Saturday, February 18, 2012
Exhibit Hall A-B1 (VCC West Building)
Light emitting diodes (LEDs) are commonly found in lighting sources due to their minimal cost and lower energy consumption compared to incandescent light sources. From previous research it has been found that LEDs can be used in reverse mode to measure light at wavelengths the LED emits essentially functioning as a photodiode. The use of an LED as a light sensor has proven to be useful for detecting the reflectance of plant canopies. For this experiment red and near infrared (NIR, 0.7 – 1 micron) LEDs were used because the red and NIR reflectances are used to calculate the normalized difference vegetation index (NDVI). The NDVI is a common index used to monitor changes in plant canopy structure by sensors on satellites. It is important to be able to monitor the plants in order to study how the plant interacts with the physical environment. Developing a rigorously tested LED sensor is important because of its low cost and ability to measure absorbance throughout the day continuously. With an efficient sensor it will be possible to determine changes in plant canopy structure accurately. These sensors also have the potential to be implemented widely for agronomic crop trials that are used to determine yield and biofuel potential.