Compact Spectroscopic System Using Linear Variable Filter
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Solution Overview
Problem
Conventional spectrometers are bulky and not suitable for portable or point-of-use applications due to their size and complexity, limiting their use in medical diagnostics, food safety, and environmental monitoring, where compact and accurate colorimetric analysis is needed.
Innovation Solution
A compact spectroscopic system integrating a linear variable filter (LVF) directly onto a smartphone image sensor, utilizing a light source and a sample holder with a planar surface to analyze light reflected or scattered from samples, allowing for spectral analysis and determination of analyte concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spectrometers are used for accurate spectral analysis, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent merges the linear variable filter directly with the image sensor by bonding the LVF to the sensor surface, eliminating the need for separate filter and sensor components. This integration maintains spectral analysis capability while dramatically reducing device size and complexity, enabling portable applications.
Solution Approach 2:
The patent uses a linear variable filter that disperses light in one dimension (spatial separation of wavelengths) rather than requiring traditional two-dimensional dispersion elements like diffraction gratings. This dimensional simplification reduces the optical path length and overall instrument size while maintaining spectral resolution.
2Measurement precision
If conventional spectrometers with long optical paths are used, then wavelength resolution is improved, but device complexity increases
Solution Approach 1:
The patent changes the key parameter from optical path length to filter gradient steepness. By using a linear variable filter with a controlled wavelength gradient across its surface, the system achieves high wavelength resolution with a compact optical path, as the resolution depends on the filter's spectral gradient rather than propagation distance.
3Device complexity
If diffraction gratings are placed directly in front of smartphone camera sensors, then device size is reduced, but wavelength resolution deteriorates
Solution Approach 1:
The patent uses a linear variable filter that replicates the spectral dispersion function of traditional diffraction gratings but in a planar, integrated format. The LVF creates a virtual spectrum on the image sensor plane without requiring the long optical paths associated with grating-based systems, achieving compact size with maintained resolution.
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 system provides accurate, quantitative spectral analysis capable of measuring absorption and scattering spectra, equivalent to conventional spectrometers, in a compact form factor suitable for integration into mobile devices, enabling point-of-use testing and diagnostics.
Implementation Method 1
A compact spectroscopic system integrating a linear variable filter (LVF) directly onto a smartphone image sensor
Implementation Method 2
utilizing a light source and a sample holder with a planar surface to analyze light reflected or scattered from samples
Implementation Method 3
utilizing a light source and a sample holder with a planar surface to analyze light reflected or scattered from samples
Data Source
AI summary
The present disclosure describes the design, fabrication, and demonstration of a compact spectroscopic analysis system that utilizes a linear variable filter chip attached directly over an image sensor array, and an integrated broadband LED illuminator that supplies light from the edge of the system to provide a low vertical dimension. The instrument is capable of accurately measuring the optical absorption spectra of colored liquids or the scattered spectra from solid objects that are placed in the illumination pathway. Due to the small vertical thickness of the system, the low cost of its components, and the accuracy with which it renders spectra in comparison to conventional spectrometers, we envision potential incorporation of the system into mobile communication devices, such as smartphones and tablets, as a means for providing a dedicated sensor for health diagnostic, environmental monitoring, and general-purpose color sensing applications.