The present invention provides a screen for separating materials according to particle size. The methods include molding a nozzle having a nozzle body containing a spray head and coupled by a live hinge to a door having a portal with a screen in the portal. In one embodiment, a waveform generator defines a modulation waveform so that a determined sequence of five or more phase shifts are set between the second light signals, including shifts of zero degrees, +90 degrees, \u221290 degrees, +180 degrees and \u2212180 degrees.