Position Sensor 2 D

Let me restate, and tell me if I'm right:

You want to locate your top & bottom tool pieces to within a few mm by other means. Then you're going to shine a laser on the membrane from one side, and pick it up with a CCD imager on the other. You'll use the position of the laser dot on the membrane to align the two tool pieces.

Right?

1. Why bother? There are inexpensive machine-tool measurement devices that'll get your accuracy down to 25um assuming a good mechanical assembly, which you'll need anyway just to be controllable down to that level. Buy four for X and Y on each side and you're done.

1. You realize that you'll have to do some serious processing of the CCD image, yes?

2. You've made sure that your membrane won't distort the laser image to the point where you get a false center?

1. A LASER? If your membrane doesn't attenuate the light a _lot_ then perhaps you just want an LED and a pinhole?

What sort of CCD output are you looking for? NTSC "TV" format? Whatever comes out of the chip? USB? IEEE-1394?

For a one-off, or just a few, this may be most cost effective to do with a web-cam. For a few more, or if you need custom optics, you may want to buy a few web cams and rip them apart just to see what chips they use.