Twinkling stars have fascinated humans since the dawn of time. But they make it difficult for astronomers to get clear pictures of the sky. Big news: Advanced technology developed by Canada’s National Research Council (NRC) is taking the twinkle and changing the game for studying our universe.
Once light from a star enters Earth’s atmosphere, it passes through several layers of air turbulence that appear to cause the light to flicker or twinkle. This effect also distorts images taken by ground-based telescopes. Fortunately, scientists can now remove this atmospheric disturbance with adaptive optics, clearing the air for these telescopes to take sharp, pure 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 its 1.2-meter McKellar Telescope in British Columbia. This project—Research, Experimentation 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, the images produced by telescopes on Earth 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 Research Center for Astronomy and Astrophysics, REVOLT has immense implications for the largest optical telescopes now in operation (up to 10 meters) and under development ( up to 39 meters). “The time on these big telescopes around the world is in high demand, so when they acquire new technology, they want to prove 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 improved resolution by a factor of 5 and sensitivity by a factor of nearly 500.
He notes that the project, which took about 2 years to complete, was successfully tested at the McKellar telescope for the first time in August 2022, with further observations planned for September. “This means we can see an object almost 500 times fainter with the same amount of observing time, which is an illustration of one of the key benefits of adaptive optics for large research telescopes,” he says Dr. Kathryn Jackson, Adaptive Optics Scientist at the Herzberg Center for Research in Astronomy and Astrophysics. The research showed that REVOLT was able to efficiently correct for atmospheric turbulence, demonstrating that 2 new technologies performed 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 the 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) to fix scintillation on the observatory’s massive telescope.
The real-time controller (RTC) of the instrument is based on HEART, created by the multidisciplinary team of the research center. HEART’s design, architecture and tools make it easy to adapt and manage any adaptive optics system. The GNAO RTC acts as the brain of the system, processing incoming signals from natural star and laser guidance sensors and issuing 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 significantly increase Gemini’s scientific productivity.” HEART will also be deployed in several adaptive optics systems at observatories around the world.
An integral part of the platform is the new C-Blue One commercial camera from First Light Imaging. The REVOLT experiment was the first time this camera was used in an AO system on a telescope observing real astronomical objects. At REVOLT, this low-noise CMOS digital camera takes 1000 high-resolution images per second.
Putting it all together
REVOLT’s multidisciplinary team includes engineers and scientists specializing in adaptive optics, software, high-precision optomechanics and electronics. They will also work with other NRC research centers that will use the test bed starting this fall.
For example, the REVOLT system will be used to feed corrected starlight into an optical fiber, to enable an on-sky demonstration of a new prototype fiber-powered instrument known as a spectral correlation sensor. This sensor, which was jointly developed by researchers from Herzberg’s Centers for Astronomy and Astrophysics and Advanced Electronics and Photonics, takes advantage of silicon photonic chip technology to produce an ultra-compact and lightweight astronomical instrument which will be used for high-sensitivity, real-time remote sensing of gases 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 (LVDMs) at REVOLT. LVDM can correct distorted images from ground-based telescopes and ground-to-space communications waves due to turbulence in the atmosphere. LVDM is key to integrating various components of a deformable mirror of the micro-electro-mechanical system, including the mirror face plate, the electromagnetic actuator, the circuits on a semiconductor wafer, and the printed circuit board, all due to of the low driving voltage used by the electromagnetic. force (known as the Lorentz force) of a powerful permanent magnet. LVDM is helping to compensate for real-time atmospheric turbulence with incredibly low power consumption, large mirror displacement, high fill factor of the deformable reflective mirror surface, and 1 millisecond response time .
REVOLT is critical to demonstrating new technologies that are critical to the advancement of adaptive optics, which is key to progress in astronomy and physics, and in our understanding of how nature works. Adaptive optics also enables disruptive technologies used in many fields, including telecommunications, ophthalmology, microscopy, and laser disease treatment.
“It has many long-term benefits for Canadians and other citizens of the world, and the faster we are able to develop these new technologies, the sooner we can make important changes,” concludes Dr. they will see