Near-infrared (NIR: 0.7µm -1µm) is widely used for depth sensing in many consumer, automotive, and industrial applications. NIR imaging relies on silicon CMOS Image Sensor technology.
SWIR (1µm-3µm) imaging has been developed for night and long-range target detection in military applications. SWIR is gaining interest in the mass markets such as consumer and automotive but will require further technological development to reach a low-enough price point.
Thermal imaging (LWIR, 8µm-14µm) was originally a military technology. Uncooled thermal imaging is broadly used nowadays in commercial applications. For example, it was widely used in 2020 and 2021 to detect elevated body temperature due to Covid.
CMOS Image Sensor technology has been developed to serve more sensing applications in the near-infrared region, bringing a transition from imaging to sensing for new functionalities in the field of 3D sensing. Mobile and consumer are the most important markets for NIR 3D sensing, with Apple leading the trend with its front-face identification and rear Augmented Reality (AR) 3D camera module solutions. The Android camp is, however, still lagging with their return into 3D sensing.
Smartphone makers now want to design phones with a 1:1 screen-to-body ratio and thus bury sensors under the display. This motivates developments in SWIR technologies for facial recognition modules since screen materials are more transparent in this wavelength than in NIR. For other AR applications, SWIR could improve detection range and reliability in high ambient light.
Beyond 3D sensing mobile applications, 3D cameras are also rapidly entering the consumer market in applications such as smart door locks and robotic cleaners.
3D sensing is also spreading into other markets, such as automotive, with LiDARs for ADAS and DMS in-cabin cameras that could adopt this technology, and industrial applications.
ADAS and AV will rely on different technologies using infrared wavelengths. These technologies provide complementary types of information and are also used in combination to provide redundancy and increased reliability of systems. LiDAR uses NIR sensing for 3D mapping of the car’s environment. SWIR would enable an increase in the detection range: SWIR light sources are less restricted than NIR by eye safety specifications.
Besides LiDAR, ADAS requires image sensors to acquire comprehensive data on the driving situation. Thermal cameras could be used in combination with visible cameras to increase AEB* reliability and efficiency. Visible cameras fail to detect dangerous situations at night or in bad weather conditions where thermal cameras are very efficient. Moreover, they are better at highlighting pedestrians or animals.
The industrial 3D sensing market is dominated by traditional LiDAR, representing small volumes but high prices. LiDAR’s applications are mainly in topography and modern wind energy. 3D cameras for manufacturing and logistics also exist within the industrial market, and their implementation has increased. Longer wavelengths are used in industrial or commercial applications for different purposes. SWIR is interesting for sorting since materials have identifiable spectral signatures in this range. Thermography is used in construction works or plant inspections, whereas thermal imaging is the best modality for early fire detection and rescue.
For defense, infrared enables night and enhanced vision by seeing through fog or smoke and is suitable for both soldier equipment and vehicle mounting. Defense vision systems often combine imaging modalities to provide the best level of information on the battleground. SWIR allows stealthy laser target designation and ammunition guidance systems. Thermal imagers are integrated into compact scopes or rifle scopes to penetrate camouflage.
*AEB: Autonomous Emergency Braking
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