ANSI - American National Standards Institute
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Astronomers Capture First-Ever Image of Foreign Solar System

Standards facilitate technology for clear, accurate telescopic images

New York, Nov 21, 2008

Scientists have captured a visual image of a multiple-planet solar system beyond our own for the first time. With the help of standards, researchers used the Gemini North telescope at the W.M. Keck Observatory in Hawaii to visually document a star and three orbiting planets located 130 light-years away from Earth.

Although solar systems have been located and observed before, astronomers have never had the advanced technology to create direct images of them until now. The solar system centers on the host star HR 8799, which is 1.5 times the mass of the sun, five times more luminous, and significantly younger. These images represent an important step in mankind’s exploration of the universe.

Several standards have fostered the development of specific technology that allowed scientists to generate the image of HR 8799 and planets that surround it. One such technology addresses the problems caused by turbulence in the Earth’s atmosphere. This turbulence leads to a distortion of light, which can generate inaccurate images. The research team counteracted this distortion with the use of adaptive optics. In this technology, wavefront sensors determine the degree of distortion, and deformable mirrors adjust their shape to compensate for this distortion – sometimes as often as 670 times per second. ISO 9039:2008, Optics and photonics - Quality evaluation of optical systems - Determination of distortion is an International Standard that specifies methods of determining distortion in optical systems for the purposes of quality evaluation. These guidelines contributed to the development of a regulated system for measuring the distortions that the deformable mirrors must correct.

ISO 9039:2008 was developed by the International Organization for Standardization (ISO) Technical Committee (TC) 172, Optics and photonics, Subcommittee (SC) 1, Fundamental standards. The American National Standards Institute (ANSI)-accredited U.S. Technical Advisory Group (TAG) administrator for TC 172 and SC 1 is the Optics and Electro-Optics Standards Council (OEOSC), an ANSI member and accredited standards developer.

A second ISO standard addresses the wavefront sensors themselves. Scientists at the Keck Observatory rely upon the Shack-Hartmann wavefront sensor, which consists of a two-dimensional microlens array focusing on a CCD chip. When a laser beam is sent through the sensor, each microlens on the array provides a focus spot on the CCD, creating a pattern of dots of light. Any deflection or aberration of these dots indicates a corresponding distortion of the light traveling through the telescope’s lens. By examining the pattern of dots, researchers can manipulate the deformable mirrors to account for any distortion and improve the quality of the telescopic image.

ISO 15367-2:2005, Lasers and laser-related equipment -- Test methods for determination of the shape of a laser beam wavefront -- Part 2: Shack-Hartmann sensors, specifies methods for measurement and evaluation of the wavefront distribution function in Shack-Hartmann wavefront sensors like those in place at the Keck Observatory.

ISO 15367-2:2005 was developed by ISO TC 172, SC 9, Electro-optical systems. OEOSC also serves as the ANSI-accredited TAG administrator for this SC.

For more information, see the Gemini press release.

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