Has a "Light Plane" sensor been invented? Hi, Does a "Light Plane" exist or has one been invented? What I need is a light beam sensor that acts on a plane, showing a difference in voltage if any part is blocked or interferred with. I'm a college student trying to come up with ways to accurately measure the speed of a ball before & after it has bounced, to calculate the change in kenetic energy. The problem is with a traditional light beam, the readings are only accurate if they go right through the very centre of the ball. Any thoughts? Nick.