Full-field OCT Optical Correction Element for Chromatic Deviation
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Solution Overview
Problem
Conventional full-field OCT methods require frequent adjustments of the object beam path to account for refractive errors in individual eyes, leading to inefficiencies and difficulties in obtaining sharp images of the ocular fundus, especially due to chromatic smearing caused by differing angles of the reference and object beam paths on the image sensor.
Innovation Solution
The method employs an optical correction element in the reference beam path to reduce chromatic deviation, allowing for computational correction of focusing errors without adjusting the object beam path's optical elements, enabling the recording of ocular fundus images without prior knowledge of optical beam paths and simplifying the imaging process by using a transmission or reflection grating to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the object beam path is adjusted for each individual eye to account for refractive errors, then sharp image representation is achieved, but the measurement process becomes time-consuming and requires trained operators
Solution Approach 1:
The patent replaces the mechanical adjustment of optical elements in the object beam path with a computational approach. Phase information derived from the interference pattern is used to calculate and apply digital phase corrections, eliminating the need for physical realignment of lenses and mirrors for each patient.
Solution Approach 2:
The patent creates a digital model of the eye's optical properties by analyzing the phase information from the interference pattern. This digital copy of the optical characteristics is then used to correct the image data computationally, avoiding the need for physical adjustments.
2Loss of information
If the reference beam path strikes the image sensor at a different angle than the object beam path, then phase information can be derived, but chromatic smearing occurs due to chromatic deviation
Solution Approach 1:
The patent introduces a computational processing step as an intermediary between the raw interference pattern and the final image. The phase information is extracted and used to guide digital correction algorithms that compensate for chromatic smearing, acting as a mediator that transforms the problematic angled interference pattern into a corrected image.
Solution Approach 2:
The patent changes the parameter space by working in the phase domain rather than directly in the spatial domain. By analyzing and correcting phase information, the system can address chromatic deviations through parameter transformations in the frequency and phase domains, then transform back to obtain corrected images.
3Reliability
If optical elements in the object beam path are adjusted to compensate for refractive errors, then focus is corrected, but the system becomes more complex and requires specialized knowledge for operation
Solution Approach 1:
The patent replaces the mechanical adjustment of optical elements with a purely computational focus correction system. The phase information from the interference pattern is processed digitally to determine and apply the appropriate focus correction, eliminating mechanical complexity.
Solution Approach 2:
The system performs self-correction by automatically analyzing the phase information from each measurement and applying the appropriate corrections without requiring external adjustment by an operator. The system serves itself by extracting and utilizing the phase information it generates.
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, focus-corrected images of the ocular fundus to be obtained in a single recording, reducing measurement errors and simplifying the imaging process, even for untrained operators, by eliminating the need for optical adjustments and effectively addressing chromatic smearing issues.
Implementation Method 1
a light source for emitting short-coherent light
Implementation Method 2
The reference beam path and part of the object beam path reflected by the ocular fundus are guided to an image sensor such that interference between the reference beam path and the object beam path arises on the image sensor
Implementation Method 3
the reference beam path strikes an optical correction element in order to reduce a chromatic deviation within the reference beam path
Data Source
AI summary
The invention relates to a full-field OCT method for generating an imaging of an ocular fundus (31), in which short-coherent light (22) is emitted and split into an object beam path (25) and a reference beam path (24). The object beam path (25) is directed onto the ocular fundus (33). The reference beam path (24) and a portion of the object beam path (25) reflected by the ocular fundus (31) are directed onto an image sensor (32), such that an interference between the reference beam path (24) and the object beam path (25) occurs on the image sensor (32), wherein the reference beam path (24) impinges on the image sensor (32) at an angle deviating from the object beam path (25). Before impinging on the image sensor (32), the reference beam path (24) impinges on an optical correction element (27) in order to reduce a chromatic aberration within the reference beam path (24). Intensity information and phase information is determined from a capturing of the image sensor. A focus-adjusted image of the ocular fundus is calculated. The invention also relates to a system that is suitable for carrying out said method. Images of the ocular fundus can be captured without the beam path being previously adapted to the refractive power of the eye lens.