I want to do the double slit experiment to demonstrate the particle-wave-duality to people outside of physics. I can do it on paper and try to explain the maths and physics behind it, but it is a dull thing for non-physicists without a demonstration. Building the slits and using a laser to show the interference pattern is easy, but how do I realize the 'measuring device', which detects through which slit a photon went?. What kind of apparatus does it take?
edit: It seems I wasn't clear. What I'm trying to achieve is to display the interference pattern of the wavefunction and then let it collapse due to the measurement of which slit my photon/electron/whatever went through.