Posted by sailplane on
URL: https://www.es-forum.com/DIY-alternative-3-in-1-low-EMF-computer-Mouse-Keyboard-Microphone-tp4030078p4030082.html

Here's an already done IR mouse,

http://www.natatech.com/products/complete-response-systems/fmri-mouse-system

and trackball,
http://www.natatech.com/products/complete-response-systems/fmri-trackball-system

emits 0 magnetic, 0 RF. Made for MRI technicians. in MRI no fields are allowed in the room.

Also some ideas:
http://benkrasnow.blogspot.ca/2011/04/fiberoptic-mouse-with-quadrature.html