In this paper, we present the tauCAM, a compact sub-nanosecond time-gated video framerate imaging camera, with our new 64×64-pixel Current-Assisted Photonic Sampler (CAPS) sensor. It features gating widths of less than 1 ns with a jitter of less than 60 ps rms on the gating width and less than 50 ps rms on the position. It has a quantum efficiency (QE) of more than 40% for near-infrared wavelengths. It’s peak QE is 61% at 675 nm. The sensor is fabricated in a conventional 350 nm CMOS process.

We give an overview of the design of the new camera hardware, with characterization of the timing circuitry and gating signals. Furthermore, the new sensor is discussed in detail. The revised pixel design yields improvements in QE, with high QE even for very short gating windows. Additionally, the Instrument Response Function of the pixel is characterized.

Time-resolved fluorescence spectroscopy is a promising and versatile spectroscopy technique. While conventional fluorescence spectroscopy is concerned with the spectral features of fluorescence emission, time-resolved fluorescence spectroscopy (TRFS) also captures the temporal behavior of the excited molecules. In addition to applications in rapid medical diagnoses, several applications were reported in forensics, chemical analysis and biology.

The existing TRFS systems are based on complex optical setups which results in bulky and large systems. Therefore, using them in practice is still not feasible. In this work, we present a miniaturized system that combines a compact Czerny-Turner based spectrometer layout with our high-speed time-gated image sensor of 32×32 pixels based on the Current-Assisted Photonic Sampler (CAPS) sensor.

The system operates in the visible wavelength range with a high spectral resolution. The novel image sensor is capable of measuring down to sub-nanosecond lifetimes. The proof-of-concept module was assembled and characterized for three fluorophores.