Imaging of LED arrays for BLSS

Area of Science:

• Plant science
• Bioregenerative Life Support Systems (BLSS)
• Optical engineering

Background:

• Light-emitting diodes (LEDs) are vital for plant growth experiments in space and Bioregenerative Life Support Systems (BLSS).
• Limited space and proximity to LED arrays in these systems cause significant irradiance variations, complicating light measurement.
• Traditional sensors struggle with accurate light level assessment due to these variations.

Purpose of the Study:

• To investigate the utility of rear projection video camera imaging for assessing irradiance uniformity from LED arrays.
• To compare video imaging measurements with traditional quantum sensor readings.
• To analyze the impact of mounting height on light uniformity and intensity.

Main Methods:

• Utilized a rear projection video camera imaging technique to analyze irradiance uniformity from LED arrays.
• Performed irradiance measurements using both a 400-700 nm quantum sensor and the video camera at various mounting heights.
• Recorded video images at different distances from the LED array.

Main Results:

• Rear projection imaging proved suitable for analyzing LED array irradiance.
• A nonlinear relationship (R² = 0.884) was observed between video image readings and quantum sensor values.
• Average photosynthetically active radiation (PAR) remained consistent with height, but spatial uniformity increased with greater mounting height.

Conclusions:

• Rear projection video imaging is a viable tool for evaluating light uniformity in LED arrays for plant growth applications.
• Mounting height significantly influences the spatial uniformity of PAR, with increased height improving uniformity.
• Findings support geometrical analyses and offer insights for optimizing lighting in confined environments like BLSS.