The ISO Michelson

Design work performed in order to prove the feasibility of the instrumentation intended for carriage on the IR space observatory (ISO) is described. The ISO has a 60 cm telescope with a prism at the focus to direct IR light onto one of four instruments. Pointing accuracy is projected to be 10 arcsec and a lifetime of 1.5 yr is planned. A near-IR camera will record data in the 2.5 micron wavelength range, the 2-25 micron band will be covered by two Michelson interferometers with a resolving power of 1:10,000, and a three or four band photometer featuring small detector arrays will be included. Attention has focused on the drive and suspension of the movable mirror, allowing 30 mm movement, and optical step size of 316 mm with 4 mm accuracy, a travel velocity of 125-315 microns/sec, a maximum beam size of 10 mm, and a FOV of 0.5-1 arcmin. An electromagnetic drive was selected, as were the vibration compensator, a double bridge movable base, and the materials.