Advanced TCSPC electronics and their use in general quantum physics and demanding analytical applications

Abstract

Time-Correlated Single Photon Counting (TCSPC) is a very powerful method for sensitive time-resolved optical measurements. Its main application was historically the measurement of fluorescence lifetime. This application is still important, however, improvements over the early designs allow the recovery of much more information from the collected photons and enable entirely new applications. In conventional TCSPC instruments the timing signals are processed by a Time to Amplitude Converter (TAC) and subsequent Analog to Digital Converter (ADC) which provides digital values to address a histogrammer. TAC and ADC must guarantee a very good linearity and short dead time. These criteria are difficult to meet simultaneously, particularly at high resolution. Even with highest technically feasible ADC resolution, the time span such a system can measure at high temporal resolution is very limited. Here we present a new TCSPC system overcoming these limitations, based on Time to Digital Converters (TDC). This allows not only picosecond timing, but can also extend the measurable time span to virtually any length by means of digital counters. Our new design uses two such circuits that work independently on each input channel but with a common crystal clock. The timing circuits are therefore precisely synchronized and provide picosecond arrival times that can be processed further in any conceivable manner. Due to the symmetrical design without any ab initio assignment of dedicated start and stop inputs, the processing provides significantly more options than in conventional TCSPC systems, while still embracing the classical case. We present measurement data and results from applications in general quantum physics as well as analytical applications including confocal time resolved fluorescence microscopy at the single molecule level.

Single‐Molecule Fluorescence Spectroscopy of Protein Folding

“…[61,73,89] An important development for the wide application of single-molecule methods to the study of biomolecules is the recent availability of comprehensive commercial instrumentation. [92] …”

A Low-Cost Test Method for Accurate Detection of Different Excited-State Species with a Lifetime Span over 5 Orders of Magnitude in One Time Window

“…Excitingly, in 2007, Wahl et al. disclosed that when an appropriate time-to-digital converter (TDC) module was introduced into a TCSPC system, the resultant instrument can run repeatedly and continuously over multiple events, through which not only picosecond timing can be realized, but also the measurable time span can even be extended to any length . Inferred from these discoveries, we conjectured that if an unequal-time-channel working manner can be implemented in TDC-modified TCSPC systems, the accurate quantification of S PF and S DF of a TADF fluorophore in just one time window may be realized.…”

“…Excitingly, in 2007, Wahl et al disclosed that when an appropriate time-to-digital converter (TDC) module was introduced into a TCSPC system, the resultant instrument can run repeatedly and continuously over multiple events, through which not only picosecond timing can be realized, but also the measurable time span can even be extended to any length. 30 Inferred from these discoveries, we conjectured that if an unequal-timechannel working manner can be implemented in TDCmodified TCSPC systems, the accurate quantification of S PF and S DF of a TADF fluorophore in just one time window may be realized. Nevertheless, although firms such as Horiba, PicoQuant, Hamamatsu, and Edinburgh Instruments have already issued some TCSPC systems bearing certain TDC accessories, 31−34 all these TDC modules are merely designed to promote faster data acquisition and cannot work in an unequal-time-channel manner due to the lack of appropriate hardware and software.…”

Introduction

“…In addition to quantum-information, single-photon detectors are used for a wide variety of applications, including DNA sequencing [95][96][97][98], bioluminescence characterization [99], Förster resonance energy transfer for protein folding observation [100][101][102], light detection and ranging for remote sensing [103,104], and light ranging on shorter scales [105], optical time-domain reflectometry [106][107][108][109][110][111][112], picosecond imaging circuit analysis (PICA) [113][114][115][116][117][118], single-molecule spectroscopy [119][120][121][122][123][124][125] and fluorescencelifetime measurements [126], medical applications such as diffuse optical tomography [127] and positron emission tomography [128], and finally, singlephoton metrology [26,[129][130][131][132][133][134][135][136]]. …”