From edo@as.arizona.edu Fri Jan 4 15:02:49 2002 Date: Wed, 5 Dec 2001 13:57:48 -0700 (MST) From: E. Olszewski To: ggwilli@as.arizona.edu, mlesser@as.arizona.edu, rwarner@as.arizona.edu Subject: zen, continued >From JBurge@optics.Arizona.EDU Wed Dec 5 13:49:10 2001 From: Jim Burge To: "'Steve Miller'" , "'E. Olszewski'" Subject: RE: L2 Date: Wed, 5 Dec 2001 13:49:08 -0700 MIME-Version: 1.0 This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C17DCE.48E1FF30 Content-Type: text/plain Steve, Ed, The radius of the L2 sphere is within spec. I calculate 1128.2 +/- 0.1 mm. The spec is 1128.1 +/- 1 mm. It is not clear whether the surface is polished out. I didn't inspect this. If it is polished out then it is done. The ding in the lens will cost the system a 2 mm obscuration. The beam diameter here is 200 mm, so we lose 1/10000 of the area. The ding will need to be painted out. Unless there is a compelling reason to do anything else, I think we should leave it and not try to excise it. There is no visible stress around the fracture. The only concern is during coating. Steve should talk to the coater. Jim -----Original Message----- From: Steve Miller [mailto:smiller@as.arizona.edu] Sent: Wednesday, December 05, 2001 1:39 PM To: Ed Olszewski Cc: Jim Burge Subject: L2 Ed, This morning it was reported that we suffered additional damage on the L2 spherical surface. This time it was Dean and he pinged the surface with the drive pin while adjusting it for a polishing run. It is a small (~1mm diam) on the surface near the center. It has also a typical conical fracture that extends into the depth of the glass probably more than a mm but is difficult to quantify since the fracture edge is not easily seen. Jim was over here this morning and he and I examined it closely. Jim's opinion is that the defect itself is small enough to ignore. Typically, we would grind out the fracture as we did for L3 but I am reluctant to carve a hole in the surface since it will increase the size of the unusable area. We were concerned over the possibility that the fracture may propagate so we looked at it under crossed polarizers and can detect virtually no stress birefringence. So it is unlikely that the fracture will propagate. However, if the coating temperature is very high it may make the fracture move. Jim suggested I speak with the coating vendor to determine what the optic will be subjected to in coating so I would like the contact information for the coater from you along with some way to identify the coating to the vendor so he knows which one I'm talking about. We are pretty sure the spherical surface is finished otherwise, but Jim is checking the measured radius now. Today, we are making a measurement of the asphere. miller