Deep UV Semiconductor Laser for Chemical Analysis
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Solution Overview
Problem
Current chemical analysis methods face challenges with deep UV laser sources, particularly in size, weight, and cost, due to difficulties in producing semiconductor lasers that emit below 300 nm, and existing radiation sources are inefficient for Raman spectroscopy due to low scatter cross-sections and fluorescence interference.
Innovation Solution
The development of electron-beam-pumped semiconductor radiation sources using wide bandgap materials like AlGaN alloys and diamond, which emit in the deep UV range through ballistic electron injection, overcoming p-doping and ohmic contact issues, and employing spectral filters for selective wavelength detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional laser sources are used for deep UV chemical analysis, then radiation can be produced, but the system size, weight, and cost become excessive
Solution Approach 1:
The patent replaces conventional mechanical laser sources with electron-beam-pumped semiconductor devices. This substitution eliminates the need for bulky laser resonators and optical cavities, reducing system weight and size while achieving deep UV radiation emission below 300 nm
Solution Approach 2:
The patent changes the emission wavelength parameter by using wide bandgap semiconductor materials (AlGaN alloys, diamond) with bandgaps corresponding to deep UV wavelengths. This material parameter change enables compact device design while achieving the required radiation wavelength for chemical analysis
2Measurement precision
If conventional radiation sources are used for Raman spectroscopy, then analysis can be performed, but scatter cross-sections remain low and fluorescence interference occurs
Solution Approach 1:
The patent changes the excitation wavelength parameter to deep UV range (below 300 nm) using electron-beam-pumped semiconductor devices. This parameter change increases Raman scatter cross-sections by approximately 100 times compared to visible light and eliminates fluorescence interference, as most materials do not fluoresce at these wavelengths
Solution Approach 2:
The patent converts the typically harmful fluorescence effect into a beneficial diagnostic tool by using wavelength-modulated detection. Fluorescence emissions are detected and analyzed to provide complementary information about the sample, while the deep UV excitation maintains low background Raman signals
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
This approach enables compact, lightweight, low-power chemical analysis systems capable of producing deep UV radiation, enhancing Raman spectroscopy by increasing scatter cross-sections and reducing fluorescence interference, thereby improving sensitivity and specificity.
Implementation Method 1
electron-beam-pumped semiconductor radiation sources using wide bandgap materials like AlGaN alloys and diamond, which emit in the deep UV range through ballistic electron injection
Implementation Method 2
which emit in the deep UV range through ballistic electron injection
Implementation Method 3
receiving emission radiation, directly or indirectly, from the sample at a spectral filter which is capable of passing a selected range of wavelengths of the emission radiation along a given optical path
Implementation Method 4
measuring an amount of the selected emission radiation present, using a detector located directly or indirectly along the selected optical path
Implementation Method 5
a small fraction is re-emitted as Raman scattered radiation. Raman emissions are dependent on excitation frequency and are measured as a sum or difference frequency from the excitation frequency
Implementation Method 6
The inelastically scattered radiation is re-emitted as fluorescence or phosphorescence at wavelengths longer than, or frequencies shorter than the irradiation frequency
Data Source
AI summary
Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.