Preliminary study for my 14" f/5 scope: The Mirror Cell - summary of PLOP simulations (1)
This page summarizes the results of a first preliminary study for finding an appropriate cell design for my primary mirror. These studies would noat have been possible without the assistance of PLOP, a free simulation tool for computing mirror deformations by means of finite elements analysis.
The cell designs included in this first study are a mix of readily available designs and other designs I created (either they were described but without a PLOP input file, or they were not described at all).
The fixed parameters in the mirror cell computation with PLOP are the diameter (356mm), thickness (24mm) and focal length (1783mm). The material for the primary mirror is conventional plate glass. The secondary has a minor axis of 75mm.
| Central obstruction | 75mm | None | 75mm | None |
|---|---|---|---|---|
| Equal forces | Unequal forces | |||
| RMS Error (nm) | ||||
| 6 points: 1 + 5 (p6_1_5) | 7.5111 | 8.35137 | - | 6.06063 (rel-force[0]: 0.165519) |
| 6 points: 1 + 5 (p6_1_5_45) | 7.43428 | - | - | - |
| 6 points: autocell 6 (p6_autocell) | 4.01092 | 3.35331 | - | N/A |
| 7 points: 1 + 6 (p7_1_6) | 3.98066 | 4.56735 | - | 3.48804 (rel-force[0]: 0.448532) |
| 8 points: 1 + 7 (p8_1_7) | 2.27135 | 2.74914 | 2.22188 (rel-force[0]: 0.86178) |
2.29268 (rel-force[0]: 0.627283) |
| 9 points: 1 + 8 (p9_1_8) | 1.62526 | 1.96363 | 1.61598 (rel-force[0]: 1.05957) |
1.84216 (rel-force[0]: 0.837113) |
| 9 points: autocell 3 + 6 (p9_autocell) | 5.46643 | 6.39845 | 3.53682 (rel-force[0]: 0.203161) |
3.45824 (rel-force[0]: 0.203267) |
| 11 points: 1 + 10 (p11_1_10) | 1.35013 | 1.46755 | - | 1.46506 (rel-force[0]: 0.969931) |
| 12 points: (p12b) | 1.76924 | - | - | - |
| 12 points: (p12c) | 1.76924 | - | - | - |
| 12 points: (p12d) | 2.10656 | - | - | - |
| 12 points: (p12e) | 2.10656 | - | - | - |
| 12 points: (p12f) | 1.69952 | - | - | - |
| 12 points: (p12i) | 1.81218 | - | - | - |
| 18 points: autocell 6 + 12 (p18_autocell) | 0.729162 | 0.867694 | 0.606075 (rel-force[0]: 0.704223) |
0.645927 (rel-force[0]: 0.654892) |
- The values represent Visual RMS Error, and in the case of unequal forces the relative force of the inner point(s) with respect to the outer points (1 means equal relative force)
- N/A: this cell layout is not applicable
- -: this cell layout has not been computed (yet)
Contents
The details of the PLOP simulations (input files, output and graphical results) are presented on the following overview pages:
- PLOP simulations with a central obstruction of 75mm (equal forces on the support points)
- PLOP simulations without central obstruction (equal forces on the support points)
- PLOP simulations with a central obstruction of 75mm (unequal forces on the support points)
- PLOP simulations without central obstruction (unequal forces on the support points)
Click on a cell layout image in order to retrieve all the related information for that particular cell.
Central obstruction: 75mm
No central obstruction
Central obstruction: 75mm, allow unequal forces on support points
No central obstruction, allow unequal forces on support points
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