Spectral Measurement Illumination for Continuous Sensor Response
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Solution Overview
Problem
Existing spectral measurement technologies face challenges with high variability in detector quantum efficiency, leading to inconsistent signal-to-noise ratios and measurement errors due to sensor inefficiencies across different wavelength ranges, and the use of band-pass filters introduces discontinuities and requires multiple image captures, limiting the acquisition of full spectral data efficiently.
Innovation Solution
A method and device utilizing multiple light sources with adjustable intensity, controlled by current flow, to achieve a continuous spectral response by ensuring sensor saturation is avoided and light intensity is adjusted based on object reflectivity, allowing for high signal-to-noise ratios and continuous signal detection without the need for filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If band-pass filters are used to reduce quantum efficiency variability, then measurement consistency is improved, but measurement time increases due to multiple image captures and spectral discontinuities are introduced
Solution Approach 1:
The patent changes the parameter of light source spectrum by using multiple LEDs with different peak wavelengths instead of a single broadband source. Each LED is driven at specific currents to adjust its spectral output, enabling the system to compensate for detector quantum efficiency variations without requiring physical filters or multiple captures, thus resolving the contradiction between measurement consistency and measurement time.
Solution Approach 2:
The patent implements dynamic control of LED drive currents to adaptively adjust the spectral power distribution according to the detector's quantum efficiency characteristics. This dynamic spectral tuning allows the system to maintain optimal signal-to-noise ratio across all wavelengths in a single capture, eliminating the need for sequential filtered measurements and resolving the time consistency trade-off.
2Adaptability or versatility
If multiple light sources with different spectra are used, then coverage of full measurement range is improved, but device complexity increases
Solution Approach 1:
The patent segments the broadband spectrum into multiple discrete wavelength regions, each covered by a specific LED with a defined peak wavelength. This segmentation approach allows comprehensive spectral coverage using individual LED components that can be independently controlled, managing device complexity through modular architecture while maintaining full measurement range capability.
Solution Approach 2:
The patent makes each LED serve multiple functions: it acts as both a spectral reference source and a measurement illumination source. The same LED array used for illuminating the sample also provides the spectral reference by measuring the detector response to each LED's known spectrum, eliminating the need for separate reference sources and reducing overall device complexity while maintaining spectral coverage.
3Measurement precision
If LED current is adjusted to compensate for quantum efficiency variations, then signal-to-noise ratio is improved, but control complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism where the system measures the actual detector response to each LED and uses this information to calculate the optimal drive current for that LED. This closed-loop feedback ensures that each LED produces the desired spectral power distribution that compensates for quantum efficiency variations, improving signal-to-noise ratio while managing control complexity through automated calculation and adjustment.
Solution Approach 2:
The patent performs preliminary characterization of each LED's spectral output at different drive currents and stores this data for later use. During measurement, the system retrieves pre-calculated optimal current values from lookup tables or stored calibration data, avoiding real-time complex calculations and reducing control complexity while maintaining optimal signal-to-noise ratio through pre-optimized LED driving conditions.
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 consistent and continuous spectral data acquisition with improved signal-to-noise ratios, enabling effective derivative calculations and eliminating measurement discontinuities, while allowing for rapid acquisition of full spectral information without filter interference.
Implementation Method 1
The illuminator comprises a plurality of light sources, in particular light emitting diodes (LEDs), which emit electromagnetic radiation at different wavelengths in the measured range
Implementation Method 2
a radiation detector, in particular an image detector, which is used to record the spectrum of light reflected from the examined object
Data Source
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AI summary
The invention relates to a method for performing spectral measurements, in which a reference plate and an examined object are illuminated or transilluminated with an illuminator consisting of at least one light source, and an image sensor records the image obtained from the reference plate and the examined object. The reference plate has a high and constant reflectivity in the analyzed wavelength range. The reference plate and the object are sequentially illuminated with light having a spectrum selected so that the recorded response of the image sensor has the highest possible value in each of the measurement bands. The intensity of the light source is adjusted based on the response of the object being examined, and the method comprises the following steps: switching off all light sources except one light source with a selected specific wavelength; adjusting the intensity of the light source with the selected specific wavelength until the response of the image sensor is close to the saturation value; switching on the next light source in terms of wavelength and adjusting its intensity until the response of the image sensor is close to the saturation value; examining the response of the image sensor to see if the saturation value of the image sensor has been reached in the previously selected specific wavelength ranges; if the saturation value is reached, the intensity of the previously selected specific light sources is reduced; the above steps are repeated until the intensity of all light sources with the analyzed wavelengths is adjusted to obtain a quasi-continuous spectral response. The invention also relates to a device implementing this method.