Magnetic Linear Encoder Reading Head - with 5 Micron

[vizion]

Hi
I would like to make a home brew a Magnetic Linear Encoder Reading Head -
with 5 Micron Resolution for a home brew robotics project. I need a number of them. These things cost an arm and a leg from commercial suppliers.

For an example of commercial offerings see:
http://www.machine-dro.co.uk/magneti...esolution.html these work with tapes such as the Part No: DRO-MG-TP-05-HA from the same site.

The tapes are cheap enough but its the heads that cost a lot.

Anyone have any ideas how to build these things? I do not know how to begin designing these things but would be capable of writing driver software to support them once I know how they work.

Thanks in advance for any help.

David

[JPHJPH]

Hi, I just joined after seeing your post. Have you made any progress? I found the source of the tape, but from England. I also found the chip that is used to read the tape. Much more investigation is needed before deciding to do the electronics. I was wondering if you have made any progress.

[daedalus]

do you mind posting details of the chip you found?

There is another type of sensor that might work out well for diy construction, that is magnetostrictive sensing, which involves sending a current pulse down a wire which has a ring magnet threaded on it. When the current pulse interacts with the magnetic field it causes an ultrasonic burst, which travels back along the wire. By timing the delay you can estimate very accurately the magnet position. Such sensors can achieve sub um resolution, and the timing ics are off the shelf.