A Micro/Nano-Integrated Polarization Solar Compass: Solar Position and Geographical Position

Insects with polarization-sensitive vision could utilize the polarized skylight as an orientation or navigation reference. Based on the bionic perception strategy of atmospheric polarization patterns and by combining skylight polarization navigation with celestial navigation, a micro/nano-integrated polarization solar compass was proposed to achieve solar position and geographical position measurement. The micropolarizer arrays consisting of meta-nanogratings, as polarization-sensitive components, were fabricated and integrated onto an image sensor by ultraviolet nanoimprint lithography (UV-NIL). A field-programmable gate array (FPGA) was used as the processor to capture, demodulate, and process the polarization image in real time. The position measurement was achieved by perceiving the orientation of polarized skylight (E-vector) from two independent sky regions, and it determined solar and geographical positions in slightly cloudy sky with a mean absolute error of 0.22 degrees in solar elevation, 0.35 degrees in solar azimuth, 0.49 degrees in longitude (54.55 km), and 0.98 degrees in latitude (83.3 km). The proposed micro/nano-integrated polarization solar compass with an overall size of 57 × 45 × 94 mm and a weight of 230 g (with lenses) is highly integrated, compact, and suitable for portable devices.