A revolutionary astronomical instrument is poised to change the way scientists see planets orbiting other stars, swapping traditional optics for the same kind of technology found in television and smartphone screens. The new device, known as the Programmable Liquid-crystal Active Coronagraphic Imager for the DAG telescope (PLACID), digitizes the process of blocking overwhelming starlight, a necessary step for detecting the faint light from an exoplanet. This new approach promises to open up previously hidden planetary systems for direct study.
Installed at the 4-meter Eastern Anatolian Observatory (DAG) in Turkey, PLACID uses a programmable liquid crystal-based mask to create an artificial eclipse inside the telescope. Unlike older coronagraphs that rely on fixed, precisely manufactured plates, this digital system can change its mask in an instant, offering unprecedented flexibility. This adaptability is crucial for studying complex star systems and marks a significant step toward the goal of directly imaging Earth-like worlds. The instrument is currently undergoing integration and is expected to capture its first scientific images in early 2026.
Reinventing the Coronagraph
For decades, the direct imaging of exoplanets has been stymied by a fundamental problem: planets are billions of times dimmer than their host stars. Spotting one is like trying to see a firefly next to a searchlight. The primary tool for this task is the coronagraph, an instrument that blocks the star’s light without dimming the light from a nearby planet. Traditionally, these have been static, physical masks carefully aligned inside the telescope. This method, while effective, is rigid and cannot be easily optimized for different stellar targets or changing conditions.
PLACID brings the coronagraph into the digital age. Instead of a fixed plate, it uses a device called a Spatial Light Modulator (SLM), which is essentially a high-resolution liquid crystal display. This is the same core technology used in everyday devices like computer monitors and phones. Each pixel on the liquid crystal screen can be individually controlled to alter the phase of the light passing through it. By programming a specific pattern into the display, astronomers can create a customized, complex mask that selectively cancels out the starlight with extreme precision. According to Ruben Tandon, a doctoral candidate at the University of Bern, this allows the team to generate any mask they want, giving them extreme adaptability.
From Static Plates to Dynamic Pixels
The transition from fixed optical components to a programmable liquid crystal array represents a major leap in instrument design. Older systems required a library of different masks, and swapping them was a complex physical process. The SLM in PLACID allows for instantaneous changes. This dynamic capability means the coronagraph can be actively optimized in real time to achieve the best possible performance for a specific observation. The project lead, Prof. Jonas Kuhn of the University of Bern, stated that PLACID will revolutionize the approach to coronagraphs. The goal is to move beyond the limitations of passive components and create a smarter, more responsive system for high-contrast imaging.
New Capabilities for Astronomers
The flexibility of a digital coronagraph opens the door to observing targets that were previously impossible to image directly. One of the most significant new areas of research will be planets in multiple-star systems. A large fraction of stars in the galaxy exist in binary or triple systems, but finding planets around them with direct imaging is exceptionally difficult for traditional coronagraphs. The complex and shifting light from two or more stars makes it hard for a static mask to effectively block the glare.
PLACID’s ability to adjust its mask in real-time is the solution. Astronomers can create custom light-blocking patterns tailored to the specific configuration of a multiple-star system at that exact moment. This will enable the first direct imaging of circumbinary planets—worlds that orbit two stars, reminiscent of the fictional planet Tatooine. Furthermore, the instrument is perfectly suited to study the swirling protoplanetary disks of gas and dust where planets are born. Observing these chaotic environments in multiple-star systems will provide crucial data for understanding how planets form and evolve in complex gravitational settings.
The Host Observatory and Strategic Importance
The PLACID instrument was developed and assembled in Switzerland over nearly a decade before being installed on the 4-meter telescope at the Eastern Anatolian Observatory (DAG) in eastern Turkey. This state-of-the-art facility, situated at a high altitude, provides the clear skies necessary for high-contrast imaging. The combination of a modern 4-meter class telescope with PLACID’s advanced coronagraphy creates a unique and powerful platform for exoplanet science.
For optimal performance, PLACID will work in tandem with an advanced Adaptive Optics (AO) system. The AO system, developed by a team at HEIG-VD in Switzerland, counteracts the blurring effect of Earth’s atmosphere by making minute, rapid corrections to the shape of a mirror. When paired, the AO system will provide a stable, corrected image, and PLACID will then remove the starlight. According to Derya Ozturk Cetni, PLACID’s instrument scientist at Turkiye National Observatories, this powerful combination will make the DAG telescope the first fully European facility in the northern hemisphere capable of directly imaging exoplanets.
Technical Integration and Future Goals
The path to discovering new worlds with PLACID is part of a broader push to advance direct imaging technology. Scientists believe this method holds the key to the future of exoplanet exploration. While indirect methods, like the transit technique, have discovered thousands of planets, they provide limited information. Direct imaging allows astronomers to capture photons from the planet itself, enabling the study of its atmosphere’s composition. Detecting molecules like oxygen or methane could provide hints about the presence of life.
Current direct imaging systems are largely limited to detecting massive, Jupiter-sized planets that are young, hot, and orbit very far from their stars. The technological advancements embodied by PLACID are stepping stones toward the ultimate goal: imaging smaller, rocky, temperate planets like Earth. Future missions, such as the proposed Habitable Worlds Observatory, will require coronagraphs capable of achieving contrasts 10,000 times better than current instruments to see an Earth-like planet next to a sun-like star. The development and on-sky validation of programmable liquid crystal coronagraphs like PLACID are essential for proving the technologies that will make those future discoveries possible.