Fabrication of Hexagonal Microlens Arrays on Single-Crystal Silicon Using the Tool-Servo Driven Segment Turning...

Area of Science:

• Materials Science
• Optical Engineering
• Manufacturing Technology

Background:

• Single-crystal silicon microlens arrays are crucial for advanced infrared optics due to their high optical efficiency.
• Fabricating these arrays with high precision and minimal subsurface damage presents significant manufacturing challenges.

Purpose of the Study:

• To develop and validate a novel fabrication method for hexagonal microlens arrays on single-crystal silicon using diamond turning.
• To improve the form accuracy and surface quality of silicon microlens arrays for infrared applications.

Main Methods:

• Utilized diamond turning on a single-crystal silicon wafer.
• Proposed and implemented a tool-servo driven segment turning method to mitigate machine tool dynamic errors during cutting.
• Conducted cutting experiments and theoretical analysis to evaluate machine tool dynamic errors.

Main Results:

• The segment turning method significantly reduced dynamic errors, leading to high form accuracy in the microlens arrays.
• Achieved precise fabrication of sharp edges between lenslets.
• Successfully produced hexagonal microlens arrays with a form error of approximately 300 nm peak-to-valley and a surface roughness of approximately 5 nm Sa.
• Minimized subsurface damage, including silicon amorphization.

Conclusions:

• The proposed segment turning method is effective in fabricating high-accuracy single-crystal silicon microlens arrays.
• The achieved form error and surface roughness meet the stringent requirements for infrared optical systems.
• This technique offers a viable solution for producing high-quality silicon microlens arrays with reduced machining-induced damage.