| Popis: |
In 1992, the European Southern Observatory (ESO) committed a phase A study of a mid- infrared instrument for the 2nd unit VLT telescope, to a consortium of laboratories (SAp at Saclay, France; SRON at Groningen, Germany; and the Kapteyn Observatory at Roden, Netherlands). The results of the study are presented. One key scientific objective for this instrument is foreseen to be the study of dust. The required observing modes are (1) diffraction limited imaging both at 10 and 20 microns, and (2) spectroscopy at low resolution (R approximately equals 500) both at 10 and 20 microns. Another key domain is the study of atomic, molecular, and ionic lines observable in the atmospheric window at 10 and 20 microns. Given the various environments where the lines originate, medium (approximately equals 5000) to high (approximately equals 30,000) spectral resolution is needed. The optical design, as well as a mechanical layout, incorporating the various modes is described. The imaging and spectroscopic channels are separated. The spectrometer is based on a long slit all reflective design. Two optical configurations have been studied in detail. Because of the need for variable magnifications, the imager is based on refractive optics. |
