PURELIGHT: a quantitative photon-counting framework unifying intensity and lifetime imaging at video rate across detector technologies
The paper introduces PURELIGHT, a unified hardware and software framework that eliminates photon pile-up distortions in time-correlated single-photon counting, enabling video-rate, quantitative fluorescence microscopy with accurate intensity and lifetime measurements across diverse detector technologies.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
In the world of biological research, scientists often need to see the invisible machinery of life working inside a living cell. To do this, they use a technique called fluorescence microscopy, where tiny molecules are tagged with special dyes that glow when hit by light. This glow provides two crucial pieces of information: how bright the light is, which tells researchers how many molecules are present, and how long the glow lasts after the light pulse hits, which reveals the chemical environment around the molecule. For decades, the most precise way to measure both of these things at once has been a method that counts individual particles of light, one by one. However, this method has a strict speed limit. If too many light particles arrive at the detector at the same time, the system gets confused and starts to miss data or record false information. This bottleneck has forced scientists to choose between taking slow, careful measurements or fast, blurry ones, effectively locking high-speed, high-precision imaging out of many dynamic biological processes.
A team of researchers has now introduced a new framework called PURELIGHT that breaks this speed limit. This system combines new hardware and software to fix the confusion that happens when too many light particles arrive at once, a problem known as photon pile-up. Instead of discarding the extra light or accepting distorted data, the new framework mathematically untangles the signals to recover the true brightness and the true duration of the glow, even when the light is arriving at rates far beyond what previous systems could handle. The researchers demonstrated that this approach works across different types of light-sensing equipment, including hybrid photodetectors, silicon photomultipliers, and photomultiplier tubes. By keeping more of the light particles that were previously lost, the system retains over three times more photons than alternative correction methods, allowing for a much clearer and more accurate picture of the biological activity.
The power of this new framework was tested using a powerful imaging technique that uses two beams of light to see deep inside living tissue. In these experiments, the researchers were able to capture video-rate images of subcellular structures inside the brains of awake mice. This means they could watch tiny parts of cells change their chemical environment in real time, something that was previously impossible with this level of precision. The system also enabled a unique way to measure ratios of different signals without interference and allowed multiple time-based signals to be sent and received without mixing up. By removing the speed barriers that have confined this type of precise measurement to slow, low-light situations, the researchers have opened the door for quantitative microscopy to be used more widely across the life sciences, allowing scientists to observe the fast, complex movements of life with a clarity that was previously out of reach.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.