Novel applications of sub-surface laser machining

Lasers can uniquely be used to create physical changes inside a bulk material. Traditional manufacturing processes are limited to surface modifications, but a laser can be focused at any location inside a material transparent to that wavelength. Using sub surface machining methods with ultrashort pulse lasers two practical applications are demonstrated. First, a laser is used to sever short-circuited wires embedded deep inside a thick piece of glass, effectively repairing a defective wire network. Second, subsurface bar-coding was shown to produce readable markings. Surface laser markings were shown to weaken the glass, but subsurface marking had virtually no effect on strength.