Published: Sat, July 21, 2018
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VLT uses adaptive optics to capture super-sharp image of Neptune

VLT uses adaptive optics to capture super-sharp image of Neptune

The European Southern Observatory's Very Large Telescope, using the MUSE instrument and a new adaptive optics system captured this stunning view of Neptune in a demonstration of unparalled ground-based resolution.

Neptune is 2.9 billion miles away from Earth and the only better pictures that many of us remember seeing is when the Voyager 2 flew by the planet back in 1989.

The same turbulence in the atmosphere that causes stars to twinkle to the naked eye results in blurred images of the Universe for large telescopes. This is extremely hard to attain in the visible and gives images comparable in sharpness to those from the NASA/ESA Hubble Space Telescope.

The Very Large Telescope, an installation located in Cerro Paranal, Chile, by the European Southern Observatory project, has recently been upgraded with so-called "adaptive optics" technology that allows for a much sharper image capture than previously possible without breaking through the atmosphere.

The Neptune image on the right is without the adaptive optics system in operation and the one on the left after the adaptive optics are switched on. From the ground, you have to find a way to correct that blur that makes distant objects unclear, hence why you need a reference point.

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Scientists installed the mirror of VLT's Unit Telescope 4 with four powerful lasers that shoots intense beam of light in the sky and excites the sodium atoms in the upper layer of the atmosphere. The telescope has achieved first light using the new optics mode and the difference in image sharpness is stunning compared to before images.

Without the adaptive optics tech, photos taken of Neptune even by the Very Large Telescope remain extremely blurry and indistinct, with zero detail or form.

When using the new Narrow Field Mode using laser tomography the team can correct nearly all the atmospheric turbulence above the telescope to create much sharper images, but only over a small region of the sky.

The pioneering MUSE instrument in Narrow-Field Mode, working with the GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere. It the allows for more precise imaging over a comparatively wide field of view, capturing clusters of stars in the night sky, as well as close details of individual celestial bodies. Adaptive optics systems consists of three main components: a wave front corrector to compensate for the distortion, a wave front sensor to measure distortion, and a control system to calculate the required correction and necessary shape to apply to the corrector.


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