Canon hails revolutionary 1-megapixel SPAD image sensor as “the eye of the future”
Canon has developed what everyone thought was impossible. And while it may not be the highest resolution camera sensor, the new Canon 1 Megapixel Single Photon Avalanche Detection (SPAD) Sensor offers huge advantages over more traditional CMOS or CCD sensors. Most importantly, all of this removes noise from your images.
It differs from CMOS sensors in the way it captures light. While CMOS sensors use electrical signals to monitor the volume of light hitting each pixel in an analog fashion, which introduces noise, before being converted to digital, SPAD sensors count each individual photon that hits it and emits a true digital signal.
In a technical article published by Canon on the new technology, they highlight some of the applications of the new sensor, including augmented and virtual reality, high frame rate shooting speeds, robot automation, computer vision and driverless vehicles.
SPAD sensors are a type of image sensor. The term “image sensor” probably conjures up the CMOS sensors found in digital cameras, but SPAD sensors work on different principles.
SPAD and CMOS sensors use the fact that light is made up of particles. However, with CMOS sensors, each pixel measures the amount of light that hits the pixel in a given time, while SPAD sensors measure each individual light particle (i.e. photon) that hits the pixel. Every photon that enters the pixel is immediately converted into an electrical charge, and the resulting electrons are eventually multiplied like an avalanche until they form a large signal charge that can be extracted.
The article also talks about the challenges encountered when developing SPAD sensors with a high pixel count. Yes, when it comes to SPAD, 1 megapixel is most definitely considered a high number of megapixels and Canon’s new development represents the highest resolution SPAD sensor available today.
Until recently, it was considered difficult to create a high pixel count SPAD sensor. On each pixel, the detection site (area available to detect incoming light as signals) was already small. Making the pixels smaller so that more pixels could be incorporated into the image sensor would result in an even greater reduction in detection sites, which in turn would result in very little light entering the sensor, which would also be a big problem.
However, Canon incorporated a proprietary structural design that used technologies cultivated through the production of CMOS sensors for commercial use. This design has managed to keep the aperture ratio at 100% regardless of pixel size, allowing all the light that enters to be captured without any leakage, even though the pixel count has been increased. The result was the realization of an unprecedented 1,000,000 pixel SPAD sensor.
In addition to virtually eliminating noise from the image the camera sees, the new sensors also deliver incredible readout speeds. Canon has equipped the new SPAD sensor with a global shutter capable of shooting up to 24,000 frames per second with 1-bit (black and white) output, with exposure times as fast as 3.8 nanoseconds.
Do you realize how fast it is? 3.8 nanoseconds = 3.8 billionths of a second. It’s basically a shutter speed of 1/263,157,895th of a second. With a global shutter. As Canon points out, the possibilities of such a sensor for scientific monitoring and observation purposes are great, indeed, allowing scientists to see things that were previously impossible.
Considering it’s taken since the 1970s for a company to produce even a 1-megapixel SPAD sensor, it’s unlikely we’ll see them hitting cameras for quite a while yet, if at all. never. But if they can ever get that inside the kinds of cameras we use, oh boy. What a camera that would be!
The totality the article is well worth a read if you fancy 5 minutes of geeking.