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- To: owner-atm@shore.net
- Subject: BOUNCE atm@shore.net: Non-member submission from [mark wilkinson <laseroptics@compuserve.com>]
- From: owner-atm@shore.net
- Date: Thu, 13 Feb 1997 12:01:29 -0500 (EST)
>From atm-owner Thu Feb 13 12:01:12 1997 Received: from dub-img-2.compuserve.com (dub-img-2.compuserve.com [149.174.206.132]) by relay1.shore.net (8.8.3/8.8.3) with SMTP id MAA29562 for <atm@shore.net>; Thu, 13 Feb 1997 12:01:07 -0500 (EST) Received: by dub-img-2.compuserve.com (8.6.10/5.950515) id MAA02941; Thu, 13 Feb 1997 12:00:13 -0500 Date: Thu, 13 Feb 1997 11:50:50 -0500 From: mark wilkinson <laseroptics@compuserve.com> Subject: Re: ATM Testing a flat Cc: stressed lap <atm@shore.net>, Spencer Roedder <ROEDDER@ROEDDER.COM> Message-ID: <199702131200_MC2-113B-3AC2@compuserve.com> You asked about testing a large flat, and wondered about a monochromatic light source. We use low pressue sodium street lamps here in the uk, the bulb costs about 20 Us dollars but you will need a ballast power supply. we have actually got a complete street lamp screwed to the wall. The wavelength is 598nm and they are good enough to visulise 10 fringes per inch of test surface. we use about 20 watts but this is plenty powerful enough. if you have a smaller refence flat about which you are confident you could at least inspect several smaller portions of the larger flat. Another bonus is that sleeks and scratches not visible in daylight can often be seen under the sodium lamp I would say it's worth getting one just for this. Mark Wilkinson Laseroptics@compuserve.com
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