laser change recommendation

Howard Shapiro hms at
Thu Aug 22 21:40:32 EST 2002

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.


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