Re: [CAD_CAM_EDM_DRO] Interferometer designs for DRO or servo control?

michael pettengill wrote:

>Out of curiosity, has/is anyone making use of interferometry for sensing position?
>
>I was browsing Lindsay Pub's reprint of "Precision lead screws, gears, and Pantographs - Machinery's Industrial Secretes" and see pictures of setup to measure lead screw quality using interferometer setups that remind me of the kinds of physics lab experiments we were doing in high school and college in the 60s.
>
>I'm sure that there are widgets that use interferometry internally, but I'm thinking more in terms of DIY.
>
>

Interferometers are used in precision measuring gear and in machine
calibration and testing
systems. But, they are extremely sensitive to vibration, and so can't
be used on live cutting
machines. Many of them are so sensitive that someone walking near the
machine will
cause the digits to just be a blur. When the person stops walking,
everything settles down
in a few seconds, but the readout doesn't settle completely for a minute
or so. I've never
heard of any machine tools using interferometers. The ruling engines
used to make
diffraction gratings do use interferometers, but these machines are
wiping a tiny diamond
across an aluminized glass plate, making scratches a few microns deep,
at most. And, they
have to be built to eliminate all vibrations, anyway.

Jon