st laser Choosing a suitable laser energy density relative to the threshold of a certain mechanism of 
vas used the material, one can change the feature form and size, through different physical processes, 
sed a i.e., evaporation, ablation, melting, crystallization, recrystallization or chemical bond breaking 
.In 1998 etc. 
Polarizer 2 plete | = Grawitched NAY AS Jaser 
array Seth 06a ray Coherence lenght ca fm 
= edn Ie hog Pd Ahm. SAWN 7 palea dunation: ne 
grating a ' i a 7 Pulse eapetition pave 10 Ha 
miei] PD Se (© 064m foc) 
d size on fi a NM nl a AS 
ell. In co ML 
MA, and = OS 
TAS © En 
x TB 7 
cial — © 
iter — — 
Figure 1 Experimental set up of nano-microstructuring with laser interference (2 beam 
configuration) 
d due to i 
won linear 2.2 Laser interference patterns 
rs. and Under the assumption of plane waves, the total field of the interference can be obtained 
ference by the superposition of the partial beams. Taking the symmetric three beam incidence 
. surface as example, as shown in figure 2, the results are 
Ors is . . oo . _ . 
E = elk x-sin ay g Hhsin o-(x-cos f—y-sin f§) + e7ik-sin o-(x-cos B+y-sin ß) 2) 
an 
eed. By the I=] E |? =[cos(kxsinat )+2cos(kcosp xsinot )cos(ksinf sino)? + 
pinged on [sin(kxsino)-2sin(kcosß xsina. cos(ksinß xsino)]” En 
se the 
of the laser 
3 
one can We have shown that two beam interference produces one dimensional linear pattern 
form, and three beam interference two dimensional dot array; another feature is that the 
4 total intensity of the interference field is four times larger relative to that of the 
) individual beam for the two beam interference, and nine times larger for the three beam, 
and 36 time larger for the six beam interference; this means, the energy will be more 
localised in definite points. or areas for multi-beam interference. 
..(3) 
31