1. Laser Dye Performance A.Jaqueline Mena University of Hawai’i- Hilo W.M. Keck Observatory Mentor: Kenny Grace Advisor: Jason Chin Funding provided through the Center of Adaptive Optics, a National Science Foundation Science and Technology Center (STC), AST-987683 Photo Credit: John McDonald, CFHT

2. Overview Background Information: –Laser Guide Star –Dye Laser Introduction: –Problem –Purpose –Goal Experiment –Set-up/Procedure Analysis –Peak-to-Valley Ratios –Spectral Slopes –Dye Concentration Measurements Results and Conclusion Acknowledgements

3. Laser Guide Star (LGS) 589nm  Excites sodium layer  Creates an artificial guide star  Allows image correction: Background Photo: http://www.kaunana.com/Default.aspx?tabid=62Courtesy of W.M.Keck and UCLA

4. Basic Dye Laser

5. Layout: Keck’s Laser DMO Dye Master Oscillator 6 Yag Lasers Yttrium Aluminum Garnet

6. Problem The observatory presently has no method for determining when its laser dye should be changed to maintain the laser guide star’s performance. Old dye can cause down time on the laser for several nights. Old dye… …new dye, see our problem? R2 Perchlorate Dye dissolved and diluted in Ethanol

7. Old DMO Dye Output power was 9 watts After the dye was replaced… Output power was 18 watts This means… The laser is twice as efficient with the new dye

8. To find consistent characteristics in old dyes’ spectra that will help determine when the dye should no longer be used. Purpose

9. Goal To create a specific procedure for analyzing laser dye samples, and to identify the spectral features that change most with dye age and overexposure. Steve Doyle holding up a small sample of old dye

10. Experiment Four Dye Samples: New Dye, Dye with 200 hours of use, Old Amplifier (Amp) dye (unknown exposure time), and Old Dye Master Oscillator (DMO) Dye (unknown exposure time)

11. New Dye 200 Hr. Dye Old Amp Dye Old DMO Dye

12. Peak-to-Valley Subtractions Subtracted: B-A, B-C, D-E, F-G A B C D E F G DMO Amp 200 Hr New

13. New Dye 200 Hr. Dye Old Amp Dye Old DMO Dye Old DMO Old Amp 200 Hr. New

14. New Dye 200 Hr. Dye Old Amp Dye Old DMO Dye 11% 127% 89%

15. Concentration Measurements New Dye: 0.22678 200 Hr. Dye: 0.22678  0% Old Amp Dye: 0.13858  39% Old DMO Dye: 0.14887  34%

16. Dye should be changed when the bar graph of the peak-to- valley subtraction calculations changes in pattern compared to the new dye. Dye should be changed when the slope changes by more than 30% of the original.

17. Dye should be changed when the concentration drops by 30% Dye should be changed when the graph’s peak at 546.69nm drops by 30%

18. Acknowledgments Center for Adaptive Optics Sarah Anderson Lisa Hunter Scott Seagroves Hilary O’Bryan Internship short course staff My internship peers Everyone at W.M. Keck Observatory Taft Armandroff Kenny Grace Ron Mouser Kathy Muller Steve Shimko Jason Chin University of Hawai’i at Hilo Institute for Astronomy Thank YOU for your time and support! Funding provided through the Center of Adaptive Optics, a National Science Foundation Science and Technology Center (STC), AST-987683

19. The following are slides that I had to cut out due to time limits.

20. Keck’s Laser This is a tunable laser. It was one of the first to achieve 589nm light at sufficient power levels to create an artificial guide star This is a 10-14 watt laser

21. Courtesy of W.M. Keck Observatory

22. Challenges Proper method of diluting samples (accurate measurement) Correct dilutions to analyze (too much or too little absorption/transmission) Correct wavelengths to perform analysis Software and hardware issues Correct sample integration times

23. Equipment Samples of dye 90% Ethanol Micropipettes Graduated cylinder Paper towels Gloves and splash goggles Spectrometer SpectraSuite Software

24. Equipment Samples of dye 90% Ethanol Micropipettes Graduated cylinder Paper towels Gloves and splash goggles Spectrometer SpectraSuite Software

25. Equipment Samples of dye 90% Ethanol Micropipettes Graduated cylinder Paper towels Gloves and splash goggles Spectrometer SpectraSuite Software

26. Spectrometer This spectrometer was used to measure the absorbance and transmission of dye over specific portions of the electromagnetic spectrum (200-850nm). The independent variable is wavelength (nm). Background Photo: Courtesy W.M. Keck