SALSA
Full Stokes polarization camera
Overview
Compact and robust, the SALSA Full Stokes polarization camera has all the attributes of a regular digital video camera (easy operation, point & shoot, Ethernet connection) plus the polarization analysis capability.
Coupled with a dedicated software, the SALSA Full Stokes polarization imaging system is able to measure all the Stokes polarization information for each pixel of the image, in real time. Applications of SALSA range from target detection and identification to 3D reconstruction and robotic vision. SALSA can be operated in passive and active imaging.
Principle
Along with the intensity and the spectrum, the polarization of light carries abundant information. The Stokes formalism allows for complete description of any partial or total polarization state. While most of the available polarization imaging cameras perform only linear Stokes polarization imaging – only the linear polarization can be quantified – the SALSA performs live measurement of the full Stokes vector for each pixel of the image at a video frame rate. Many polarization-related parameters can be visualized in real time such as the Stokes parameters (S0, S1, S2 , S3), the Degree Of Polarization (Linear or Circular), the Angle Of Polarization or the Ellipticity angle.
This example shows two pairs of glasses. Left ones are linearly polarized sunglasses; right ones are circularly polarized 3D-movies glasses
Stokes
parameters
Advanced
parameters
SALSA software can acquire – in real-time – the raw polarization images and display the resulting Stokes vector images. Different polarization images (Angle Of Polarization, Degree Of Linear Polarization, Normal to the observed surface, etc.) are then easily computed at video rate.
Applications such as image contrast enhancement, imaging through canopies and shades, target detection and identification and complex 3D surface reconstruction can be easily carried out.
Technology
The first polarization cameras were made with mechanical rotation of polarizer(s) and waveplate(s) between each frame. Those systems are usually quite slow and very sensitive to motion of the scene between frames. We use a patented polarization filter based on ferroelectric liquid crystals (FLC) which dramatically reduces the time required to acquire the polarization frames. This architecture allows fast acquisition of four polarization frames that are later used to calculate the Stokes vector for each pixel of the image.
The critical point is to link the polarization raw frames to the Stokes parameters. We developed a calibration procedure to determine the calibration matrix that permits to calculate the four Stokes parameters for any incident polarization state, partial or total.
Specifications
(80mm x 80mm x 100mm) | |
Resolution (pixels) | 1,600 x 1,200 1,920 x 1,080 |
(1,040 x 1,040 version) | 20 frames/second (8 bits) |
(custom in visible wavelength upon request) | |
(other option available upon request) | |
Contact us for more details.
* Due to Bossa Nova Vision continuous improvement policy, specifications are subject to change without notice.
Applications examples
Dehazing through fog
Top : Without our multispectral polarimetric method
Bottom : With our multispectral polarimetric method
Stress application
For more details please check the following article :
SPIE 2016 – Time translation architecture
Article on SPIE website
3D reconstruction
For more details please check the following article :
SPIE 2010 – SALSA – 3D reconstruction
Biology
Top : Intensity image
Bottom : Ellipticity image obtained with the SALSA
Resources
SALSA resources include litterature (articles & application notes) and videos to download.
Additional references
- R. Chris Olsen, Michael Eyler, Angela M. Puetz, Chelsea Esterline
Initial results and field applications of a polarization imaging camera
Proc. SPIE 7461, Polarization Science and Remote Sensing IV, 74610F (11 August 2009) - Vedel, M., Lechocinski, N., and Breugnot, S.
Compact and robust linear Stokes polarization camera
European Physical Journal Web of Conferences, 2010, vol. 5, Art. no. 01005 - Gilerson, A., Carrizo, C., Tonizzo, A., Ibrahim, A., El-Habashi, A., Foster, R., & Ahmed, S.
Polarimetric imaging of underwater targets
Proceedings of SPIE, 8724, Ocean Sensing and Monitoring V, 872403 (2013) - Gilerson, A., Carrizo, C., Ibrahim, A., Chowdhary, J., & Ahmed, S.
Comparison of results of polarimetric imaging and radiative transfer modeling of the atmosphere-ocean system - Gu, Y., Carrizo, C., Gilerson, A. A., Brady, P. C., Cummings, M. E., Twardowski, M. S., Sullivan, J. M., Ibrahim, A. I., & Kattawar, G. W.
Polarimetric imaging and retrieval of target polarization characteristics in underwater environment
Applied Optics, 55(3), 626-637 (2016) - Bao F., Duan J., & Dong S.
Experimental study on polarization imaging characteristics of underwater targets
Journal of Applied Optics, 40(1), 27–32 (2019) - Bliss, Mary, Bruce E. Bernacki, and Keith A. Kaplan.
Polarization Imaging for International Safeguards
Pacific Northwest National Laboratory, Richland, WA, 2020 - El Ketara, Mohamed, Hirokazu Kobayashi, and Etienne Brasselet
Sensitive vectorial optomechanical footprint of light in soft condensed matter.
Nature Photonics, vol. 15, no. 7, 2021 - Pan T, He X, Zhang X, Liu J, Bai Y, Gong F, Li T.
Experimental Study on Bottom-Up Detection of Underwater Targets Based on Polarization Imaging
Sensors. 2022; 22(8):2827 - Manisha, Stuti Joshi, Saba N Khan, Bhaskar Kanseri, and P Senthilkumaran
Investigation of partially coherent vector vortex beams with non-isotropic states of spatial correlation
Opt. Express 30, 32230-32243 (2022) - Fu, Qiang, Nan Liu, Hongrui Guo, Xuanwei Liu, Yujiaqi Yan, Dong Geng, Su Zhang, Juntong Zhan, and Jin Duan
Multi-Band Polarization Imaging in a Harsh Sea Fog Environment
Applied Sciences, vol. 13, no. 1, 2023 - Fu, Qiang, Chao Dong, Kaikai Wang, Qingyi He, Xiansong Gu, Jianhua Liu, Yong Zhu, and Jin Duan
Underwater target laser polarization suppression scattering detection technology and verification
PLOS ONE, vol. 19, no. 6, 2024 - Liu P, Zhai Y, Zhu H, Ye Z, He Q, Tang Z, Tang P.
An Underwater Polarization Imaging Technique Based on the Construction and Decomposition of the Low-Rank and Sparse Matrix in Stokes Space for Polarization State Imaging
Sensors. 2025; 25(3):704