Holographic Tomographic Microscope Wavelength Scanning
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Solution Overview
Problem
Conventional optical coherence tomography (OCT) methods face challenges in achieving high-resolution tomographic imaging of translucent objects due to limitations in lateral resolution and the inability to accurately determine the phase of object light, leading to low signal-to-noise ratio and difficulty in imaging moving subjects with early-stage disease diagnosis.
Innovation Solution
A holographic tomographic microscope using wavelength-scanning coherent light, off-axis spherical wave reference light, and in-line spherical wave reference light to acquire and generate holograms, which are then processed to produce high-resolution, distortionless tomographic images without mechanical scanning, enabling accurate imaging of translucent objects and moving subjects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional OCT methods use laser light with narrowed spot size, then lateral resolution is improved, but mechanical scanning is required which limits image pickup speed
Solution Approach 1:
The patent replaces mechanical scanning systems (Galvano scanners or movable heads) with a digital holographic approach. By using wavelength-scanning laser light and recording holograms at multiple wavelengths, the system achieves high-resolution tomographic imaging without mechanical movement, thereby improving image pickup speed while maintaining lateral resolution.
Solution Approach 2:
The patent changes the wavelength parameter of the laser light source dynamically. By scanning the wavelength and recording holograms at each wavelength, the system reconstructs tomographic images through digital processing, eliminating the need for mechanical scanning while preserving resolution.
2Productivity
If digital holography is used to eliminate mechanical scanning, then image pickup speed is improved, but the phase of object light cannot be accurately determined leading to low signal-to-noise ratio
Solution Approach 1:
The patent employs periodic wavelength scanning of the laser light source. By scanning through multiple wavelengths and recording holograms at each wavelength, the system accumulates phase information that enables accurate determination of object light phase through digital reconstruction, thereby improving signal-to-noise ratio while maintaining high-speed imaging without mechanical scanning.
3Device complexity
If wavelength-scanning light is used for tomographic imaging, then mechanical scanning is eliminated, but the method cannot accurately image translucent objects due to phase determination issues
Solution Approach 1:
The patent extends the imaging approach by recording holograms in the wavelength dimension. By capturing holographic data at multiple wavelengths and processing them together, the system obtains both amplitude and phase information necessary for accurate reconstruction of translucent objects, overcoming the limitations of single-wavelength methods while keeping the optical system relatively simple.
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
The method achieves high-resolution, distortionless tomographic imaging with improved signal-to-noise ratio, allowing for accurate observation of internal structures and movement, particularly in biological tissues, and enables the generation of three-dimensional volume images with high-speed image acquisition.
Implementation Method 1
a light source which is a wavelength-scanning type and emits a coherent light
Implementation Method 2
an optical system which generates an illumination light (Q), an off-axis spherical wave reference light (R), and an in-line spherical wave reference light (L) from the light emitted by the light source, and transmits the generated lights and an object light (O) emitted from the object illuminated with the illumination light (Q)
Implementation Method 3
a photo-detector which changes light intensity into an electric signal and outputs it
Data Source
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AI summary
In the present invention, a tomographic image can be accurately generated at high speed in a holographic tomographic microscope, a method for generating a holographic tomographic image, and a data acquisition method for the holographic tomographic images. The present method includes a data acquisition process (S1) and tomographic image generation processes (S2 to S7). In the data acquisition process, holograms (IjOR, IjQR, IjLR) of an object light (O) and so forth are acquired for each light with a wavelength (λj) by changing the wavelengths of the illumination light (Q), off-axis spherical wave reference light (R), and inline spherical wave reference light (L). In the tomographic image generation process, a reconstructed light wave (hj) of the object light (Oj) and a reconstructed light wave (cj) of the illumination light (Qj) on a reconstruction surface (z=zP) are generated from these holograms. A reconstruction light wave (hj/(cj/|cj|) with adjusted phase is added up for each wavelength (j=1, .., N) to generate a tomographic hologram (HP).From this, an accurate and focused tomographic image Sp=|Hp|2 without distortion can be generated.