초록 ▼

A fast and smooth scanning for achieving a uniform ablated surface without relying on any synchronization between the laser pulses and the scanner mirror positions. The scanning takes a series of close loops and the scanning speed on each loop is fine-tuned according to the perimeter of the loop. A

A fast and smooth scanning for achieving a uniform ablated surface without relying on any synchronization between the laser pulses and the scanner mirror positions. The scanning takes a series of close loops and the scanning speed on each loop is fine-tuned according to the perimeter of the loop. A uniform and close-packed pulse disposition along each loop can be achieved by multiple successive scans along the loop, while the consecutive pulses of a scan can be well separated. The scanning pattern is designed such that the energy distribution is uniform for every layer and the smoothness of the ablated surface remains substantially unchanged as the number of the layer increases.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for scanning a pulsed laser beam for uniform surface ablation comprising the steps of:providing a laser source producing a pulsed laser beam having a predetermined laser wavelength, pulse energy, pulse duration, and a high repetition rate;inserting an optical a

[ What is claimed is:] [1.]1. A method for scanning a pulsed laser beam for uniform surface ablation comprising the steps of:providing a laser source producing a pulsed laser beam having a predetermined laser wavelength, pulse energy, pulse duration, and a high repetition rate;inserting an optical assembly into a laser beam path to obtain and control a small spot size of said laser beam on a target surface;providing a two-dimensional scanner receiving said laser beam and scanning said laser beam on said target at a scanning rate;providing a computer interfaced with said scanner to control the scanning of said laser beam in a programmable fashion so as to produce a scanning pattern of a series of smooth, close circular loops on a layer without synchronization between laser pulses and scanner positions and without predetermining pulse positions on the target;controlling a scanning speed of said laser beam along each close circular loop so that consecutive laser pulses are uniformly separated in each scan on said target and that a plurality of successive scans are carried out on each close circular loop, wherein the scanning speed for a circular loop of a perimeter of P for a given pulse repetition rate K is mPK/(nm+1), where n is a number of laser pulses in each scan and m is a number of said plurality of successive scans on each close circular loop; andscanning said laser beam smoothly from loop to loop and then from layer to layer according to said scanning pattern so that the smoothness of the ablated surface remains substantially unchanged as the number of layers increases.