RE: Beam splitter (definition)

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

BobH writes:

> I decided to look it up in "The Focal Dictionary of Photographic
> Technologies" by D. A. Spencer 1st Ed. 1973 Focal Press
>
>    beam splitter:  "Arrangement of prisms or semi-reflecting mirrors or
> dichroic filters or transparent pellicles which will divide a beam of
> light into two or more parts directed to different stations. Used in
> reflex viewfinder systems in some cine cameras and still cameras,
> optical rangefinders, single lens systems for making stereo photographs,

Ah yes but that's another type of 3D arrangement:


                          \
                           \  <- 100% reflective mirror
                            \
 <- object                       ____
                          \    _|    |
                           \  |_|    |  <- camera
                            \   |____|
                          ^
                          |

                   50% reflective mirror
                     (beamsplitter)

This was a cheap 3D movie camera setup something like 50 years ago.
I don't remember the details of the design as I wasn't impressed with it.
Saw it in JOSA, I think.

John B


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