Lens selection for ADNS optical mouse sensor?

Hi all,

I'm looking to use the ADNS 2610 or 3060 optical mouse sensor for position estimation of my helicopter during a hover (without GPS). Since I won't be flying at altitudes of 2 mm, I need to select and retrofit the sensor with a new lens. I have no optics experience and was looking for a little advice. I'd be flying at altitudes of around

5-10 feet so I guess I am looking for a lens that gives me a focused image at that distance. Any help would be appreciated.

Thanks,

-weg

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. :-)

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