Low Light Detection

A fraction of a silicon wafer with integrated CMOS-SPADs is shown
© Fraunhofer IMS
CMOS-integrated SPADs show a high potential for applications based on single photon detection

Low light detection

Highly sensitive image sensors can detect single photons with spatial and temporal resolution without loss of information.

For many applications, detection of very low light levels is essential, for example, to suppress noise, save energy, or make low-energy phenomena visible. In some, it is even indispensable when only a few photons are available to carry relevant information.

In optical spectroscopy, for example, often only small amounts of light are emitted by the material under investigation, and these are also separated according to wavelength. In order to make quantum phenomena visible, the detection of single photons, often with time information, is normally also necessary.  

The reliable detection of small amounts of light places high demands on suitable optical sensors, which ideally must detect single photons with high probability without being affected by intrinsic noise. Only certain types of sensors have this capability and can be used for low-light detection.



With the Single-Photon Avalanche Diode, the Fraunhofer IMS has access to a high-performance device designed for the detection of single photons. The SPAD has been integrated into the company's proprietary 0.35 µm CMOS technology and can thus be built directly into an IC to form the basis of a single photon detector. With the goal of achieving high speed while maintaining high temporal resolution and sensitivity, experience has been gained over many years in the design of the circuitry used to drive and readout the SPAD. In addition, the device was optimized with respect to noise, thus realizing the SPAD with the world's lowest dark count rate.


Further information about activities of the Fraunhofer IMS in Low Light Detection can be found in the following info sheets.

CSPAD αlpha

3D-integrated BSI SPAD sensor with in-pixel TDC for time- and spatially-resolved single photon detection

Wide-angle LiDAR

Prototype LiDAR system with MEMS scanner and 180° horizontal FoV


LiDAR camera as platform for evaluation and demonstration of 3D sensors


QVGA ToF sensor for a compact and cost-effective underwater camera

Our technologies - Innovations for your products


High-performance image sensors with high time resolution provide an optimal basis for reliable distance determinations

High-Speed Imaging

High-resolution and high-frequency optical sensor systems allow ultra-fast measurements of profiles and surfaces

Our technology areas - Our technologies for your development

Integrated Sensor Systems

Covers all electronic components for sensor signal conditioning and readout.

Optical Systems

Comprises 3D-Sensors, High-Speed-Imaging, detection of extreme low light as well as scientific imaging.

Wireless and Transponder Systems

Incorporates the wireless acquisition of sensor and ID-data even in passive systems.


Smart Sensor Systems

Here you can get back to the overview page of the core competence Smart Sensor Systems (SSS).