Imaging Light Source Spectrum Extension via Amplified Frequency Doubling
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Solution Overview
Problem
Current broadband laser light sources for fluorescence microscopy are costly and inefficient in generating a broad spectrum, particularly in the short-wavelength region of the visible spectrum, leading to reduced light output and short fiber lifetime due to increased stress on micro-structured glass fibers.
Innovation Solution
A light source unit that directs broadband laser light into an amplifier beam path for wavelength-specific amplification and frequency shifting, extending the spectrum into the short-wavelength region without additional sources, using a beam extraction unit, optical amplifier, and frequency changing unit to generate laser light outside the original spectrum, ensuring cost-effectiveness and fiber longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If micro-structured glass fibers are used to generate broadband laser light, then a wide spectrum is obtained, but the fibers suffer from increased stress and short lifetime especially in the short-wavelength region
Solution Approach 1:
The broadband laser light is segmented into different wavelength ranges using a beam extraction unit. The short-wavelength portion (below first wavelength) is separated and directed through a nonlinear optical crystal for frequency doubling, while the long-wavelength portion continues through the original path. This segmentation allows different parts of the spectrum to be handled by optimized paths, protecting the micro-structured fibers from excessive stress in the short-wavelength region.
Solution Approach 2:
The invention changes the wavelength parameter of specific portions of the laser light by passing them through a nonlinear optical crystal where frequency doubling occurs. This transforms light at the first wavelength to light at half that wavelength (second wavelength), extending the short-wavelength coverage without directly exposing the micro-structured fibers to high-intensity short-wavelength light that would cause stress and reduce lifetime.
2Adaptability or versatility
If multiple laser light sources are used to cover the entire visible spectrum, then broadband coverage is achieved, but the system becomes complex and expensive
Solution Approach 1:
A single broadband laser light source performs multiple functions: it provides both the original broadband spectrum and, through the frequency doubling process in the nonlinear optical crystal, generates extended short-wavelength coverage. This multi-functionality eliminates the need for separate laser sources while maintaining comprehensive spectral coverage, thereby reducing system complexity and cost.
Solution Approach 2:
The nonlinear optical crystal acts as an intermediary that converts light from the single broadband laser source into additional wavelength components. This intermediary enables spectrum extension without requiring additional laser sources, simplifying the overall system architecture while achieving the goal of covering the entire visible spectrum.
3Extent of automation
If the broadband laser light source is pulsed, then synchronization is achieved for fluorescence lifetime imaging, but the intensity fluctuates
Solution Approach 1:
The invention maintains continuous useful action by combining the frequency-doubled short-wavelength light with the original broadband light in a beam combining unit. This ensures that both wavelength ranges are available simultaneously and continuously, providing stable illumination intensity while preserving the synchronization capability needed for fluorescence lifetime imaging applications.
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 provides a cost-effective, compact, and versatile light source capable of exciting various fluorescent dyes and proteins across the visible spectrum, including the blue region, with extended fiber lifetime and synchronized pulsed excitation for improved fluorescence imaging applications.
Implementation Method 1
an optical amplifier unit that is arranged in the amplifier beam path and configured to amplify the laser light having the first wavelength
Implementation Method 2
a frequency changing unit that is arranged in the amplifier beam path and configured to generate laser light having a second wavelength from the amplified laser light having the first wavelength
Data Source
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AI summary
A light source unit (100) for an imaging device comprises a beam extraction unit (106, 302) configured to receive broadband laser light (104), to direct at least a part of the broadband laser light (104) having a first wavelength into an amplifier beam path (108), and to direct a residual laser light into a first illumination beam path (110). The light source unit (100) also comprises an optical amplifier unit (112) arranged in the amplifier beam path (108) and being configured to amplify the laser light having the first wavelength. The light source unit (100) further comprises a frequency changing unit (114) arranged in the amplifier beam path (108) and configured to generate laser light having a second wavelength from the amplified laser light having the first wavelength.