Polvision Dermatoscope

We introduce a novel application of our patented Polvision technology, engineered specifically for advanced dermatological assessment. The new Polvision Dermatoscope integrates our state-of-the-art, real-time full-Stokes polarimetric camera with a custom ring LED illumination system that uses circularly polarized light.

This unique configuration allows the system to non-invasively capture a complete polarization dataset from the skin, measuring many critical parameters simultaneously:

  • Degree of Polarization (DoP)
  • Degree of Linear Polarization (DoLP)
  • Degree of Circular Polarization (DoCP)
  • Angle of Linear Polarization (AoLP)

Alongside this quantitative imaging data, a color image of the investigated region is also recorded, providing full clinical context.

Traditional dermatoscopes often struggle with polarization artifacts caused by surface reflection and skin topography. The Polvision Dermatoscope’s use of circular polarization as an illumination source fundamentally overcomes this limitation. This approach effectively minimizes sensitivity to superficial topographic effects, allowing the light to penetrate the epidermis and interact with subsurface structures.

Photo of our lab protype

Hower our full-Stokes sensor retains the ability to capture linear polarization signatures generated by birefringent structures within the dermis, such as collagen fibers. This dual capability—bypassing surface effect while remaining highly sensitive to subsurface biomarkers—provides an unprecedented diagnostic detail.

Cosmetic and Clinical Applications

Our technology platform enables two powerful, distinct applications for clinical and cosmetic dermatology.

Skin Age

The “skin age” of an individual may not correlate directly with their chronological age, as it is heavily influenced by extrinsic and intrinsic factors. The Polvision Dermatoscope offers a straightforward, quantitative method to evaluate skin health and age.

  • The Mechanism: In skin, the epidermis is a primary source of light scattering, a process that strongly depolarizes incident light. As a person ages, the skin undergoes significant structural changes, including the thinning of the epidermis.
  • The Biomarker: A thinner epidermis results in less light scattering. Consequently, the light reflected back to the sensor is less depolarized, registering a higher Degree of Polarization (DoP).
  • The Result: Our preliminary in-vivo studies (conducted on the dorsum of the hand of volunteers) demonstrate a clear and robust correlation between chronological age and the measured Degree of Polarization, with the DoP increasing significantly with age.

This capability unlocks a non-invasive, objective biomarker for tracking skin health, evaluating the efficacy of anti-aging treatments, and providing personalized patient consultations.

 

DoCP vs. Age measured with our prototype after examining the dorsum of the hand in more than 30 participants from our university. Each data point corresponds to the average value over a 1.8 × 1.5 cm region in the image. Complementary data at the bottom of the page.

 

Compared DoCP for two women of differents. Images are shown  on the same scale.

Quantitative Analysis of Skin Lesions

The Polvision Dermatoscope provides enhanced data to facilitate the differentiation of benign and malignant skin lesions. By analyzing a lesion’s complete polarization signature—the system can detect subtle changes in tissue architecture that are invisible to the naked eye.

Generally, high melanin content in a lesion (which will make it appears dark) increases the DoP. This occurs because melanin’s strong light absorption dramatically reduces multiple scattering which is the primary depolarizing effect. However, this DoP elevation will occur in both benign and malignant lesions, so additional contrast is needed.

  • Benign Lesions (e.g., Nevi): These features are typically non-invasive. Even if highly pigmented (which will highly increases the DoP), they preserve the organized, birefringent collagen network of the dermis. This results in a significant high Degree of Linear Polarization (DoLP), indicating structural integrity. I.e. the collagen matrix will convert part of the incomming circular polarizated into linear polarization.
  • Malignant Lesions (e.g., Melanoma): Malignancy is characterized by invasive, chaotic growth that actively degrades and destroys the dermal collagen network. This architectural breakdown causes a significant loss of birefringence and a corresponding low levels of DoLP signal (note that DoCP and DoP will be still high for heavily pigmented lesions).
Nevus: The lesion is bright in both the DoP (pigmented) and DoLP images. The high DoLP signal (right) is the key identifier, proving the underlying collagen structure is intact and the lesion is benign.

Who We Partner With

We are seeking strategic partners to integrate our unique tissue analysis technology into medical and aesthetic applications.

  • Medical Dermatology & Oncology: For clinics and hospital networks seeking to improve skin cancer diagnostic accuracy and reduce unnecessary biopsies.
  • Cosmetic & Anti-Aging: For aesthetic clinics and brands that need to objectively measure skin health, and track the efficacy of anti-aging treatments.
  • Medical Device Distributors: To add a breakthrough, dual-market platform (oncology and aesthetics) to your advanced imaging portfolio.
  • AI & Imaging Companies: To leverage our exclusive polarization data, adding deep structural biomarkers (like collagen integrity) to your diagnostic algorithms.

Further data

All parameters at adquired at video-rate (10-20 fps). This is capture of how real-time data is visualized.

 

Example: hand dorsum under real-time stretching.

 

More polarimetric parameters vs age

New group members

In September 2025, several new members joined the group:

  • Miguel Ares has joined as technical staff under the POLVISION project. He is working on further developing applications and software for our patentend full-Stokes polarization camera.

  • Shuang Chen is a new PhD student from Huaqiao University (Xiamen, China). During his Master’s studies, he carried out excellent work on visibility enhancement using polarimetry. In our group, he will focus on new approaches to polarimetric imaging and on designing novel operating modes for our spectroscopic polarimeters and ellipsometers.

  • Lourdes Camblor is also a new PhD student. She completed the Photonics Master’s program (UPC/UB/UAB) and will be working on methods to encode spectral information using polarization.

Additionally during September and October 2025 my lab hosts PhD students Guang Chen and Luobin Chen from Jiliang University in Hangzhou (China).

Technology Transfer Opportunities in Polarization Instrumentation

In the last years, we have had some proof-of-concept or “product” projects to develop  cutting-edge polarization imaging and measurement solutions. We are currently seeking partners interested in licensing our technologies. While our primary goal is to collaborate with companies for technology transfer, we very much welcome inquiries from end-users who may benefit directly from our instruments.

We have three self-developed polarization devices, each offering unique capabilities not available in commercial systems. Click on the links to get detailed information on each device.

1. Mueller Matrix Microscope

A high-precision imaging system capable of capturing the Mueller matrix at microscopic resolution in a quick and efficient way. Ideal for advanced material characterization, biomedical research, and nanostructure analysis.

Key features:

  • Full polarimetric characterization at the microscale

  • Quantitative mapping of birefringence, dichroism, and depolarization

  • Compatible with a wide range of samples, from biological tissues to photonic devices

  • Video-rate birefrigence mapping.

2. Full-Stokes Polarization Camera

A compact, real-time imaging system that measures all four Stokes parameters (also the last one!) in a single snapshot. Designed for environments where speed and robustness are critical.

Key features:

  • Instantaneous full polarization capture

  • High sensitivity in both natural and controlled lighting

  • Applicable to remote sensing, industrial inspection, and vision enhancement in scattering media


3. Snapshot Generalized Ellipsometer

A novel spectroscopic instrument for instantaneous ellipsometry measurements, enabling full characterization of materials without moving parts or sequential acquisition.

Key features:

  • Measures generalized ellipsometric parameters in a single shot

  • Suitable for dynamic samples and processes, or mapping/imaging optical properties

  • Good spectral compatibility


Partner With Us

Our technologies are the result of years of research in Mueller matrix polarimetry and advanced optical instrumentation. By partnering with us, companies can integrate these unique solutions into their product portfolios with reduced development time and risk. All our technology transfer activities are carried out in collaboration with Fundació Bosch i Gimpera which is the tech transfer office of Universitat de Barcelona.

If you are interested in licensing, co-development, or direct acquisition, please contact me to explore opportunities.

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.

Visualization of beetles illuminated with right-circular polarization.

 

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.

Figure 5

  • 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

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.