| Detail | ： | Low Res. ( 85 KB) / Mid. Res. ( 1.46 MB) / High Res. ( 9.3 MB) When we look up at the night sky, we see stars that appear to twinkle. This twinkling occurs because the light from the stars is disturbed by turbulence in Earth’s atmosphere caused by changes in the air’s refractive index. For ground-based telescopes, this atmospheric turbulence results in blurry images of stars. Adaptive optics is a technology that overcomes the effects of atmospheric turbulence. It works by using a wavefront sensor to detect how the light from a nearby bright star, called a guide star, is being distorted as it passes through the atmosphere. The system then controls a deformable mirror to cancel out the distortions, allowing telescopes to capture much sharper images of stars as if they were in outer space. If there is no bright star near the target object, an artificial guide star, called a laser guide star, can be generated from a laser beam. In this image, the laser beam from the laser guide star system stretches across the night sky of Maunakea. By utilizing adaptive optics technology in conjunction with the laser guide star system, the Subaru Telescope and other large ground-based telescopes can capture sharp images of stars. (Credit: Dr. Vera Maria Passegger/NAOJ) |
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