3 Control

The universal control of MISC and all attached systems, e.g. CCD cameras, has been complemented by a specialized and very efficient setup in which the PC of the CCD controls the whole system.

  

Figure 5: Schematic diagram of the scanner control for its general mode

  

Figure 6: Schematic diagram of the scanner control in its fast mode

Figure 5 shows the general setup for using MISC with any camera that fits. The scanner is controlled by a 68HC11 microcontroller which also triggers the camera. The parameters for the scan, stepwidth, number of positions, time between two exposures etc., are transmitted by the telescopes main computer to the microcontroller, which then performs the scan. A remote control allows to move the scanner manually and to set the starting position.

When MISC is used with the LaVision CCD it is easier and faster to use the scheme depicted in Fig. 6. The SC/CL3.1 software from LaVision can control stepping motors, therefore the scanner control can be integrated into the sequence of exposing and storing the spectra. The main PC serves primarily as the controller for the CCD, but integrates all functions of the MISC system. A simple remote control allows to operate MISC manually for certain purposes. To keep the scanning as fast as possible the camera PC is equipped with 64MB of RAM. The spectra obtained during the scan are stored in RAM and are transferred to a hard disc afterwards. The hard disc capacity of approximately 2GB permits storage of more than 100 scans, depending on the number of spectra per scan and the use of binning.