36-Point Cells

Hughes LaRoche used Plop to design this layout for a 36 point astatic mirror cell for his 1.138 meter diameter BVC mirror. Yes, that is 1.138 meters, 44.8 inches! Plop says the residual deformations will be 2.67 nanometers RMS (1/187 wave), 22.6 nanometers P-V (1/22 wave).

An astatic cell does not use the layered pivots of a flotation cell. Instead, three of the triangles will be pivoted on fixed mountings while the remaining nine will be supported by counterweighted astatic levers.

Here is the Plop Setup.

;

; 36 pts inspired from Luc Arnold paper 1995

; Modified this for my 45 BVC incher.

; Gave 1/22 wave PV, 1/ 190 RMS (wave=0.00055 m)

;

;

; H. Laroche, 11 June 2004

; 

;BVC glass mirror diameter 1138.0 mm), thickness (67. mm), focal length (4240.0 mm),

;and secondary size (203.0 mm) are fixed design elements.

;

;

;

;

;

;

;support-angle 0 -0.301534 0.396445 20.3698 40.316

;optimize support-angle 1 0.25

;optimize support-angle 2 0.25

;optimize support-angle 3 0.25

;optimize support-angle 4 0.25

;

;

diameter 1138

thickness 67

density 2.44e-06

modulus 7200

poisson 0.23

focal-length 4240

n-mesh-rings 32

rel-support-radii 0.285376 0.590118 0.853489 0.845856 0.845822

rel-force 1 0.95001 1.07085 1.11985 1.1202

num-support 6 12 6 6 6

support-angle 0 0 0 20 40

basis-ring-size 6

basis-ring-min 0

obstruction-diam 203

part triangle 3 point 0 0 point 1 1 point 0 1

part triangle 3 point 1 0 point 2 0 point 3 0

part triangle 3 point 4 0 point 2 1 point 1 2

part triangle 3 point 3 1 point 4 1 point 1 3

© 2005 Mark D. Holm