A theoretical approach to photosynthetically active radiation silicon sensor

•Design of radiometers to measure photosynthetically active radiation•The study has used a filter and a Si sensor to modify spectral response.•Dielectric multilayers on glass and silicon sensor•Spectral response related to different incidence angles, materials and spectra.

This paper presents a theoretical approach for the development of low cost radiometers to measure photosynthetically active radiation (PAR). Two alternatives are considered: a) glass optical filters attached to a silicon sensor, and b) dielectric coating on a silicon sensor. The devices proposed are based on radiometers previously developed by the Argentine National Atomic Energy Commission. The objective of this work is to adapt these low cost radiometers to construct reliable instruments for measuring PAR.The transmittance of optical filters and sensor response have been analyzed for different dielectric materials, number of layers deposited, and incidence angles. Uncertainties in thickness of layer deposition were evaluated.