System and method for laser ultrasonic bond integrity evaluation

A method for evaluating the integrity of a bond on an element, comprising the steps of:

• Using a collimated light source and an optical subsystem to apply a pulse to a target point;
• Detecting the passage of said pulse of light along an optical path between said collimated light source and said target point, and providing an output signal indicating the presence of said pulse;
• Detecting the propagation of vibrations in said element, and collecting for analysis a vibration signature reflecting said propagation of said vibrations;
• and,
• monitoring said firing detection means to determine the timing of said pulse transmission, and in response thereto, activating a monitoring means to enable analysis of a pertinent part of said vibration signature relative to said timing of said pulse transmission.

A method for evaluating the integrity of a bond on an element, comprising the steps of:

• Using a continuous wave laser and interferometer to produce an interference pattern from light reflected by said bond or said element;
• Using a detecting means to monitor changes in said interference pattern over time;
• Selecting a preset point of optimum system sensitivity along the duration of said changes;
• Automatically triggering a collimated light source to apply a pulse to a target point on said element when said selected preset point is reached;
• and,
• Using said detecting means to detect the propagation of vibrations in said element resulting from said pulse, and collecting for analysis a vibration signature reflecting said propagation of said vibrations.

A laser ultrasonic system for evaluating a bond between an element and a substrate, comprising:

• Pulse application means including a collimated light source and an optical subsystem deployed between said collimated light source and a target point on said bond to provide an optical path to transmit a pulse of light from said collimated light source to said target point;
• Firing detection means in said optical path for detecting the passage of said pulse of light along said optical path and providing an output signal indicating the presence of the pulse;
• Monitoring means for detecting the propagation of vibrations in said substrate, and collecting for analysis a vibration signature reflecting said propagation of said vibrations;
• Synchronization control means connected to said pulse application means and said firing detection means for selectively actuating said pulse application means to provide a light pulse to said target point, monitoring said firing detection means to determine the timing of said pulse transmission, and in response thereto, activating said monitoring means to collect a pertinent part of said vibration signature relative to said timing of said pulse transmission.