iSPEX2: a universal smartphone add-on for portable spectroscopy and polarimetry

11 June 2020

iSPEX-2 is a low-cost, smartphone based tool for taking ocean colour and aerosol measurements. In his latest paper, MONOCLE researcher O. Burggraaff presents an upgraded version of its predecessor which works on all smartphones and uses the SPECTACLE method and  database  for  camera  calibration, offering  data  similar  in  quality  to  professional  radio-meters. This powerful instrument is now moving from the design phase into production and testing for future use in low-costs laboratory and portable spectroscopy and more widely by citizen scientists to measure surface reflectance. Read full paper for more information.


Spectropolarimetry is a powerful technique for remote sensing of the environment. It enables the retrieval of particle shape and size distributions in air and water to an extent that traditional spectroscopy cannot. SPEX is an instrument concept for spectropolarimetry through spectral modulation, providing snapshot, and hence accurate, hyperspectral intensity and degree and angle of linear polarization. Successful SPEX instruments have included groundSPEX and SPEX airborne, which both measure aerosol optical thickness with high precision, and soon SPEXone, which will fly on PACE. Here, we present a low-cost variant for consumer cameras, iSPEX 2, with universal smartphone support. Smartphones enable citizen science measurements which are significantly more scaleable, in space and time, than professional instruments. Universal smartphone support is achieved through a modular hardware design and SPECTACLE data processing. iSPEX 2 will be manufactured through injection molding and 3D printing. A smartphone app for data acquisition and processing is in active development. Production, calibration, and validation will commence in the summer of 2020. Scientific applications will include citizen science measurements of aerosol optical thickness and surface water reflectance, as well as low-cost laboratory and portable spectroscopy.

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Related information and links

iSPEX 2: A universal smartphone add-on for portable spectroscopy and polarimetry

O. Burggraaff, A. Perduijn, R. van Hek, N. Schmidt, C. Keller and F. Snik (2020). "A universal smartphone add-on for portable spectroscopy and polarimetry: iSPEX 2"

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  • Diagram of iSPEX

    Image above: Diagram of iSPEX