244
I. M. Dmitruk et al.
Fig. 2 SEM image of the surface of Zr sample (No. 2) treated with femtosecond laser with the
wavelength of 800 nm and the pulse irradiation energy density of 0.46 J/cm 2 (a), the cross section
of 2D Fourier transform of presented SEM image (b)
Fig. 3 SEM image of the surface of Zr sample (No. 3) treated with femtosecond laser with the
wavelength of 800 nm and the pulse irradiation energy density of 0.35 J/cm 2 (a), the cross section
of 2D Fourier transform of presented SEM image (b)
LIPSS, two different periods, 475 and 245 nm, have been discovered. For the sample
No. 3, two periods of LIPSS, namely, 673 and 336 nm, have been revealed.
It should be also mentioned so-called “coarse ripples,” which have characteristic
dimensions of the order of microns and exhibit quasiperiodicity in a direction parallel
to the polarization plane of the laser beam.
It has been revealed the structures known as “fine ripples” which have a period in
the range of several tens to 200 nm and exhibit a well-pronounced periodicity in the
direction perpendicular to the polarization plane of the laser beam. The appearance
of “fine ripples” is irregular, and as usual, they cover a small percentage of the total
area of the treated surface (see Fig. 4).
I. M. Dmitruk et al.
Fig. 2 SEM image of the surface of Zr sample (No. 2) treated with femtosecond laser with the
wavelength of 800 nm and the pulse irradiation energy density of 0.46 J/cm 2 (a), the cross section
of 2D Fourier transform of presented SEM image (b)
Fig. 3 SEM image of the surface of Zr sample (No. 3) treated with femtosecond laser with the
wavelength of 800 nm and the pulse irradiation energy density of 0.35 J/cm 2 (a), the cross section
of 2D Fourier transform of presented SEM image (b)
LIPSS, two different periods, 475 and 245 nm, have been discovered. For the sample
No. 3, two periods of LIPSS, namely, 673 and 336 nm, have been revealed.
It should be also mentioned so-called “coarse ripples,” which have characteristic
dimensions of the order of microns and exhibit quasiperiodicity in a direction parallel
to the polarization plane of the laser beam.
It has been revealed the structures known as “fine ripples” which have a period in
the range of several tens to 200 nm and exhibit a well-pronounced periodicity in the
direction perpendicular to the polarization plane of the laser beam. The appearance
of “fine ripples” is irregular, and as usual, they cover a small percentage of the total
area of the treated surface (see Fig. 4).