THE FLAT TELESCOPE FT
This is Labs second flat telescope project and the first modern FT conducted at the Humanoido Asian Lab in 2013. Highly experimental, it's made with a single flat very thin mirror that acts as the primary objective to "project" the celestial image at a great distance to the target. The Flat Telescope is a spinoff of the pinhole telescope which also projects the celestial or terrestrial image.
FLATS
These thin flats are flexed slightly by various means. The annular supporting ring mount supports the mirrors perimeter producing flexure into a curved surface and the center pull mount tugs on the rear of the mirror creating a more spherical shape. Complex flexing is introduced with small annulars that induce a figure more resembling a parabola.
RESOURCES
Mirror are commonly available in square and rectangular sheets which can be cut or more easily and readily masked to circular dimensions.
MOUNTING
The mounts are for the mirror's stability and the image forming platform. The FT is a spinoff of the pinhole telescope but with an aperture equal to the full diameter of the circular flat mirror.
ACCURACY
The accuracy of this mirror's roundness will affect image quality. Experiments continue with several flats, one is a commercial round cosmetic mirror and the other is a 1/25th wave high precision secondary diagonal ellipsoidal astronomical mirror. The ellipse is tilted 45 degrees and form a circular appearance to the line of projection.
LFT FIGURE
For LFT long focal length telescopes, the surface of the primary objective may remain spherical instead of parabolic to meet the Rayleigh criterion of 1/4th wave. For ultra long focal lengths, with a projection design, a range of F10 to F100 is possible. Such a design can use prime focus, thereby annulling any secondary requirements.
THE LIMIT
There are limits as to the amount of flexing the mirror will take before breakage. This depends on the thickness of the mirror, the mirrors XY dimensions, how it's supported and the amount of applied deformation force. Outside this limit, the mirror will break.
CURVING TECHNIQUES
Vacuum
Center Line String
Annular Deformation
4-INCH MIRROR F# VS FL " & '
F010 040" 03'04"
F020 080 06'08
F030 120 10'00
F040 160 13'04
F050 200 16'08
F060 240 20'00
F070 280 23'04
F080 320 26'08
F090 360 30'00
F0100 400 33'04
LINKS
Nano Telescope
http://humanoidolabs.blogspot.tw/2012/02/nana-telescope.html
Fifty Inch Pinhole Telescope FPT
http://humanoidolabs.blogspot.tw/2013/04/ftp-fifty-inch-pinhole-telescope.html