Method for optimizing a piezoelectric actuator structure for a deformable lens

A method of optimizing a piezoelectric actuator arrangement of a micro-tunable lens body, the method comprising:

• building a simulation model executable in a computer system of an initial arrangement of Interdigitated Electrodes on a flexible lens body surface by:
• arranging by a computer program concentric circular or concentric polygonal shaped piezoelectric elements comprising electrodes configured on a surface of a piezoelectric material deposited on a surface of a flexible lens body, thereby constituting piezoelectric actuators on the surface of the flexible lens body around a central located transparent part of the lens body,
• wherein the piezoelectric actuators comprise a first positive electrode and a second negative electrode, each comprising a radially configured electrode part connected to branches of concentric circular or polygonal shaped electrodes surrounding the transparent part of the lens body,
• wherein branches of the positive electrode and negative electrode are arranged sequentially with opposite polarity and in a parallel configuration, with respective different distances from the transparent part or optical axis of the lens body, and
• wherein the method further comprises transferring the simulation model to a simulator by applying the simulation model executable in a computer system, the model being adapted to simulate a resulting bending force distribution of the lens body surface according to simulated applied voltages to the electrodes of the piezoelectric elements in the initial arrangement of the electrodes on the flexible lens body surface,
• wherein the method further comprises performing an iterative process further comprising:
• modifying the initial arrangement of the electrodes of the piezoelectric elements by applying a first electrical connection between branches of the first concentrically configured electrode part and applying a first electrical connection between branches of the second concentrically configured electrode part, wherein the simulation model is applied to re-simulate a resulting bending force distribution of the lens body surface according to simulated applied voltages to the electrodes of the piezoelectric elements,
• and when applying an electrical connection between two branches of one radially oriented electrode part, an opening in the branch of opposite polarity of the other radially oriented electrode part being arranged in between the two branches is provided for, thereby allowing the passing of the electrical connection,
• then continuing the iterative process by modifying the arrangement of the electrodes and applying further electrical connections between branches of the first electrode part and between branches of the second electrode part of the piezoelectric elements, and wherein the simulation model is applied in each iterative step to re-simulate a resulting bending force distribution of the lens body surface according to simulated applied voltages to the electrodes of the piezoelectric elements, wherein each iteration step comprises:
• a) randomly selecting an electrical connection of the first electrode part and moving the connection in a randomly selected direction around the branches to which the electrical connection is connected to,
• b) when the electrical connection is moved, an opening arranged in the second electrode part arranged between the two branches of the first electrode part, which the electrical connection of the first electrode would be passing when moved, then moving the electrical connection together with the opening to a randomly selected location,
• c) randomly selecting an electrical connection of the second electrode part and moving the electrical connection in a randomly selected direction around the branches to which the electrical connection is connected to,
• d) when the electrical connection is moved, an opening arranged in the first electrode part arranged between the two branches of the second electrode part, which the electrical connection of the second electrode would be passing when moved, then moving the electrical connection together with the opening to a randomly selected location, and
• e) re-simulate a resulting bending force distribution of the lens body surface according to simulated applied voltages to the electrodes of the piezoelectric elements in accordance with the configuration of electrodes provided for by performing steps a) to d), and comparing the resulting bending force distribution with a target measure for the bending force distribution,
• wherein the iterative process comprises continuing steps a) to e) until the bending force distribution of the lens body is within a predetermined tolerance with respect to the defined target measure for the bending force distribution of the lens body, or alternatively stopping after a predetermined maximum number of iterations, and
• wherein after the bending force distribution of the lens body is within the predetermined tolerance with respect to the defined target measure for the bending force distribution of the lens body, or alternatively after the predetermined maximum number of iterations, the method further comprises physically providing a micro-tunable lens comprising piezoelectric actuators configured in a pattern on the surface of the micro tunable lens according to the configuration of electrodes provided for by steps a) to e).