Re: Surgeons Magnifting Glasses



"amdx" <amdx@xxxxxxxxxxx> writes:

http://www.sheervision.com/index.asp?PageAction=VIEWCATS&Category=3&gclid=CJCWx-Tk-ZACFRpdagodkXRB2Q

Yes, aren't those cool? and expensive!
So what type lenses are used to make these?

My dentist uses something like this, except that the two telescopes are
permanently mounted on the lenses of his regular glasses, instead of
having an external frame clamped to the glasses. Probably reduces
weight quite a bit.

The optics appear to be Galilean telescopes - a positive lens at the
front, a negative lens near the eye. The focal lengths used determine
magnification and size of the assembly. If you just want to experiment,
plain lenses from some place like Edmund might be good enough. But for
quality equivalent to the commercial ones, you'll probably need to make
each "lens" an achromat, and be anti-reflection coated. Or find a good-
quality pair of "opera glasses" and dismantle them for the optical
parts.

If you want to build the mechanical assembly yourself, you're going to
need access to a machine shop. The individual telescope barrels need to
hold the lenses in alignment, probably with some means of changing
spacing for focusing. Then the mounting frame has to hold the barrels
with exactly the correct spacing to match the user's eyes, with
exactly correct horizontal convergence and minimal vertical aim error
in order to get the two images to fuse properly into a stereo pair.
You'll need some amount of adjustability for this - either in the final
mechanics, or in a jig that you use to measure your particular eyes
(whose measurements are then used to make a non-adjustable framework
that is customized for you).

Essentially, you're building a specialized pair of binoculars that are
focused and converged at a specific distance instead of infinity.

Dave
.