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CASSEGRAINIAN CALCULATIONS.

In making the calculations for Cassegrainian optics I intended making I decided to use the dimensions from the specifications of a f/15 Maksutov given on Page 9 of Sky and Telescope Bulletin C. (Maksutov Articles from Gleanings for ATM's). With the intention of trying my hand at making a Maksutov corrector lens the tooling for this could be used for the Cassegrainian secondary.

While I intended keeping radius of curvature of both primary and secondary to the design specification I did not consider" that critical to have to go to undue trouble. The distance between the two mirrors could be set to suit their radi ; of curvature. These radii can be measured with a spherometer and the seperation calculated from the equation below.

 

 
2p'p
r = ---------- = 2.66p
p' - p
       
Where
r =
Radius of curvature of secondary mirror
 
P =
Distance secondary to primary focal point
 
p'=
Back focal length = 4p
       
 
r
p = ---------
2.66


CASSEGRAINIAN -- MAKSUTOV TELESCOPE.


These dimensions are what I intend using for the Cassegrainians optics I am making. The tooling can be used to make Maksutov optisc later on.

Maksutov f/15

Symbol
Characteristic
f/15
     
Dc
Diameter of Corrector Lens
5.877"
Tc
Thickness of Corrector Lens
0.492" +/- 0.010"
Dm
Diameter of Primary Mirror
6.000"
Tm
Thickness of Primary Mirror
1.000"
Ds
Diameter of Secondary Spot
1.270"
Dh
Diameter of Hole in Mirror
1.250"
R1
1st. Radius of Curvature of Lens
-5.984" +/- 0.070''
R2
2nd. Radius of Curvature of Lens
-6.262" +/- 0.070"
R3
Radius of Curvature of Primary Mirror
-28.030" +/- 0.500"
R4
Radius of Curvature of Secondary Spot
-6.262" +/- 0.700"
CA
Clear Aperature of Corrector Lens
5.454"
BA
Back Aperature of Corrector Lens
5.727"
S
Seperation of Lens and Mirror
11.697"
BFL
Back Focal Length
15.600"
EFL
Effective Focal Length
81.820"