Rotating PSF Design for 3D Imaging
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Solution Overview
Problem
Traditional imaging systems face challenges in maintaining high sensitivity and resolution for 3D image acquisition due to the rapid broadening of the point-spread function (PSF) away from the Gaussian image plane, requiring scanning in focus and resulting in reduced efficiency.
Innovation Solution
A rotating PSF is generated using Fresnel zones in the entrance pupil with spiral phase profiles, allowing the PSF to maintain its shape and size while rotating with defocus, and enabling encoding of spherical aberrations, thus improving sensitivity and depth information recovery across a 3D field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional diffraction-limited imaging is used, then high resolution is achieved in the Gaussian image plane, but the PSF broadens rapidly away from that plane resulting in loss of sensitivity and resolution
Solution Approach 1:
The patent applies dynamics by making the PSF rotate dynamically with defocus while maintaining its shape and size. The rotating PSF is generated by superposing light states with different orbital angular momentum quantum numbers, creating a dynamic point-spread function that adapts to different axial positions without broadening, thus maintaining both resolution and sensitivity across the 3D volume.
2Measurement precision
If scanning is done in focus to maintain high sensitivity and resolution, then measurement precision is maintained, but productivity is reduced due to slice-by-slice acquisition requirement
Solution Approach 1:
The patent enables continuous 3D image acquisition by generating a rotating PSF that maintains high sensitivity and resolution across the entire axial range, eliminating the need for sequential slice-by-slice scanning. This allows simultaneous capture of 3D information in a single shot, achieving continuous useful action throughout the imaging volume.
3Loss of information
If GL modes are superposed to create rotating PSF, then axial coordinate encoding is achieved, but light efficiency is reduced and the PSF has double-helix form with two separated lobes
Solution Approach 1:
The patent optimizes the parameters of the superposed light states by adjusting the weights and phases of different orbital angular momentum modes. This parameter optimization transforms the double-helix PSF into a single-lobe rotating PSF, improving light efficiency by concentrating intensity in one lobe while preserving the axial encoding capability through the rotation behavior.
4Reliability
If conventional imaging aperture is used, then clear well-corrected imaging is achieved, but the PSF broadens rapidly away from the Gaussian image plane
Solution Approach 1:
The patent creates a composite optical system by combining a conventional clear aperture with a phase mask that generates orbital angular momentum states. This composite approach maintains the wavefront quality of the clear aperture while adding the rotating PSF functionality through the phase mask, achieving both good image quality and extended axial depth range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient and sensitive 3D image acquisition with high resolution and extended depth of field, maintaining PSF shape and size over larger axial depths, and improved sensitivity even under low-light conditions.
Implementation Method 1
The present invention solves the above noted drawbacks by generating a rotating PSF that uses Fresnel zones in the entrance pupil of the imager
Implementation Method 2
with successive zones carrying spiral phase profiles of regularly spaced topological quantum number
Implementation Method 3
The discovery of orbital-angular-momentum (OAM) states-of-light beams has resulted in a number of important applications
Implementation Method 4
By linearly superposing light states with different OAM quantum numbers possessed by different Gauss-Laguerre (GL) modes under free-space propagation
Implementation Method 5
yields a PSF consisting of approximately non-diffracting Bessel modes that rotates with defocus while keeping its shape and size over much larger axial depths
Data Source
AI summary
An optical imaging system having an aperture comprised of a plurality of concentric annuli. The outer radius of each annulus is proportional to the square root of the number of annuli. Each annulus also having an azimuthally linearly increasing phase profile comprising for a given light wavelength. The system also includes a birefringent plate and the aperture and birefringent plate are adapted to jointly encode the full spatial and polarimetric degrees of freedom of a point source.