Introduction

This manual describes all steps involved in making MOS masks for ALFOSC.

To make a MOS mask, it is required to first obtain a temmask image of the field obtained with ALFOSC, to be able to account for the field distortion of ALFOSC. When the temmask image is acquired, the observer can then produce a mask layout using the mosmask program. The mask layout is written to a CNC file by the mosmask program. After this has been completed, the CNC-machine operator produces the MOS mask.

As of a few years ago, the MOS masks have been fabricated in Copenhagen. As the masks have to be shipped to the NOT, the design of the masks has to be started timely, e.g. not later than 1 month before the run. This implies that any required pre-imaging has to be planned about 2 months before the run, at the latest.