Polarimetric and Multi-spectro-polarimetric imaging systems have a high potential for different applications such as biomedical, surface evaluation and roughness, remote sensing and imaging through turbid mediums. The liquid crystal variable retarders (LCVRs) are propitious candidates to combine a polarization control devices in polarimetric imaging systems due to their exceptional properties such as retardation tunability using low voltages and minimal power consumption, in addition to being cost-effective and compact.
In this work, we present a new broadband ellipso-polarimetric camera based on tunable achromatic waveplate (AWP)[2,3] consisting of LCVRs. This AWP can be tuned between three modes: quarter, half and full waveplate in wide spectral band. Also, the operation band can be tuned with the three modes. By capturing images at the three modes of the AWP, the system can extract various EP parameters: two Stokes parameters (S1 and S3), sin(2ψ) and cos(Δ). Particularly we show that cos(Δ) images are superior over many known polarimetric imaging quantities. The performance of the imaging system was demonstrated in different applications such as tissue for biomedical imaging, fingerprints and its residuals on the surface, old coins and remote sensing.
In addition to the spatial and polarimetric information, integrating a narrowband LC tunable filter into imaging systems provides the ability to extract the spectral information which helps to characterize the object better. In this work, we shall present the performance of Multispectral camera and Multi-spectro-polarimetric camera based on our developed LC devices for different applications.
1. M. J. Abuleil and I. Abdulhalim, "Broadband ellipso-polarimetric camera utilizing tunable liquid crystal achromatic waveplate with improved field of view," Opt. Express (2019), accepted.
2. I. Abdulhalim and M. J. Abuleil, "Tunable achromatic liquid crystal waveplates," U.S. patent 10,146,095 B2.
3. M. J. Abuleil and I. Abdulhalim, "Tunable achromatic liquid crystal waveplates," Opt. Lett. 39(19), 5487 (2014).
4. M. Abuleil and I. Abdulhalim, "Narrowband multispectral liquid crystal tunable filter," Opt. Lett. 41(9), 1957 (2016).