In this technical note we can get explanation about spectral response, quantum sensors, errors, and photosynthetic photon flux. The technical note contains discussion such as calibration, light sensors, measurement errors, and the spectral response.
There are many explanation like the wavelength range, wavelength, measurement, and wavelength range are described inside the technical note. Here are taken from this technical note:
Almost all the energy on the earth’s surface comes directly or indirectly from the sun. Plants convert this energy into usable forms through photosynthesis. Historically, measuring photosynthetically active radiation (PAR) was somewhat subjective because scientists disagreed about what constitutes PAR and how it should be quantified, but a consensus has emerged regarding the definition of PAR. Building upon the research of Federer and Tanner (1966) and Biggs et al. (1971), which advanced the standardization of PAR measurement instruments, numerous commercial manufacturers produce sensors intended to measure PAR.
Also, this technical note tells the reader info about intensity, photon flux, sensor, and response.