NUS scientists are developing a new light sensor for building 3D movies at an unprecedented resolution. Color-coding systems for dynamic imaging have potential applications in areas such as autonomous driving, virtual reality and biological imaging.
A research team from the Faculty of Science of the National University of Singapore (NUS), led by Professor Liu Xiaogang from the Department of Chemistry, has developed a 3D imaging sensor with extremely high dimensional resolution, which matches the ability of optics to distinguish.
The points of the object are separated by a small angular distance, of 0.0018o. This new sensor works with a unique color and angle reflection pattern, allowing it to detect 3D light sources across the spectrum from X-rays to visible light.
The light source includes light connections and the direction of light rays, which the human eye can adjust to accurately determine the relationship between objects. Traditional light-sensing technologies don’t work very well. Most cameras, for example, can only produce two-dimensional images, which is good enough for casual photography but not good enough for advanced applications including virtual reality, self-driving cars and biological imaging. These applications require the construction of an accurate 3D position of a particular space.
For example, self-driving cars can use space detection to see the street and better identify road hazards to adjust their speed appropriately. Field vision can also allow surgeons to image the patient’s body in a more accurate way, allowing them to make more precise incisions and make better diagnoses. patient risk of injury.
“Currently, light detectors use multiple lenses or photonic crystals to acquire multiple images of the same lens from many different angles. However, combining these with semiconductors for practical use is complex. distant and expensive,” explained Professor Liu. “Comparative technologies can only detect light in the short range from ultraviolet to visible light, leading to extreme limitations in X-ray detection.”
In addition, compared to other light sensors such as microlens arrays, the light sensor of the NUS group has a uniform size of more than 80 degrees, a high resolution that can be less than 0.015 degrees for small sensors, and Broad spectral response is between 0.002 nm and 550 nm. These details enable the new sensor to capture 3D images with high depth resolution.
The breakthrough was published in the prestigious journal Nature on May 10, 2023.
Made possible by perovskite nanocrystals
At the heart of the new light sensor are inorganic perovskite nanocrystals – compounds with excellent optoelectronic properties. Due to their controlled nanostructures, perovskite nanocrystals are efficient light emitters, with a wide range of excitations extending from X-rays to visible light. The relationship between perovskite nanocrystals and light rays can also be adjusted by carefully changing their composition or introducing small impurity atoms.
The NUS researchers formed perovskite crystals and thin transparent films and attached them to a color-coded device (CCD), which converts incoming light signals into output color signals. This crystal conversion system includes one active part of the light sensor.
When incident light hits the sensor, the nanocrystals are excited. In turn, perovskite units emit their own light in different colors depending on the angle of incoming light. The CCD captures the output color, which can be used to reproduce 3D images.
“One single value, however, is not enough to determine the absolute position of the object in three spaces,” said Dr. Yi Luying, a researcher in the Department of Chemistry at NUS and the first author of the paper. “We found that adding another crystal detector to the side of the original detector and combining it with an optical scanning system can provide even more spatial information about the object in question.”
They tested their bright field sensor in a proof-of-concept and found that their approach can capture realistic 3D images – in deep depth and detail – of objects placed 1.5 meters away.
Their tests also showed the ability of the new light sensor to resolve even fine details. For example, a sharp image of a computer keyboard was created that captured the shallow keystrokes of individual keys.
Future research
Professor Liu and his team are exploring ways to improve the spatial accuracy and resolution of their light sensors, such as using advanced color detectors. The group has filed an international patent for the technology.
“We will explore the advanced technologies to make perovskite crystals more abundant and with an infinite number of seeds, which can lead to a better resolution of space.
The use of other materials other than perovskite can also expand the variety of the light sensor,” said Professor Liu.
Source: National University of Singapore
