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G. Feng et al.
Fig. 7.15 a Experimental setup for laser scanning process. Inset, array of pulse-irradiated craters.
b Process sequence for fabricating close-packed micro-lenses over a silicon wafer. Step A, laserinduced material modification; Step B1, forming concave microstructure by chemical etching; Step
B2, etching until adjacent concave microstructures squeeze with each other. c SEM image of lasermodification zone. d SEM image of circular concave microstructures. e SEM images of irregular
concave microstructures [30]
In 2015, the Feng Chen group of Xi’an Jiaotong University School of Electronic and Information Engineering reported a novel fabrication method of largearea concave micro-lens array (MLA) on silicon by combination of high-speed laser
scanning [30], which would result in single femtosecond laser pulse ablation on
surface of silicon and subsequent wet etching. A dimpled lens was fabricated on a
1 cm × 1 cm silicon sheet. The dimensionally adjustable aspheric profile micro-lens
array has been developed and can be applied to infrared (IR) optical elements. The
processing of the micro-lens array is shown in Fig. 7.15. The processing steps of the
microscopic lens on the silicon wafer are listed as follows: Firstly, the material is
modified by laser-induced; then, the micro-structure is formed by chemical etching;
finally, the adjacent concave micro-structures are pressed against each other.
7.3.2 Preparation of Aluminum Coated Silica
The size of a fused silica sheet is 1 cm × 1 cm × 1 mm. For optimal fabrication,
the surface of the silica must be appropriately cleaned to remove contamination.
Initially, the fused silica sheet was cleaned with alcohol and deionized water in an
ultrasonic bath for 25 min to clear any contamination (loose particles/powder) on
the surface. The aluminum film was deposited on the surface of the silica sheet by
femtosecond pulsed laser deposition in a high-vacuum chamber (below 5 × 10
−4 Pa),
as shown in Fig. 7.16. In our experiments, a commercial femtosecond Ti:sapphire
G. Feng et al.
Fig. 7.15 a Experimental setup for laser scanning process. Inset, array of pulse-irradiated craters.
b Process sequence for fabricating close-packed micro-lenses over a silicon wafer. Step A, laserinduced material modification; Step B1, forming concave microstructure by chemical etching; Step
B2, etching until adjacent concave microstructures squeeze with each other. c SEM image of lasermodification zone. d SEM image of circular concave microstructures. e SEM images of irregular
concave microstructures [30]
In 2015, the Feng Chen group of Xi’an Jiaotong University School of Electronic and Information Engineering reported a novel fabrication method of largearea concave micro-lens array (MLA) on silicon by combination of high-speed laser
scanning [30], which would result in single femtosecond laser pulse ablation on
surface of silicon and subsequent wet etching. A dimpled lens was fabricated on a
1 cm × 1 cm silicon sheet. The dimensionally adjustable aspheric profile micro-lens
array has been developed and can be applied to infrared (IR) optical elements. The
processing of the micro-lens array is shown in Fig. 7.15. The processing steps of the
microscopic lens on the silicon wafer are listed as follows: Firstly, the material is
modified by laser-induced; then, the micro-structure is formed by chemical etching;
finally, the adjacent concave micro-structures are pressed against each other.
7.3.2 Preparation of Aluminum Coated Silica
The size of a fused silica sheet is 1 cm × 1 cm × 1 mm. For optimal fabrication,
the surface of the silica must be appropriately cleaned to remove contamination.
Initially, the fused silica sheet was cleaned with alcohol and deionized water in an
ultrasonic bath for 25 min to clear any contamination (loose particles/powder) on
the surface. The aluminum film was deposited on the surface of the silica sheet by
femtosecond pulsed laser deposition in a high-vacuum chamber (below 5 × 10
−4 Pa),
as shown in Fig. 7.16. In our experiments, a commercial femtosecond Ti:sapphire