control articles

[John Sheahan <jrsheahan-at-optushome.com.au>]

maybe of interest 

the March 2003 circuit cellar magazine 
(see http://www.circuitcellar.com/electronic-edition )

had a maybe EMC-useful construction article . on a 2D optical 
position sensor using a laser-pointer type beam and an XY 
optical sensor.   quoting

..produce an instrument that gives the
2-D coordinates of a laser beam on its
active surface with a resolution of
0.0001, an accuracy of 0.001, and a
measurement range ..........2. With
this sensor and a laser level, you can
measure the straightness, flatness,
angle, centration, and parallelism of
virtually any surface. 

The prior month had some relevant USB items given the plethora of 
alternate-interface suggestions recently.  
(although I still recomment ethernet)

don't know if the artice is on the web site, some are.
I get the pdf version. The paper copy is purchasable if 
you look around.