Re: [CAD_CAM_EDM_DRO] Laser Linear Scales

On Mon, 31 May 2004 19:01:48 -0500, you wrote:

>This may have been covered before but ...
>
>With the availability of good quality laser diodes these days wouldn't it be
>possible to build a low cost/high precision linear position sensor based on
>Laser Interferometry?
>
>... I assume not, or I'd see them everywhere. What's the sticking point?
>
>I suspect that one of the problems might be the ability to track fringes caused
>by normal machine vibration.

From what I understand, the laser beam from the average diode is
coherent only for the first few inches, if that. Without that
coherency, no interferometer. I understand that (perhaps) the higher
priced diode lasers might be ok, and that the gas lasers are coherent
enough.

Harvey

>
>Cheers,
>
>Chuck Hackett
>"Good judgment comes from experience, experience comes from bad judgment"
>7.5" gauge Union Pacific Northern (4-8-4) 844
>http://www.whitetrout.net/Chuck
>
>
>
>Addresses:
>FAQ: http://www.ktmarketing.com/faq.html
>FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
>Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
>Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
>List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@..., timg@...
>Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
>URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
>OFF Topic POSTS: General Machining
>If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
>http://www.metalworking.com/news_servers.html
>
>http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
>NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
>bill
>List Mom
>List Owner
>
>
>Yahoo! Groups Links
>
>
>
>
>