IR stream interference

[rupak-d]

Required Info
Camera Model	D435
Firmware Version	5.12.06.00
SDK Version	2.33

Issue Description

Is it possible for the infrared stream of the D435 cameras to interfere with elevator door closing sensors?

[MartyG-RealSense]

Hi @rupak-d RealSense 400 Series cameras do not interfere with each other, though they can interfere with non-RealSense infrared devices.

[MartyG-RealSense]

Hi @rupak-d Do you require further assistance with this case, please? Thanks!

[MartyG-RealSense]

Case closed due to no further comments received.

[rupak-d]

Is there any way of distinguishing if there are multiple IR sources?

[MartyG-RealSense]

Apparently there is a phenomenon that can be taken advantage of with a smartphone where if you switch to front camera view and film a scene, sources that are emitting infrared (like the red flash on a remote control when pushing buttons) will show up as a visible light in the digital camera image on the phone screen.

The reason why front camera mode should be used is that there may be an IR filter on the rear camera of the smartphone that prevents IR light sources from being visible on the camera image.
.
https://www.carolina.com/knowledge/2020/02/20/make-the-invisible-visible

[rupak-d]

Sorry I meant is there a way for the D435 cameras to distinguish between it's own IR vs one from a different source?

[MartyG-RealSense]

The 400 Series cameras can see all wavelengths from the visible to near IR, as they do not have an IR Cut filter. As far as I know, there is no built-in function for identifying which IR wavelength belongs to which source. It should be able to see the wavelength though.

#1070 (comment)

The projector on the 400 Series cameras uses the 850 nm wavelength.

[rupak-d]

Thanks for the info!
We've seen two situations where the camera is stopping elevator doors from closing when pointed at it. Any ideas on how to solve this would be welcome.

[MartyG-RealSense]

The bottom of Section 4.3 of Intel's white-paper document on physical optical filters states how using notch filters can block wavelengths and so enable devices to co-exist with each other. Perhaps such a filter could be applied over the top of the elevator door sensors so that they ignore the wavelengths of the 400 Series camera.

https://dev.intelrealsense.com/docs/optical-filters-for-intel-realsense-depth-cameras-d400#section-4-the-use-of-optical-filters

To quote the section:

"The use of a notch filter (essentially the inverse of a bandpass filter) would be useful in scenarios where there are specific wavelength bands that may interfere with or reduce the depth quality. For example, if another device is using a laser of a specific wavelength to illuminate or scan a scene, then a notch filter can be used to block only that wavelength. This approach is sometimes used to let devices that operate at 850nm and 940nm co-exist without affecting each other at all".