After 10 years of development and testing, the Gemini Planet Imager (GPI)—designed to image faint planets next to bright stars and probe their atmospheres—is finally operational, having just captured an image ofBeta Pictorus, a 10-million-year-old planet that is 63 light years away from Earth.
GPI detects infrared radiation from young planets in wide orbits around their stars, and every planet that GPI can see, can be studied in detail. As it stands now, planets that are known about are only known because of indirect methods that let us know that a planet is there, but with GPI, the direct imaging of a planet around stars is enabled, which in essence allows scientists to dive into a planet’s atmospheric makeup and characteristics, according to Bruce Macintosh of the Lawrence Livermore National Laboratory, who led the team that built the instrument.
GPI described by the Gemini Observatory as an extreme adaptive optics imaging polarimeter/integral-field spectrometer, which will provide diffraction-limited data between 0.8 µm and 2.4 µm. It provides spectroscopy or dual-beam polarimetry of any object in the field of view (2.8 arcseconds on a side, with a 14 milliarcsecond sampling). GPI is comprised of four main optomechanical systems:
- An adaptive optics system, responsible for fast measurement of instantaneous wave front, and for providing wave front control via two deformable mirrors.
- An infrared wave front sensor calibration unit that provides measurements of the time-averaged wave front at the science wavelength and coronagraph focal plane to suppress persistent speckles caused by quasi-static wave front errors in the final image. It also provides pointing and focus sensing to keep the target star centered on the coronagraph with 1mas accuracy and slow low to high-order aberration corrections.
- The coronagraph, which uses a combination of apodized masks and focal-plane stops to control diffraction and pinned speckles.
- The integral field spectrograph, which produces the final science image, including simultaneous multiple channels to suppress residual speckle noise in the spectroscopy mode or polarimetric imaging.
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