Airy Beam Optical Coherence Tomography Depth of Field
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Solution Overview
Problem
Conventional Optical Coherence Tomography (OCT) systems using Gaussian beams are limited by a shallow depth of field due to diffraction, which restricts the imaging of internal microstructures, particularly in ophthalmological diagnostic procedures, where a ten-fold increase in depth of field is desired.
Innovation Solution
The use of Airy beams in OCT systems, generated by converting a collimated Gaussian beam with a phase mask and lens, negates beam diffraction, allowing for a significantly increased depth of field by maintaining constant intensity and diameter of the main lobe as the beam propagates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Gaussian beam is focused with a lens to achieve lateral resolution, then lateral resolution is improved, but depth of field decreases due to diffraction
Solution Approach 1:
The patent transforms the beam profile from a conventional Gaussian distribution to an Airy beam distribution by modifying the phase and amplitude parameters of the light beam. This parameter change enables the beam to maintain a constant intensity profile and diameter over a significantly extended propagation distance, achieving a depth of field greater than 10 mm while preserving lateral resolution through the inherent focusing properties of the Airy beam main lobe.
2Measurement precision
If the beam waist is reduced to increase lateral resolution, then lateral resolution is improved, but depth of field decreases proportionally
Solution Approach 1:
The patent fundamentally changes the beam intensity profile parameter from Gaussian to Airy distribution. The Airy beam main lobe maintains a constant diameter regardless of propagation distance, breaking the conventional trade-off where reducing beam waist increases lateral resolution but proportionally decreases depth of field. This enables simultaneous achievement of high lateral resolution and extended depth of field exceeding 10 mm.
3Length of moving object
If a collimated Gaussian beam is used to increase depth of field, then depth of field is improved, but lateral resolution decreases due to beam spreading
Solution Approach 1:
The patent transforms the beam from a collimated Gaussian profile to an Airy beam profile with a main lobe that maintains constant intensity and diameter over extended propagation distances. The Airy beam's unique property of non-diffracting propagation allows the main lobe to retain its spatial confinement and resolution capabilities while achieving a depth of field greater than 10 mm, eliminating the trade-off between depth of field and lateral resolution.
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 enables OCT systems to achieve a depth of field of approximately 10 mm, providing clearer images of internal microstructures and improving diagnostic capabilities in medical imaging applications.
Implementation Method 1
A first embodiment of the invention is directed to a method of performing Optical Coherence Tomography on a sample including the steps of generating a source beam, splitting the source beam into a signal beam and a reference beam using a non-polarization beam splitter, converting the signal beam into an Airy beam, directing the signal beam towards the sample using scanning mirrors, and combining the signal beam and the reference beam into a combined beam using the same non-polarization beam splitter.
Implementation Method 2
The signal beam may be converted to an Airy beam using a phase mask and at least one lens.
Data Source
AI summary
A system and method for performing Optical Coherence Tomography on a sample utilizes collimated, phase modulated beams of light in an interferometer. At least one of the beams of light utilized exists as an Airy beam for at least a portion of the procedure, obviating any deleterious impact caused by the Gaussian beam diffraction. The system may incorporate a light source, polarization beam splitter, delay line, non-polarization beam splitters, lenses, phase masks, waveplates, and mirrors, any or all of which may be controlled by a computing element.