High-order-helix point spread functions for monocular three-dimensional imaging with superior aberration robustness

Area of Science:

• Optics and Photonics
• Optical Metrology

Background:

• Accurate passive optical depth measurement is crucial for various applications.
• Aberrations in optical systems can significantly degrade depth retrieval accuracy.
• Existing methods for depth measurement often struggle with robustness against optical imperfections.

Purpose of the Study:

• To present a novel approach for designing purely refractive optical elements.
• To generate engineered, multi-order-helix point spread functions (PSFs) with large peak separation.
• To analyze the impact of aberrations on PSF rotation and depth estimation accuracy.

Main Methods:

• Numerical and analytical studies of aberration influence on PSF rotation.
• Investigation of Zernike modes and their effect on PSF rotation.
• Experimental demonstration using cost-efficient phase elements fabricated via UV-replication.

Main Results:

• Identified specific Zernike modes that cause PSF rotation and depth errors.
• Demonstrated that high-order-helix designs exhibit superior robustness against aberrations.
• Successfully imaged an extended scene with severe aberrations using the novel optical elements.

Conclusions:

• Purely refractive optical elements can generate engineered PSFs for robust optical depth measurement.
• High-order-helix designs offer significant advantages in mitigating aberration-induced errors.
• Cost-efficient, wafer-scale fabrication enables practical implementation of these advanced optical solutions.