CaeSaR Tags – unclonable patterns for secure authentication

  • University of Luxembourg
  • From Luxembourg
  • Responsive
  • Innovative Products and Technologies

Summary of the technology

The CaeSaR tag, functioning as a Physical Unclonable Function (PUF), can be integrated in the item during production or printed or coated afterwards, as most suitable. Manual coating can be done as simple as applying a drop of nail polish whereas rapid automized coating would be realized by depositing a liquid droplet onto the target surface, cured into a solid by brief UV illumination. Read-out can be done with a mobile device together with low-cost optical components.

University of Luxembourg

Details of the Technology Offer

Cholesteric Spherical Reflector (CSR; CaeSaR) are omnidirectional chiral Bragg reflectors, which means that they strongly reflect a narrow wavelength range (color) of light with specific (circular) polarization in every direction when illuminated. Bringing several CSRs of slightly different types into a locked-in random arrangement leads to dynamic optical pattern formation by optical cross communication between the CSRs. Because the location, color and polarization of each spot in this pattern is uniquely defined by the arrangement of CSRs and how the tag is illuminated and viewed, the tag comprises a unique fingerprint for the protected object, which cannot be cloned or simulated.


– Tags can be made visible or invisible, as desired, for overt or covert labels. They can be applied to any shape of surface, added as a coating or integrated near the surface during production of the item to be protected/tracked.

– Each tag generates an extremely rich set of unique optical patterns, with large variations depending on
viewing angle, illumination direction, illuminated/viewed area and wavelength and polarization of light

– Circular polarization of reflected light makes a tag easy to detect for the right device, although it is invisible to humans.


A fundamental method for making the CSRs in a way that their optical performance is maximized and that scattering due to refractive index mismatch with the surrounding is avoided has been patented (pending). Applications are in progress for patents related to the read-out technology, recognition algorithms, methods for upscaling CSR production to industrial scale, and for realizing the rapid-solidifiable matrix material.

Attached documents

Related Keywords

  • Smart Appliances
  • Colours and varnish
  • Composite materials
  • Fine Chemicals, Dyes and Inks
  • Industrial Technologies
  • Colours, dyes related to Chemical Technology and engineering
  • Industrial Products
  • Chemicals and Materials
  • Coatings and adhesives manufactures

About University of Luxembourg

The University of Luxembourg, founded in 2003, is multilingual, international and strongly focused on research. Its students and staff have chosen a modern institution with a personal atmosphere, close to the European institutions, international companies and the financial place.

Teaching, research and knowledge transfer at the highest international level: those are the goals that this university set from the start. With 270 professors, associate professors, assistant professors and senior lecturers, students from 130 different countries and lecturers originating from 20 different countries, the University offers a multicultural environment. Exchange agreements and research cooperations exist with 354 universities around the world.

About 6,783 students (Bachelor, Master, PhD/Doctorate, learning courses, vocational training and lifelong learning) can choose from over 60 degrees, offered by:
- The Faculty of Science, Technology and Medicine,
- The Faculty of Law, Economics and Finance,
- The Faculty of Humanities, Education and Social Sciences.

The central research priorities of the University of Luxembourg are:
- Materials Science
- Computer Science & ICT Security
- European and International Law
- Finance and Financial Innovation
- Education
- Digital and Contemporary History

as well as cross-disciplinary themes (details at
- Health and Systems Biomedicine
- Data Modelling and Simulation (formerly known as Computational Sciences)

University Rankings
- Among the top 250 universities in the Times Higher Education (THE) World University Rankings 2021.
- No. 3 worldwide in the THE “international outlook” Rankings 2021.
- No. 20 worldwide in the THE Young University Rankings 2021.

University of Luxembourg

Never miss an update from University of Luxembourg

Create your free account to connect with University of Luxembourg and thousands of other innovative organizations and professionals worldwide

University of Luxembourg

Send a request for information
to University of Luxembourg

About Technology Offers

Technology Offers on Innoget are directly posted
and managed by its members as well as evaluation of requests for information. Innoget is the trusted open innovation and science network aimed at directly connect industry needs with professionals online.


Need help requesting additional information or have questions regarding this Technology Offer?
Contact Innoget support