is just a component of the back. I have found references of the LM54 being used in machining applications. Thanks again.

[EdSawyer]

Whatever it is it looks bloody precise! Maybe something for IC masking making chips? Or military mapping from aerial negatives?