Heat Diffusion

Heat Diffusion can severely reduce the accuracy of the micromachining operation. With conventional lasers, heat diffuses away from the focal spot and melts an area that is much larger than the laser spot size. It is therefore difficult to do very fine machining. In other words, the boiling that results in material removal is not limited to the spot size of the beam itself. Thus, while the minimum laser spot size might be in the range of one micro or less, in many materials it is not possible to create features with dimensions much smaller than 10 to 30 microns.

When machining with ultrafast laser pulses, heat diffusion is virtually eliminated. This effect does not affect the ultimate accuracy of the machining process.