Night vision goggle compatible LCD

[RU482]

I have an LCD that has been reworked with an LED backlight. If I wanted to rework the backlight again so that the LCD can be seen by someone with night vision goggles, what wavelength LED would I need to use?

 

[CycloWizard]

You want to make a regular LCD viewable to someone wearing nightvision? The key would be to simply decrease the intensity (brightness) of the monitor. If you left it at normal intensity, it would probably saturate the nightvision sensor and would just be a very bright rectangle. The wavelength will not have a huge effect, since nightvision systems are designed to be sensitive to a broad spectrum of photons.

 

[flyboy84]

Originally posted by: CycloWizard
You want to make a regular LCD viewable to someone wearing nightvision? The key would be to simply decrease the intensity (brightness) of the monitor. If you left it at normal intensity, it would probably saturate the nightvision sensor and would just be a very bright rectangle. The wavelength will not have a huge effect, since nightvision systems are designed to be sensitive to a broad spectrum of photons.

Correct. Reduce the brightness.

 

[Cogman]

You aren't going to get a very good picture through night vision though. for one, all night vision (that I know of) translates the low light levels in the green plane. So, your picture will look, green. And, even though it is good for seeing people and things, the static for night vision would make reading something on an LCD screen nearly impossible.

 

[RU482]

Originally posted by: flyboy84

Originally posted by: CycloWizard
You want to make a regular LCD viewable to someone wearing nightvision? The key would be to simply decrease the intensity (brightness) of the monitor. If you left it at normal intensity, it would probably saturate the nightvision sensor and would just be a very bright rectangle. The wavelength will not have a huge effect, since nightvision systems are designed to be sensitive to a broad spectrum of photons.

Correct. Reduce the brightness.

Currently, the LCD has the ability to take the brightness down to zero. In testing, we have not had any luck being able to read the LCD with night vision goggles by dialing down the brightness. There are companies out there that produce "night vision goggle compatible" LCD displays for military applications. They achieve this by having a dual function backlight...one that produces light in the visible spectrum...another that can be switched to that produces light in the infrared spectrum. I was hoping someone might know what the wavelength that might be...guess I need to do more research.

 

[bobsmith1492]

You just want infrared? Most LEDs and/or phototransistors I've seen are around 600-1000nm... why don't you just get a couple of infrared LEDs and set them up as the backlight? You could get some with a few different wavelengths and try them out to see which ones work best.

Go to Digi Key, punch in "LED", scroll down under "Optoelectronics," click "LEDs - <75mA, Discrete (7,817 items)", and select "Infrared" under the Color column. They have a few in stock at 850-940nm and anywhere from $0.5 to $11. Order a few different ones and try them out.

Good luck!