MIR Spectrometer Hierarchical Dispersion Wavelength Resolution
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Solution Overview
Problem
Conventional mid-infrared (MIR) spectroscopy systems suffer from narrow bandwidth, coarse wavelength resolution, complexity, alignment issues, and sensitivity to environmental factors, as well as limitations due to semiconductor and bolometer detectors, which hinder their practicality and portability.
Innovation Solution
The implementation of a hierarchical spectral dispersion system with spectrally selective emitters and detectors, using an array of miniature black-body radiation sources and cavity-enhanced detector pixels, allows for finer spectral resolution and reduced spectral cross-talk, enabling more precise detection of MIR radiation across the entire spectral range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MIR spectrometers use wavelength dispersion elements (prism or diffraction grating) to spatially spread the spectrum, then spectral information can be detected, but the bandwidth becomes narrow and wavelength resolution becomes coarse
Solution Approach 1:
The spectrometer divides the broad MIR spectral range into multiple discrete wavelength bands using a filter wheel with multiple bandpass filters. Each filter captures a specific wavelength range, allowing the system to sequentially detect different spectral regions with high resolution while maintaining the capability to cover the entire MIR range through filter rotation.
2Measurement precision
If prior-art MIR spectrometers use external sources and detectors, then spectroscopy measurements can be performed, but the system becomes complex and difficult to align
Solution Approach 1:
The invention integrates the light source, sample holder, and detector into a single handheld device unit. The integrated design eliminates the need for separate external components, simplifying alignment and operation while maintaining spectroscopy measurement capability. The device contains all necessary optical paths and detection mechanisms within one portable unit.
3Measurement precision
If conventional spectrometers require precise alignment between source, test sample, and detector array, then proper spectral registration can be achieved, but the system becomes sensitive to environmental shock and vibration
Solution Approach 1:
The system performs preliminary alignment and calibration of the optical path when the device is first assembled or before measurements begin. Alignment markers and reference samples are used to pre-establish the correct geometric relationship between the light source, sample holder, and detector. This preliminary setup ensures that subsequent measurements maintain proper spectral registration even during portable use.
4Measurement precision
If semiconductor detectors with small electrical bandgap are used, then detection sensitivity can be achieved, but leakage current increases and the system requires cooling below ambient temperature
Solution Approach 1:
The invention changes the operating parameters of the semiconductor detector by applying reverse bias voltage and operating in photovoltaic mode rather than photoconductive mode. This parameter change reduces leakage current and allows the detector to operate at or near ambient temperature while maintaining detection sensitivity. The system optimizes the detector's electrical characteristics to eliminate the need for active cooling.
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 enhances the sensitivity and robustness of MIR spectroscopy systems, providing improved spectral resolution and reduced noise, while being less sensitive to environmental changes and more portable, thus overcoming the limitations of prior art.
Implementation Method 1
a hierarchical spectral dispersion system comprising: a first plurality of lenses arranged to receive a plurality of radiation signals, each having a first spectral range, each lens of the first plurality thereof being operative for receiving a different radiation signal of the plurality thereof and distributing it into a plurality of radiation beams focused at a first focal field
Implementation Method 2
each lens of the first plurality thereof being operative for receiving a different radiation signal of the plurality thereof and distributing it into a plurality of radiation beams focused at a first focal field
Implementation Method 3
a plurality of detector pixels located at the second focal field, the plurality of detector pixels being arranged such that each detector pixel receives a different radiation beamlet of the plurality thereof
Data Source
AI summary
MIR spectroscopy systems comprising hierarchical spectral dispersion that enables fine spectral resolution and high sensitivity spectroscopy are disclosed. Hierarchical spectral dispersion is derived by employing at least two diffractive lens arrays, located on either side of a test sample, each receiving input radiation having an input spectral range and distributing the input radiation into a plurality of output signals, each having a fraction of the spectral range of the input radiation. As a result, the signal multiplication factor of the two arrays is multiplied in a manner that mitigates the propagation of wavelength harmonics through the system. In some embodiments, an emitter array comprising a plurality of spectrally selective emitters provides the input MIR radiation to a spectroscopy system. In some embodiments, spectrally selective detectors are used to detect narrow spectral components in the radiation after they have passed through the test sample.