IR proximity sensorbar

Projects General Guidance
1

Hi all,

I'm working on a new project :slight_smile:

I would like people to wave their hands in front of a window.
From behind the window I would like to detect their hand(s) and the proximity.

The goal is to control lights and color based on movement.

I have this concept worked out but I'm not 100% sure this will work.
Input on feasibility would be welcome.

So my question is, could this work ?

Thanks !

  • A sensor bar as pictured below
  • The IR LED's (clear) emit IR
  • The IR photodiodes (darkgrey) receive a level of IR
  • The IR photodiodes are isolated in PVC tubes
  • The bar is covered (on the "sensor side") with semi-translucent plexiglass

Click:

  • The IR LED's are constantly at full brightness
  • The IR photodiodes detect the level of IR that is reflected from the user.

I would use a sparkfun 16 channel analog multiplexer to read out the analog values from the IR photodiodes

2

Will the IR penetrate glass?

Long wavelength IR is reflected by common glass

3

Well, that's a good question :slight_smile:
The cover for the sensorbar will be plexiglass, PMMA, I think that should work.

But double glazed silica glass... interesting point.

4

mrExplore:
Well, that's a good question :slight_smile:
The cover for the sensorbar will be plexiglass, PMMA, I think that should work.

But double glazed silica glass... interesting point.

A relatively quick test would be to put a tv with IR remote control in place of your unit and try to get the remote to work through the window.

Another test would be to use a smart phone adapter that allows heat pictures and see if that will see hands through the glass.

Be aware, if it does work, to some extent, what your project will see will be the glass re-radiating the IR is absorbed from the hand. Could be several seconds delayed.

Paul