Developed by researchers at the University of Bern and the University of Applied Sciences Western Switzerland in Yverdon (HEIG-VD), PLACID will join a select group of high-contrast imaging systems in the northern hemisphere. Its innovative approach and upcoming science capabilities were presented at the EPSC-DPS2025 Joint Meeting in Helsinki.
Most of the nearly 6000 known exoplanets have been detected through indirect techniques that track subtle shifts in a host star's light or position. Direct imaging, however, requires masking a star's glare to reveal nearby planets, discs, or brown dwarfs - a process enabled by a coronagraph. Because an exoplanet is billions of times fainter than its star, only a few dozen have been directly imaged to date, though these rare observations yield unique insights into planetary formation and atmospheric composition.
"With recent developments in technology and the construction of increasingly large telescopes, the future of exoplanet detection lies in direct imaging. PLACID is one of the stepping stones towards this future," said Prof Jonas Kuhn of the University of Bern, who leads the project. "It will revolutionise our approach to coronagraphs and bring them into the digital domain."
Instead of relying on static, precisely aligned physical plates, PLACID uses a Spatial Light Modulator (SLM) based on liquid crystals to digitally shape light. Each pixel on the SLM can adjust the optical phase of incoming light waves, allowing researchers to generate custom masks instantly.
"We use SLM screens all the time in every-day devices, such as our phones, TVs or computers. In PLACID, the liquid crystals influence how the light passes through each pixel, so we can display any mask we want, giving us an extreme adaptability," explained Ruben Tandon, a doctoral candidate at the University of Bern.
This adaptability makes PLACID uniquely capable of directly imaging circumbinary planets and proto-planetary discs around multiple-star systems. Traditional coronagraphs struggle with such configurations because each system's geometry requires bespoke optical plates. Since roughly half of all stars are part of binary or multiple systems, PLACID's flexibility opens an entirely new observational frontier.
"With PLACID, we can simply adapt the mask in real time to perfectly block the light of any star systems we choose to observe through the night," Tandon said. "While we will start by targeting the small number of exoplanets that have already been directly imaged to better understand the instrument behaviour, our next step will be to try to directly image exoplanets orbiting binary stars, which will be a first."
The instrument, nearly a decade in development, was assembled at HEIG-VD's Swiss laboratories before being shipped to Turkey in early 2024 and installed at the DAG telescope in January 2025. Backed by Switzerland's NCCR PlanetS and the University of Bern's Division of Space Research and Planetary Science, PLACID also received funding from Turkiye National Observatories and the European Research Council.
For optimal performance, PLACID will operate in tandem with an Adaptive Optics (AO) system developed by Prof Laurent Jolissaint's team at HEIG-VD, which compensates for atmospheric turbulence. Together, these systems will make the DAG telescope the first fully European facility in the northern hemisphere capable of directly imaging exoplanets.
"We are happy to welcome PLACID. Its capacities, coupled with our 4-meter class telescope, will lead to the first fully-European instrument in the northern hemisphere able to directly image exoplanets," said Derya Ozturk Cetni, PLACID's instrument scientist at Turkiye National Observatories.
Research Report:The Programmable Liquid-crystal Active Coronagraphic Imager for the 4-m DAG telescope (PLACID) instrument: Discovery Space and Status
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