Patent ID: 7388889

Claim:
A method for producing subsurface markings in a transparent material body comprising the following steps: applying excitation pulses to an optical pump source for a laser material, in order to produce population inversion in the laser material; focusing a pulsed laser beam in the interior of the material body in such a way that the laser beam exceeds a destruction threshold of the material body at least in a respective focal point to produce a permanent marking; and creating a relative movement between the laser beam and the material body to create individual markings that form a freely selectable internal engraving; wherein a pulse energy (P) of a laser pulse from the laser beam is varied by means of a discharge pulse (E) using a Q-switch selected from the group consisting of an active light switch, an acousto-optical modulator and an electro-optical modulator, said discharge pulse having an adjustable time delay from an excitation pulse (A) such that markings with different optical properties are produced in dependence on the pulse energy (P); and wherein a falling edge of the excitation pulse (A) is utilized as a starting pulse for the adjustable delay time up to a beginning of the discharge pulse.