title: Characterization of a smartphone camera's response to ultraviolet A radiation.
abstract: As part of a wider study into the use of smartphones as solar ultraviolet radiation monitors, this article characterizes the ultraviolet A (UVA; 320-400 nm) response of a consumer complementary metal oxide semiconductor (CMOS)-based smartphone image sensor in a controlled laboratory environment. The CMOS image sensor in the camera possesses inherent sensitivity to UVA, and despite the attenuation due to the lens and neutral density and wavelength-specific bandpass filters, the measured relative UVA irradiances relative to the incident irradiances range from 0.0065% at 380 nm to 0.0051% at 340 nm. In addition, the sensor demonstrates a predictable response to low-intensity discrete UVA stimuli that can be modelled using the ratio of recorded digital values to the incident UVA irradiance for a given automatic exposure time, and resulting in measurement errors that are typically less than 5%. Our results support the idea that smartphones can be used for scientific monitoring of UVA radiation.
authors.affiliation: Faculty of Sciences, University of Southern Queensland, Toowoomba, Australia. damienpaul@gmail.com
authors.forename: Damien
authors.initials: D
authors.lastname: Igoe
authors.forename: Alfio
authors.initials: A
authors.lastname: Parisi
authors.forename: Brad
authors.initials: B
authors.lastname: Carter