Improving image sensors for machine vision

Image sensors measure light intensity, but angle, spectrum, along with other areas of light must be extracted to significantly advance machine vision.

In Applied Physics Letters, researchers at the University of Wisconsin-Madison, Washington University in St. Louis, and OmniVision Technologies highlight the most recent nanostructured components integrated on image sensor chips which are most likely to help make the biggest impact in multimodal imaging.

The developments could enable autonomous vehicles to see around corners rather than just a straight line, biomedical imaging to detect abnormalities at different tissue depths, and telescopes to look out of interstellar dust.

“Image sensors will gradually undergo a transition to end up being the ideal artificial eyes of machines,” co-author Yurui Qu, from the University of Wisconsin-Madison, said. “An evolution leveraging the remarkable achievement of existing imaging sensors will probably generate more immediate impacts.”

Image sensors, which converts light into electrical signals, are comprised of an incredible number of pixels about the same chip. The task is how exactly to combine and miniaturize multifunctional components within the sensor.

Within their own work, the researchers detailed a promising method of detect multiple-band spectra by fabricating an on-chip spectrometer. They deposited photonic crystal filters comprised of silicon on the surface of the pixels to generate complex interactions between incident light and the sensor.

The pixels under the films record the distribution of light energy, that light spectral information could be inferred. The deviceless when compared to a hundredth of a square inch in sizeis programmable to meet up various dynamic ranges, resolution levels, and nearly every spectral regime from noticeable to infrared.

The researchers built an element that detects angular information to measure depth and construct 3D shapes at subcellular scales. Their work was inspired by directional hearing sensors within animals, like geckos, whose heads are too small to find out where sound is via just as humans along with other animals can. Instead, they use coupled eardrums to gauge the direction of sound inside a size that’s orders of magnitude smaller compared to the corresponding acoustic wavelength.

Similarly, pairs of silicon nanowires were constructed as resonators to aid optical resonance. The optical energy stored in two resonators is sensitive to the incident angle. The wire closest to the light sends the strongest current. By comparing the strongest and weakest currents from both wires, the angle of the incoming light waves could be determined.

An incredible number of these nanowires could be positioned on a 1-square-millimeter chip. The study could support advances in lensless cameras, augmented reality, and robotic vision.

This article “Multimodal light-sensing pixel arrays” is authored by Yurui Qu, Soongyu Yi, Lan Yang, and Zongfu Yu. This article can look in Applied Physics Letters on July 26, 2022.