IN Brief:
- Litavis combines 256 × 256 photon-counting imaging with a 64 × 64 macropixel timing architecture.
- In-pixel processing supports TCSPC, multi-event timing, histogramming, time gating, and simultaneous spatial and temporal measurements.
- Software-configurable operation targets machine vision, robotics, spectroscopy, medical imaging, quantum sensing, and industrial automation.
Singular Photonics has launched Litavis, a software-configurable single-photon image sensor combining photon-counting imaging, timing, histogramming, and photon statistics on one chip. The Edinburgh fabless semiconductor company describes the device as the first SPAD sensor to combine those functions through in-pixel processing, allowing operating modes to be changed in software without redesigning the sensor hardware.
Litavis uses single-photon avalanche diodes, or SPADs, which detect individual photon events by operating a semiconductor junction above its breakdown voltage. The resulting sensitivity makes the technology useful where light levels are low or where the arrival time of individual photons provides information beyond conventional image intensity.
The sensor provides continuous 256 × 256-pixel photon-counting imaging while generating time-stamped photon events through a 64 × 64 macropixel grid. Singular specifies approximately 37ps timing resolution and a 4.3ns dead time, while its current product data gives photon-detection efficiency of 47% at 785nm under the stated operating conditions.
That combination gives the device two related measurement layers. The full-resolution array records spatial intensity information, while the macropixel timing architecture captures temporal information at lower spatial resolution. The approach reduces the need to transfer every photon event off-chip simply to derive timing or statistical information elsewhere in the system.
Litavis supports several time-correlated single-photon counting and time-to-digital converter configurations using internal or external clocks. Other modes include high-dynamic-range photon counting, programmable time windows, coincidence detection, combined timestamping and imaging, multi-event timing, and in-pixel histogramming.
Multi-event timing allows several detected photons within an excitation cycle to be assigned individually to time bins rather than recording only a first event. Histogramming can then accumulate the distribution of those events close to the detector, providing information for applications including fluorescence lifetime imaging, dynamic light scattering, spectroscopy, depth measurement, and quantum sensing.
Moving part of that processing into the sensor changes the external electronics requirement. Raw photon-event streams can become large quickly, particularly across arrays operating at high event rates. Reducing that stream before it reaches an FPGA, processor, memory subsystem, or host computer can lower interface bandwidth and latency while reducing the amount of downstream computation required to produce a useful measurement.
The trade-off is greater programmability within the sensor itself. Timing modes, acquisition windows, counting behaviour, and histogram configuration become part of the application design, so firmware, calibration, and configuration control carry more responsibility than they would with a fixed-function imaging device.
Shahida Imani, chief executive of Singular Photonics, said: “Litavis combines the sensitivity advantages of SPAD technology with the adaptability and scalability increasingly required by modern multimodal imaging.” Singular says it has already received significant pre-order volumes from companies and institutions internationally.
The company is positioning Litavis across machine vision, robotics, physical AI, industrial automation, medical and scientific imaging, spectroscopy, depth sensing, and quantum technologies. Those markets share a need for information extracted from weak or time-varying light signals, but place very different demands on frame rate, timing precision, calibration, optical design, power, and data processing.
Litavis is a 3D-stacked backside-illuminated CMOS SPAD device measuring 3.5mm square. Its architecture places computational circuitry beneath the detector array, continuing Singular’s approach of moving digital processing closer to photon detection rather than treating the image sensor solely as a source of raw data.
The device joins Singular’s Andarta and Sirona sensor families and follows an August funding round intended to expand engineering capacity and accelerate new sensor development. Litavis will be demonstrated at SPIE Sensors + Imaging in Edinburgh and at VISION in Stuttgart.
For system designers, the attraction is the possibility of using one sensing platform for several measurement modes instead of building separate timing and imaging chains. Whether that reduces total system complexity will depend on the application, but putting photon counting, timing, and statistical processing inside the sensor gives engineers more scope to decide which data needs to leave the chip in the first place.
