Diffraction Grating Wavelength Selection for SLO
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Solution Overview
Problem
Line-scan scanning laser ophthalmoscopy systems face challenges in selecting a narrowband of wavelengths without the high cost associated with tunable lasers, which are either too expensive or require multiple discrete lasers.
Innovation Solution
A system utilizing a broadband extended source, a diffraction grating, and a rotatable component to selectively output a narrowband of wavelengths, allowing for tunable illumination of the retina at a lower cost by using an extended source and rotating the diffraction grating or a mirror to direct specific wavelengths to an output slit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tunable laser is used to provide continuous frequency selection, then wavelength tunability is improved, but system cost increases significantly
Solution Approach 1:
The patent segments the broadband spectrum into multiple discrete wavelength bands using a diffraction grating and multiple output slits. Each output slit is assigned to a specific wavelength band, allowing the system to achieve wavelength selection without requiring a tunable laser. The segmented approach converts a continuous tuning requirement into discrete band selection, reducing system complexity and cost.
Solution Approach 2:
The patent introduces a diffraction grating as an intermediary device between the broadband light source and the output slits. The grating disperses the broadband light into its spectral components, enabling wavelength selection through spatial separation. This intermediary mechanism replaces the need for expensive tunable lasers while maintaining wavelength selectivity.
2Adaptability or versatility
If multiple discrete lasers are used to provide wavelength selection, then wavelength coverage is improved, but system size and cost increase
Solution Approach 1:
The patent merges multiple wavelength selection functions into a single optical system. Instead of using multiple separate laser sources, the system combines a single broadband light source with a diffraction grating and multiple output slits to achieve the same wavelength coverage. This consolidation reduces system size while maintaining the ability to select across multiple wavelength bands.
Solution Approach 2:
The diffraction grating serves multiple functions simultaneously: it disperses the broadband spectrum, separates different wavelength bands spatially, and enables selection of multiple wavelengths through fixed output slits. This multi-functional component replaces what would otherwise require multiple specialized laser sources, reducing both system size and complexity.
3Device complexity
If a broadband source with diffraction grating is used for wavelength selection, then system cost is reduced, but wavelength selection precision may be compromised
Solution Approach 1:
The patent applies local quality by assigning each output slit to a specific wavelength band with precise spatial positioning. The diffraction grating creates angular separation of wavelengths, and each output slit is positioned to accept light from a specific angular range, ensuring high wavelength selection precision for each band. This localized precision at each slit compensates for the broadband nature of the source.
Solution Approach 2:
The patent replaces mechanical wavelength tuning mechanisms (such as tunable laser cavities or acousto-optic modulators) with a static optical system consisting of a diffraction grating and fixed output slits. The wavelength selection is achieved through the geometric and optical properties of the grating and slit positioning rather than mechanical adjustment, maintaining precision while reducing system complexity and cost.
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
Enables cost-effective tunability of wavelengths for line-scan scanning laser ophthalmoscopy systems by using a broadband source and a diffraction grating or mirror to select narrowbands, reducing system size and cost while maintaining continuous frequency selection.
Implementation Method 1
a diffraction grating positioned to receive a broadband of light from the extended source and output an angular separation of the frequencies of the broadband of light
Data Source
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AI summary
In line-scan scanning laser ophthalmoscopy (SLO) a narrowband of wavelengths is required. For greater flexibility the frequencies of this narrowband should be selectable. This is possible using a broadband tunable single mode source, but such a solution is expensive. A system is provided in which an extended broadband source is used. Light from the extended source passes to a diffraction grating, which introduces a wavelength dependent angular separation when reflecting the light. By rotating the diffraction grating, only light of a selectable narrowband passes through a fixed output slit for use by the line-scan SLO system. Alternatively, the diffraction grating can be fixed and a rotatable mirror lying between the diffraction grating and the output slit can be used to select the wavelengths reaching the line-scan SLO system.