Stereo microscopes 1600.s and now

[P3D Peter Homer <P.J.Homer@xxxxxxxxxxxxxxxxx>]

I dont have access to my E mail over weekends and a number of questions have=
 been asked which seem to require an answer from me .
William Carter quotes me " Cherubim De Orleans stereomicroscope still was=
 not a stereoscope even if it had two objective lenses and the right sort of=
 working distance as they would have probably been converged ont actual=
 objects rather than parrallel or even divergent as would be required of a s=
tereoscope"
He replied I dont get it peter? but I am not quite shure what he doesn,t get=
..
 This was conjecture on my part as to whether stereo pairs could have been=
 produced before Wheatstone. Da-Vinci's camera obsura could have produced=
 the images in the 1500 even 1400 depending when he actualy made it but free=
 viewing would seem to be the only possibility for viewing them . A stereo=
 microscope in the 1600,s would fill the criterion for close up viewing with=
 both eyes but would have to have  at least parrallel tubes rather than=
 convergent which would be required of a microscope so it could not have=
 done this .
 He then quotes Neil Harrington who was under the impression that Cherubin=
 De Orleans microscope was of the beamspliter type which he thought could=
 not give a stereoscopic image . Leaving aside that I think these type of=
 microscopes can give a stereo image for the reasons I have already=
 described I thought that Cherubins microscope was probably a "true"=
 stereoscopic one . But the Wredden illustration which is presumably from=
 Cherubins "La Diotrique Occulaire " or Zahns "Oculus Artificialis=
 Teledioptricus Sive Telescopium" did not confirm either way . Nor was the=
 text from "La Vision Parfait" to me but the new information fro Willliam=
 Carter would seem to.
"Also I have a constructional diagram supposedly taken from Cherubin's 'La=
 Vision Parfaite',1677. In it is shown what appears to be a single plano=
 convex objective and two occulars converging on it (raked as Peter=
 suggested). A simple and practical design for the time, and similar to many=
 dissecting microscopes today.)".
 We have a Olympus stereo zoom microscope at work that does this with=
 optional auxiliary objectives which we dont have as yet. They screw in=
 across both obectives to increase or decrease magnification  and increase=
 or decrease convergence as they come in 0.5X,0.75X, 1.5X and 2.0X .
The diagram in the microscopes manual actualy shows one in place in dotted=
 lines and it is a plano convex lens so it must be one of the reducing=
 lenses either 0.5 or 0.75 . None of our other twin tube stereo microscopes=
 use this arrangment but some one in a folio I am in made a prismatic=
 attatchment for a camera using what he called "Dove prisms " shaped=
 something like <I> for stereo close ups . He got the idea from a stereo=
 microscope which had dove prisms with the apexes flatened behind a single l=
ens.
 Thanks to William Carter about the information about the Edge improved=
 anaglyph method for the microscope and Schultze,s polaroid system as far=
 back as the 20,s which must make it among the earliest uses of polaroid ?.=
 Shurely the anaglyph method could have been used even earlier but neither=
 are mentioned in Becks book from 1921 among his methods for getting stereo=
 from a microscope with a single object glass. At least I did not dream=
 these methods!.     P.J.Homer



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