Gen2 NIR Tech Extends Image Sensors’ Night Vision
By Mat Dirjish
OmniVision’s second-generation near infrared (NIR) technology, dubbed Nyxel 2, enables image sensors to operate in low to no ambient light conditions. Launching the first generation more than two years ago, Nyxel 2 provides a 25% improvement in the invisible 940-nm NIR light spectrum and a 17% boost at the barely visible 850-nm NIR wavelength.
According to OmniVision, the sensitivity improvements enable image sensors to see better and farther under the same amount of light. Camera systems employing the technology require fewer LED lights, resulting in lower power consumption and longer battery life. These features make Nyxel 2 viable for surveillance systems, automotive in-cabin driving monitoring systems, and for extending the use of under-display sensors in mobile devices.
Machine and night vision camera applications rely on NIR technology because NIR light illuminates objects with wavelengths outside the visible spectrum, avoiding any interference with the surrounding environment. Continuing CMOS approaches for NIR image sensing continue to rely on thick silicon to improve NIR sensitivity. Reportedly, this results in cross-talk and reduces the modulation transfer function (MTF).
Attempts to overcome this by introducing deep trench isolation (DTI) often lead to defects that corrupt the dark area of the image. OmniVision says its Nyxel 2 refines the approach to NIR imaging by combining thick-silicon pixel architectures with careful management of wafer surface texture to improve quantum efficiency (QE) along with extended DTI to retain the MTF levels of the first generation without affecting the sensor’s dark current.
Nyxel 2 achieves 50% QE at 940 nm, deemed a 25% improvement over the first generation, measurable using data from a 2.9-µm pixel. At the 850-nm NIR wavelength, it provides a 70% QE, a 17% improvement over the first generation, putting it on par with the QE levels of top RGB sensors that operate with visible light. For more information, visit the Nyxel overview page.
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