Method for enhancement of laser material processing via modulation of laser light intensity
The present disclosure relates to a laser-based system and method for providing efficient melt removal of material from a surface of a material sample being acted on in a laser machining operation. In one implementation the system may make use of a continuous wave (CW) laser for generating a laser beam directed at a spot on the surface of the material sample. The CW laser may be configured to be modulated at a predetermined frequency such that the laser beam excites and amplifies surface capillary waves on the surface of the sample up to a melt ejection point, which ejects molten material from the spot being acted on by the laser beam, to more rapidly facilitate material removal from the spot.
1 . A method for providing efficient liquid melt removal of material from a spot on a surface of a material sample, the method comprising:
using a continuous wave (CW) laser to generate a collimated laser beam;
focusing the collimated laser beam to a desired spot size on the surface of the material sample; and
modulating the collimated laser beam from the CW laser at a predetermined frequency, which matches a natural resonant oscillation frequency of the liquid melt, and wherein an output power of the laser beam is also modulated within a predetermined power range, both of which combined are sufficient to excite and amplify surface capillary waves on the surface of the sample up to a melt ejection point, to fully eject the liquid melt from the spot on the surface of the sample.
2 . The method of claim 1 , wherein generating a collimated laser beam comprises using a laser beam having a peak power of 600 watts and an average power of 330 watts.
3 . The method of claim 1 , wherein focusing the collimated laser beam to a desired spot size comprises using a focusing lens.
4 . The method of claim 1 , wherein modulating the collimated laser beam at a predetermined frequency comprises determining the predetermined frequency of the capillary waves using an expression: ω=(σk 3 /ρ) 1/2 , where “σ” is surface tension, “k” is a wave number, and “ρ” is a metal density of the sample.
5 . A method for providing efficient melt removal of material from a spot on a surface of a material sample, the method comprising:
using a continuous wave (CW) laser to generate a collimated laser beam;
focusing the collimated laser beam to a desired spot size on the surface of the material sample; and
modulating the collimated laser beam from the CW laser at a predetermined frequency, and having a peak power of 600 watts and an average power of 330 watts, which is sufficient to excite and amplify surface capillary waves on the surface of the sample up to a melt ejection point, to eject material from the spot on the surface of the sample.