News: Optoelectronics
1 June 2023
ams OSRAM adds built-in eye-safety to 940nm IR VCSEL emitter for in-cabin monitoring
ams OSRAM GmbH of Premstätten, Austria and Munich, Germany has enhanced its portfolio of infrared laser modules for automotive in-cabin sensing with the TARA2000-AUT-SAFE family of vertical-cavity surface-emitting lasers (VCSELs), which is said to offer a more reliable and robust eye-safety feature than existing automotive VCSEL modules.
A top-10 global car manufacturer has already selected this new product for a new design, and ams OSRAM will supply it in mass-production volumes starting in 2024.
The new TARA2000-AUT-SAFE, which produces a tightly controlled beam of infrared light at a peak wavelength of 940nm, is suitable for the same use-cases as the existing TARA2000-AUT family: driver monitoring, gesture sensing, and interior (cabin) monitoring. It consists of an ams OSRAM VCSEL chip and micro-lens array (MLA) packaged in a compact module.
The TARA2000-940-W-AUT-SAFE, which has a wide field of illumination of 116° x 87°, is optimized for cabin monitoring with 2D near-infrared (NIR) imaging and 3D indirect time-of-flight (iToF) cameras. A forthcoming version TARA2000-940-UN-AUT-SAFE, with a narrow field of illumination of 46° x 41° suitable for driver monitoring, is currently sampling with customers.
ams OSRAM previously released the world’s first AEC-Q102-qualified and ISO 26262-compliant VCSEL flood illuminator, the TARA2000-AUT, which has been in mass production and shipping to multiple automotive customers since second-quarter 2021. The TARA2000-AUT-SAFE family now offers increased reliability and simpler implementation for automotive manufacturers, due to the new, built-in interlock loop method for protecting eye safety.
The new device’s resistive interlock circuitry is integrated on the MLA. Providing a near-instant response (<1µs) to fault conditions, the TARA2000-AUT-SAFE can directly detect faults that could compromise eye safety, such as diffuser cracking or shear-off.
The TARA2000-AUT-SAFE solves various design and implementation challenges, and at a lower cost than competing products on the market today, it is reckoned. The fast and reliable response is in contrast to the built-in photodiode method for eye-safety protection in competing automotive VCSELs, the firm adds, in which the photodiode signal is prone to faults caused by non-eye-safety-related factors such as reflective objects in front of the VCSEL module, impairing the system’s ability to protect eye safety.
Also, the TARA2000-AUT-SAFE’s interlock loop is said to be easier to integrate, as its read-out circuit only requires one AND gate or MOSFET. In comparison, the complex read-out circuit for a photodiode includes an increased number of more expensive components, so the photodiode method results in a higher bill-of-materials cost as well as a slower response to events that carry a risk to eye safety.
In addition, the photodiode’s response is strongly temperature-dependent, making system design more complex and less reliable. This is a particular drawback for automotive applications, which are exposed to a wide range of operating temperatures.
“We have been able to take our experience in other application areas and directly apply it to enhancing the TARA2000 family,” says senior global marketing manager Firat Sarialtun. “ams OSRAM has deep knowledge of interlock-based eye-safety designs, as we have had products that use the interlock method in mass production in other end markets, such as consumer and industrial, for many years,” he adds.
“We were the first in the industry to start mass production of an AEC-Q102- and ISO26262-compliant IR VCSEL module for in-cabin sensing in Q2/2021, and now we are taking VCSEL technology a step further with the interlook loop feature,” Sarialtun continues. “Thanks to our deep engineering expertise across the whole optical assembly, the interlock circuit has been integrated directly on the lens and package, drawing on our deep understanding of each sub-component and technology in a complete VCSEL module.”
The design of the TARA2000-AUT-SAFE builds on the high performance of the TARA2000-AUT. Housed in a robust ceramic package, the new device offers a higher maximum operating temperature of 125°C, supporting AEC-Q102 Grade 1 qualification as well as ISO 26262 for functional safety. The peak optical power output of a 100µs pulse at 25°C/2% duty-cycle/5A is 4W.
Both the TARA2000-940-UN-AUT-SAFE and TARA2000-940-W-AUT-SAFE VCSEL emitters are sampling now.
ams introduces first AEC-Q102- and ISO 26262-compliant VCSEL flood illuminator
