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G. Feng et al.
Fig. 7.21 Images of micro-hole on silica (left column) and aluminum coated silica (right column)
a Microscopic photographs of micro-hole array pattern on silica, b micro-hole array pattern on
aluminum coated silica, c SEM image of micro-hole array on silica, d SEM image of micro-hole
array after washing the aluminum film, e a hole in figure c, f a hole in figure d [36]
image of a randomly selected hole in the holes array, and no debris and recast layer
could be discovered around the hole. The microstructures around the hole and the
internal walls were very smooth.
In Fig. 7.21e, f, the microstructures inside the hole were in combination as annulus
in shape. That was, because, the multiple femtosecond laser pulses produce multiple
shock waves that forced the nanoparticles outward and made the density near the
holes increase. Under the action of a series of femtosecond laser pulses, the ring
structure was formed inside the holes. Comparing Fig. 7.21e with Fig. 7.21f, there
was an evident zone with many cracks around the hole edges in Fig. 7.21e. The zone
was formed by the redeposit of the fusant and vaporized fused silica sheet. However,
there was a better morphology left in Fig. 7.21f. That may be one benefit of the
aluminum film on the fused silica sheet.
Subsequently, the diffraction characteristic of the micro-hole array was examined
by using a He–Ne laser beam. In this experiment, the He–Ne laser passed through a
lens to form a magnified image of the focused laser beam spot [35]. Then, the focal
beam spot passed through the micro-hole array. Parallel light passed through a small
hole array, and the image on the screen was regular bright spot array. The micro-hole
closer to the central micro-hole in the micro-hole array has the higher brightness
in the diffraction characteristic of the micro-hole array. As shown in Fig. 7.22a,
the diffraction characteristic of the micro-hole array on silica was obvious, but there
were many dark spots that randomly distributed in diffraction light spots. As shown in
Fig. 7.22b, the diffraction characteristic of the micro-hole array on silica coated with
aluminum was significantly obvious. Compared these two pictures, the micro-hole
array on silica coated with aluminum is more uniform than the one on silica.
G. Feng et al.
Fig. 7.21 Images of micro-hole on silica (left column) and aluminum coated silica (right column)
a Microscopic photographs of micro-hole array pattern on silica, b micro-hole array pattern on
aluminum coated silica, c SEM image of micro-hole array on silica, d SEM image of micro-hole
array after washing the aluminum film, e a hole in figure c, f a hole in figure d [36]
image of a randomly selected hole in the holes array, and no debris and recast layer
could be discovered around the hole. The microstructures around the hole and the
internal walls were very smooth.
In Fig. 7.21e, f, the microstructures inside the hole were in combination as annulus
in shape. That was, because, the multiple femtosecond laser pulses produce multiple
shock waves that forced the nanoparticles outward and made the density near the
holes increase. Under the action of a series of femtosecond laser pulses, the ring
structure was formed inside the holes. Comparing Fig. 7.21e with Fig. 7.21f, there
was an evident zone with many cracks around the hole edges in Fig. 7.21e. The zone
was formed by the redeposit of the fusant and vaporized fused silica sheet. However,
there was a better morphology left in Fig. 7.21f. That may be one benefit of the
aluminum film on the fused silica sheet.
Subsequently, the diffraction characteristic of the micro-hole array was examined
by using a He–Ne laser beam. In this experiment, the He–Ne laser passed through a
lens to form a magnified image of the focused laser beam spot [35]. Then, the focal
beam spot passed through the micro-hole array. Parallel light passed through a small
hole array, and the image on the screen was regular bright spot array. The micro-hole
closer to the central micro-hole in the micro-hole array has the higher brightness
in the diffraction characteristic of the micro-hole array. As shown in Fig. 7.22a,
the diffraction characteristic of the micro-hole array on silica was obvious, but there
were many dark spots that randomly distributed in diffraction light spots. As shown in
Fig. 7.22b, the diffraction characteristic of the micro-hole array on silica coated with
aluminum was significantly obvious. Compared these two pictures, the micro-hole
array on silica coated with aluminum is more uniform than the one on silica.