I often have adverse health effects when sitting behind a monitor for more than a short period of time. I am interested in finding out, what exactly it is that's affecting me. For example, I have certain monitors behind which adverse health effects start after 15 minutes -- even if it's couple feet away; others take a couple hours to kick in. By measuring different aspects of these monitors, I was hoping to be able to zero in on, what exactly it causing these effects.

The first thing I was planning to do was, to measure the frequency of the screen flicker by hooking up a photodiode to an oscilloscope. However, I do not expect the results to be very different from, say, a regular LED lamp. On the other hand, LED lamps do not affect my health adversely -- so, it is probably only certain wavelengths which affect me adversely.

So the other thing that I would need is, a spectrometer to measure the light from the monitor, to see which frequencies occur how often. Preferably, it should be something that can be adapted to tell me the frequency also -- but even a regular spectrometer I'll take. The only types of spectrometers I've been able to find either measure the spectrum of liquids, gases, or give only the single highest frequency. I am not familiar enough with spectroscopes to know, whether any of these types can be adapted to measure visible light.

No budget limit right now, just a matter of seeing whether it's possible.

  • I'm voting to close this question as off-topic because it isn't within the scope of this site's recommendations.
    – JMY1000
    Commented Nov 26, 2018 at 21:29

1 Answer 1


For monitors, you don't need to do this at all. It's in the monitor spec. Have you ever seen a monitor boast it has a 120hz Refresh Rate? In perhaps the simplest equivalency in computing, 1 Hertz = 1 Frame each second.

Frames are the still images displayed by the screen. Just like movies, we still view our screens as a series of rapidly changing still images. This is why when you experience "graphics lag", you get visual stuttering, as the computer hangs on a frame and fails to send updates to the monitor. Low refresh rates, common in older, CRT monitors and early LCDs, can cause headaches and eye discomfort. High refresh rates allow for improved clarity, a more comfortable viewing experience, and more fluid motion.

Makers are required by law in many places to display this information on the packaging, due to the very health concerns you're experiencing. They're more than happy to provide the information, as it's an accurate measure of image quality and they're eager to show off high rates that allow for 3D Stereoscopic viewing; however, if the monitor has aged, this can degrade the monitor quality with use. It shouldn't be noticeable, but if you're like me and hang on to monitors until they go black and never turn on again, it might be something that has happened. For situations like that, you can use the computer itself to test the monitor (as it must internally just to sync its images) using tools provided by your graphic card manufacturer or websites like this one. You can just look up the monitor model online for the base spec, and you can view the monitor properties in Device Manager or Display Properties on a Windows system to see its operational Refresh Rate.

By all means, give this a try and post your rates, it might be a good supplement to the question to know your results!

  • I guess I didn't explain this well, but it's not the refresh rate that's causing my health problems (otherwise, LED lamps would cause them too, which they don't). I'm guessing it's the frequencies involved -- that's what I'm trying to measure. The story about the refresh rate says that it would be nice if the frequencies could update at least as fast as the refresh rate, so I can analyse the frequencies in both the On and the Off states.
    – Alex
    Commented Nov 13, 2018 at 17:57
  • Are you sure? The refresh rate of an LED bulb is a very different thing. The average LED bulb remains on constantly, as it's not refreshing an image, so it doesn't actually flicker or does so at such a rate it's not worth detecting. Screens flicker just because they have to do so in order to project the next frame. They operate on the same wavelengths as LED bulbs.
    – CDove
    Commented Nov 13, 2018 at 19:42
  • Yes: see the link eevblog.com/forum/testgear/… from my original post. Most LEDs are always on, others flicker; but even the flickering ones don't give me problems. But for a LED, the frequency is always the same; screens have many frequencies, including invisible ones. I am not sure, but it might even be the invisible frequencies which are giving me health problems.
    – Alex
    Commented Nov 13, 2018 at 19:56

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