I am in the process of building a device that will track eye movement via a camera. To light the eye I am using an array of infrared LED's and my camera is sensitive to IR light.

After using the device for several hours today (testing and the like) I have noticed a slight headache similar to eye strain but only in the eye that I have been testing with.

My quesion is as my eye is constantly having a bright IR light shone in it, but I can't percieve it as it outside of my visual spectrum, are there still parts of my eye that are sensitive to this kind of light and might be strained/damaged by this?

It could very well just be a normal eyestrain headache (as I am sat at a computing while doing this work) but I would rather be armed with more information before I continue this work (as this product might be tested on people other than myself)



The light being sent out has a wave length of 940 nm

2 Answers 2


I'm an Electrical Engineer not a doctor but I've some knowledge about IR. Although you can not see it, IR is electromagnetic waves and it carry heat to your eyes. So, The eyes is negatively affected without your knowledge (If there is too much Infra red). It is similar to ultraviolet that damage the skin although it is invisible rays.

I don't know the cause of your headache because I'm not a doctor. But high power IR is dangerous for the eye. Don't look at it for long time.

This question is similar to yours: https://biology.stackexchange.com/questions/13691/is-it-safe-to-look-at-infrared-leds


Normally IR should not cause any troubles. However its all power-dependent. What is the overall power output of the LED you are using? I suggest you to compare it with the power output in similar existing eye-tracking devices on the market (you can contact the manufacturers, tell them you use their device and ask for specs due to safety concerns). I guess it wouldn't be nice to blast your eyes with even 5 mW.

  • Full power the LED produces 70 mW, however I am using a variable resistor to tone it down quite considerably. The plan now is to use fiber optics to diffuse the light source evenly, hopefully getting better results and reducing the amount of direct light hitting the eye.
    – Aphire
    May 12, 2016 at 12:50
  • a 50mW laser can light a match. Be very careful, cause exposure to such power might produce too much heat.
    – user2361
    May 12, 2016 at 15:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.