Scientists from Singapore have developed a new light-field sensor with unprecedented angular resolution - 0.0018 °. It has many applications, the most popular of which promises to be volume holographic communication - like in "Star Wars". This is encouraged by a person's innate binocular vision, for which a three-dimensional picture is trivially more informative as opposed to a flat screen without depth of scene.
A light field is a more or less complete set of such data about a scene or field of vision as the direction of light propagation (angle of view) and its intensity in that direction. Rays of light with their color and intensity are reflected from each object visible to us in the field of view. Each eye sees and captures these rays with unprecedented resolution, and the final picture is collected in our brain. We see everything without "pixels"-as a continuous image.
With technology, it's still complicated. There are simply no sensors with the same resolution as the eye and the ability to record beams at different angles, and even those that are available - with relatively low resolution - must be maintained with a high computational load. The photo below shows a 17-inch stereoscopic light-field display from JDI in Japan as an example, with an 8K stereoscopic video player on the right.
Researchers at the National University of Singapore used an unusual and somewhat expected material, perovskite, to create a highly sensitive light-field sensor. Over the past decade or so, perovskite has been seen as a promising semiconductor for photovoltaic applications and beyond. One of its interesting properties is the ability to change sensitivity in a wide range of electromagnetic waves from ultraviolet to visible and further to X-rays with the help of impurities.
By the way, this is also an important factor in the new development. Imagine a surgical device capable of accurately scanning the human body in depth and building a three-dimensional image for the surgeon during surgery. Previously developed light-field sensors were not capable of this.
Researchers from Singapore have applied an array of perovskite nanosensors to a thin, transparent substrate. To each sensor perpendicularly (to collect more information about the light signal) attached another nanosensor from perovskite, and below the substrate placed a regular color CCD. The essence of the development is that each nano-sensor lights up a certain color for a strictly defined angle of incidence of light. Thus, the angle of incidence of light is encoded in color, which is perfectly readable by the CCD matrix.
According to the developers, this allows to record the light field of the scene with unprecedented angular resolution - in the perspective of less than 0.015 ° and spectral sensitivity from 0.002 nm to 550 nm. Alternative developments are far from such figures, as reported in a recent issue of Nature.
"Currently, light field detectors use an array of lenses or photonic crystals to produce multiple images of the same space from different angles. However, integrating these elements into semiconductors for practical use is a difficult and expensive task," explained Professor Liu Xiaogang. - Traditional technologies can only detect light fields in the wavelength range from ultraviolet to visible light, which leads to limited applications in X-ray sensing.
The developers have already applied for an international patent for the invention. In the future, they will focus on methods to improve the spatial accuracy and resolution of their light-field sensor, for example by using higher-grade color detectors.
