Depth-Resolved Wavefront Sensing via Coherence Gating
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Solution Overview
Problem
Current wavefront sensors are limited in providing depth-resolved aberration information, are sensitive to stray reflections, and ignore chromatic aberrations, leading to suboptimal imaging quality, especially in thick specimens and the retina, where shallow layers distort deeper layers and aberrations vary with depth.
Innovation Solution
The development of depth-resolved wavefront sensors using low coherence interferometry (LCI) and coherence gating principles, which allow for 3D aberration mapping and reduced sensitivity to stray reflections, enabling dynamic spectral compensation and improved attenuation of stray reflections through balance detection and polarization-sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavefront sensors (SH/WFS, LRT) are used, then 2D aberration information is obtained, but depth-resolved aberration information is lost due to limited numerical aperture and large depth of focus
Solution Approach 1:
The wavefront sensing measurement is segmented into multiple depth layers through coherence gating. By dividing the depth range into discrete coherence gates, the system obtains aberration information for specific depth planes rather than averaging over the entire depth of focus, achieving depth-resolved wavefront sensing
Solution Approach 2:
A reference beam is introduced as an intermediary to create low-coherence interference with the object beam. This interference pattern serves as a depth selector, allowing only light from specific depth ranges to contribute to the wavefront measurement, thereby achieving depth resolution without requiring physical segmentation of the optical path
2Measurement precision
If conventional wavefront sensors are used, then aberration measurement is performed, but sensitivity to stray reflections from optical elements increases
Solution Approach 1:
The reference beam acts as an intermediary that enables coherent detection only from the desired object path. Stray reflections from optical elements do not generate coherent interference with the reference beam, effectively filtering them out and reducing their harmful impact on measurement accuracy
Solution Approach 2:
The system converts the potential harm of stray reflections into a benefit by using low-coherence interference. Only light from the specific coherence gate depth range produces constructive interference, while stray reflections at other depths are suppressed, turning the depth-selective nature of coherence gating into a useful filtering mechanism
3Productivity
If conventional wavefront sensors with large depth of focus are used, then imaging is performed, but aberrations from shallow layers distort deeper layers
Solution Approach 1:
The imaging process is segmented into depth-specific measurements using coherence gating. By dividing the total depth range into multiple gates, the system can selectively measure and correct aberrations from specific depth layers, preventing shallow layer aberrations from contaminating deeper layer measurements
Solution Approach 2:
The system applies local quality by making aberration correction depth-specific. Different depth layers have their own aberration characteristics that are measured and corrected independently, allowing optimal imaging quality at each depth rather than using a single average correction for the entire 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
These sensors provide enhanced imaging resolution by offering 3D aberration information, reducing the impact of stray reflections, and compensating for chromatic aberrations, resulting in improved optical coherence tomography (OCT) and microscopy images with reduced aberrations.
Implementation Method 1
These wavefront sensors can operate under large stray reflections in the optics and therefore lead to simplification of adaptive optics (AO) assisted imaging instruments
Implementation Method 2
Methods and devices are presented for enhancing the performance of wavefront sensors using principles of low coherence interferometry (LCI)
Data Source
AI summary
Methods and devices are disclosed for acquiring depth resolved aberration information using principles of low coherence interferometry and perform coherence gated wavefront sensing (CG-WFS). The wavefront aberrations is collected using spectral domain low coherence interferometry (SD-LCI) or time domain low coherence interferometry (TD-LCI) principles. When using SD-LCI, chromatic aberrations can also be evaluated. Methods and devices are disclosed in using a wavefront corrector to compensate for the aberration information provided by CG-WFS, in a combined imaging system, that can use one or more channels from the class of (i) optical coherence tomography (OCT), (ii) scanning laser ophthalmoscopy, (iii) microscopy, such as confocal or phase microscopy, (iv) multiphoton microscopy, such as harmonic generation and multiphoton absorption. For some implementations, simultaneous and dynamic aberration measurements/correction with the imaging process is achieved. The methods and devices disclosed can provide wavefront sensing in the presence of stray reflections from optical interfaces.