The 6-point cells described here all use six support points arranged equidistant around a circle. Each pair of points is located on a pivoted bar. The bar pivot points are midway between the two mirror support points.
Diameter = Mirror Blank Diameter in Inches
Thickness = Mirror Blank Edge Thickness in Inches
f/ = Focal Length in Inches / Diameter
Obs Dia. = Central Obstruction Diameter in Inches (This is usually the diagonal mirror minor axis.)
r1 = Radius of circle on which the bar pivot points lie as a fraction of mirror blank radius.
d = Distance separating the two support points on the bar as a fraction of mirror blank radius.
r2 = Radius of circle on which support points lie as a fraction of mirror blank radius
P-V = Peak to Valley Mirror Deformation with this cell in Waves (1 wave = 500nm)
RMS = Root Mean Square Mirror Deformation with this cell in Waves (1 wave = 500nm)
Pyrex | |||||||||
---|---|---|---|---|---|---|---|---|---|
Diameter | Thickness | f/ | Obs. Dia. | r1 | d | r2 | P-V | RMS | Focus Shift |
12 | 1 | 5.3 | 2.36 | 0.501 | 0.588 | 0.588 | 1/58 | 1/303 | -0.041mm |
12.5 | 1.25 | 4.98 | 2.14 | 0.504 | 0.582 | 0.582 | 7.96nm | 1.41nm | -0.028mm |
12.5 | 1.5 | 12 | 0 | 0.490 | 0.565 | 0.565 | 1/65 | 1/464 | |
12.5 | 1.5 | 8 | 1.83 | 0.494 | 0.571 | 0.571 | 1/71 | 1/443 | |
12.5 | 1.5 | 6 | 1.83 | 0.496 | 0.573 | 0.573 | 1/71 | 1/437 | |
12.5 | 1.5 | 5 | 2.14 | 0.499 | 0.499 | 0.576 | 1/72 | 1/436 | |
12.5 | 2.2 | 12 | 0 | 0.483 | 0.558 | 0.558 | 1/74 | 1/566 | |
12.5 | 2.2 | 8 | 1.83 | 0.487 | 0.562 | 0.562 | 1/80 | 1/580 | |
12.5 | 2.2 | 6 | 1.83 | 0.488 | 0.563 | 0.563 | 1/80 | 1/577 | |
12.5 | 2.2 | 5 | 2.14 | 0.490 | 0.565 | 0.565 | 1/80 | 1/580 | |
13.1 | 1.0 | 4.4 | 3.1 | 0.517 | 0.597 | 0.597 | 11.7nm 1/43 | 2.36nm 1/211 | -0.042mm |
13.1 | 1.5 | 6 | 2.14 | 0.483 | 0.558 | 0.575 | 1/63 | 1/382 | |
13.1 | 1.5 | 5 | 2.60 | 0.487 | 0.562 | 0.579 | 1/64 | 1/381 | |
13.1 | 1.5 | 4.5 | 2.60 | 0.495 | 0.563 | 0.580 | 1/64 | 1/378 | |
13.1 | 2.35 | 6 | 2.14 | 0.488 | 0.564 | 0.564 | 1/73 | 1/534 | |
13.1 | 2.35 | 5 | 2.60 | 0.0.491 | 0.567 | 0.567 | 1/79 | 1/538 | |
13.1 | 2.35 | 4.5 | 2.60 | 0.0.491 | 0.567 | 0.567 | 1/79 | 1/537 | |
14.5 | 1.5 | 6 | 2.14 | 0.500 | 0.578 | 0.578 | 1/48 | 1/277 | |
14.5 | 1.5 | 5 | 2.60 | 0.502 | 0.580 | 0.580 | 1/48 | 1/272 | |
14.5 | 1.5 | 4.5 | 2.60 | 0.503 | 0.581 | 0.581 | 1/47 | 1/270 | |
14.5 | 2.375 | 6 | 2.14 | 0.489 | 0.565 | 0.565 | 1/59 | 1/413 | |
14.5 | 2.375 | 5 | 2.60 | 0.491 | 0.568 | 0.568 | 1/53 | 1/416 | |
14.5 | 2.375 | 4.5 | 2.60 | 0.492 | 0.568 | 0.568 | 1/59 | 1/414 | |
16 | 1.625 | 6 | 2.60 | 0.501 | 0.579 | 0.579 | 1/39 | 1/223 | |
16 | 1.625 | 5 | 2.60 | 0.503 | 0.581 | 0.581 | 1/39 | 1/220 | |
16 | 1.625 | 4.5 | 3.10 | 0.506 | 0.584 | 0.584 | 1/39 | 1/219 | |
16 | 3.00 | 6 | 2.60 | 0.488 | 0.563 | 0.563 | 1/49 | 1/365 | |
16 | 3.00 | 5 | 2.60 | 0.490 | 0.565 | 0.565 | 1/53 | 1/368 | |
16 | 3.00 | 4.5 | 3.10 | 0.490 | 0.566 | 0.566 | 1/53 | 1/367 | |
18 | 1.75 | 6 | 2.60 | 0.502 | 0.579 | 0.579 | 1/29 | 1/166 | |
18 | 1.75 | 5 | 3.10 | 0.513 | 0.583 | 0.583 | 1/30 | 1/165 | |
18 | 1.75 | 4.5 | 3.10 | 0.506 | 0.585 | 0.585 | 1/29 | 1/163 | |
18 | 3.25 | 6 | 2.60 | 0.487 | 0.563 | 0.563 | 1/39 | 1/282 | |
18 | 3.25 | 5 | 3.10 | 0.489 | 0.565 | 0.565 | 1/39 | 1/284 | |
18 | 3.25 | 4.5 | 3.10 | 0.490 | 0.566 | 0.566 | 1/39 | 1/283 | |
20 | 4.00 | 6 | 2.60 | 0.486 | 0.561 | 0.561 | 1/32 | 1/237 | |
20 | 4.00 | 5 | 3.10 | 0.487 | 0.562 | 0.562 | 1/32 | 1/239 | |
20 | 4.00 | 4.5 | 3.50 | 0.488 | 0.564 | 0.564 | 1/32 | 1/240 |
Plate Glass | |||||||||
---|---|---|---|---|---|---|---|---|---|
Diameter | Thickness | f/ | Obs. Dia | r1 | d | r2 | P-V | RMS | Focus Shift |
6 | 0.375 | 6 | 1.3 | 0.516 | 0.596 | 0.596 | 1/159 | 1/773 | |
200mm | 15mm | 7 | 40mm | 0.520 | 0.600 | 0.600 | 1/120 | 1/622 | -0.036mm |
8 | 0.375 | 6 | 1.52 | 0.526 | 0.608 | 0.608 | 1/51 | 1/234 | |
8 | 0.5 | 6 | 1.52 | 0.518 | 0.598 | 0.598 | 1/86 | 1/417 | |
8 | 0.75 | 6 | 1.52 | 0.505 | 0.582 | 0.582 | 1/124 | 1/692 | -0.024mm |
10 | 0.875 | 12 | 0 | 0.496 | 0.572 | 0.572 | 1/70 | 1/409 | |
10 | 0.875 | 8 | 1.52 | 0.502 | 0.579 | 0.579 | 1/74 | 1/411 | |
10 | 0.875 | 6 | 1.83 | 0.506 | 0.584 | 0.584 | 1/74 | 1/405 | |
10 | 1.3 | 12 | 0 | 0.488 | 0.563 | 0.563 | 1/89 | 1/619 | |
10 | 1.3 | 8 | 1.52 | 0.493 | 0.569 | 0.569 | 1/97 | 1/631 | |
10 | 1.3 | 6 | 1.83 | 0.496 | 0.572 | 0.572 | 1/100 | 1/631 | |
10.5 | 0.875 | 6.68 | 1.83 | 0.506 | 0.584 | 0.584 | 1/64 | 1/345 | -0.056mm |
12.5 | 0.875 | 12 | 0 | 0.500 | 0.577 | 0.577 | 1/35 | 1/190 | |
12.5 | 0.875 | 8 | 1.83 | 0.507 | 0.586 | 0.586 | 1/37 | 1/190 | |
12.5 | 0.875 | 6 | 1.83 | 0.511 | 0.590 | 0.590 | 1/36 | 1/183 | |
12.5 | 0.875 | 5 | 2.14 | 0.514 | 0.593 | 0.593 | 1/35 | 1/177 | |
12.5 | 1.5 | 12 | 0 | 0.489 | 0.565 | 0.565 | 1/55 | 1/371 | |
12.5 | 1.5 | 8 | 1.83 | 0.494 | 0.571 | 0.571 | 1/60 | 1/376 | |
12.5 | 1.5 | 6 | 1.83 | 0.496 | 0.573 | 0.573 | 1/60 | 1/371 | |
12.5 | 1.5 | 5 | 2.14 | 0.499 | 0.576 | 0.576 | 1/61 | 1/370 | |
12.5 | 2.125 | 12 | 0 | 0. | 1/ | 1/ | |||
12.5 | 2.125 | 8 | 1.83 | 0. | 1/ | 1/ | |||
12.5 | 2.125 | 6 | 1.83 | 0. | 1/ | 1/ | |||
12.5 | 2.125 | 5 | 2.14 | 0. | 1/ | 1/ | |||
13.1 | 1.0 | 4.4 | 3.1 | 0.517 | 0.597 | 0.597 | 13.8nm 1/36 | 2.77nm 1/180 | -0.048mm |
13.1 | 1.5 | 6 | 2.14 | 0.498 | 0.575 | 0.575 | 1/54 | 1/324 | |
13.1 | 1.5 | 5 | 2.60 | 0.501 | 0.579 | 0.579 | 1/55 | 1/324 | |
13.1 | 1.5 | 4.5 | 2.60 | 0.502 | 0.580 | 0.580 | 1/54 | 1/321 | |
16 | 0.875 | 6 | 2.6 | 1/ | 1/ | ||||
16 | 0.875 | 5 | 2.6 | 0.501 | 0.601 | 0.601 | 1/14 | 1/68 | |
16 | 0.875 | 4.5 | 3.1 | 1/ | 1/ | ||||
16 | 1.625 | 6 | 2.6 | 1/ | 1/ | ||||
16 | 1.625 | 5 | 2.6 | 0.503 | 0.581 | 0.581 | 1/33 | 1/187 | |
16 | 1.625 | 4.5 | 3.1 | 0.506 | 0.584 | 0.584 | 1/33 | 1/187 | |
16 | 1.875 | 6 | 2.6 | 1/ | 1/ | ||||
16 | 1.875 | 5 | 2.6 | 0.499 | 0.576 | 0.576 | 1/36 | 1/220 | |
16 | 1.875 | 4.5 | 3.1 | 0.501 | 0.579 | 0.579 | 1/37 | 1/220 | |
16 | 2.125 | 6 | 2.6 | 1/ | 1/ | ||||
16 | 2.125 | 5 | 2.6 | 0.496 | 0.572 | 0.572 | 1/39 | 1/247 | |
16 | 2.125 | 4.5 | 3.1 | 0.498 | 0.575 | 0.575 | 1/40 | 1/248 | |
1/ | 1/ |
BVC | ||||||||
---|---|---|---|---|---|---|---|---|
Diameter | Thickness | f/ | Obs. Dia | r1 | d | r2 | P-V | RMS |
10 | 1.25 | 6 | 1.83 | 0.497 | 0.574 | 0.574 | 1/116 | 1/718 |
12 | 1.5 | 6 | 1.83 | 0.497 | 0.574 | 0.574 | 1/79 | 1/488 |
12.5 | 1.5 | 6 | 1.83 | 0.498 | 0.575 | 0.575 | 1/71 | 1/432 |
14 | 1.5 | 5 | 2.6 | 0.503 | 0.580 | 0.580 | 1/53 | 1/309 |
16 | 1.5 | 5 | 2.6 | 0.506 | 0.584 | 0.584 | 1/36 | 1/198 |
© 2002 Mark D. Holm