System and method for multi-pulse laser processing

A method of processing a multi-material device including a substrate and at least one microstructure that occurs with multiple pulses in a single pass operation along a relative trajectory and that is controlled with a positioning subsystem of a processing system, the method comprising the steps of:

• inducing relative motion between the multi-material device and a laser beam waist;
• initiating an impingement interval related to a target position during relative motion that allows one or more laser pulses to impinge a workpiece at a target location;
• generating a first laser pulse at a time corresponding to the target location in the relative trajectory;
• irradiating the target during the impingement interval with the first laser pulse,
• generating a second laser pulse at a time delayed relative to the first pulse during a non-impingement interval adjacent to the impingement interval, and
• blocking the second pulse from irradiating the target,
• wherein a first beam waist associated with the first pulse and the target substantially coincide, and wherein the delay is a predetermined time relative to the first pulse that is small enough to maintain stable laser operation and large enough to move the delayed pulse from the impingement interval to the adjacent non-impingement interval.

A method of selecting laser pulses from a group of laser pulses with an optical modulator, said method comprising the steps of:

• generating a group of laser pulses corresponding to a laser timing signal, a first portion of the group of laser pulses corresponding to a workpiece target moving relative to the laser pulses, and a second portion of the group of laser pulses corresponding to a non-impingement interval adjacent to an impingement interval that is associated with the first portion of the group of laser pulses;
• controlling an optical modulator according to a command sequence of impingement intervals and non-impingement intervals,
• selecting the first portion of the group of laser pulses with the optical modulator to allow each selected pulse to impinge the workpiece target during a pulse impingement interval;
• and
• blocking the second portion of the group of laser pulses from impinging the workpiece.

A method of stabilizing a laser pulse sequence in an aligned multiple pulse laser processing system, said method comprising the steps of:

• generating a first sequence of laser pulses, wherein pulses in a first portion of the first sequence are generated at times corresponding to positions of targets of a workpiece moving along a continuous processing trajectory relative to the laser pulses;
• selecting one or more pulses of the first sequence with an optical modulator that is controlled according to a command sequence of impingement intervals and non-impingement intervals to allow each selected pulse to impinge a workpiece target during a pulse impingement interval;
• and
• adjusting pulse timing of a second portion of the first sequence of laser pulses relative to the workpiece, wherein pulses in the second portion of the first sequence are generated at times corresponding to non-impingement intervals that are adjacent to impingement intervals, thereby blocking pulses of the first pulse sequence from impinging the workpiece;
• wherein the steps of generating and adjusting maintain a substantially continuous and stabilized first pulse sequence.

A stabilized system for laser processing a multi-material device including a substrate and at least one microstructure that occurs with multiple pulses in a single pass trajectory, said stabilized system comprising:

• pulse generating means for generating first and second pulses in response to an adjustable laser timing signal;
• modulator means for modulating the first and second laser pulses in response to a command sequence of impingement intervals corresponding to microstructures and adjacent non-impingement intervals;
• signal generating means for generating the adjustable laser timing signal according to the trajectory and a desired pulse delay between the first and second pulses;
• command generating means for generating the command sequence of impingement intervals and non-impingement intervals during the trajectory;
• and
• irradiating means for irradiating the microstructure during the impingement interval with selected pulses, wherein a beam waist associated with each selected pulse and the microstructure substantially coincide,
• wherein said modulator means includes means to block the second pulse when the second pulse delay relative to the microstructure is large enough to moved the second pulse from the impingement interval an adjacent non-impingement interval thereby blocking the second pulse from irradiating at least one microstructure, and
• wherein the adjustable laser timing signal provides for selection of the first pulse during the impingement interval and wherein the delay is small enough to maintain stable operation.