How to measure thickness of fog?

Other Hardware Sensors
1

I have a container which will be filled with fog (generated by a cheap atomizer) and I'm trying to figure out a way to detect how "thick" or how dense the fog build up is.

I've attempted using a DHT22 to check humidity, but, it's WAYYYY too humid for that. I'm currently using a turbidity sensor (aka a light + photodiode in a waterproof container), but, I'm getting pretty varied results. Part of it is there's light that leaks in sometimes, but also, I think sometimes the fog will condense on to the sensor.

I'm going to try one of those cheap soil moisture sensors (basically electrical resistance) later today or tomorrow, but, don't have high hopes.

Is there anything else I could try (in terms of sensors)?

I could try to find some hydrophobic coating for the outside of the turbidity sensor and fully black-out the container - might help?

I'm also wondering if it'd be worth it to try and use a lux sensor with a 532nm laser that's focused exactly on to the lux sensor - would the fog cause enough light dispersion for the sensor to detect a decrease in intensity?

Anyways, any ideas would be greatly appreciated! :slight_smile:

2

Light scattering is usually used.

Everything must be in a light-tight container, with the detector at right angles to the light source (e.g. a laser). The detector needs to be very sensitive, for example you might use an avalanche photodiode or a photomultiplier tube.

3

jremington:
Light scattering is usually used.

Everything must be in a light-tight container, with the detector at right angles to the light source (e.g. a laser). The detector needs to be very sensitive, for example you might use an avalanche photodiode or a photomultiplier tube.

Okay, will try fully blacking out the container and testing again, thanks!

Also, is there a recommendation for how far away the light source should be from the photodiode? The container everything is in is about 36"x18"x18"... should I be trying use as much space as possible or as little space as possible between the light and photodiode?