IoT

QuantumFilm image sensors for authentication, autonomy, and augmented or virtual reality

Smart devices are transforming our lives. They help us drive safely, make stories more interactive, give us a hint when we need one, and allow us to customize our environments. Optimized for the near-infrared spectrum in the Spark™ product line, QuantumFilm enables IoT devices to operate more accurately in all conditions with less system power.

Applications for near-infrared QuantumFilm cameras include:

  • Authentication: iris and face recognition
  • Autonomy: robotics and collision avoidance
  • Augmented and Virtual Reality: 3-D mapping and gesture, eye and head tracking
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Customizable Sensitivity

QuantumFilm is uniquely positioned to bring the visible and infrared light-sensing capability of any smart device to the next level. The fact that the diameter of the quantum dots in QuantumFilm is adjustable means that their bandgap—and, thus, their sensitivity to light of certain wavelengths—is customizable. When optimized for infrared light sensitivity, QuantumFilm brings the same benefits it has in the visible spectrum to invisible, infrared light applications, with a QE of 40% at the 940-nanometer wavelength.

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Sharpness

The small pixel size and lower crosstalk of our QuantumFilm pixel can sample fine transitions from light to dark in the infrared spectrum, resulting in unprecedented sharpness. For example, devices can detect finer levels of detail in an iris being imaged for authentication purposes or when navigating through thick foliage.

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Global Shutter

Accurate motion capture is crucial to collision avoidance and augmented and virtual reality applications, and by making global shutter possible at smaller pixel sizes than ever, QuantumFilm brings a higher level of performance to more compact IoT devices. In InVisage’s Spark™ products, global shutter not only eliminates rolling shutter distortion, but it also enables huge system power savings and improved performance outdoors.

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Low Power Consumption

IoT devices equipped with infrared-sensitive cameras can gather information about their environments by projecting patterns of infrared light, then analyzing changes to those patterns as they are reflected back to the camera. This mode of active illumination is called structured light, and requires infrared cameras to be paired with infrared LEDs. In the case of conventional silicon NIR sensors, these LEDs demand a significant amount of energy (in the range of 1W) and heavier batteries. With QuantumFilm’s global shutter, however, infrared LEDs can be pulsed in sync with global shutter's brief exposure time at a higher light level instead of remaining on continuously. This pulsing enables up to fifty times less system power consumption.

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Outdoor Infrared Performance

Sensing structured light outdoors can be tricky with conventional photosensitive silicon. More than half of ambient sunlight is in the infrared range and can overwhelm the light projected by an infrared LED, effectively saturating the image. Whether or not a device can accurately analyze its environment or find its way past obstacles depends on its camera's ability to detect infrared LED light outside.

Operation at the 940-nanometer wavelength solves this outdoor challenge. 940 nanometers is optimal for infrared camera systems for two reasons: 1) the abundant water in the atmosphere absorbs more infrared light at 940 nanometers, making it easier for LEDs to shine through, and 2) infrared light at that wavelength is invisible. At the wavelength conventionally used in devices like a remote control—850 nanometers—infrared light is still visible and will produce a noticeable red glow. Silicon CMOS image sensors operate at the 850-nanometer wavelength because they are not sensitive enough to operate effectively at longer wavelengths.

InVisage’s sensors have demonstrated 40% quantum efficiency at 940 nanometers—about five times the sensitivity of silicon. This means the QuantumFilm sensor can accurately isolate invisible infrared light from an LED in a wash of sunlight. Pulsing the LED for less than a millisecond as opposed to keeping it on continuously, as shown in the diagram below, means that the pulse can be bright enough to overcome irradiance from the sun and still save significant power.

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