Dual-Phosphor Wavelength Converter for High-Contrast Fluorescence Imaging
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Solution Overview
Problem
Conventional devices for fluorescence imaging, such as the ICG fluorescence method, face challenges in separating visible light and near-infrared light emissions, leading to low contrast in imaging due to high deep red light noise, which hinders simultaneous normal and special observations.
Innovation Solution
A wavelength converter incorporating a first phosphor activated with Cr3+ and a second phosphor activated with Ce3+ or Eu2+, emitting a fluorescence spectrum with a peak intensity in the green to yellow range and minimizing deep red light intensity, allowing for effective separation of visible and near-infrared light components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional light source device combines deep red phosphor and other phosphors to emit both visible and near-infrared light, then both normal observation and fluorescence imaging are enabled, but the fluorescence spectrum shows insufficient separation between visible and near-infrared components and high deep red light intensity that creates noise
Solution Approach 1:
The patent applies local quality by selecting specific phosphors with tailored emission characteristics. The first phosphor (Y3Ga5O12:Cr3+) is chosen to emit primarily in the near-infrared region (700-900nm) with minimal visible light, while the second phosphor (YAG:Ce3+) emits in the visible yellow-green region (500-560nm) with minimal deep red component. This localized optimization of each phosphor's emission spectrum achieves sufficient separation between visible and near-infrared components, reducing deep red light noise that creates image contrast problems.
Solution Approach 2:
The patent employs composite materials by combining multiple phosphors with complementary emission spectra in a single wavelength converter. The composite structure consists of Y3Ga5O12:Cr3+ phosphor particles and YAG:Ce3+ phosphor particles dispersed in a transparent resin matrix. This composite approach enables the simultaneous emission of separated visible and near-infrared light components, achieving both normal observation and fluorescence imaging capabilities while minimizing overlapping spectral regions that cause noise.
2Reliability
If conventional phosphors are used to emit near-infrared light for fluorescence imaging, then ICG excitation is achieved, but the deep red light component becomes relatively high causing low contrast in the obtained image
Solution Approach 1:
The patent applies parameter changes by carefully selecting phosphors with specific emission wavelength parameters. The first phosphor Y3Ga5O12:Cr3+ is selected because its emission spectrum peaks in the near-infrared region (700-900nm) and has minimal intensity in the deep red region (600-680nm), whereas conventional phosphors often have significant deep red emission. This parameter optimization ensures that the excitation light for ICG fluorescence imaging contains minimal deep red components, thereby improving image contrast and measurement precision.
3Device complexity
If a single phosphor is used to emit both visible and near-infrared light, then device complexity is reduced, but sufficient separation of fluorescence spectrum components cannot be achieved
Solution Approach 1:
The patent applies segmentation by dividing the wavelength conversion function into two separate phosphor components instead of using a single phosphor. The first phosphor (Y3Ga5O12:Cr3+) is dedicated to near-infrared emission for fluorescence imaging, while the second phosphor (YAG:Ce3+) is dedicated to visible light emission for normal observation. This segmentation achieves sufficient spectral separation between the two emission regions, eliminating the harmful overlap and noise that would occur with a single phosphor attempting to cover both regions.
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 enables improved contrast in fluorescence imaging by separating green to yellow and near-infrared light components, enhancing both normal and special observation capabilities while reducing deep red light noise.
Implementation Method 1
a first phosphor activated with Cr 3+ the fluorescence spectrum of fluorescence emitted by the first phosphor has a peak intensity in a wavelength range of 700 nm or more
Implementation Method 2
a second phosphor activated with Ce 3+ or Eu 2+ the fluorescence spectrum of fluorescence emitted by the second phosphor has a peak intensity in a wavelength range of less than 700 nm
Data Source
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AI summary
A wavelength converter (1) includes a first phosphor (2) activated with Cr3+; and a second phosphor (3) activated with at least one ion of Ce3+ or Eu2+. A fluorescence spectrum of a fluorescence emitted by the second phosphor (3) has a peak where a fluorescence intensity shows a maximum value in a wavelength range of 500 nm or more to less than 580 nm. The wavelength converter (1) emits a fluorescence having a light component over an entire range of 500 nm or more to less than 580 nm. The wavelength converter (1) emits a light having a spectrum in which a ratio of a minimum light emission intensity to a maximum light emission intensity is 40% or less in a wavelength range of 550 nm or more to 700 nm or less.