Intensified optical camera with Timepix4 readout

TL;DR

This work demonstrates a time-stamping optical camera based on Timepix4 readout, coupled to a fully depleted optical silicon sensor and a fast image intensifier, achieving sub-nanosecond timing for single-photon events. Timepix4 delivers a 195 ps ToA bin and a larger 512×448 pixel matrix with high throughput, representing a significant improvement over Timepix3. Key results show non-intensified timing down to ~0.32 ns and intensified timing improvements to the 0.6–1.5 ns range after timewalk corrections, with performance sensitive to sensor bias, scintillator response, and ToT selection. The findings establish Timepix4-based optical cameras as scalable platforms for quantum optics, ultrafast imaging, and time-correlated photon counting, and point to avenues for further gains via faster scintillators or alternative sensor technologies.

Abstract

We report the first characterization results of an optical time-stamping camera based on the Timepix4 chip coupled to a fully depleted optical silicon sensor and fast image intensifier, enabling sub-nanosecond scale, time-resolved imaging for single photons. The system achieves an RMS time resolution of 0.3 ns in direct detection mode without the intensifier and from 0.6 to 1.5 ns in the single-photon regime with an intensifier for different amplitude-based signal selections. This shows that Timepix4 provides a significant improvement over previous Timepix3-based cameras in terms of timing precision, and also in pixel count and data throughput. We analyze key factors that affect performance, including sensor bias and timewalk effect, and demonstrate effective correction methods to recover high temporal accuracy. The camera's temporal resolution, event-driven readout and high rate capability make it a scalable platform for a wide range of applications, including quantum optics, ultrafast imaging, and time-correlated photon counting experiments.

Figures (8)

• Figure 1: Left: Experimental setup with intensified camera and 450 nm laser with pulse duration of 90 ps, triggered with a pulse generator running at 185 kHz. The fiber-coupled light flash had provisions to be attenuated before collimation onto the camera. The measurements have been performed with and without an intensifier, but only the intensified configuration is shown here. Right: the camera (x,y) occupancy map in configuration with an intensifier for a focused beam.
• Figure 2: Left: Distribution of measured distances between consecutive TDC pulses demonstrating the laser stability; Right: Two-dimensional distribution of time differences between the laser synchronization signal and ToA of one of the hit Timepix4 pixels versus the pixel ToT. The pixels were activated with a direct flash of light from the laser.
• Figure 3: Left: Distribution of time differences between the laser synchronization signal and ToA of one of the hit Timepix4 pixels without any TOT range selection. Right: Distribution of time differences between the laser synchronization signal and ToA of one of the hit Timepix4 pixels with TOT selection in a 25 ns slice shown in Figure \ref{['fig:nointensifier']} (right). The measurements were performed at a bias voltage of 50 V.
• Figure 4: Left: Distribution of ToT versus time difference between the laser and pixel. The TOT selection in a 200 ns range, from 2000 to 2200 ns, is indicated with red dashed lines. Right: Distribution of time differences between the laser synchronization signal and ToA of one of the hit Timepix4 pixels with TOT selection in the 200 ns range fit with a Gaussian function. The measurements were performed at a bias voltage of 70 V.
• Figure 5: Left: results of the Gaussian fit for the mean values as a function of ToT. The mean values are marked with red dots on the top of the time difference versus the ToT distribution. Right: time difference distribution versus ToT after the timewalk correction.