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25 Jun 2019
Startup and major players target hot emerging market with MEMS mirrors, laser diodes and smart CMOS detectors.
A series of established and brand new companies from Germany used a panel session on the LASER World of Photonics trade show floor to tout newly developed photonic components aimed at the market for automotive lidar.
Familiar names in the session included Jenoptik, Osram Opto Semiconductors, and First Sensor, who were joined by OQmented – a recent spin-off from the Fraunhofer Institute for Silicon Technology (ISIT) in Itzehoe.
Vacuum-packed MEMS
Founded by company president Ulrich Hofmann, OQmented specializes in MEMS mirror technology, which it has licensed exclusively from ISIT. Speaking at the lidar panel session, Hofmann – a 25-year veteran of MEMS mirror development – highlighted the need to replace bulky lidar scanners seen on early autonomous vehicles with much more compact, reliable, robust, and affordable alternatives.
“MEMS mirrors can solve these problems,” he said. And while many rival MEMS mirror manufacturers are out there, not to mention the scores of lidar companies targeting the automotive industry with an apparently endless variety of solutions, Hofmann believes that this company’s hermetically sealed, vacuum-packed devices provide the best option.
Hofmann said that, essentially, two different types of lidar sensor will be needed for autonomous cars. He expects those vehicles to feature two long-range sensors (100 m-plus) with a narrow field of view (FOV), and as many as six shorter-range sensors (30-60 m) with a wide field of view.
What OQmented is offering is a solution for shorter-range scanning lidar sensors, combining a 170° FOV with a speed of up to 3000 frames per second. Pointing out that unprotected mirrors will fail due to corrosion in much less than the 15-year lifetime period demanded by car manufacturers, he stressed the need for vacuum packaging to ensure longevity in the harsh automotive environment.
And while many companies are targeting solid-state designs for automotive lidar, Hofmann says that such options are unable to offer the same kind of beam quality possible with MEMS-based scanners.
Laser transmitters
The same panel session featured Osram Opto’s Andreas Bauer, who extolled his company’s long-standing expertise in the automotive sector and presence in early lidar sensor designs already used in commercial advanced driver assistance systems (ADAS).
Comparing and contrasting the relative virtues of 905 nm versus 1550 nm edge-emitting diodes, along with VCSELs, Bauer came down firmly on the side of the 905 nm devices – although the longer wavelength does have better attributes for long-distance sensors thanks to eye-safety regulations.
While he expects 1550 nm lasers to prove too expensive for auto applications, Bauer indicated that VCSELs may have a place in future designs, despite current challenges with temperature stability and narrow emitting area.
“We see 905 nm edge-emitters as the best option overall,” he commented.
Right now, Osram Opto has a 125 W 905 nm laser diode qualified for automotive-grade mass production, with new surface-mounted device (SMD) options featuring a pulse width of only 2 nanoseconds scheduled for release in the final quarter of 2019.
Regarding further developments, Bauer said that the Osram team had demonstrated a 490 W emitter with a pulse width of just 2.5 nanoseconds.
Also taking part in the lidar panel session were Hagen Schweitzer and Martin Wölz from Jenoptik, respectively describing the Jena optics giant’s efforts in free-form polymer optics and laser transmitter modules for lidar sensors.
They were complemented by Jennifer Ruskowski from Fraunhofer IMS, who opened the session with a description of the institute’s “smart CMOS” detectors. Marc Schillgalies from Berlin-based First Sensor rounded off the session with details of the company’s latest lidar receiver designs.
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