New Mexico Geochronology Research Laboratory
Hardware — CO2 Laser
The CO2 laser system used by the NMGRL consists of...
- Advantages of a CO2 laser system
- Inexpensive to purchase, operate and maintain
- excellent beam coupling to silicate minerals
- rapid sample heating relative to the resistance furnace
- very low argon background or blank levels relative to resistance furnace
- ideal for identifying sample heterogenities (e.g. non-desirable mineral phases, xenocrysts)
- capable of step-heating with special lenses
- Disadvantages of a CO2 laser system
- incapable of very small (<1 mm beam spot sizes, as is necessary for in-situ argon extraction (see UV laser)
- even with special lenses for step-heating, homogeneous heating difficult
The field of view in the video is approximately 5 mm across. Each hole (~1.7 mm in diameter) contains an individual sanidine feldspar crystal. The computer moves the sample chamber/tray (x-y position) to the next hole to be analyzed and activates the CO2 laser (power = ~2 watts). The laser begins to fuse the silicate mineral. To ensure complete argon extraction, the tray is then jogged through all four quadrants of the hole (only the beginning of the job cycle is shown). After approximately 15 seconds, the laser is deactivated and the argon gas is cleaned and moved to the mass spectrometer to be analyzed.