Re: SL3D Microscope

[P3D Chuck Hassen <deck_0@xxxxxxxxxxxxx>]

-- [ From: Chuck Hassen * EMC.Ver #2.5.02 ] --

Hi all,

This note is just to throw some fuel on the stereo / binocular microscope
question.

I happen to be the happy owner of a fine quality binocular microscope,
manufactured by E. Leitz in Wetzlar, Germany (no date -- no reference to
"which Germany", so I estimate its age at roughly late 30's).  This scope
has three objectives: one 10x, diameter 0.8 cm; one 40x, diameter perhaps 1.
0 mm; and one oil objective 100x, slightly smaller diameter.

At 10x, when looking at objects with some thickness and no coverslip, the
image does indeed appear 3-d, even though only one lens is used; some of my
friends can convince themselves that this effect occurs at the higher
magnifications, but I am unable to observe it.

One feature of this style microscope is that it projects a real image of the
the subject just below the prism assembly  that splits the light into a left
eye channel and a right eye channel.  In the case of my scope, the binocular
assembly is a spring-loaded bayonet assembly that allows easy removal of the
optics so it becomes possible to observe the real image directly, from above
without magnification.  This image, like most free-floating (non-diffused)
real images of 3-d objects, is 3-d itself.  So, it follows that there may be
a way to look at this 3-d real image from slightly different angles, and
thereby create a SL3D effect.  This is the principle behind the Common Main
Objective design.  According to my empirical observations, this is easier to
do when the object is viewed through a large objective lens, simply because
the exit pupil diameter for such a lens is physically large; not a single
point, or an approximation of a single point as is the case for a small
diameter optic.

A note here is that very small microscope objectives were probably more
difficult to make well in the 1600's than medium sized ones.  Therefore we
may assume that the objectives employed by early manufacturers were limited
by necessity to ones with apertures large enough to provide adequate 3-d
information to allow the image to be seen as a stereo pair....

Chuck Hassen


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