MIDI

MIDI in a nutshell

MIDI operates at wavelengths around 10 microns (20-micron option planned for the future). Its "cold optics" (32 K) section, built at ASTRON, combines beams from separate (1.8 or 8.2 metre) telescopes of the VLTI. The goal is to measure the complex correlation between these beams by measuring, in one way or another, the fractional intensity and spatial phase of the fringes formed on the (7 K) detector array. Such a measured correlation is a single sample of the spatial autocorrelation of the electromagnetic field in the pupil plane of the VLTI. A coordinated set of such measurements allows one to construct, by Fourier Transformation, an image (intensity map) of  a small area of sky, with a resolution on the sky determined by the largest distance between the pair of telescopes (that process is called 'aperture synthesis', the pair of telescopes with their correlator is known as an 'interferometer'; the total instrumental process is very complicated and requires the expertise and facilities of several instrumental groups, hence the consortium).             

 

Poster presentation at SPIE, Hawaii, August 2002.

See also the MPIA site: http://www.mpia-hd.mpg.de/MIDI/About.html

See also  the ESO site: http://www.eso.org/sci/facilities/paranal/instruments/midi/index.html

Click on the pictures below for some optical impressions and the real instrument.

   

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