"Vendors are responding by increasing sensor spectral range, integrating new capabilities into devices, and adding features such as 3D imaging. The result can be rapid growth in sensors, even in areas that are relatively stable. For instance, the worldwide market for cars is expanding at a relatively modest pace, according to Geoff Ballew, senior director of marketing in the automotive sensing division of chipmaker ON Semiconductor Corp. of Phoenix.
However, tepid growth is not the case for the automotive imaging solutions. “The number of sensors consumed and attached to those cars is growing wildly,” he said. “The image sensor chip business is growing in excess of 15 to 20 percent a year. The reason for that is cameras increasingly are adding new functionality to cars.”
Automotive sensors are expected to work from -40 to 125 °C. That interacts with the dynamic range requirement because as the operating temperature rises, so too does the dark current in the sensor. Vendors such as OmniVision must take special care within the manufacturing process to drive that dark current down, thereby expanding the operating temperature and preserving the high dynamic range.
Besides automotive, another area pushing imaging capability is the IoT. Refrigerators, washing machines, and home security systems are adding image sensors for cataloging food, recognizing people, and other tasks. But the IoT brings its own requirements, and they affect sensors, according to Nick Nam, head of emerging markets at OmniVision Technologies.
For instance, power consumption often may need to be minimized, particularly for IoT applications running on batteries.
Depth or 3D sensing is a capability being added to automotive, the IoT, and other applications. There are competing 3D imaging methods, and which is best will be different for different situations
Imaging in the shortwave IR region out to about 2 µm offers improved performance in poor visibility or at night. When combined with capabilities in the visible and UV, the resulting multispectral or hyperspectral imaging can provide important information not obtainable by visible imaging alone. While not new, the hybrid approach offers the advantage that as CMOS technology improves, so can the performance of the sensors. What’s more, the hybrid technique can be extended to other materials, allowing sensors to capture information in the mid- and thermal-IR at 5 or 10 µm, or more."
On a similar matter, most of PWC's list of 8 emerging technologies in one way or another rely on image sensing: artificial intelligence, augmented reality, blockchain, drones, IoT, robotics, virtual reality, and 3-D printing:
San Diego-based image sensor distributor AlliedSens reveals that Brookman 1.3MP BT130C and 2MP BT200C are used in Japanese color night vision cameras, such as this one.
KB ViTA kindly sent me an info about their latest LWIR camera that senses polarization:
"It all was started with the fact KB ViTA has developed a very sensitive thermal imaging module VLM640, which had a sensitivity of at least 20 mK in 8 — 12 µm band. The sensor manufacturer turned to KB ViTA and offered an engineering sample from an experimental wafer of bolometric detectors with integrated polarization filters. For KB ViTA it was honorable but, at the same time, there was no understanding of what it is expected to ultimately obtain. The technology and the very idea of seeing the own polarization of the thermal photons of objects that surround us is absolutely new and hardly anyone has experience of processing such information.
Below we will show you how the polarization in the IR spectrum looks.
There were a polarizing sensor and electronics from VLM640 camera with 20 mK sensitivity. The interesting thing about the sensor is each pixel in the group of four is covered with a polarizer. The polarization of each filter differs by 45deg. As a result, the polarization angles are 0—180deg, 45—225deg, 90—270deg, 135—315deg.
In the resulting videos, there are three images (from left to right): video from a conventional thermal imager, reconstructed polarization angles, a complex image, where the brightness is thermal radiation and the color is the polarization angle."
The example videos below show a light bulb and a painted box:
"So far, KB ViTA can say polarization shows us the object surface quality. There are assumptions (based on the results of communication with the detector manufacturer, colleagues at exhibitions and very scarce information on the Web) that the effect of evaluating the polarization of radiating and reflecting objects can be used in the following areas:
The difference between objects own radiation and reflection (for example, a warm car and a glare of the sun in a puddle or sand).
Search for camouflaged objects.
Oil stains detection on the water surface.
Defect search.
3D scanning.
Detection of warm objects on a water surface (a drowning person, for instance), distinguishing its own radiation from reflected light on water."
Science Magazine publishes a paper on wideband light sensing device "Ultrabroadband photosensitivity from visible to terahertz at room temperature" by Dong Wu, Yongchang Ma, Yingying Niu, Qiaomei Liu, Tao Dong, Sijie Zhang, Jiasen Niu, Huibin Zhou, Jian Wei, Yingxin Wang, Ziran Zhao, and Nanlin Wang from Peking University, Tianjin University of Technology, and Tsinghua University, China.
"Charge density wave (CDW) is one of the most fundamental quantum phenomena in solids. Different from ordinary metals in which only single-particle excitations exist, CDW also has collective excitations and can carry electric current in a collective fashion. Manipulating this collective condensation for applications has long been a goal in the condensed matter and materials community. We show that the CDW system of 1T-TaS2 is highly sensitive to light directly from visible down to terahertz, with current responsivities on the order of ~1 AW−1 at room temperature. Our findings open a new avenue for realizing uncooled, ultrabroadband, and sensitive photoelectronics continuously down to the terahertz spectral range."
Everything is great about the new photodetection mechanism, except the dark current, which is about 15 orders of magnitude higher than in Si photodiode:
"The Columbia Engineering researchers have created the first flat lens capable of correctly focusing a large range of wavelengths of any polarization to the same focal point without the need for any additional elements. At just 1µm thick, their revolutionary "flat" lens offers performance comparable to top-of-the-line compound lens systems.
The team’s next challenge is to improve these lenses' efficiency. The flat lenses currently are not optimal because a small fraction of the incident optical power is either reflected by the flat lens, or scattered into unwanted directions. The team is optimistic that the issue of efficiency is not fundamental, and they are busy inventing new design strategies to address the efficiency problem."
Globenewswire: Atomera licenses its Mears Silicon Technology (MST) technology to ST. MST is an additional non-silicon implant that reduces transistors variability at a given processing node. Also, 1/f noise is reduced due to the elimination of halo implant (also called pocket implant by some fabs).
Why is this relevant for image sensors? First, if Sony pixel-parallel ADC presented at ISSCC 2018 gets the market traction, the reduction of mismatch between transistors might become more important to reduce pixel-level FPN coming from multiple ADCs. Second, reduction of SF gain variations across the pixel array might reduce PRNU in the regular image sensors. Although 1/f noise reduction might not directly affect pixel transistors that do not have halo implant anyway, for the most part, other parts of the image sensor still might benefit from it.
