Various system architectures can be used to realize in-cabin sensing systems: from 2D NIR imaging-based NCAP- and regulation-compliant systems up to more advanced 3D-capable designs like active stereo vision (ASV), structured light (SL), and indirect time of flight (iToF).
The most common in-cabin sensing systems are realized with 2D NIR imaging cameras and use flood illumination based on IRED or VCSEL technologies, depending on the system preferences of the end customer. Flood illumination means projecting a curtain of infrared light onto the scene for 2D image extraction, compared to pattern illumination that projects certain patterns onto the scene for 3D-depth extraction (e.g. dots, lines etc.).
The emerging 3D-sensing systems also use flood illumination, however with different constraints. Whereas ASV has similar IR illumination needs as 2D imaging, SL-based systems require an additional pattern projector for depth extraction, which is best realized using VCSEL-based illuminators. The iToF systems on the other hand – which are by far the most common 3D-sensing architecture used in cars today – benefit greatly from VCSEL illumination, thanks to the fast rise-and-fall times of the VCSEL signal, which in turn enables higher modulation frequencies and better depth resolution for iToF systems.
Most in-cabin sensing systems today operate at 940 nm wavelength while some also use 850 nm. The choice of illumination technology, light path design, and wavelength, requires careful consideration and this is where ams OSRAM provides design support in close partnership with customers, thanks to extensive expertise in system design with both technologies and wavelengths.
ams OSRAM offering
ams OSRAM offers an extensive range of illumination and sensing solutions, like the Oslon Black and Synios families of IR LEDs, which leads the market in IR Illumination, or TARA2000-AUT, the first AECQ-102 qualified VCSEL module in the market, in mass production for many customers since Q2-2021. The ams OSRAM AS8579 capacitive sensor uses a novel technique for foolproof, hands-on detection design. It enables sensing placement within the steering-wheel industry’s first completely reliable solution for hands-on detection and offers the simplest way for car makers to comply with the UN Regulation 79. Photodiods and LEDs can be used for simple gesture detection.