Laser Darkens Luminous Sign?
“I pointed a laser pointer at a glow in a dark EXIT sign. Where the light was a dark spot formed on the sign. Why is this?? It seems like the laser light stops the glow in the dark. This was your average EXIT sign above the door at work. We also shined a flashlight on the sign while we were doing this and were still able to see the dark spot only not as bright. I have tried it with other Glow In-The Dark items and I get the same thing. Similar effects can be demonstrated with other fluorescent materials including the phosphors in some CRTs and fluorescent lamps. However, photons of sufficient energy are required for this effect – putting the sign in a microwave oven won’t do it. 🙂 (From: Steve Roberts (steven@akrobiz.com).
“I pointed a laser pointer at a glow in a dark EXIT sign. Where the light was a dark spot formed on the sign. Why is this?? It seems like the laser light stops the glow in the dark. This was your average EXIT sign above the door at work. We also shined a flashlight on the sign while we were doing this and were still able to see the dark spot only not as bright. I have tried it with other Glow In-The Dark items and I get the same thing. Similar effects can be demonstrated with other fluorescent materials including the phosphors in some CRTs and fluorescent lamps. However, photons of sufficient energy are required for this effect – putting the sign in a microwave oven won’t do it. 🙂 (From: Steve Roberts (steven@akrobiz.com).) You’re either depleting the trapped or stored electrons in the upper levels of the material that emits the light by causing it to speed up with the red stimulation or you’re moving them to a point where they don’t fall down and emit a visible photon but fall to ano
