I just came across this animation I created nearly 20 years ago (originally in Flash, now converted to video). It’s a bit off-topic, but interestingly, 2005 also marked the 100th anniversary of special relativity.
Mueller Matrix Polarimetry
Welcome to the website of Oriol Arteaga. Here you will mostly hear about my research activities which mainly focus in polarimetry, ellipsometry or, more in general, in light-matter interactions. You can contact me at oarteaga(AT)ub.edu and at www.ub.edu/plat
Full-Stokes Polarization Camera
Our Full-Stokes Polarization Camera technology introduces a new approach to capturing the complete polarization state of light in real-time, including the often-overlooked circular polarization. To the best of our knowledge, this is the smallest and simplest fully operational Full-Stokes camera developed to date.
Key Technical Features
- Complete Stokes Vector Measurement
Measure all four Stokes parameters—total intensity (S₀), linear polarization components (S₁, S₂), and circular polarization (S₃)—in a single shot, enabling detailed analysis of light’s polarization state. Results can also be shown in terms of the degree of circular polarization (DoCP), degree of linear polarization (DoLP), and angle of linear polarization (AoLP) - Innovative Dispersive Retarder Technology
A homogeneous waveplate with natural wavelength-dependent retardation is positioned before the sensor. This component introduces precise phase shifts across RGB color channels, allowing differentiation of polarization states without the need for complex or costly microretarder arrays. - Optimized for Real-Time Performance
With an effective resolution of 612 × 512 pixels for each Stokes parameter and a frame rate of up to 75 frames per second or 24 frames per second (after noise-reduction averaging), the system is designed for real-time applications without sacrificing accuracy. - Seamless Compatibility
Built on a commercial polarized color camera ( Sony IMX250MYR sensor), the system integrates effortlessly into existing workflows. Its compact design maintains standard camera dimensions, requiring no additional bulk or power.
How It Works?
The Full-Stokes Polarization Camera utilizes the wavelength-dependent retardance of a custom waveplate to produce well-controlled phase shifts across the sensor’s RGB color channels. By analyzing polarization states at different wavelengths—primarily through the red and green channels—the system reconstructs the complete Stokes vector, under the assumption that the input polarization is not strongly wavelength-dependent. A custom calibration procedure ensures accurate performance, accounting for parameters such as retardance, depolarization, and retarder orientation.
What Kind of Retarder Does the Camera Use?
The system employs a custom-made elliptical retarder, specifically designed to introduce optimal phase differences between the red and green channels of the camera sensor.
How Has the Camera Been Modified?
The only modification required is the addition of the custom retarder to a commercial color polarization camera. No other changes are necessary, and the system contains no moving or active polarization components.
How Is the Full Stokes Vector Calculated?
The full Stokes vector is computed in real time by the computer connected to the camera. The algorithm combines information from the red and green channels to reconstruct the polarization state. The calculation is straightforward and could potentially be implemented directly in the camera’s onboard electronics or FPGA.
What Are the Camera’s Limitations?
Since the method relies on combining data from two color channels, both must receive sufficient signal. For example, the system cannot function correctly under purely monochromatic green illumination. As a result, the camera must generally be used with a broadband light source or under ambient lighting conditions that span the relevant spectral range.
Which are are the output’s of the camera?
Stokes parameters can also be expressed in terms of other parameters directly related to the polarization of light (AoP, DOP, Ellipticity, etc) . For example, all these 5 images can be simultaneously provided by the camera:
Applications
- Advanced Imaging/Vision: Achieve enhanced image quality by analyzing polarization effects in scenes, ideal for scientific research and industrial inspections or imaging in harsh environments (underwater vision, navigation through the fog, etc).
- Remote Sensing: Capture detailed polarization data for environmental monitoring, atmospheric studies, and geological surveys.
- Augmented Reality & Display Technology: Enhance user experiences by integrating both linear and circular polarization insights into AR systems or display designs, improving contrast and realism.
Why detecting also circular polarization?
Circular polarization is an important but often underutilized aspect of light’s polarization state, offering valuable insights into light-matter interactions that go beyond linear polarization analysis. While our Full-Stokes Polarization Camera is not sensitive enough to detect very subtle effects like molecular chirality, it excels in practical applications where circular polarization provides macroscopic information about surfaces, materials, and environments. For example, circular polarization can enhance target detection by distinguishing between natural and artificial materials, reducing glare in challenging scenes, and improving visibility in turbid media like fog or water. Additionally, it can reveal stress-induced birefringence (see the second video as an example), surface roughness, and other material properties critical for industrial inspections, remote sensing, and imaging in harsh environments.
Examples
The first video shows a real-time Stokes vector imaging of a scene comprising two perpendicular polarizers and a rotating achromatic waveplate in front of a linear polarizer. At the top of the scene, there are also 3D glasses with filters of opposite circular handedness.
The second video shows a scene recorded while varying the stress applied to a glass microscope slide (BK7 glass) by pressing it with fingers. A laptop screen generating a horizontal linear polarization state serves as the background (S₁ close to 1). When pressure is applied to the edge of the glass slide, stress is immediately induced, leading to birefringence due to the photoelastic effect, that the camera detects as some circular polarization (S₃), reaching the camera.ss
The camera offers quantitative results for all Stokes parameters. For example, this is a quarter-wave plate being rotated in front of a polarizer.
Snapshot ellipsometry. Check our prototype in a video
Check out these videos showcasing our snapshot generalized ellipsometer (which measures eight elements of the normalized Mueller matrix). Additional details and explanations can be found in the video description.
Companies interested in this technology are welcome to contact me for more information, as I think this is very interesting for many applications demanding high speed.
Today I have taken these videos to demonstrate some reflection and transmission measurements.
Our current prototype works in the spectral range 400 nm – 850 nm (graphs in the computer show this spectral range).
1-year positions available in our project POLVISION
We have 2 positions available within the POLVISION project in our PLAT research group. This project, funded by AGAUR (the Catalan Agency for Research and Universities) through the Knowledge Industry program, aims to foster an economy driven by knowledge by promoting the transfer of research results from academic institutions to the market.
Our project focuses on bringing to market a novel method for complete polarization vision (full-Stokes vision) that we have developed. This method offers unprecedented simplicity and represents a significant advancement in the field of polarization optics.
Position Details:
The two positions are for 1 year (up to ~14 months, due to the project duration). The positions available are:
- Postdoc position
- Early-career researcher (e.g., Master’s student) that ideally could serve as a starting point for a PhD.
The successful candidates will contribute to developing a fast, intuitive, and user-friendly interface for our polarized vision system. Additionally, they will actively participate in technology transfer activities related to the project and support other research initiatives within our group.
Key Qualifications (especially for the postdoc):
- Strong programming skills in LabVIEW, Python, and/or MATLAB
- A keen interest and experience in polarization optics, hands-on experimental work, and the implementation of calibration algorithms
- A strong commitment to research excellence and continuous development
Additional Information:
- Salary: Commensurate with experience and according to the guidelines in Spanish universities for postdocs and early-career researchers.
- Working Place: Physics Faculty, Universitat de Barcelona.
Late 2024 Update
It is time to update the various activities carried out in 2024. Hopefully, in 2025 this website will see more updates.
- Dr. Huihui Li (Jimei University) did a 6-month postdoctoral research stay in our lab working on polarimetric imaging for scattering turbid media. A paper about the work she carried out is already published:
https://doi.org/10.1016/j.optlaseng.2024.108804
- Mr. Han Tong (Huqiao University) did a 7-month predoctoral stay in our lab. Working on the calibration of Mueller matrix ellipsometer.
- In autunm 2024 Beáta Hroncová from Masaryk University, Brno did another stay of 3 months in our lab funded under an Erasmus+. She continued exciting work on spatial dispersion. Stay tuned for a publication.
- In November 2024 I did a short trip to China as I was invited to the 1st International Conference on Metrology and Standards (ICMS2024) in Hangzhou, China. On the same trip, I also visited the city of Xiamen to meet collaborators and friends Dr. Huihui Li and Dr. Ziqing Li and the city of Shanghai where I visited Prof. Xiaoyan Cui (http://cuilabs.com/), a friend and colleague from my Postdoc times in NYU, now Prof. in East Normal University.
- In December 2024 I was invited to the NETLINCS workshop in Trieste “New Trends in Linear and Non-linear Spectroscopic Chirality Studies”.
- We got a new Project, IdC product (AGAUR) for the project “A System for Complete Polarization Vision (POLVISION)”. In this project, we develop a system for complete (full-Stokes) polarization vision to be transferred to the industry.
Early 2024 update
Long time without updates. I try to summarize in brief bullet points some of the accumulated news, without following any particular order.
- Our recent paper about the “Spatial dispersion of Silicon” was selected a Editor Pick in Phys. Rev. B.
- A few months ago I got a “Consolidación” project. The project is titled SPECTROPEM – Ultrasensitive polarization encoded spectroscopy without monochromator based on photoelastic modulators. This project will involve not only some research activities, but brings some new lab spaces and renewal works.
- We also got another project from the PID2022 call. The project is titled “Imagen polarimétrica para la mejora de la visibilidad y la detección en medios turbios” and it is our first project that approaches biomedical imaging aspects. The project has just started now.
- Our student Subiao Bian got a Fi-SDUR 2023 fellowship to complete his PhD.
- Last Spring-Summer Beáta Hroncová from Masaryk University, Brno did a stay of 3 months in our lab funded under an Erasmus+. She did some very interesting work on spatial dispersion (on different materials) that now needs to be completed.
- Las summer I visited Huaqiao University in China. It was the kick-off of a 111 project (“Introducing Intelligence Base of Intelligent Manufacturing Technologies for Brittle Material”) where we participate. China’s “111 Project” or “Project 111”, launched in 2005, is a national programme that aims to draw about 1000 leading overseas scholars and researchers from worldwide top 100 universities and research institutes to over 100 “innovation bases” in China.
- Last autumn Akash Tiwari from New York University (USA) did a stay in our lab of 3 months. Akash was interested in learning all the tricks of the 4-PEM Mueller matrix polarimeter.
- During Jan and Feb 2024 Prof. Kevin McPeak from Louisiana State University is visiting our group. We are trying to finish some pending on tricky chiroptics of metamaterials.
Spotlight on the Geometric Phase
View Spotlight analysis of the #OPG_JOSA_A paper Wave description of geometric phase https://t.co/Pyqqs8G7P6 Spotlight Summary by Oriol Arteaga #Polarization pic.twitter.com/xor2D2qnV3
— Optica Publishing Group (@OpticaPubsGroup) March 13, 2023
From the same authors, it is also very recommendable this article: https://arxiv.org/abs/2301.04359 which I think will be soon published in Optica.
New SGR Group about “Polarized light Applications & Technologies (PLAT)”
Research in Catalan Universities is organized through Research Groups recognized by the Agency for Management of University and Research Grants (AGAUR). In the last call, I led the application for a new emergent research group called “Polarized light Applications & Technologies (PLAT)”, which was granted.
I made a preliminary (under-construction) website of the group at: www.ub.edu/plat
However, this (www.mmpolarimetry.com) personal website will of course continue to exist, as it already has a long history, offers more personal views on research topics, and is easier to update.
History papers
Here I share some historical papers/documents/books about polarization optics that are very hard to find and that I consider important or very nice.
Soleillet Thesis (1929) [First description of Stokes-Mueller calculus]
https://www.mmpolarimetry.com/wp-content/uploads/2022/12/SoleilletThesis.pdf
Perrin 1942 (English translation) [First work describing Mueller matrix symmetries]
https://www.mmpolarimetry.com/wp-content/uploads/2022/12/perrin1942.pdf
Mueller 1943 (Memorandum on the polarization optics of the photoelastic shutter] [The most relevant available work by Hans Mueller]
Walker 1904, The analytical theory of light [book] [The only English book that described Stokes parameters way before they were rediscovered]
November update
Many months without updates. So this is a summary of the latest news (without following any particular order)
New Book Chapter
New Optics letter paper about spatial dispersion selected as an editor’s pick
(more research on this topic will follow)
2022 Horizon Award from Royal Society
I participated in the large international team of scientists that developed chiral organics for photon/electron spin control.
New projects starting!
Two new projects funded by Spanish Ministerio de Ciencia, Innovación y Universidades, will start very soon.
- “Microscopio de matriz de Mueller” (PDC2022-133625-I00).
- “Caracterización óptica de células solares altamente texturizadas para optimizar su eficiencia” (TED2021-129639B-I00).
Funding opportunities for interested students may be possible (contact me).
Listed in the “Stanford list”
For a second consecutive year, I have been listed in the list of the top 2% of most influential researchers in their field. The database gathers the leading scientists in different disciplines and is made from the information provided by the Scopus database.