Multi-Channel Lighting Calibration for Accurate Spectral Output
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Solution Overview
Problem
Existing calibration methods for multi-channel lighting systems fail to account for varying reflection properties of environments and luminaire production variability, leading to significant errors in achieving desired spectral power distributions and light recipes.
Innovation Solution
A calibration method that generates a matrix to convert luminous flux values into calibrated illuminance values, compensating for different reflection indexes and luminaire batch deviations by using actual measurements at the area of interest, and incorporating spectral distribution mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple calibration method using total light output is used, then the calibration process is simple and quick, but the calibration error increases to around 10% due to unaccounted reflection properties and production variability
Solution Approach 1:
The calibration method segments the spectral distribution into multiple discrete wavelength ranges (e.g., blue 400-499nm, green 500-599nm, red 600-699nm, far-red 700-799nm). By measuring and calibrating each spectral segment separately rather than using a single total light output measurement, the method achieves precise calibration while maintaining operational simplicity. This segmentation allows the system to account for different reflection properties at different wavelengths without complicating the overall calibration process.
2Adaptability or versatility
If multiple LED chips with overlapping spectra are used to create desired spectral power distribution, then the lighting system achieves color mixing capability, but the difficulty of detecting and measuring increases due to spectral overlap and interference
Solution Approach 1:
The method segments the spectral measurement into distinct wavelength ranges, measuring the light output of each LED chip type (blue, green, red, far-red) separately in its dominant wavelength range. This segmentation allows the system to detect and measure each component's contribution to the spectral power distribution, making it easier to calculate the overall SPD even when chips have overlapping spectra. The segmentation approach transforms a complex measurement problem into multiple simpler, non-interfering measurements.
Solution Approach 2:
The calibration method applies local quality by measuring and calibrating the spectral characteristics at specific wavelength ranges rather than using a single broad measurement. Each LED chip type is measured in its optimal wavelength range where it produces the highest light output, allowing the system to account for local spectral variations and overlaps. This localized measurement approach enables precise control of the spectral power distribution while simplifying the measurement process compared to attempting to measure all wavelengths simultaneously.
Data Source
Figure 1~2
AI summary
A method is provided of calibrating a lighting system to enable conversion between i) light output settings for a plurality of lighting channels of the lighting system, each channel having a respective color spectrum from a first set of color spectra, and ii) a light intensity at an area of interest for each of a second set of color spectra. The method derives a calibration matrix, based on a set default light outputs from the lighting channels, a mapping to light spectra to be measured, and light intensities measured at those light spectra. This calibration procedure takes advantage of the fact that using the same measurement device conventionally used for a simple calibration, it is possible to retrieve not only the total measured PPFD, but also partial PPFD values per spectral range.