Mike W wrote:
> GM folks,
> I'm trying to find the 'proper' stuff to make a reflective opto
> quadrature rotary encoder.
>  I'm having problems in as much as the black ( spirit based felt tip
> pen ) is reflecting as much IR as the white

Try different markers, you will find that different colors (as well as
same colors, but different ink mixtures) will reflect varying amounts of
IR light.  It may be that a bright yellow hi-liter gives you a low
reflection level of IR, while black gives you high reflectivity.  You
might be able to find two markers with the same human visible color, but
one reflects IR and one doesn't.  That should keep the reverse engineers
guessing for a while.   ;-)

I think someone else mentioned using a black and white camera or webcam
to view a homemade samples chart illuminated by a remote control.

michael brown

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