Features
- Data Management: iSPEX 2 data are automatically uploaded to a back-end server through the associated app. This server processes and catalogues the data and sends them to the MONOCLE back-end database, where they can be compared to other data.
- Sensor Measurements:
- Sensor measures the polarised intensity of light in two orthogonal directions (horizontal and vertical polarisation),
- Hyperspectrally from 390-700 nm at approx. 9 nm resolution (exact figures depending on the smartphone used).
From this data the unpolarised spectrum and angle of linear polarisation can be retrieved which is used to infer properties of the water.
- How it works:
Two slits, side by side, let through light from a single direction. This is modulated by a set of SPEX optics (λ/4 retarder, multi-order retarder, linear polarisers) that encode the polarisation information into the spectrum as light and dark bands. Finally, a grating disperses the light onto the smartphone camera, in the form of two rainbows (one per slit) with opposing light/dark bands. The smartphone camera registers these data and they are processed using SPECTACLE.
Specifications
- Resolution: Spectral resolution approx. 9 nm (FWHM), depending on smartphone optics.
- Dimensions: 5 cm long, 10 cm tall, 7,5 cm wide
- Power requirement: Add-on does not need power, smartphone has a battery
- Method to transmit data: Through smartphone (Wi-Fi, 3G/4G/5G)
- Deployment method: By citizen scientists on a smartphone, from the shore or a boat
Publications
Standardized spectral and radiometric calibration of consumer cameras. Burggraaff O. et al. Optics Express, Vol 27, Issue 14, 2019.
A universal smartphone add-on for portable spectroscopy and polarimetry: iSPEX 2. Burggraaff O. et al. Proc. SPIE 11389, Micro- and Nanotechnology Sensors, Systems, and Applications XII, 2020.
Technical Resources
Technical drawing
Technical diagram of the iSPEX 2 sensor