Quantum Sensors and Meters

Quantum Sensors and Quantum Meters measure Photosynthetic Photon Flux (PPF) in μmol m^-2 s^-1.

Cosine Response

A "cosine corrected" sensor is designed to maintain its accuracy when radiation comes from different angles. For quantum sensors this is important for measuring scattered light, typical in under-canopy measurements. Apogee Quantum Sensors achieve this through the curvature and optical qualities of the convex lens.

Our long term tests indicate that the cosine errors between completely sunny and heavily overcast days are less than 0.5 percent. Cosine errors between the summer and the winter solstice are also less than 0.5 percent.