Wavelength-Tunable Light Source for OCT with Reduced Adjustment Complexity
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Solution Overview
Problem
Current wavelength-swept laser light sources for optical coherence tomography require complex adjustments of multiple injection currents, leading to increased man-hours for achieving continuous, linear, and monotonic wavelength change, and are susceptible to mechanical disturbances.
Innovation Solution
An optical coherence tomographic imager utilizing a wavelength-tunable light source with multiple drive parameters, where the output light wavelength is determined by these parameters, and a processor reorders interference light intensity measurements based on the wavelengths to achieve continuous, linear, and monotonic wavelength sweeping, reducing evaluation time and mechanical disturbance susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wavelength-swept laser light source with multiple injection currents is used to achieve continuous and linear wavelength change, then the wavelength sweeping quality is improved, but the adjustment complexity and man-hours required increase significantly
Solution Approach 1:
The patent changes the control parameter from multiple independent injection currents to a single tuning current that controls the tuning element. This single parameter control approach simplifies the adjustment process while maintaining the ability to achieve continuous and linear wavelength change across the desired spectrum range.
Solution Approach 2:
The patent introduces a tuning element as an intermediary component between the light source and the output. This tuning element, controlled by a single tuning current, mediates the wavelength selection process and enables precise wavelength control without requiring direct manipulation of multiple injection currents.
2Stability of the object's composition
If a spatial optical system with diffraction grating is used for wavelength sweeping, then continuous wavelength change is achieved, but the system becomes susceptible to mechanical disturbances
Solution Approach 1:
The patent replaces the mechanical spatial optical system with a photonic integrated circuit approach. The wavelength tuning is achieved through optical phase modulation and interference effects within the photonic circuit, eliminating moving parts and mechanical components that are susceptible to disturbances.
Solution Approach 2:
The patent transitions from a three-dimensional spatial optical system to a two-dimensional photonic integrated circuit plane. This dimensional change allows wavelength control through phase and frequency domains rather than physical spatial arrangement, reducing mechanical vulnerability.
3Manufacturing precision
If a VCSEL with MEMS wavelength filter is used for wavelength sweeping, then mode-hop-free operation is achieved, but the output light intensity cannot be increased due to short cavity
Solution Approach 1:
The patent merges the wavelength filtering function and the light amplification function into a single photonic integrated circuit structure. The constructive interference condition within the photonic circuit simultaneously achieves wavelength selection and light intensity enhancement, eliminating the need for separate MEMS filters and allowing higher output power.
Solution Approach 2:
The patent employs composite photonic structures within the integrated circuit, combining different optical path lengths and refractive index materials to create a composite resonance condition. This composite structure enables both precise wavelength control and enhanced light intensity through coordinated optical interference 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
The solution reduces the number of man-hours required for evaluation and enhances the stability of wavelength sweeping operations, ensuring continuous, linear, and monotonic wavelength change while minimizing mechanical disturbances.
Implementation Method 1
a wavelength-tunable light source whose output light wavelength is determined by a plurality of light source drive parameters
Implementation Method 2
a photoelectric conversion measuring part that obtains interference light intensity measurement values by causing object light scattered from the object to be measured and the reference light to interfere with each other
Implementation Method 3
the interference light spectra in a wide wavelength band are measured, and the Fourier transform thereof is performed to obtain structural data in a depth direction
Data Source
AI summary
An optical coherence tomographic imager for contributing reduction of the number of man-hours for evaluation to obtain a wavelength sweeping operation of continuous, linear, and monotonic change while utilizing a wavelength-tunable laser having a structure that is less susceptible to mechanical disturbance. The optical coherence tomographic imager includes a wavelength-tunable light source, a branching means, an irradiation means, a photoelectric conversion measuring means, and a processor. The wavelength-tunable light source outputs light whose wavelength is determined by a plurality of light source drive parameters. The branching means branches output light of the wavelength-tunable light source into object light and reference light. The irradiation means irradiates an object to be measured with the object light. The photoelectric conversion measuring means obtains interference light intensity measurement values by causing object light scattered from the object to be measured and the reference light to interfere with each other and to be guided to a light receiver. The processor reorders the interference light intensity measurement values based on the output light wavelengths.