High resolution Shack-Hartmann sensor based on array of nanostructured GRIN lenses.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Gradient index (GRIN) micro lenses offer unique optical properties.
• Fabrication of micro-optical elements with high fill factors remains challenging.
• Integration of micro-optics into compact devices requires novel manufacturing techniques.

Purpose of the Study:

• To present a new method for fabricating hexagonal arrays of gradient index (GRIN) micro lenses.
• To demonstrate the utility of these micro lens arrays in optical wavefront sensing.
• To achieve a high fill factor and flat optical element for versatile integration.

Main Methods:

• Utilized a modified stack-and-draw technology, originally for photonic crystal fibers.
• Employed nanorod structures made of two glass types to achieve refractive index variation.
• Fabricated a hexagonal array of 469 GRIN micro lenses (20 µm diameter, 100% fill factor).

Main Results:

• Successfully developed a completely flat micro lens array element.
• Demonstrated the GRIN micro lens array's effectiveness in a high refractive index medium.
• Constructed a Shack-Hartmann wavefront sensor utilizing the fabricated micro lens array.
• Achieved a sampling density of 50 lenses/mm in the Shack-Hartmann detector.

Conclusions:

• The modified stack-and-draw technology provides an effective route for fabricating GRIN micro lens arrays.
• The resulting flat optical elements are suitable for integration and use in diverse optical environments.
• The GRIN micro lens array is a viable component for advanced wavefront sensing applications.