One of the drawbacks the $3,499 Apple Vision Pro faces is that its video passthrough— despite being the best among its peers— is still video. Despite technological advancements, video has yet to accurately replicate what we see exactly the way we see it.
While the likes of Samsung and LG showed off their transparent display technologies at CES earlier this year, camera sensors— crucial for head-tracking in augmented reality (AR) and virtual reality (VR) applications— remain an opaque obstacle.
This, however, could soon change.
Researchers from The Barcelona Institute of Science and Technology’s ICFO–Institut de Ciencies Fotoniques have developed the first ever semi-transparent image sensor.
This sensor comprises an 8?8 array of semi-transparent photodetectors and electrodes disposed on a fully transparent substrate. Each pixel in the array is of size 60 x 140 ?m and has an optical transparency of 85-95 percent, according to the study.
These photodetectors capture light while allowing a considerable portion of it to pass through— a necessary trait for applications where transparency is essential, such as in smart displays on AR and VR devices.
Additionally, this sensor sports a design that balances light capture with visibility, making it suitable for applications requiring both sensing capabilities and transparency.
Extensive information capture
Given their ability to capture huge amounts of information, image sensors are essential. Conventional approaches implementing image sensors are held back given their proximity to the eyes, obstructing the user’s view.
However, the new technology aims to combat this issue by developing a nearly invisible camera.
Researchers in Spain developed the technology by adding small dots of lead sulfide into graphene sheets.
These dots emit electrons which flow across the layer of carbon items and generate a current when struck by photons.
This approach allows for the creation of photodetectors that are nearly invisible to the naked eye while maintaining high sensitivity to light.
95% passthrough
Through experimentation, the research team engineered the first semi-transparent camera with the potential to allow 95 percent of light to pass through it.
Upon further testing with a projection of grayscale patterns onto the photodetector, the team compared the result with a standard image sensor.
The outcome turned out to be promising, illustrating the technology’s potential for applications such as eye tracking in virtual reality helmets, automotive assistance devices, and advertising tracking.
While more work is needed before the technology can be applied to practical devices such as standard eyeglasses or contact lenses, the development represents a significant step forward in the field of transparent imaging technology.
“As the semi-transparent photodetectors have a large amount of built-in gain, the opaque read-out electronics can be placed far away from the detector array to ensure maximum transparency and fill factor,” the authors in the study stated.
“Indeed, the operation and appearance of transparent image sensors present a fundamental shift in how we think about cameras and imaging, as these devices can be concealed in plain sight,” they added.
The study was published in the journal ACS Publications.
Study Abstract
Due to their ability to capture vast amounts of information, traditional image sensors play a pivotal role in today’s society. However, the opaque nature of both their pixels and stacked read-out electronics can be a limiting factor in applications such as human–computer interfaces, smart displays, and both augmented and virtual reality. In this paper, we present the development and analysis of the first semitransparent image sensor and its applicability as an eye-tracking device. Consisting of an 8 ? 8 array of semitransparent photodetectors and electrodes deposited on a fully transparent substrate, the sensor’s pixels achieve an optical transparency of 85–95% and high sensitivity, with more than 90% of these pixels demonstrating a noise equivalent irradiance <10–4 W/m2 for wavelengths of 637 nm. The fabrication of such sensors represents a fundamental shift in how we think about cameras and imaging as these devices can be concealed in plain sight.
