Design of digital correlation systems for low-intensity precision photon spectroscopic measurements

Architectures and design considerations for correlators to be used in single photon spectroscopy with a large spread of time offsets (lag times) are investigated. An extraordinary dynamic range of 10¹² is achieved by using the multiple sampling time architecture, where the sampling time is increased systematically for larger correlation time intervals. Short sampling times below 10 ns, important for the analysis of fast processes, are achieved by partitioning of the system into a fast semi-custom ASIC and an off the shelf digital signal processor (DSP). Accuracy aspects and normalisation issues of correlator architectures are discussed and performance and hardware efficiency are compared to existing solutions