Sony image sensor enables accurate, high-speed distance measurement

Sony image sensor enables accurate, high-speed distance measurement

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Sony Corporation (Tokyo, Japan) has developed a back-illuminated time-of-flight (ToF) image sensor with a 10µm pixel pitch, the industry's smallest, according to the company. The device combines the ToF image sensor technology of Softkinetic Systems S.A., a Sony subsidiary acquired in 2015, and Sony's back-illuminated CMOS image sensor technology.
By Rich Pell

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By measuring the time it takes for light from a light source to reach the object and reflect back to the sensor, ToF image sensors capture the distance information for every pixel, resulting in highly accurate depth maps.

At the heart of the ToF technology in Sony’s new product is Softkinetic’s proprietary Current Assisted Photonic Demodulator (“CAPD”), which employs a unique pixel architecture capable of high-speed modulation using drift current in the pixel, allowing for detection of the light signal with an improved accuracy. This methodology raises the accuracy of distance measurement at the level of every pixel, thereby delivering accurate measurement and depth map acquisition even at significant distances.

Image taken by CMOS image sensor.

Sony combined CAPD with its back-illuminated CMOS image sensor pixel technology to develop the new back-illuminated ToF image sensor, with a 10µm pixel pitch. The new sensor builds on the advantages of a back-illuminated pixel structure, which layers the circuitry beneath the photo detector.

By optimizing the pixel construction and circuitry for CAPD, the new Sony product delivers improved light collection efficiency and enables high-speed distance measurement processing. The design delivers accuracy equivalent to conventional methods, even at 1.5x the distance.

The higher level of light collection efficiency also makes it possible to use a less-powerful light source, and this keeps power consumption down and allows the ToF camera module to be more compact. The ToF sensor is operated at 100MHz, it has a depth accuracy of 5.9mm at 1m.

Comparison of obtained depth map at the same distance: New sensor (left) and conventional sensor (right).

Sony Corporation – www.sony.com

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