  This paper describes the automation of a laser heating arrangement for
synthesizing and studying materials at high pressures (up to ~ 1 Mbar) and high
temperatures (up to ~ 5000 K). In this arrangement, a diamond anvil
high-pressure cell (DAC) containing a microscopic sample of typical diameter
~50-100 micrometer, is mounted on a precision X-Y nanomotor stage that forms
part of an IR laser heating optical assembly. Automation of this stage has been
accomplished using a LabVIEW virtual instrument program to manipulate the X and
Y stages using nanopositioning systems. This has a major feature of enabling a
rastered heating of the sample over a user-defined circular area, without any
operator intervention in addition to a virtual joystick to position the sample
with respect to the laser spot. This auto-rastering feature has the advantage
of offering uniform exposure of a circular area of the sample to the incident
heating laser beam apart from drastic reduction in scan time compared to a
manual scan. The diameter of the circle can be varied from a maximum of ~24 mm
down to the focal spot size of the laser (~few micrometers), enabling thereby
usage of the laser heating arrangement for heating microscopic samples under
high-pressure in a DAC, as well as bulk samples at atmospheric pressure.
Examples for both macro and micro scale automated laser-heating experiments
have been presented. In particular, at the micro scale, auto-raster heated
carbon samples at ~ 17 GPa and ~2000 K showed excellent signatures of diamond
formation compared to manually raster heated samples, highlighting the unique
advantage of auto-raster heating.
