ATM Aplanatic 4-mirror telescope system

[kwhitefire@juno.com]

Of course, I'm always the theorist.  This is what I have:

This design features 4 mirrors on-axis.  The field curvature is in excess of 250 miles with excellent construction and polishing techniques.  There are no exotic curves, though the primary does have a huge perforation.  Field of view is .25 degrees half-angle.

All preliminary tracing done using Dave Stevick's Spotplot, Kevspot version, which allows the operator to choose paraboloids as +1 or -1.  I used -1 in these numbers to determine the figures.

The data:
Primary Mirror:
D = 13.2 inches
roc = 82.5 inches
b = -.8305

Secondary Mirror:
D = 3.25 inches
roc = -17 inches
b = -.0148

Tertiary mirror:
D = 7.75 inches
roc = 50 inches
b = -.0949

Quaternary mirror is a flat placed for convenient viewing between primary and tertiary mirrors.

Primary to secondary distance = 32 inches
Secondary to tertiary distance = 64 inches
Tertiary to quaternary distance = 26 inches
Quaternary to focal point = 3.35 inches

The results:
f/D system = 6.17
Astig = -.003382
Coma 'S = -.000579
Coma 'T = -.001738
Field curvature = 1361912 inches
Approximate tube length: 77 inches

Newtonian comparison, same D and f/D:
Astig = .0015
Coma 'S = -.000583
Coma 'T = -.001754
Field curvature = 81.0424 inches
Approximate tube length: 95 inches

It looks a bit like this:
---------------- )                  )
        )------- )    /             )
---------------- )                  ) 
                      ep
        2        1    4             3

Kevin of Eastern Iowa
Seeker of the Darkness





________________________________________________________________
Sign Up for Juno Platinum Internet Access Today
Only $9.95 per month!
Visit www.juno.com