Evaluation of a smartphone sensor to broadband and to narrow band ultraviolet A radiation

Evaluation of a smartphone sensor to broadband and to narrow band ultraviolet A radiation

This research compares the smartphone image sensor response when exposed to broadband and narrow passband (340 nm and 380 nm) UVA wavelengths (320-400 nm) and builds on previous studies that have demonstrated that the smartphone image sensor is able to provide quantifiable response to narrow passband solar irradiances at 380 nm and 340 nm and can be used to reconstruct broadband UVA irradiances. This current research provides a comparison of the two main methods of ultraviolet irradiance observation and measurement, broadband and narrowband sensing, as applied to a common readily accessible smartphone. This research shows that the smartphone image sensor, with a broadband UVA filter possesses a strong sensitivity to long wavelength UVA irradiances from 370 nm, with a peak at 380 nm. However, the use of narrow passband and neutral density filters allows for quantifiable observations at the photobiologically important wavelength of 340 nm. Narrow passband filter observations also have far less variation at 340 nm than that observed for broadband measurements. The results indicate that the smartphone image sensor, with the addition of narrow passband and neutral density filters can be a viable tool for UVA observations, but is unsuitable for broadband measurements with a broadband filter.

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