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SPECIAL REPORT: EMBEDDED VISION
Depth Sensing Takes Machine Vision

into Another Dimension

By Anne-Françoise Pelé

hat can human vision do that computer vision can’t? can be much larger compared with the distance achievable with a 3D
Humans perceive the world in three dimensions, and flash system. “Edge-emitting lasers [EELs] are the product of choice for
depth sensors are key to enabling next-level machine this system architecture, as they deliver a particularly large amount of
Wvision and unlocking autonomy. light in a small space via a small emission area and thus also score in
More and more machines are endowed with the ability to sense, act, terms of power and range,” Hoenig said.
and interact with their environment, supported by recent advances in Osram, now part of Ams, said it has recently made progress with the
sensing technologies. EE Times Europe scanned the 3D vision land- waveguide stability of its lasers as the temperature in the package rises
scape to get a clearer picture of the market drivers, the opportunities during application. Products with a higher number of wavelengths for
and challenges for component suppliers, and the technologies emerging LiDAR applications are also being explored.
to enable higher levels of depth sensitivity. Regarding laser diodes, EELs are currently the largest market oppor-
tunity, but vertical-cavity surface-emitting lasers (VCSELs) will rapidly
GOING DEEP catch up in the future, Yole predicts. VCSELs combine the high power
At the module level, the 3D sensing market is currently valued at density and simple packaging of an infrared LED with the spectral width
US$6.8 billion and will grow at a 15% CAGR to US$15 billion by 2026, and speed of a laser.
according to Yole Développement. “The advantages of the technology, including excellent beam quality,
“In the mobile and consumer markets, which are the driving force, simple design, and advances in miniaturization, explain the growth of
there is a temporary hiatus in growth due to the Huawei ban as well as the VCSEL market,” said Hoenig. “In general, they require somewhat
the fact that the Android camp has de facto abandoned 3D sensing,” more installation space than EEL emitters but offer advantages for
Pierre Cambou, principal analyst in the photonics and sensing division certain fields of application.” For instance, their radiation characteris-
at Yole Développement, told EE Times Europe. On the other hand, he tics make them particularly suitable for flash LiDAR systems as well as
added, “Apple is accelerating the trend by including LiDAR sensors in for active stereo vision in industrial applications such as robotics and
iPads and iPhones.” logistics vehicles, he said.
Also accelerating is the use of 3D in the automotive context, said
Cambou. LiDAR sensors and in-cabin 3D cameras are being adopted,
and “we are very optimistic about 3D sensing in the automotive market,
which should quadruple in the next five years.”
At present, the prevalent 3D imaging technologies are stereo vision,
structured light, and time of flight (ToF).
Stereo vision has been very strong for long-range sensing applica-
tions beyond 10 meters, such as consumer drones from companies like
DJI and forward-looking ADAS cameras like those in Mercedes, Jaguar,
and Subaru models, said Cambou.
Structured light has been the preferred approach for short-range
sensing below 1 meter, typically in the Apple iPhone for front-mounted
Face ID but also in some industrial applications, addressed by compa-
nies such as Photoneo. Yole expects the automotive market for 3D sensing to quadruple
Time-of-flight systems are mainly used for medium ranges and over the next five years. (Source: Yole Développement)
currently come in two flavors, Cambou said. Indirect ToF was used in
Android phones (from vendors such as Huawei, Samsung, and LG) on As for technical challenges related to VCSELs, Hoenig said Ams-
the rear side in 2019 and 2020 for photographic purposes. Direct ToF is Osram is working on higher optical output. Following its acquisition of
used by Apple in its most advanced smartphones. “Direct time of flight Vixar in 2018, it demonstrated dual- and triple-junction VCSELs that
is the technology being used for LiDARs [for example, by Velodyne, provide better efficiency and speed than single-junction VCSELs. At
Innoviz, Ibeo, Hesai, and RoboSense], which may eventually use a this year’s Photonics West, it launched the PowerBoost VCSEL portfolio
matrix-shaped sensor on the receiver side,” said Cambou. “It is gaining based on this multi-junction technology. The company is also exploring
ground due to the excitement around autonomy.” various ideas to improve heat dissipation — for instance, by making a
change from top- to bottom-emitting components.
EELs OR VCSELs? All common 3D sensing approaches depend on the smooth interac-
LiDAR’s ability to capture the entire scene makes it a valuable technol- tion of the various system building blocks, said Lei Tu, senior marketing
ogy for machine-vision applications. The two systems most commonly manager at Ams-Osram. Usually, these systems consist of a light source,
used to get a three-dimensional point cloud are flash LiDAR and scan- special optics, a detector, and downstream software that processes the
ning LiDAR. In a scanning LiDAR system, a focused pulsed laser beam is detected signals accordingly. In the future, she continued, “for compo-
directed to a certain small solid angle by either a mechanical rotat- nent manufacturers such as Ams-Osram, the focus will be on meeting
ing mirror or a microelectromechanical-system (MEMS) mirror, said customers’ requirements in the best possible way. This includes the
Matthias Hoenig, global marketing manager at Ams-Osram. Because miniaturization of components [and optimization of] their optical
the high-power laser beam is controlled so that it is emitted into only performance, lifetime, and, of course, ease of use.” Tu added that some
a small solid angle, the reachable distance with the optical power used customers prefer “a ready-made, pick-and-place solution,” while others

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