ams Osram improves eye safety of IR sensors for in-cabin applications
Technology provider ams Osram has expanded and improved its portfolio of solutions for automotive interior sensing with the new TARA2000-AUT-SAFE family of infrared laser modules. The new product offers greater reliability and more robust eye safety features than existing solutions.
The TARA2000-AUT-SAFE family produces a tightly controlled beam of infrared light with a wavelength of 940 nm and is suitable for the same use cases as existing products in this family – driver monitoring, gesture recognition and interior monitoring. It consists of an ams Osram VCSEL chip and a microlens array (MLA) housed in a compact module.
The TARA2000-940-W-AUT-SAFE, with a wide 116° x 87° field of illumination, is designed for cabin surveillance with 2D near-infrared (NIR) and 3D time-of-flight (iToF) indirect cameras. According to the manufacturer, one vehicle OEM from the global top 10 has already selected the laser module for a new design, and ams Osram plans to supply the component in mass production starting in 2024.
A forthcoming version with a narrow 46° x 41° illumination field, the TARA2000-940-UN-AUT-SAFE, is suitable for driver monitoring. This product is currently being sampled by customers.
The design of the TARA2000-AUT-SAFE builds on the high performance of the TARA2000-AUT. Housed in a rugged ceramic package, the new device offers a higher maximum operating temperature of 125°C and supports AEC-Q102 Grade 1 and ISO 26262 functional safety qualification. The peak optical power of a 100μs pulse at 25°C/2% duty cycle/5A is 4W.
ams Osram has a history of supplying OEMs and Tier 1 companies with automotive-grade advanced interior sensing technology. The company has launched the world’s first AEC-Q102 qualified and ISO 26262 compliant VCSEL flood illuminator, the TARA2000-AUT, which has been in volume production since the second quarter of 2021 and is being shipped to several automotive customers. The TARA2000-AUT- SAFE family continues the innovation series, offering automotive manufacturers more reliability and easier implementation thanks to the new built-in interlock loop method for eye safety.
The new device’s resistive interlock circuitry is integrated with the MLA. The TARA2000- AUT-SAFE responds to fault conditions with a barely measurable delay of less than 1μs, allowing it to directly detect faults that could compromise eye safety, such as cover cracks or shear-offs.
The TARA2000-AUT-SAFE solves several design and implementation challenges, at a lower cost than competitive products on the market today. The fast and reliable response contrasts with the built-in photodiode method for eye safety in competing automotive VCSELs. In competing products, the photodiode signal is susceptible to errors caused by non-eye safety factors such as reflective objects in front of the VCSEL module, which compromises the system’s ability to protect the eyes.
In addition, the TARA2000-AUT-SAFE’s interlock loop is easier to integrate because the readout circuit requires only an AND gate or MOSFET. In comparison, the complex readout circuit of the photodiode circuit includes a larger number of more expensive components. This means that the photodiode method has a higher material cost and slower response to events that pose a risk to eye safety.
In addition, the photodiode response is highly temperature dependent, making system design more complex and less reliable. This is a particular disadvantage for automotive applications that are exposed to a wide range of operating temperatures.
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