Lens selection for ADNS optical mouse sensor?

What is the active area of the sensor?  That is the first thing that
you need to know to choose a lens.

Lenses for CCTV cameras are widely available and fairly cheap.
Old vidicon cameras used lenses that covered a 1/2, 2/3, or 1-inch
diagonal image area.  The "normal" focal length lens for a 1-inch
vidicon was 25mm, and 16mm was normal for a 2/3" vidicon.  These
lenses can still be used on modern solid-state cameras, as slightly
telephoto lenses.

Modern CCD or CMOS video cameras usually have sensors of 1/4" or
1/3" (diagonal).  A focal length of 6mm or 8mm gives a "normal"
angle of view, and these are usually the cheapest lenses available.

My guess is that a CCTV lens designed for a 1/4" CMOS sensor would
more than cover the area of your sensor, but you should use a
longer focal length (10 or 12mm), to restrict the "view" to the
area under the helicopter, to avoid confusing the sensor with
objects at the periphery.


Another thing to consider:  What kind of illumination?  

* If it's just visible room light, flourescent lights have lots
of flicker, and might "strobe" against the refresh rate of your
optical mouse sensor.  Incandescent would be better.

* If you're using infra-red light for the sensor, the CCTV lens
might not pass IR very well, if it's an expensive glass lens.
Cheap acrylic plastic lenses usually pass IR just as well as they
pass visible light, so they are a good choice if you need IR.

Most CCTV lenses screw into a C or CS mount.  Female (chassis
mount) C or CS mounts are expensive if you have to BUY one, but
free if you dismantle old CCTV cameras and save the parts. :-)


----------------------------------------------------------------
 If a person who reads books is a bookworm,
 what is a person who listens to tapes?
----------------------------------------------------------------