Re: RE: That encoder stuff.

> I haven't come across the term 'Talbot distance' before - is it a calculable
> figure or only arrivable at by experiment? Presumably such a factor would
> vary depending on the wavelength of the light source??

Presumably it has to do with when the setup starts to look like a
double (or multiple) slit diffraction experiment. The sine wave would
arrise from the interference pattern. The theory is all there in a
high school physics text, so it should be possible to calculate it
given the scale spacing, line width, light wavelength, and relevent
distances. Just don't ask me how ;-)

Chris

--
Christopher C. Stratton, stratton@...
Engineer, Instrument Maker & Horn Player
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