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SPHEROMETERS

Page 5.

The ring type were made from outer races of ball baring. The pins in (1) were the shanks of old high speed steel taps and were hard and sharp.



Sagitta measurements were now made on a Cassegrain primary and secondary mirrors. I used a .0001" micrometer with (7) & (8), also a .001" dial indicator on (7). On all the others a .01 mm. (.0004") dial indicator was used. All spherometers were zeroed on an optical flat.

Primary Mirror
"D"
"S"
"R"
"R"
(1)
5.5105"
0.13496"
28.192"
28.192"
(2)
5.5143"
0.13669"
27.999"
+ 0.1249"
27.999"
(3)
3.937"
0.06921"
28.029"
+ 0.1249"
28.154"
(7)
3.940"
0.0664"
29.257"
29.257"
Dial Gauge
(7)
3.940"
0.0669"
29.039"
29.039"
Micrometer
Secondary Mirror
(4)
1.184"
0.02941"
5.973"
+ 0.1249"
6.0979"
(5)
1.184"
0.02941"
5.973"
+ 0.1249"
6.0979"
(6)
1.375"
0.03937"
6.022
6.022"

I made a measurement, centre of mirror to knife edge on primary, and while I did not have a internal micrometer to do this I measured it at 28.187".

well that's it. Draw your own conclusions.


          Page 5 of 5