Automatization of a multipurpose astronomical spectrograph

This article deals with the study and fabrication of a system for the autom ation of a multipurpose spectrograph used in Astronomy. This system allows the 19 movements of the instrument to run by using high-level software, a " master" board, and 19 "slave" boards. The Astrophysique Lineal et BIdimensi onal par REseaux Optiques (ALBIREO) spectrograph has three working modes an d is installed in the Observatorio de Sierra Nevada, Granada, Spain. We des cribe a low-cost system realized for the automatization of a multifunction spectrograph. It allows the control of a large number of motors: 19 for Alb ireo; the theoretical limit is 32 768! Another advantage of this architectu re based on "slave" boards is to supply each motor with exactly the current it needs to reach the required torque (reliability and repetitivity of mot ions are obtained when the motor torque is at least twice the resistant tor que). Thus, we can avoid unnecessary overheating which would be detrimental to the material as well as to the local image quality (seeing). The reliab ility of the system is obtained by software filtering the commands and also by using optocoupled electronics to avoid interference. For a complex inst rument, the high-level software must be user friendly. The efficiency of th e present software in this respect has been appreciated since first being u sed on the telescope. This system may be of interest to laboratories and ob servatories with similar needs for automation of motions. The adoption of t his system will be supported by the IAA Laboratory, Granada, Spain. (C) 200 0 American Institute of Physics. [S0034-6748(00)01606-3].