Revolutionary Rohm Infra-Red Light Source Enhances Driver Monitoring

Rohm has introduced a new type of infra-red light source, called VCSELED, which combines a vertical cavity surface emitting laser (VCSEL) with a resin optical diffusion material. This light source is designed to enhance vehicle driver and in-cabin monitoring systems (DMS and IMS).

Driver Monitoring Systems (DMS) are being installed more frequently in vehicles equipped with advanced driver assistance systems (ADAS) to help detect drowsy, sleepy, or distracted driving, thereby improving automotive safety. In Japan, the Ministry of Land, Infrastructure, Transport & Tourism (MLIT) has set guidelines outlining how these systems should be designed and function. Meanwhile, the European Union plans to mandate DMS installation in all new vehicles sold from July 2024.

Automakers and suppliers are also advancing In-Cabin Monitoring Systems (IMS) to detect other occupants besides the driver. This demand has underscored the need for high-performance light sources that can enhance detection accuracy.

Enter VCSELED, which offers highly precise sensing thanks to minimal wavelength temperature variation and a wide emission beam angle. This makes it ideal not only for IMS but also for inspection systems in robots and industrial equipment, as well as spatial recognition and ranging systems.

The VCSELED broadens the irradiation angle to be on par with LEDs, thanks to its high-performance VCSEL element and light diffusion material. This design enables more accurate sensing over a wider area, making it more effective than traditional VCSELs. Furthermore, the compact integration of the light emitting element and light diffuser contributes to smaller and thinner applications.

The VCSEL element in VCSELED has a narrow emission wavelength bandwidth of 4nm, which is about one-seventh that of LEDs. This narrow bandwidth improves resolution on the receiving end and eliminates the red glow often seen with LEDs. Additionally, the wavelength temperature variation is just 0.072nm/˚C, much less than the 0.3nm/˚C typical of LEDs, ensuring high-accuracy sensing even with temperature changes. The light response time is also very quick at 2ns—about 7.5 times faster than LEDs—boosting performance in Time of Flight (ToF) applications that measure distance using infra-red light.

Rohm is working to commercialize VCSELED as a new technology brand for infra-red light components. Prototype samples are now available for purchase, with consumer samples scheduled for release in October 2024, and automotive samples in 2025.