Scientists create high-speed coding system

January 23, 2018, National Research Nuclear University

Scientists of the National Research Nuclear University MEPhI (Russia) have proposed a scheme for optical encoding of information based on the formation of wave fronts, and which works with spatially incoherent illumination. This scheme is effective in creating highly secure, high-speed coding systems. Security is provided by the two-dimensionality of dynamically replaced coded keys. The study is published in Laser Physics Letters.

Scientists from around the world are actively conducting research on the creation of optical encoding systems. The main direction of such studies is the encoding of advanced optical information systems with fully coherent laser illumination. Such studies are incompatible with standard cameras, because they require the use of complex holographic methods and are focused on a next-generation elemental base.

The development of optical coding using spatially incoherent quasi-monochromatic (single color) illumination is regarded as a more effective approach. This provides the possibility of hardware implementation on the basis of commercially available photo and video cameras.

In this case, information for encoding is displayed as a QR code on the LCD amplitude-spatial light that is illuminated by monochromatic laser radiation. Radiation is passed through a rotating frosted diffuser, which destroys the spatial coherence. The researchers used a liquid-crystal phase light modulator as the encoding , where pre-synthesized diffraction optical elements are displayed. The camera's image sensor detects the optical convolution of the image that is produced by the amplitude modulator with the pulse response of the diffractive element, derived on the phase modulator.

The use of such modulators allows changing encoding keys in real-time. Decoding is performed by software-based method of digital deconvolution (inverse convolution in signal processing) with stabilization solution.

The scientists successfully encoded and decoded the images of QR codes with a size up to 129×129 elements. The percentage of erroneously decoded pixels didn't exceed 0.05 percent. This is a high ratio of signal to noise.

"The novelty of our work is, first, in the application of monochromatic spatially incoherent illumination of the encoding scene – it allows you to avoid the speckle noise and does not require holographic methods of registration. Second, the use of computer-synthesized phase diffractive elements allows you to generate required coding wave front and minimizes the loss of radiation in the system," said Associate Professor Vitaly Krasnov.

Explore further: Researchers achieve major improvement for lensless computational microscopy

More information: P A Cheremkhin et al. QR code optical encryption using spatially incoherent illumination, Laser Physics Letters (2017). DOI: 10.1088/1612-202X/aa5242

Related Stories

Quasi noise-free digital holography

December 29, 2016

Noise originating from the coherent nature of laser light is the scourge of digital holography, reducing the quality of holographic images below that of conventional photographs. Now, Pasquale Memmolo of ISASI-CNR and collaborators ...

Optoelectronics without glass

November 3, 2017

Researchers at ETH Zurich have developed the first opto-electronic circuit component that works without glass and is instead made of metal. The component, referred to as a modulator, converts electrical data signals into ...

X-ray imaging with a significantly enhanced resolution

August 15, 2017

Physicists from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Deutsches Elektronen-Synchrotron (DESY, Hamburg) have developed a method to improve the quality of X-ray images over conventional methods. The ...

Recommended for you

New thermoelectric material delivers record performance

January 17, 2019

Taking advantage of recent advances in using theoretical calculations to predict the properties of new materials, researchers reported Thursday the discovery of a new class of half-Heusler thermoelectric compounds, including ...

Zirconium isotope a master at neutron capture

January 17, 2019

The probability that a nucleus will absorb a neutron is important to many areas of nuclear science, including the production of elements in the cosmos, reactor performance, nuclear medicine and defense applications.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.