Two-dimensional array of diffractive microlenses fabricated by thin film deposition

Area of Science:

• Optics and Photonics
• Materials Science
• Microfabrication

Background:

• Diffractive optical elements offer miniaturization and novel functionalities.
• Fresnel zone plates (FZPs) are key components for manipulating light via diffraction.
• Developing efficient and scalable fabrication methods for diffractive lenslet arrays is crucial.

Purpose of the Study:

• To fabricate and characterize a 2-D array of diffractive lenslets.
• To evaluate the performance of lenslets based on Fresnel zone plate principles.
• To determine the diffraction efficiency of the fabricated micro-optics.

Main Methods:

• Fabrication of a 10x10 array of diffractive lenslets using photolithography.
• Deposition of thin films of silicon monoxide on a quartz glass substrate.
• Implementation of the Fresnel zone plate pattern as an eight-level phase structure.

Main Results:

• Successfully fabricated a 10x10 array of diffractive lenslets, each with a 1.5 mm x 1.5 mm rectangular aperture and a 47 mm focal length.
• The lenslet performance is based on light diffraction at a Fresnel zone plate.
• Measured a high diffraction efficiency of 91% for the fabricated lenslets.

Conclusions:

• The fabricated diffractive lenslet array demonstrates high performance.
• The use of Fresnel zone plate structures with multi-level phase profiles is effective.
• The achieved diffraction efficiency indicates suitability for various optical applications.