what is the Kinect transfer function

how can one extract the transfer function of the kinect device ? more simply , just the part for tracking the skeleton. i know that it emits beams of laser from laser diods and it spreads from the lens. then its sensed with an IR sensor after the laser is reflected off the body.

[volt(input)]--->[gain(constant)]--->[laser diod(T.F)]--->[Laser beam(output)]--->[IR sensor(T.F)]--->???

T.F:Transfer Function.