Laser harp sensors?

[egasimus]

For those of you that remember my obscenely-titled thread from several months ago, all of my exams are finally over and I'm kinda back.

So, I wanna build myself a simple open frame laser harp-ish MIDI controller on the cheap. Kinda like what Jean-Michel Jarre uses, a lot smaller ofc. For now, I've ordered a batch of 10 5mw red laser diodes from Ebay and I'm still waiting for them to arrive; having small to medium club gigs in mind (and lights turned down during laser harp performance), would the beams be visible enough?

Also, I'm still confused about what sensors should I use. I know that it's better not to rely on the lasers themselves. On Hackaday, I've seen proximity sensors built of an IR LED and a photo(resistor/transistor/diode) next to each other; however, I'm not sure what photosensitive element should I actually use. In order to avoid cross-sensor interference, I'm considering pulsing each LED at a different frequency, and then having a band pass filter for each photocell.

Or maybe I should build myself ultrasonic distance sensors instead? I've read good things about them, but they don't look too compact...

The values are going to be read using the ADC of an Atmel MCU, and sent via MIDI; could the analog signals from the sensors be connected through a 4052 or something into a single MCU input?

[PRR]

For those who are as old and confused as me:
http://en.wikipedia.org/wiki/Laser_harp
http://www.harpelaser.com/

[egasimus]

Hmm, the second page looks interesting... from what I see, they're only using 3 powerful laser diodes and a rotating mirror creates separate beams? Cool.