Method and system for laser marking in the volume of gemstones such as diamonds

摘要

Three methods for adaptive control of the creation of indicia in the bulk of a gemstone specimen are disclosed. The methods include using a series of laser pulses in the femtosecond range focused below the surface of the specimen. The indicia identify the specimen without affecting the surface of the specimen and are invisible under 10X magnification. The first method comprises: predetermining characterising features of the indicia to be created; executing a predetermined marking protocol for the series of laser pulses using parameters selected from among the group comprising wavelength, pulse duration, number of pulses, repetition rate, energy per pulse, numerical aperture of focusing optics and target coordinates; automatically monitoring the creation of the indicia as the protocol is being executed; and automatically interrupting further execution of the protocol when the monitoring reveals that the indicia exhibits the characterising features. The second method comprises: generating an identification code for association with the specimen; determining a characteristic pattern for a plurality of indicia corresponding to the identification code; and executing a marking protocol for the series of laser pulses by applying the pulses to attempt to sequentially create each of the indicia according to the characteristic pattern. If execution of the protocol creates one but not all of the indicia according to the characteristic pattern, the method includes generating a new identification code corresponding to a new characteristic pattern that is consistent with those of the indicia that have been successfully created, and if required executing a marking protocol to create additional indicia to attempt to complete the new characteristic pattern. The third method comprises: establishing a marking protocol for an ultrashort laser pulse marking system comprising a plurality of predetermined sets of parameters, each set comprising parameters selected from among the group comprising wavelength, pulse duration, number of pulses, repetition rate, energy per pulse, numerical aperture of focusing optics, and target coordinates; attempting to create an indicium by executing a first set of parameters determined by the protocol; and automatically assessing whether an indicium was created using the first set of parameters. If an indicium was not created, the method includes automatically attempting to create an indicium according to a second set of parameters predetermined by the protocol.