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Re: Knife Edge Testing

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Posted by Joe /">Joe on May 4, 1999 12:53:03 UTC

I have another point of confusion then. There are two axis that the knife edge can move upon. The first is longitudinally toward and away from the mirror. I understand that this is the measurement that must be taken to measure the SA because when I move it lognitudinally, there are supposed to be shadows on the mirror (but there are none now). However, the second is where I can move the knife in towards the "lighthouse". If I move it more toward the "lighthouse" a shadow moves across the mirror until all of the light is blocked. Then I can move it away from the "lighthouse" and the light reappears. How do I know when I have the knife positioned corrected toward the "lighthouse" so I can begin to move it in the longitudinal direction so I can take measurements?

Thanks, Joe

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