lasers (Score 1)

You can blind a camera using lasers that produce near infrared light. Check out http://www.naimark.net/project... for some examples.

That leaves detecting the camera and pointing the laser at it. You can either detect the reflections from the lens or the light from the autofocus.

Overall, it's not an easy problem to solve. I don't know that I'd waste my time/money on it.