Line-field Holoscopy Astigmatic Optics OCT
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Solution Overview
Problem
Existing interferometric optical imaging techniques face challenges in achieving high lateral resolution and power efficiency while being susceptible to multiply scattered photons and light from surfaces far from the object of interest, particularly in sensitive tissues like the eye.
Innovation Solution
The integration of astigmatic optics in a holoscopic line-field OCT system, which focuses a line of light on an object and combines it with reference radiation, allowing the narrow axis of the line focus to be imaged directly to the detector and defocusing along its long axis, encodes lateral spatial frequency along the detection line, enabling spectral information to be reconstructed using a 2D Fourier transform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If full field holoscopy is used to achieve wide field of view and high power efficiency, then light exposure on sensitive tissues is increased, but the system becomes susceptible to multiply scattered photons and light from surfaces far from the object of interest
Solution Approach 1:
The patent segments the field of view into a matrix of independently addressable spots or lines on the retina. Instead of illuminating the entire field simultaneously, the system selectively activates only the necessary spots or lines for a given measurement, reducing overall light exposure while maintaining adequate illumination for the specific region of interest.
Solution Approach 2:
The system applies local quality by providing high illumination intensity only at the specific spots or lines being measured, rather than uniformly across the entire field. This allows concentrated light power on sensitive tissues only where needed, reducing total light exposure while maintaining measurement quality.
2Object-affected harmful factors
If point scanning systems are used to achieve confocal light restriction and reduce susceptibility to out-of-focus light, then susceptibility to multiply scattered photons is reduced, but the amount of light allowed on sensitive tissues is limited
Solution Approach 1:
The patent transitions from one-dimensional point scanning to two-dimensional line or spot scanning across the retina. By illuminating and detecting along lines or across spots simultaneously, the system maintains confocal restriction benefits while increasing the amount of light that can be safely applied to the tissue through parallel measurement channels.
Solution Approach 2:
The system merges multiple point scanning measurements into simultaneous line or spot measurements. By combining the confocal restriction principle with multi-point detection, the system achieves both out-of-focus light rejection and increased light exposure capacity through parallel acquisition channels.
3Illumination intensity
If line field illumination is used to increase light exposure capacity, then greater light can be applied to sensitive tissues, but lateral resolution and power efficiency are compromised
Solution Approach 1:
The patent segments the line field illumination into discrete spots or line segments that can be independently controlled and measured. This segmentation allows each spot or segment to maintain high lateral resolution while the aggregate system achieves greater light exposure capacity through parallel measurement of multiple segments.
Solution Approach 2:
The system uses line field illumination (adding a spatial dimension) while maintaining resolution through digital processing and reconstruction algorithms. The line geometry provides increased light capacity in one dimension while resolution is preserved through computational methods and appropriate detection geometry.
4Productivity
If fast cameras and high power swept sources are used in full field systems to achieve high speed acquisition, then frame rate is increased, but the system becomes more susceptible to multiply scattered photons and requires complex hardware
Solution Approach 1:
The patent segments the acquisition process into sequential spot or line measurements rather than requiring simultaneous full field capture. This segmentation allows use of simpler, lower-speed detectors while achieving comparable overall acquisition rates through parallel processing of multiple segments, reducing hardware complexity and scattered light susceptibility.
Solution Approach 2:
The system employs periodic scanning or modulation of the illumination spots or lines across the retina, acquiring data in sequential periods. This periodic action allows integration over multiple measurement cycles, achieving high effective resolution and signal-to-noise ratio without requiring ultra-fast cameras or high-power sources.
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 achieves a balance between wide-open full field holoscopy and precise confocal point scanning systems, providing high lateral resolution and power efficiency at greater depths with reduced sensitivity to out-of-focus reflections, enhancing signal-to-noise ratio and allowing greater light exposure on sensitive tissues.
Implementation Method 1
the light scattered from an object and reference surface from a swept frequency source
Implementation Method 2
interferometric optical imaging
Implementation Method 3
exposing a 2D sensor array to the light scattered from an object
Implementation Method 4
The data may be reconstructed to a volume by three-dimensional Fourier transform
Implementation Method 5
the introduction of astigmatic optics into the return path such that the narrow axis of the line focus is substantially imaged directly to the narrow axis of the detector and such that the line focus is defocused along its long axis on the sensor array
Implementation Method 6
this line of light at the detection plane is projected onto the entrance slit of a spectrometer, such that at the 2D array sensor of the spectrometer, the spectral information along one axis of the sensor caries the axial frequency spectrum of the object
Data Source
AI summary
A novel imaging method, line-field holoscopy is presented. A line of light is projected across an object to be investigated through an imaging system. The light scattered from the investigated object is combined with reference radiation. The combined light is projected onto a detector providing a confocal restriction in one dimension. Astigmatic optics in the return path transform the light asymmetrically such that at the detector, the line focus is imaged to the confocal restriction, while the orthogonal direction is defocused. Embodiments including a swept source with linear detection array, and spectrometer based systems utilizing a 2D detector array are described. The data may be reconstructed to a B-scan by two-dimensional Fourier transform or other reconstruction method with or without combination of more complex algorithms.