From edo@as.arizona.edu Fri Jan 4 14:48:13 2002 Date: Fri, 30 Mar 2001 11:49:07 -0700 (MST) From: E. Olszewski To: ggwilli@as.arizona.edu Subject: lens 3 here's what i'm finding in old email 3 May 2000 I stoned out the chingus on the flat side of lens 3 also. It's ugly but it's small. THE ABOVE IS FROM STEVE MILLER Below is from Jim Burge April 3 2000 Ed, The flat surface on lens 3 was damaged in processing. There is a 1/8 inch ding in the surface about 1.8 inches from the edge. I see 3 options: 1. Start over. The substrate cost around $2k. There are a couple weeks work getting the lens to where it is now. Both surfaces polished, but final figuring not complete. 2. Live with it. The thing could be ground out to about 3 mm diameter. The beam for a single field point is 88 mm in diameter. The clear aperture for the lens is 240 mm. The ding would act like a bubble, scattering light out of 0.22% of the light out of any image that falls on it. It would be completely out of focus in the detector plane, but it could reduce contrast across the field if a bright star hits it. It could be painted black to minimize this. Unless you need photometric quality better than 1%, I recommend that we simply grind this out and paint it black. 3. Reduce the thickness of the optic by enough to grind through this. The edge thickness of the 260 mm diameter lens is already only 12 mm. We would have to reduce it by 2-3 mm, which gets pretty small. Warren could look at the deflections of the lens. Jim Date: Mon, 3 Apr 2000 12:59:11 -0700 (MST) From: John Hill Message-Id: <200004031959.MAA03894@abell.as.arizona.edu> To: edo@as.arizona.edu Subject: Re: the text that magically didn't get pasted (90prime) Cc: hill@as.arizona.edu X-Sun-Charset: US-ASCII Content-Length: 76 Status: RO Either option 1 or option 2 seems OK to me. I wouldn't thin the lens more. Date: Mon, 3 Apr 2000 13:35:01 -0700 (MST) From: Gary Schmidt Message-Id: <200004032035.NAA15374@chinadoll.as.arizona.edu> To: edo@as.arizona.edu Subject: Re: the text that magically didn't get pasted (90prime) X-Sun-Charset: US-ASCII Content-Length: 285 Status: RO Ed- My opinion is to live with it and paint it black. . . . Gary