A method of detecting inconsistencies in a composite structure is presented. A pulsed laser beam is directed towards the composite structure comprised of a number of composite materials. Wide-band ultrasonic signals are formed in the composite structure when radiation of the pulsed laser beam is absorbed by a surface of the composite structure. The wide-band ultrasonic signals are detected over a duration of time to form data. The data comprises an ultrasonic A-scan spectrum. The data is processed to identify a structure signal in a frequency domain of the ultrasonic A-scan spectrum. The structure signal of the ultrasonic A-scan spectrum is compared to a structure signal of a composite structure standard to determine whether the inconsistencies are present in the number of composite materials.