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16" F/1.2 Baker-Schmidt

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#26 Flybywire



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Posted 25 April 2011 - 11:57 PM

As I posted earlier in the thread, I also own one of these mirrors. I originally purchased it without any intention of using it for an optical application, however, now I am wondering if it would be feasible to build a scope with a sub-aperture corrector.

#27 richardteles


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Posted 13 February 2013 - 09:09 AM


#28 ed_turco


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Posted 13 February 2013 - 11:01 AM

I saw one of these collimators at Wright-Patterson in 1962. It was 16" in diameter and the plate was a Schmidt corrector. As it was at the radius of curvature of the mirror, the dimensions seem right.

I was introduced to this by a Ph.D. Supervisor who explained the whole thing to me. His name was Pryor as I recall. It was quite the thing to test various lenses with this device and see what they could do!

#29 Geo.



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Posted 16 February 2013 - 10:22 AM

Yes, the Terabeam contract makes sense. Guess laser communications have gone the way of the dodo.

Here are some notes from my files:

Optics (terabeam telescope)

Both Meade and Terabeam destroyed their files on these systems after they became obsolete. One surplus dealer was able to acquire these measurements:

The specs of the primary mirror as measured by a professional in optics manufacturing:

Pyrex Spherical Mirror by Meade - MSRP $2500

Speed = f/1.2
Spherical figure ~ ΒΌ wave Clear Aperture
Diameter = 16"Radius = 35"Bore = 4.25"
Pyrex cast blank (not sagged), avg. thickness = no less than .75"
Aluminum Coated with SIO overcoat
Ronchi test showed smooth parallel lines
Uniform .75" thickness allows for very quick temperature acclimation.

There are three ways to use this mirror for a telescope:

1) Use the primary only and find a company to build a schmit corrector plate (there are many)
2) Use the primary only and put a curved filmholder at the prime focus
3) Use the secondary mirror and the meniscus lens to render an image with negligible coma

To align the optics use a laser pointer and spread the beam into a line with a cylindrical lens. Align the primarywith the beam so that it sends the beam back upon itself then bolt on the secondary and adjust it so that the beam reflects in the same plane. A piece of tissue paper about 1" wide will make this easy. Repeat the process in the perpendicular plane by rotating the axis of the cylindrical lens 90 degrees

Don't attempt to test the optics over short distances as I was never able to obtain an image that way. Use the moon for initial testing as it's at infinity.
If you are new to telescope building I have one word of caution: Don't allow anything to ever contact the primary mirror, don't even try to clean the mirror. Use a can of compressed gas (Dust Off) but don't invert the can as it will spray liquid gas on the mirror and crack the aluminum coating due to thermal shearing.

Electronics(terabeam telescope)

The stepper motors included with the system are bipolar:

The steppers are manufactured by Lin engineering.

Wire Color Code:
Red -A
Blue- A'
Green - B
Black - B'

Lin Engineering wiring page www.linengineering.com/our_products/wiringcon.htm

The Included gearboxes are manufactured by Harmonic Drive.

Here's how it works:
The teeth on the non-rigid Flexspline and the rigid Circular Spline are in continuous engagement. Since the Flexspline has two teeth fewer than the Circular Spline, one revolution of the input causes relative motion between the Flexspline and the Circular Spline equal to two teeth. With the Circular Spline rotationally fixed, the Flexspline rotates in the opposite direction to the input at a reduction ratio equal to one-half the number of teeth on the Flexspline.

Attached Files

#30 Ed Jones

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Posted 16 February 2013 - 01:56 PM

Here's one idea but uses only 14 inches of it. The oblate R2 would be a challenge.

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#31 Larry Silvestri

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Posted 16 February 2013 - 02:29 PM

It would make a nice Hindle sphere.

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