System for determining and controlling the peak amplitude and phase of an oscillating member

A method for resolving one or more of the amplitude of the oscillatory motion of an oscillating member, and the relative phase of the oscillatory motion of oscillating members oscillating at the same frequency, comprising:

• providing a clock oscillator signal;
• reflecting optical beams off of different portions of an oscillator and generating fringes from the interference of the reflected beams, and AC coupling the fringe signal to convert the fringe signal pattern to one with a median of zero volts and comprising a plurality of signal zero crossings;
• saving the c lock oscillator output at each zero crossing of the AC coupled fringe signal;
• and determining, from the saved clock outputs, one or more of the amplitude of the oscillatory motion of the oscillating member and the phase of the oscillatory motion of the oscillating members.

A system for determining the amplitude and phase of an oscillating member which oscillates relative to a fixed structure, comprising:

• means for determining the times at which the oscillating member passes through a fixed reference angle on each side of the oscillation peak, comprising:
• indicating means on the oscillating member;
• detector means, responsive to the indicator means, and coupled to the fixed structure, the detector means determining the position of the indicating means relative to the fixed structure, over time, as the oscillating member oscillates;
• and
• means, responsive to the detector means, for creating a pulse each time the member passes through the fixed reference angle;
• a stable clock reference;
• and
• means for determining, from the pulses and the clock reference, the amplitude and phase of the oscillating member.