Methods and apparatus to control acousto-optic deflectors

An acousto-optic lens comprising:

• a first acousto-optic deflector arranged to support a first acoustic wave;
• a second acousto-optic deflector arranged to support a counter-propagating second acoustic wave;
• a driver for synthesizing first and second drive signals for said respective first and second acousto-optic deflectors;
• wherein said driver is arranged to synthesize a first drive signal that is phase-modulated by a first function that is capable of being expressed as a first Taylor series having one or more coefficients greater than second order, wherein at least one of said first Taylor series coefficients greater than second order has a magnitude of at least 3.2 divided by the factorial of the order of the at least one of said first Taylor coefficients;
• wherein said driver is arranged to synthesize a second drive signal that is phase-modulated by a second function that is capable of being expressed as a second Taylor series having one or more coefficients greater than second order, wherein at least one of said second Taylor series coefficients greater than second order has a magnitude of at least 3.2 divided by the factorial of the order of the at least one of said second Taylor coefficients;
• and
• wherein said acousto-optic lens further comprises:
• a memory for storing drive parameters associated with respective focal positions in space, wherein said acousto-optic lens is arranged to use said stored drive parameters when it is intended to focus electromagnetic radiation at a respective position in space.

A method for determining drive signals of an acousto-optic lens for use in deflecting a beam of electromagnetic radiation with said acousto-optic lens, said method comprising:

• storing drive parameters associated with respective focal positions in space,
• using said stored drive parameters to determine a first drive signal that is phase-modulated by a non-sinusoidal first function that is capable of being expressed as a Taylor series having one or more coefficients greater than second order, and
• using said stored drive parameters to determine a second drive signal that is phase-modulated by a non-sinusoidal second function that is capable of being expressed as a Taylor series having one or more coefficients greater than second order,
• wherein said first and second drive signals are for causing respective first and second acoustic waves to be propagated in an acousto-optic lens, so as to focus electromagnetic radiation at a respective position in space.

An acousto-optic lens comprising:

• a first acousto-optic deflector arranged to support a first acoustic wave;
• a second acousto-optic deflector arranged to support a counter-propagating second acoustic wave;
• a driver for synthesizing first and second drive signals for said respective first and second acousto-optic deflectors;
• wherein said driver is arranged to synthesize a first drive signal that is phase-modulated by a non-sinusoidal first function that is capable of being expressed as a Taylor series having a third order coefficient but substantially no coefficients greater than third order;
• and
• wherein said driver is arranged to synthesize a second drive signal that is phase-modulated by a non-sinusoidal second function that is capable of being expressed as a Taylor series having a third order coefficient but substantially no coefficients greater than third order.