Quartz halogen continuum sources, ThAr calibration arcs, and a stabilized He--Ne
Å laser with diffuser disk are mounted in the preslit area.
Different ThAr and
quartz lamps are used for UCLES and UHRF, though all lamps are selected with a
similar control syntax, ARC QUARTZ/THAR/LASER. The control program
selects the lamps appropriate to UCLES and UHRF. The light from all lamps
except the UHRF ThAr passes through a telescope pupil simulator. (The UHRF ThAr
arc intensity was found to be too low when passing through the
calibration lamp optics, and prohibitively long exposure times were required.
The UHRF ThAr lamp now illuminates the image slicer directly.)
The UCLES calibration lamp system has two 8 position filter wheels containing
neutral density and colour filters. The current filter specifications
are found by typing HELP FILTERS; filters as at Feb 1995 are
presented in Table 
.
Table: Calibration Lamp Filter Specifications.
Main commands: ARC QUARTZ/THAR/LASER; LF1 n, LF2 n