8-channel acquisition system for time-correlated single-photon counting

Abstract

Nowadays, an increasing number of applications require high-performance analytical instruments capable to detect the temporal trend of weak and fast light signals with picosecond time resolution. The Time-Correlated Single-Photon Counting (TCSPC) technique is currently one of the preferable solutions when such critical optical signals have to be analyzed and it is fully exploited in biomedical and chemical research fields, as well as in security and space applications. Recent progress in the field of single-photon detector arrays is pushing research towards the development of high performance multichannel TCSPC systems, opening the way to modern time-resolved multi-dimensional optical analysis. In this paper we describe a new 8-channel high-performance TCSPC acquisition system, designed to be compact and versatile, to be used in modern TCSPC measurement setups. We designed a novel integrated circuit including a multichannel Time-to-Amplitude Converter with variable full-scale range, a D∕A converter, and a parallel adder stage. The latter is used to adapt each converter output to the input dynamic range of a commercial 8-channel Analog-to-Digital Converter, while the integrated DAC implements the dithering technique with as small as possible area occupation. The use of this monolithic circuit made the design of a scalable system of very small dimensions (95 × 40 mm) and low power consumption (6 W) possible. Data acquired from the TCSPC measurement are digitally processed and stored inside an FPGA (Field-Programmable Gate Array), while a USB transceiver allows real-time transmission of up to eight TCSPC histograms to a remote PC. Eventually, the experimental results demonstrate that the acquisition system performs TCSPC measurements with high conversion rate (up to 5 MHz/channel), extremely low differential nonlinearity (<0.04 peak-to-peak of the time bin width), high time resolution (down to 20 ps Full-Width Half-Maximum), and very low crosstalk between channels.

Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

“…Similar results were obtained with all the available FSRs, i.e., 11, 22, 45, and 88 ns. 26 In order to measure the DNL of the F-TAC, the outputs of two pulsers working at different frequencies were used as start and stop signals, thus being these signals uncorrelated. Experimental results were quite similar for all the eight tested channels and the available full-scale ranges.…”

“…A first prototype of the F-TAC was implemented by exploiting an 8-channel acquisition board, 26 developed in our lab. The board, whose schematic is reported in Figure 9, includes two four-channel integrated TAC chips whose outputs are fed to a commercial, eight-channel ADC (Analog Devices AD9252) featuring 14 bit resolution and a maximum conversion rate of 50 Msps.…”

16-Ch time-resolved single-molecule spectroscopy using line excitation

“…4. The 16-channel TCSPC module is based on integrated time-to-amplitude converters (TAC) and has a mean resolution of 3.3 ps (minimum TCSPC bin size) and 2 14 bins (~50 ns measurement window). Due to the internal TAC architecture, the TCSPC resolution (i.e.…”

“…12, 13 Their configuration involved a linear microfluidic channel in which single-molecule flowed through the line excitation and a electron-bombarded CCD camera for detection. Here, we use a simple standing drop, freely-diffusing single molecule sample and a 16-pixel SPAD array connected to a 16-channel TCSPC module, 14, 15 demonstrating high-throughput lifetime-based smFRET measurements on simple model DNA molecules.…”

Diffuse optical mammotomography: state-of-the-art and prospects

“…The streak-camera is a large-size device with a limited field of view, nonlinear temporal characteristic and relatively narrow dynamic range, not adapted for use in multichannel detection systems. Therefore, in time-domain DOT the digital registration is preferred with the use of multi-cathode micro-channel PMTs operating in the mode of time-correlated single photon counting [224,231,[233][234][235]. Fig.…”