How Can It Hurt My Eyes If I Can’t See It?
It can be a little confusing to consider, but the light coming from a laser is harmful to your eyes, even if it’s invisible.
How Do Invisible Laser Lights Hurt My Eyes?
The thinking is generally, “How can it hurt my eyes or vision if I can’t see it?” The truth is, invisible laser radiation is actually more dangerous than visible radiation in many ways because of its very nature: it can harm you, but you can’t see it.
Your eyes are very specialized and sensitive sensory organs which cannot heal from many types of injuries. One of these permanent injuries is burning of the retina. Since your cornea focuses light coming into your eye upon your retina, it’s no wonder that harmful light radiation is especially dangerous for your vision.
So why is invisible radiation capable of harming your eyes?
- Your eye’s rods and cones detect and transmit signals from light in the “visible spectrum,” which is all light between the wavelengths of 400 and 700 nanometers (roughly). Lasers can operate within or well outside of this range, but their dangerous nature has more to do with their power than their operating wavelength.
- Laser radiation is dangerous to your retina not because of the brightness of the colors it creates so much as the power of the beam. A powerful laser beam can heat a surface to an incredible heat in a small fraction of a second. If such a beam, or even a reflection of such a beam, passes through your cornea, it will burn your retina so quickly that you may not even feel pain right away.
- Your retina is filled with neurons (what most people think of as nerve cells) which light must actually pass through to get to your rods and cones. These neurons transmit information from your eyes towards your brain. Burning these neurons is a permanent injury because current medicine has little to no methods of repairing burned neurons.
- Your cornea is basically a magnifying glass. A laser beam that can burn your skin will cause a worse burn to your retina after passing through your cornea, and it will probably burn your cornea as well.
- Some lasers are so powerful that even scattered radiation can damage or destroy your eyes. Imagine the light that fills a dark room when you shine a flashlight on one of the walls; the light “scatters” after hitting the wall and dimly illuminates the rest of the room. Lasers can scatter in this way as well, and even though the scattered laser radiation contains only a small percentage of the power of the laser’s beam, it may be enough to seriously harm you.
As you can see, the way we think of “light” from our personal experiences with vision is different from “light” in the world of laser radiation and physics.
In this context, light can be considered any radiation in the electromagnetic spectrum that can be emitted in a beam capable of creating heat. And, while even this method of explanation does not adequately encompass the nature of laser radiation, it is helpful to think of lasers in this way when it comes to personal protective equipment used to protect against their beams.
Staying safe from lasers is of the utmost importance when working with them; one mistake can easily lead to blindness. Hopefully, this quells any curiosity of what would happen if you take your laser safety glasses off in the presence of an invisible beam. What has your experience with laser safety been? Have you or anyone you’ve known suffered a consequence of not taking laser safety seriously? Tell us about it in the comments below, and as always, stay safe!