Re: Stereo rangefinders

[T3D <BD3D@xxxxxxxxxx>]

George wrote:
>It occurred to me that the parallax bar, as I described it, works as
>a stereo rangefinder.  Bill Ewald, who presented the keynote talk at
>the NSA Rochester convention, demonstrated a prototype of one of those
>which he built while he was working in Kodak.  I believe that this
>prototype is now in the hands of Bill Davis.

>Looking through the rangefinder you can see two orange arrows and your
>regular scene.  Fusing the two arrows creates a floating point.
>Ajusting the rangefinder dial you can make the floating point stand
>over a certain subject and then read the distance of the subject from
>your rangefinder dial.
[...]

I would say you're pretty well correct on all counts, George.  The range-
finder operates on the principle you described, using linked sliding gates
in front of a machined base plate with matching but opposite cutouts.  The
gates with the v-notch pointing "out" slide outwards from the matching vee 
on the base and you get a pair of diamonds increasing in size while the 
center-to-center distance increases.  If you put an illuminated lucite 
strip behind the apertures you can provide bright images.  This setup, facing 
forward in the r.f., is reflected in semi-permeable mirrors back to the
user, who fuses them exactly as George describes.

The thing I'm not sure of, although I have a sneaking suspicion that I'm
correct :--), is that a unit of this nature must be calibrated to each user
due to individual interocular separation.  

By the way, thanks to John or Bob or the glitch in their software that got 
me invited to this list.  This should prove to be a long-awaited breath of fresh 
air.  I will try not to get in the way of the more capable posters on the
list and promise to only address a subject if I know something about it
or really want to know about it.

Best regards,
Bill Davis


------------------------------