Abstract: Systems for optical wavefront sensing and control based on a phase contrast Fourier domain filtering technique. Optically or electronically controlled phase spatial light modulators (SLM) are used as the Fourier domain filter. A direct adaptive-optic feedback system using the optical wavefront sensing systems. A differential Zernike filter is also disclosed.

Abstract: An integrator-multiplier-integrator circuit scheme usable in transverse fers, a transverse filter employing such a circuit, and a method for using each. The multiplier-integrator-multiplier has a capacitatively loaded integrating amplifier fed by a transistor. The current through the transistor, and hence the time it takes to charge the integrating capacitor, depends largely on the bias of the transistor, not the size of the capacitor, permitting one to set and control integration time by setting the transistor's parameters, and controlling its bias, effectively controlling integration time by us of only one semiconductor device. An additional circuit for auto-zeroing (i.e. canceling quiescent offset) increases adaptivity of the circuit. Preferably the phase of inputs to the first multiplier is made selectably variable to minimize phase difference at the multiplier, thus increasing circuit stability.

Abstract: A continuous-time multiplier-integrator-multiplier circuit in which the integrator is a transconductance-C circuit. This permits the integrators to have long time constants despite being tightly fabricated on an integrated semiconductor chip. The multipliers can preferably be Gilbert multipliers, to improve circuit frequency response.