These devices look deceptively safe in the hands of the speaker pointing at the screen but it can cause serious eye damage if used inappropriately.
The same way manufacturers argue that cell phone radiation posses no risk, it's no wonder that the makers of laser pointers insists that they pose minimal dangers to your eye-sight. They claim that these devices lack the power to cause blindness. The reality is the light from some laser pointers can damage the eye if stared at directly for more than 10-15 seconds.
The biggest concern with laser pointers and the eyes is temporary optical problems. The light energy that these tools can aim into the eye can be more damaging than staring directly at the sun. This light may result in flash blindness, glare, and after-images.
Flash blindness: It occurs whenever someone is exposed to a bright light source. Fortunately, eye injury is usually prevented by the natural blinking reaction of the eye.
Laser pointers should never be used as toys or pointed directly at someone else. Some speakers, oblivious of the dangers they expose their audience to, point at and shine the laser on them, especially when they want to pick on an individual to contribute to their discussion. While it only lasts for a few seconds it can be extremely dangerous when someone is involved in a task which requires vision, such as driving or operating machinery. Temporary flash blindness symptoms may last from several seconds to several minutes.
Afterimages: There have been cases where people have shone laser pointers at aircraft causing the pilot to experience afterimages that interfere with their ability to safely operate the plane. Afterimages can last for several days, and take the form of small spots in the vision.
Glare: it's a reduction of visibility caused by bright light, occurs when the laser pointer is directed at the eyes. more profound optical damage can also result, if the exposure is prolonged.
Powerful Laser Pointers To Avoid
Most Laser pointers have a very low power output, but when it is focused on the retina through the lens of the eye, it can cause damage. Continuously staring into a laser pointer through a fully dilated eye for over one minute may cause a retinal burn.
How do you tell the power of your laser printer? The laser pointer should have a 'caution' label which also indicates which class the laser is in, and the power output.
Most laser pointers are IIIA devices, meaning that there is a potential for damage with direct exposure to the laser. Class two laser are less powerful and are better choice for laser pointers if you are concerned about safety. However, the lower light output may not be effective in a lecture hall.
You should be wary of laser pointers without the 'caution' label. they are more likely to be untested, low quality and probably exposing users to more dangers than others.
However, if used responsibly, a laser pointer should not present a damage. Remember. one should never point the laser towards surfaces such as windows, which can reflect infrared light back to the user. This is especially slightly dangerous because many modern energy-saving windows have coating designed specifically to reflect infra-red.