Re: [ATM] webcam and foucault test?

["Jerry" <wa4guu@verizon.net>]

It seems to me ....

if you got the camera very close to the knife that only a small central part
of the lens would be used. It would be best to have the knife centered and
in contact with the lens and fixed in position with the lens.

It might be best if the vertical extent of the slit were small.

Then a calibration of the image distortion so that when you are measuring a
zone, the location of that zone in the image is known precisely, would be a
good idea. In visual Foucault testing the mask serves this purpose. If the
webcam test is used in the same manner as visual testing, with a mask on the
mirror this calibration would not be necessary. If the mask is put on the
monitor screen it would be a good idea to calibrate.

Some people put rule marks on the mirror for testing for seeing directly the
distance from center of defects. Fine for visual testing but probably no
help for robo-testing unless you have a routine for detecting the rule
marks.

Jerry



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