Spectral Encoding Heterodyne Interferometry for 3D Endoscopic Imaging
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Solution Overview
Problem
Current 3D endoscopic imaging techniques using small diameter flexible probes face challenges in achieving a large three-dimensional field of view and high-speed volumetric imaging due to limited clear aperture and increased complexity with additional hardware requirements.
Innovation Solution
The system employs spectral encoding heterodyne interferometry with a broadband light source, a diffraction grating, and a rapidly-scanning optical delay to generate spectrally-encoded lines, enabling high-speed volumetric imaging within a fiber optic probe by scanning the line perpendicular to the sample and detecting interference between the encoded line and the reference radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If confocal imaging through a fiber-bundle using a high numerical aperture lens is used, then depth information is provided, but the three-dimensional field of view is limited to less than a few millimeters
Solution Approach 1:
The patent transitions from spatial scanning to spectral encoding by mapping depth information to wavelength dimensions. A diffraction grating disperses light spectrally, encoding depth as wavelength rather than requiring physical scanning, thereby expanding the three-dimensional field of view while maintaining depth resolution.
Solution Approach 2:
The patent replaces mechanical scanning systems with spectral encoding using a diffraction grating. Instead of physically moving components to obtain depth information, the system uses wavelength multiplexing to encode depth, eliminating mechanical limitations and expanding the imaging field of view.
2Area of stationary object
If stereo imaging or structured illumination techniques are used to obtain 3D endoscopic images, then three-dimensional field of view is improved, but more components are required increasing size, cost, and complexity
Solution Approach 1:
The patent employs a single optical fiber that performs multiple functions: delivering broadband light to the sample, collecting reflected light, and guiding it through the diffraction grating for spectral encoding. This multi-functional approach eliminates the need for separate stereo cameras or structured illumination components, reducing hardware complexity while maintaining three-dimensional imaging capability.
Solution Approach 2:
The patent changes the encoding parameter from spatial coordinates (in stereo imaging) or projected patterns (in structured illumination) to wavelength frequency. By measuring interference patterns across different wavelengths, the system extracts depth information without requiring additional optical components, thereby simplifying the device while expanding the three-dimensional field of view.
3Measurement precision
If a reference mirror is held stationary to within an optical wavelength during image acquisition, then fringe visibility is maintained, but scanning at high rates required for real-time volumetric imaging becomes very difficult
Solution Approach 1:
The patent replaces the mechanically scanned reference mirror with a fixed diffraction grating that performs spectral encoding. Depth information is extracted by analyzing interference patterns across wavelengths rather than by scanning the reference mirror through space, enabling real-time volumetric imaging without compromising fringe visibility.
Solution Approach 2:
The patent shifts the measurement from spatial domain (scanning reference mirror position) to spectral domain (analyzing wavelength-dependent interference). By encoding depth as wavelength information captured in a single shot by a spectrometer, the system achieves both high precision depth measurement and high-speed volumetric imaging simultaneously.
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 high-resolution, real-time three-dimensional imaging with improved spatial and depth resolution, reducing hardware complexity and increasing the number of resolvable points, while maintaining a compact probe size.
Implementation Method 1
a broadband light source capable of providing the electromagnetic radiation
Implementation Method 2
a diffraction grating configured to separate the first radiation into spectral components
Implementation Method 3
a lens configured to focus the first radiation to provide the spectrally-encoded line and to focus the third radiation
Implementation Method 4
A detection arrangement can also be provided that is configured to detect an interference between the third and fourth radiations
Implementation Method 5
spectral encoding heterodyne interferometry techniques for imaging
Data Source
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AI summary
Systems, arrangements and methods for obtaining three-dimensional imaging data are provided. For example, a broadband light source (100) can provide a particular radiation. A first electro-magnetic radiation can be focused and diffracted, and then provided to at least one sample (140) to generate a spectrally encoded line. A second Electro-magnetic radiation may be provided to a reference, which may include a double-pass rapidly-scanning optical delay (160), where the first and second Electro-- magnetic radiation’s can be based on the particular radiation. An interference between a third Electro-magnetic radiation (associated with the first Electro-magnetic radiation) and a fourth Electro-magnetic radiation (associated with the second Electro-magnetic radiation) can be detected. The spectrally encoded line may be scanned over the sample in a direction approximately perpendicular to the line. Image data containing three-dimensional information can then be obtained based on the interference. The exemplary imaging methods and systems can be used in a small fiber optic or endoscopic probe.