opened and closed in the correct sequence for accurate loading and safety. Compressor: Responsible for compression of the gas. The compressor employs a dual-stage air-driven diaphragm design that creates pressure and avoids contamination. Able to achieve 207 MPa of pressure. Valves: Valves open and close via the PLC to regulate which gases enter the high-pressure vessel. Burst disks: Two burst disks in the system – one for the high-pressure system and one for the low-pressure system. These disks act as a pressure relief system that protects the system from over-pressurization Pressure transducers: A pressure sensor for the low- and high-pressure systems. Produces a 0–5 V output over their pressure range. Pressure meters: Digital displays connected to each pressure transducer and the PLC system. Vacuum pump and gauges: Cleans the system (by evacuation) before loading. Optical system: Used visual observation; allowing in situ observations of gasket deformation. Ruby fluorescence system: Pressure in the sample chamber can be measured during loading using an online ruby fluorescence system. Not all systems have an online ruby fluorescence system for in situ measuring. However, being able to monitor the pressure within the chamber while the DAC is being sealed is advantageous – ensuring the desired pressure is reached (or not over-shot). Pressure is measured by the shift in the laser induced luminescence of rubies in the sample chamber. Laser heating History The development of laser heating began only 8 years after Charles Weir, of the National Bureau of Standards (NBS), made the first diamond anvil cell and Alvin Van Valkenburg, NBS, realized the potential of being able to see the sample while under pressure. William Bassett and his colleague Taro Takahashi focused a laser beam on the sample while under pressure. The first laser heating system used a single 7 joule pulsed ruby laser that heated the sample to 3000 °C while at 260 kilobars. This was sufficient to convert graphite to diamond. The major flaws within the first system related to control and temperature measurement. Temperature measurement was initially done by Basset using an optical pyrometer to measure the intensity of the incandescent light from the sample. Colleagues at UC Berkeley were better able to utilize the black-body radiation and more accurately measure the temperature. The hot spot produced by the laser also created large thermal gradients in between the portions of sample that were hit by the focused laser and those that were