Advantages of CO2 laser systems

Disadvantages of CO2 laser systems
  • Inexpensive to purchase, operate and maintain
  • excellent beam coupling to silicate minerals
  • very fast relative to the resistance furnace
  • very low argon blank relative to resistance furnace
  • ideal for identifying sample heterogenities (e.g. other mineral phases, xenocrysts)
  • capable of step-heating with special lenses
  • incapable of very small (<1 mm) beam spot sizes needed for in-situ argon extraction (see UV laser)
  • even with special lenses for step-heating, homogeneous heating difficult

Data

 

 

 

 

 

 

 

 

 

 

 

Schematic of NMGRL CO2 Laser setup (see parts list below)


 

List of Components:

 

1) Color TV camera, Polnux TMC-574

2) Optical Lens

3) IR transparent optical mirror

4) Vibration isolated workstation, Newport

5) Automated stage: 2 x Newport 443; 2 x Newport VW-3046-OPT71

6) Sample Chamber: Base 3.375" flange; Window ISI ZnSe 1.5" Window in 3.375" flange

7) Copper sample holder; 9 to 221 sample pits

8) KBr cover slip: 2mm thick x 38.1 diameter, Hilger

9) XX x XX silicon mirror,

10) 1" diameter 5" focal length ZnSe meniscus lens, II-VI #376587

11) Beam integrator lens

12) Laser power meter head; Molectron PM150-19-C, swings in or out of beam path

13) Laser feedback diode, Synrad CA-48-CL

14) 50-watt CO2 laser, Synrad 48-1-28W

15) He-Ne Pointer laser, Synrad He-Ne

16) Two-axis motion controller w/ IEEE4888, Newport PMC200-P

17) Laser power meter, Powermax 5100

18) CO2 laser controller w/ 0-10 volt input, Synrad UC-1000

19) 0-40 volt, 10 amp power supply w/ 0-10 volt input, Lambda LLS8040

 

 

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CO2 Laser Photo Gallery (more pictures coming soon)

 

 

 

Photo of the CO2 laser chamber used by the NMGRL. In the background are several copper planchets with up to 221 individual pits. Each pit holds one single crystal with 15 crystals comprising one complete sample population.
 

 

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Video Clip of CO2 Laser Fusion

To view the video, click on the button below.

Explanation: the image you will see is approximately 5 mm across. Each hole (~1.7 mm in diameter) contains an individual sanidine feldspar crystal. The computer moves the tray (x-y position) to the next hole to be analyzed and fires the laser (power = 1.8 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 turned off and the argon gas is cleaned and moved to the mass spectrometer to be analyzed.






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