Photo Sensor Array Using Mathematical Coefficients to Reduce Spectral Error
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Solution Overview
Problem
Current photo sensors lack an equal response to all photons within the 400-700 nm range, leading to significant spectral errors in measuring photosynthetic photon flux density (PPFD), with existing solutions either being expensive or having substantial spectral errors, necessitating a cost-effective solution.
Innovation Solution
A photo sensor array comprising photodiodes with red, green, and blue filters, along with unfiltered photodiodes, where the output is calculated using predetermined mathematical coefficients to approximate an ideal spectral response curve, minimizing spectral errors across the 400-700 nm range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive filter arrays are used to achieve equal response to all photons within the 400-700 nm range, then measurement precision is improved, but device cost increases significantly
Solution Approach 1:
The patent divides the photo sensor array into multiple segments, each with different spectral response characteristics (UV-sensitive, blue-sensitive, green-sensitive, red-sensitive photodiodes). By segmenting the sensor array and assigning specific wavelength ranges to each segment, the system achieves comprehensive spectral coverage and accurate PPFD measurement without requiring expensive broad-spectrum quantum sensors or filter arrays.
2Ease of manufacture
If unfiltered gallium arsenide phosphide photodiodes are used, then device cost decreases, but spectral error increases significantly
Solution Approach 1:
The patent applies local quality by assigning different spectral sensitivity characteristics to different portions of the sensor array. Each photodiode type (UV-sensitive, blue-sensitive, green-sensitive, red-sensitive) is optimized for specific wavelength ranges, allowing the system to achieve accurate spectral measurement across the entire 400-700 nm range using inexpensive photodiodes rather than requiring expensive uniformly responsive quantum sensors.
Solution Approach 2:
The patent introduces mathematical coefficients as intermediaries to correct the spectral response of inexpensive photodiodes. By applying wavelength-dependent correction coefficients to the raw measurements from each photodiode type, the system compensates for their non-ideal spectral characteristics and achieves accurate PPFD measurement equivalent to expensive quantum sensors.
3Measurement precision
If blue enhanced filtered silicon photodiodes are used, then spectral response accuracy is improved, but device cost increases significantly
Solution Approach 1:
The patent creates a multi-functional sensor array where four types of photodiodes (UV-sensitive, blue-sensitive, green-sensitive, red-sensitive) work together to measure the entire photosynthetically active radiation spectrum. This universal approach allows the system to replace expensive specialized quantum sensors with a combination of inexpensive photodiodes that collectively perform the same measurement function.
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 achieves a spectral response error of no more than 5% between 450 nm and 700 nm, providing a cost-effective alternative with improved accuracy compared to commercially available sensors, while maintaining a low cost by eliminating the need for expensive special filters.
Implementation Method 1
A photo sensor array comprising a plurality of photodiodes; a first portion of the plurality of photodiodes having a red filter; a second portion of the plurality of photodiodes having a green filter; a third portion of the plurality of photodiodes having a blue filter
Data Source
AI summary
A cost effective multicolor sensor and related software achieves a spectral response that closely approximates an ideal photo response to measure optical measurement, for example photosynthetic photo flux density (PPFD). The spectra error of the sensor is smaller than that of the best commercially available sensor at a significantly reduced cost. The sensor may include an 8×2 array of filtered photodiodes and spectral photo sensors that are linearly combined with the appropriate mathematically determined coefficients to create a corrected spectral response curve that has a spectral error much smaller than the best commercial available sensors made by physical coating methods for the entire desired range.