Hermes is a single photon counting camera based on a 2-D imaging array of 64 x 32 smart pixels. Each pixel comprises a single-photon avalanche diode detector, an analog front-end and a digital processing electronics. This architecture allows for single-photon sensitivity, high electronic noise immunity, and fast readout speed. The imager can be operated at a maximum frame rate of about 96’000 frames per second with negligible inter-frame dead time. The camera differs from conventional Charge-Coupled Devices or CMOS sensors because it performs a “fully digital” acquisition of the light signal. Each pixel effectively counts the number of photons which are detected by the sensor during the acquisition time. 

    At the maximum frame-rate photon-counting dynamics is 8-bit, but camera processing electronics allows noiseless frame-binning, thus providing higher dynamics at lower framerates. It features also high photon-detection efficiency in the visible and near UV spectral region, very low dark-counting rates, even at room temperature and very low detector dead-time.

    Each pixel includes three independent gate-able counters, two of them with up-down capability for lock-in acquisition. Such gating capability enables the counting during specific time-windows only, which means that the Hermes camera can also be used for Fluorescence Lifetime Imaging (FLIM) or for indirect ranging measurements (iTOF). The high-speed gated-mode FLIM acquisition is fully automated by the camera and can be enabled and configured by user via a simple interface. Application Notes on how to use the camera for ranging measurements are available on request.

Hermes can be easily integrated into common optical setups thanks to the direct compatibility with Thorlabs® SM1 and the 30 mm cages systems. A C-mount adaptor further expands its integration capabilities. The Hermes camera can be connected to a PC via a Super-Speed USB-C computer interface. Cross-platform shared libraries for easy integration in most applications (such as C/C++, C#, Python, etc.) are provided.

    The imaging array, inside Hermes, is available in two versions: (1) without a micro-lens array, i.e., with the native imager fill factor of 3.14%; (2) with a micro-lens array (MLA) able to recover the fill factor up to 75%, while being still optimal for microscope use. Indeed, MLA performance depends slightly on the incoming beam wavelength and greatly on its aperture as shown here.