optical tach through a printed housing?

I have a project im working on, a water cooling system for my printer. been building this up over several years now. I keep trying to compact the system down more and more.

Currently I am trying to integrate a flow meter into a printed housing. Due to size it will have to be custom made and was considering having the main housing being printed in clear resin and bouncing the optical tach off the blades of the wheel inside.

*** I cant use a hall effect since this will be right next to the pump motor.

Im just wondering if anyone has had any idea if an optical IR or laser diode based sensor can work through the clear resin or if i should design it and then try to seal exposed LED's in the fluid flow.

... for clear resins either visual or IR/NIR LED's would be OK.

You can use a "trick" for the flow detection too, with a bit space inside a housing or the outlet into the water-reservoir -- let the water flow through a free spacing, so the water jet will form a "bow" (or arc) and point with a focussed LED or laserpointer through this bow on a sensor on the other side. With flowing water the bow will reflect the beam along its inside, so the light will point down, into the reservoir ... without the water the beam will point straightforward onto the sensor ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]