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NRC’s adaptive optics helps astronomers see better and farther in space

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Twinkling stars have enchanted humans since the dawn of time. But they make it difficult for astronomers to get clear images of the sky. Good news: cutting-edge technology developed by the National Research Council of Canada (NRC) eliminates flicker and is a game-changer for studying our universe.

Once light from a star enters the Earth’s atmosphere, it passes through several layers of atmospheric turbulence that appear to cause the light to twinkle or twinkle. This effect also distorts images taken by ground-based telescopes. Fortunately, scientists can now eliminate this atmospheric disturbance with adaptive optics, clearing the air so these telescopes take crisp, clean images.

Researchers at NRC’s Herzberg Research Center for Astronomy and Astrophysics have developed an experimental adaptive optics system that is undergoing rigorous testing at their 1.2-meter McKellar Telescope in British Columbia. This project—Research, Experiment and Validation of Adaptive Optics with a Legacy Telescope (REVOLT)—uses advanced cameras, high-speed computers, and flexible mirrors to correct for the effects of atmospheric turbulence. With adaptive optics, images produced by terrestrial telescopes can be as high quality and high resolution as they would be from telescopes in space above the atmosphere, and cost much less.

According to Dr. Jean-Pierre Véran, Adaptive Optics Team Leader at the Herzberg Center for Astronomy and Astrophysics Research, REVOLT has immense implications for large optical telescopes currently in place (up to 10 meters) and in development. (up to 39 meters). “Time on these large telescopes around the world is in high demand, so when they acquire new technology, they want proof that it has a very high level of maturity,” he says. “REVOLT serves as a test bed that allows us to validate new technologies on a small telescope under operational conditions.

The image of the star Alpha Persei with the system off (left) and on (right) shows that REVOLT has improved resolution by a factor of 5 and sensitivity by a factor of nearly 500.

He points out that the project, which lasted about 2 years, was successfully tested on the McKellar telescope for the first time in August 2022, with further sightings scheduled for September. “This means we can see an object almost 500 times fainter with the same observing time, which illustrates one of the main advantages of adaptive optics for large research telescopes,” says Dr Kathryn Jackson, scientist in adaptive optics at the Herzberg Research Center for Astronomy and Astrophysics. The research showed that REVOLT was able to effectively correct atmospheric turbulence, demonstrating that 2 new technologies worked as expected when tested under operational conditions. These are the Herzberg Extensible Adaptive Real-Time Toolkit (HEART) and a new commercial high-speed camera called C-Blue One.

Real-time control platform and camera

HEART’s first customer, the Gemini North Observatory in Hawaii, commissioned the researchers to work with the Gemini North Adaptive Optics (GNAO) imager to correct for flicker in the observatory’s massive telescope.

The instrument’s real-time controller (RTC) is based on HEART, created by the research center’s multidisciplinary team. HEART’s layout, architecture and tools make it easy to adapt and drive any adaptive optics system. The GNAO RTC acts as the brain of the system, which processes incoming signals from natural and laser-guided star trackers and sends commands to the deformable mirrors.

“This system will be able to capture astronomical images with unprecedented resolution, sensitivity and contrast,” says Jennifer Dunn, head of the research center’s software group. “Once installed, it will greatly increase Gemini’s scientific productivity.” HEART will also be deployed on several adaptive optics systems in observatories around the world.

First Light Imaging’s new C-Blue One commercial camera is an integral part of the platform. The REVOLT experiment was the first time this camera was used in an AO system on a telescope observing real astronomical objects. In REVOLT, this low-noise CMOS digital camera shoots 1000 high-resolution frames per second.

put it all together

REVOLT’s multidisciplinary team includes engineers and scientists specializing in adaptive optics, software, high-precision opto-mechanics and electronics. They will also work with other NRC research centers that will use the testbed starting this fall.

For example, the REVOLT system will be used to feed corrected starlight to an optical fiber, to enable an in-sky demonstration of a new fiber-powered prototype instrument known as the Spectral Correlation Sensor. This sensor, jointly developed by researchers from the Herzberg Astronomy and Astrophysics and Advanced Electronics and Photonics Research Centers, exploits the advantages of silicon photonic chip technology to produce an ultra-compact and lightweight astronomical instrument that will be used for high sensitivity , remote and real-time gas detection in stellar and planetary atmospheres. This will be the first field test of this new instrument technology, using real operating conditions on a professional-grade telescope.

In addition, the NRC Nanotechnology Research Center will test a new generation of Low Voltage Deformable Mirrors (LVDM) on REVOLT. LVDM can correct distorted images from ground-based telescopes and ground-to-space communication waves due to turbulence in the atmosphere. LVDM is essential for integrating various components of a micro-electro-mechanical system deformable mirror, including mirror face sheet, electromagnetic actuator, circuitry on a semiconductor wafer, and printed circuit board, all due to the low drive voltage used by the electromagnetic system. (known as the Lorentz force) of a strong permanent magnet. LVDM helps compensate for atmospheric turbulence in real time with incredibly low power consumption, high mirror displacement, high fill factor of the mirror’s deformable reflective surface, and 1 millisecond response time.

REVOLT is instrumental in demonstrating new technologies that are essential to the advancement of adaptive optics, which is essential to advances in astronomy and physics, and to our understanding of how nature works. Adaptive optics also enables disruptive technologies used in many fields, including telecommunications, ophthalmology, microscopy, and laser treatment of disease.

“This has many long-term benefits for Canadians and other global citizens, and the sooner we are able to develop these new technologies, the sooner we can make significant changes,” concludes Dr. Véran.