Hi Richard,

I think light is extremely directional and by turning the source thru a fraction of a degree would change the incident intensity on the target sensor.

However, in case of the project I want to build, I don't think I will be using light.

I want to build an auto tracking vidoe camera tripod. You just fix the handycam on it and put the sonic transmitter in your pocket (open to sky) and leave the rest to sensors. Where you go the camera turns toward you keeping you in the frame.

The subject may not be free enough to hold the torch (light) for the sensors to track it.

I think better embark on trial and error approach, and do lot of experimentation to infer something sensible to see whether workable or not.

Regards

Babar/