Glass transmitted solar irradiances on horizontal and sun-normal planes evaluated with a smartphone camera

The research reports on a characterisation and evaluation of the ability of a smartphone camera to measure UV radiation through various types and thicknesses of glass and evaluated the capability of smartphone image sensors to detect glass filtered UVA radiation. This was undertaken for both horizontal plane and for planes normal to the sun. In situ image of the data gathering equipment for a sample sun-normal measurement. Both the smartphone camera (B) and the UVA sensor (A) are arranged beneath the 2 mm clear glass sample slide. The sun targeting apparatus protrudes from the front of the array (C). [Display omitted] •Characterised and evaluated a smartphone camera to measure UVA through glass.•Undertaken for both sun-normal and horizontal plane observations.•Red and blue pixel values of the camera sensor calibrated to the UVA irradiances.•Strong correlations were obtained between smartphone responses and UVA measurements.•Mean absolute errors of ≤17.4% (horizontal plane) and ≤5.6% (sun-normal plane). This paper characterised and evaluated the ability of a smartphone camera to measure ultraviolet radiation (UVR) through various types and thicknesses of glass. Image sensor responses from a smartphone with UVA transmitting filters were measurably stronger in the red colour channel than the blue, with the green colour channel responding weakly. Strong correlations of up to R2 = 0.96 have been determined from calibration of the red and blue channel image responses against measured UVA irradiances for data obtained from both the horizontal plane and the sun-normal plane. For the validation data of the red channel and the blue channel respectively, the mean absolute error was 13.7% and 17.4% for the horizontal plane and 3.8% to 5.6% for the sun-normal plane. This research has concluded that it is possible to determine UVA irradiances through glass, of different thicknesses, using a smartphone camera with high degree of accuracy.