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Svetliy\/Shutterstock<\/span><\/p>\n Laser pointers can be surprisingly powerful. Their light can reach a mile or more into the sky, which is exactly why laser pointers can be dangerous for airplanes. It may surprise you to know that when you shine one across a TV screen, the bright dot seemingly vanishes.<\/p>\n The reality is that the light hasn’t actually disappeared. What has changed is how much of it is able to reach your eyes after it hits your television. The key is reflection: For a dot to be visible, the surface it lands on needs to send some of the pointer’s light back to your eyes.<\/p>\n Most walls and blank sheets of paper work well for showing a laser dot, because their rough surfaces scatter light in multiple directions in an effect called diffuse reflection. This allows people standing in different spots all see the dot at the same time. A smoother surface produces what’s called specular reflection, which sends the reflected light off in one main direction, like a mirror.<\/p>\n On a glossy TV, the part of the beam that’s reflected may bounce away from where you’re standing instead of creating a dot that’s visible from anywhere in the room. The same mirror-like finish is why lamps and windows show up as bright spots on many screens. Much of the light that isn’t reflected is absorbed by the screen’s dark layers and coatings, which are designed to soak up room light. Results still vary from TV to TV, though. Matte screens diffuse more light, so the dot may remain visible, and your viewing angle plays a role too.<\/p>\n
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HomeAndSea\/Shutterstock<\/span><\/p>\n High-powered lasers can be hazardous, which is the real reason most of the world has banned powerful laser pointers. Yet they can also be foiled by something as simple as a screen treatment. An anti-reflective coating on your TV reduces reflections by using interference between light waves, which can make a laser pointer much harder to see on your flatscreen. However, an anti-glare coating may actually have the opposite effect, since they scatter light, which can help reveal the dot of a laser pointer, as described above.<\/p>\n You may have seen claims online that lasers can take out surveillance gear. Can green lasers damage Flock cameras? Yes, but it’s more complicated than you think, and the odds that you’ll damage your TV with an ordinary laser pointer are low. For one, most pointers sold to consumers aren’t powerful enough to damage electronics. In most cases, you’d also need long, concentrated exposure on the same spot to generate enough heat to harm a TV panel. The bigger risk is to people, since a glossy screen can bounce the beam into someone’s eyes.<\/p>\n If you’re presenting on a TV, a digital pointer that appears inside the picture is the safest and most effective option. PowerPoint has a built-in laser pointer: In Slide Show mode on Windows, hold Ctrl, then click and drag with the left mouse button to move it. Google Slides has a similar feature. While presenting, open the three-dot menu to turn it on, then press the L key to toggle it on or off.<\/p>\n
Screen coatings matter, though not for a digital pointer<\/h2>\n
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