Ray Hester wrote- >Spectra Physics has the Model 177 air-cooled argon with power supply for >about $11,400 but it only puts out 100 mW of 488 whereas we normally run at >about 200 mW of 488 for our standard analysis of FITC/PE/PI/GFP/live-dead >reagents/etc. This laser (our 5-watt argon) has never seemed too stable >below 200 mW. > >So my question is, will we be able to do most routine analyses such as those >mentioned above on a Vantage with 100 mW of 488? Does anyone have a >recommendation for an air-cooled argon other than the SP model 177? My old (15 and more years ago) experience with water-cooled ion lasers was that their light regulation was not good at low power levels, presumably because only a very small fraction of the light output was diverted to the photodiode used to sense power output in the regulator feedback circuit. I never ran my big lasers much below 200 mW at 488 nm. If I remember correctly, however, some studies by Mike Loken, David Houck, et al at B-D years ago established that 50-100 mW at 488 nm was all that was needed to maximize the fluorescence intensity ratio of fluorescein-stained and unstained cells on a FACS system, and this is reasonably easy to obtain from a high-power air-cooled argon laser. I have used an Omnichrome model 543 air-cooled argon laser for years when I have needed 50-100 mW output; Melles Griot, which absorbed Omnichrome, makes a similar product. I also had a chance to play with a Uniphase high-power air-cooled argon laser, and it worked well. Either of these may cost slightly less than the Spectra-Physics model. Of course, there is also Coherent's 200 mW, 488 nm "Sapphire" laser; it won't save you money unless electricity costs in Alabama reach the levels prevalent in California during Enron's heyday, but it blows a lot less hot air into your lab than a 100 mW air-cooled argon laser does. -Howard
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