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At the beginning of the decade, California-based technology company, InVisage Technologies, announced the development of its ground-breaking invention, a new image sensor technology known as QuantumFilm. The technology promised to radically improve on the image quality of current cell phone technology, increasing the resolution by four times that possible with traditional silicon-based sensors.
The company envisioned creating a camera that could go further than those on the market using silicon-based sensor technology. They wanted to significantly increase both sensitivity and resolution. At the time, there were devices capable of taking high-quality photos and videos, such as digital SLRs, and those that were convenient and portable, such as camera phones. The company wanted to create a technology to allow a portable device to have the image quality of a larger, more dedicated device.
The solution came in the form of quantum dot technology. InVisage developed a new sensor material that integrated quantum dot technology to give it the capability of capturing 95% of the image. The technology was rapidly applied to digital photography and video followed closely by cell phones.
How it Works
Before quantum image sensors, digital cameras relied on silicon as the light sensors incorporated into CMOS image sensors. These silicon sensors only sensed light up to about a 25% efficiency, in other words, for every four photons of light hitting the sensor, only one is translated into a photoelectron. This fundamentally limited the resolution and quality of the photos created.
There were two key reasons for this constraint on sensitivity, the first being that silicon is a weak absorber of light, the second is known as the fill factor problem, where the layers of metal interconnect wires over the top of the sensor obstruct the light. Because of this, at the time quantum image sensors were developed, it was difficult to create a small device, such as a cell phone, capable of taking high-quality images.
InVisage Technologies innovated a way to overcome these limitations. They developed a photosensitive layer comprising of quantum dots that replaces silicon. It was created to be efficient at absorbing light, and consequently, the sensors were tested to prove that they converted 100% of the light entering into the sensor. Also, further capabilities were added due to the fact that the ultra-high sensitivity could be switched on and off rapidly. This gave the device the functionality of capturing motion accurately.
10 Years Later, What Directions are Quantum Image Sensors Taking?
It’s almost 10 years since InVisage Technologies announced QuantumFilm, and work is still ongoing to develop the sensor’s capabilities and broaden their applications.
Currently, some of the world’s biggest players in the technology space are investing significant funds into evolving the technology, hoping to extend its functionality to impact the future of video. Because of the high efficiency of quantum dots, the images generated by quantum image sensors have low pixel counts in comparison to other sensors. For example, 100k quantum dot photosites may be produced in comparison to the 2+ million pixels generated by regular HD cameras. This means that the sensors can be produced at a very small scale without impacting their image quality, so “better-than-cinema” image quality can be offered by a cell phone.
From these highly efficient imagers, powerful sensors can be shrunk dramatically in size without sacrificing image quality. This means that it could be possible to get better-than-cinema quality imaging from a sensor inside a smartphone.
In fact, Apple eventually acquired the makers of the quantum image sensor back in 2017. The move aimed to increase the image quality offering of their phones and to assist in creating advanced augmented reality features. Also, experts envision that technology will enable new applications in authentication, autonomy, and virtual reality.
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