U of A Imaging Technology Laboratory unveils a new vision in infrared innovation

TUCSON, Ariz. – From handheld smartphone cameras to sophisticated satellite images, the world relies on increasingly precise digital imagery. But for scientists and astronomers studying distant exoplanets or monitoring Earth’s climate, imaging technology is at the very heart of the work they do.

Ongoing research within the University of Arizona Imaging Technology Laboratory (ITL) has led to the development of some of the most advanced astronomical image sensors available anywhere in the world. From space-based to ground-based observing, these sensors have enabled countless discoveries. And, under new leadership, the lab is further expanding its range of capabilities.

ITL specializes in developing technologies for semiconductor and photonic devices used in applications like astronomy, Earth observation, semiconductor manufacturing and high-energy physics. Operated by Steward Observatory and affiliated with the Center for Semiconductor Manufacturing, ITL plays a critical role in increasing the overall efficiency of image sensors for prominent missions that have helped to shape scientists’ understanding of Earth and space. 

New Frontiers

As ITL pushes the boundaries of sensor technology, the implications clearly reach far beyond academia. Whether it’s mapping the universe’s dark matter, tracking environmental changes or optimizing detectors to observe longer wavelengths, these advanced sensors are set to transform the way humans understand the universe.

Jarron Leisenring, PhD, assistant research professor at Steward, recently stepped into the role of ITL director. With an extensive background in infrared technology and exoplanet detection, he aims to leverage his expertise to optimize sensor performance and foster stronger collaborations with university departments and external industry partners.

“There’s such an impressive portfolio that ITL has put together over the years, and I’m just happy to continue working on that legacy,” Leisenring said.

Leisenring and the new deputy lab director and chief engineer, Andre Wong, both have backgrounds in infrared detector technology and are collaborating with incoming professor Brittany Miles, PhD, to establish the Arizona Infrared Detector (AIRD) Laboratory and complement ITL’s existing capabilities. Infrared detectors require different materials compared to ITL’s current sensors, but many of the manufacturing processes overlap such that ITL could help optimize sensors that detect these longer wavelengths.

This type of infrared detector would be useful for NASA’s next generation flagship telescope, the Habitable World Observatory (HWO), which is currently under development. Leisenring and others at U of A are searching for ways to contribute, which could include optimizing and developing extremely sensitive sensors able to distinguish and count individual photons.

“We want to directly image Earth-like planets orbiting other stars, that's kind of the ultimate goal,” Leisenring said. “We need to spread out the light and measure the spectra of these Earth's to search for biosignatures like water vapor, oxygen and all the things that we know are necessary for life as we know it.”

ITL researchers are currently exploring a variety of advanced sensor technologies to enhance astronomical imaging. They are investigating skipper charge-coupled devices, which take multiple measurements of charge in each pixel to minimize noise, making them ideal for exoplanet imaging at ultraviolet, optical and near-infrared wavelengths. Additionally, the lab is considering avalanche photodiodes for their ability to detect dim light sources. Microwave kinetic inductance detectors are also under examination; these devices could pinpoint the energy of individual photons but require extreme cryocooling. 

ITL’s sensors may soon support these new devices and discoveries that bring researchers closer to solving some of today’s most compelling scientific mysteries.

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ITL’s History

Since the lab’s creation in the 1990’s, it has delivered over 4,000 devices to scientific and industrial communities worldwide, according to Michael Lesser, PhD, former long-term ITL director. The lab began as a Charged Coupled Device (CCD) laboratory, later becoming the ITL in the early 2000s as it expanded.

Image sensors function by capturing light particles through tiny pixels, turning them into electrical signals. A filter over the sensor helps each pixel capture different wavelengths of light. These signals are then converted into digital data, which is used to create a complete image.

There are two main types of image sensors, CCDs and Complementary Metal-Oxide Semiconductors (CMOS), that ITL manufactures and customizes for observing projects. According to Lesser, CMOS sensors are starting to gain popularity in industry because they are cheaper, use less power and their complex functions allow for data to be processed faster with less read noise.

“These silicon-based technologies have been developed over the last 50 years to function incredibly well, so now you get very high performance out of silicon,” Lesser said. “This material is sensitive in the right wavelength regions that we want, from X-rays all the way to the near infrared.”

The lab is most noted for its research involving Quantum Efficiency (Q.E.), which optimizes the fraction of light able to be detected by an image sensor, leading to more precise observations. ITL improves Q.E. through many processes, such as precise thinning of the absorbing silicon material, designing advanced anti-reflective coatings and early pioneering of backside illuminated (BSI) devices.

“A lot of semiconductors are imaged on the front side, which means the light is hitting all of the metallization on the device,” said Anita Sobey, lab manager of ITL. “This causes a lot of reflection, loss and absorption, so we flip the device over and image through the silicon on the backside. This allows us to collect as many photons as possible, especially for low-light level astronomy projects.”

ITL’s optimized sensors are implemented into a wide variety of ground-based projects such as DESI (Dark Energy Spectroscopic Instrument), aimed at mapping the large-scale structure of the universe to better understand dark energy, and space-based projects such as the Geostationary Lightning Mapper instrument on the latest NOAA GOES-19 weather satellites that observes lightning strikes and storms.

Another recent project includes NASA’s PACE primary sensor called the Ocean Color Instrument (OCI). OCI is an advanced spectrometer that measures light properties across the electromagnetic spectrum with finer detail than any other NASA satellite sensor. The sensor collects crucial ocean color data records for climate research. 

ITL has also developed sensors capable of detecting extremely short X-Ray wavelengths, which have medical applications. Similarly, ITL processes sensor for electron beam microscopy used to measure some of the small structures attainable by biomedical imaging devices.

As ITL innovates and contributes to major upcoming projects, their advanced sensors will continue making a lasting impact on science and industry.

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