Parallel Fourier Domain OCT Phase Modulation for Crosstalk Reduction
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Solution Overview
Problem
Current Optical Coherence Tomography (OCT) systems with parallel Fourier domain detection face challenges in visualizing deeper layers due to optical crosstalk and speckle noise, limiting their ability to image structures like the choroid layer effectively.
Innovation Solution
The implementation of spatially varying modulation of light and independent control of angular distribution of sample illumination using devices like rotating or sliding diffusers, piezoelectric or liquid crystal elements, and galvanometric scanners to reduce optical crosstalk and speckle noise, allowing for improved imaging of deeper biological structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If parallel Fourier domain detection is used to achieve high-speed imaging, then imaging speed is improved, but optical crosstalk and speckle noise increase
Solution Approach 1:
The patent applies dynamic phase modulation by vibrating a diffuser at frequencies above the camera integration time, creating time-varying phase shifts that randomize speckle patterns. This dynamic element transforms the static harmful interference into randomized noise that can be averaged out, allowing high-speed imaging to proceed without being degraded by optical crosstalk and speckle artifacts
Solution Approach 2:
The patent employs periodic vibration of the diffuser at high frequencies during the camera exposure period. This periodic modulation creates multiple independent speckle realizations that are incoherently summed, effectively reducing the contrast of speckle noise while maintaining the high imaging speed characteristic of parallel Fourier domain detection
2Measurement precision
If spatially coherent light source is used to achieve high sensitivity, then detection sensitivity is improved, but optical crosstalk increases
Solution Approach 1:
The patent introduces a vibrating diffuser as an intermediary element between the coherent light source and the sample. This diffuser acts as a mediator that breaks the spatial coherence of the light while preserving the interference contrast necessary for sensitive detection. The rapid vibration ensures that the coherent light is transformed into an incoherent illumination pattern that reduces optical crosstalk between adjacent detection elements
3Manufacturing precision
If high numerical aperture is used to achieve high resolution, then imaging resolution is improved, but optical crosstalk increases
Solution Approach 1:
The patent uses dynamic phase modulation via high-frequency diffuser vibration to decorrelate the optical paths of light rays passing through different numerical aperture angles. This dynamic randomization prevents coherent crosstalk between rays while maintaining the high angular acceptance required for high numerical aperture imaging, thus preserving resolution without the harmful crosstalk effects
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 significantly reduces optical crosstalk and speckle noise, enhancing the quality of cross-sectional imaging and enabling the visualization of previously inaccessible deeper layers, such as the choroidal layer, with improved contrast and resolution.
Implementation Method 1
a multi-element photodetector which converts light into electrical signals that are further analyzed by a processing device
Implementation Method 2
based on the interference of the beam of light reflected from the reference mirror with the beam of light scattered on the structural components of imaged object
Data Source
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AI summary
The subject of the invention is a device for imaging objects by Optical Coherence Tomography with parallel Fourier domain detection, containing a light source (LS), a multi-element photo-detector (DET), an interferometer comprising at least one beam splitter (BS), a reference mirror (M1), two optical systems (U1, U2) and an optical system (U3) forming an image on a light detector (DET), characterized in that a device (D1) introducing spatially varying modulation of the phase of light is placed in the path of the light beam between the light source (LS) and the interferometer. The invention also relates to a method of Optical Coherence Tomography with parallel Fourier domain detection using a broadband spectrum light source (LS) and a multi-element photodetector (DET) in which interference images are recorded for different optical frequencies in the range of the light source (LS) used, which are used to create an image reconstructions of the three-dimensional structure of the object (Ob), characterized in that time-variable and spatially varying modulation of the phase of light is employed before the beam emitted by the light source (LS) is split into the reference and object beams, and the obtained interference images are integrated in a complex manner.