Respectfully, I built my first lasers in the mid-seventies in high school, back in the olden days. A dye laser (rhodamine, IIRC, from Scientific American plans), nitrogen gas laser, and a He-Ne gas laser for which I destroyed literally hundreds of pounds of glass tubing while learning to make apparati. As I recall, that one never did work right! But I do appreciate all the nuances, Ivo. One needn't know all the ins-and-outs of lasers in order to make an informed purchase. For the vast majority of what is currently marketed and legal in the US as pointer-style lasers, duty cycle is indeed a reasonably accurate predictor of intensity at a given output rating- yes you are right that there are reasons for operating the module at less than 100% duty cycle- -BUT- it certainly appears to be the primary reason why some "5mw" lasers are significantly brighter than other "5mw" lasers, all other things being equal. I plan to purchase a true 5mw, 100% duty-cycle unit, and will gladly make it available for side-by-side comparisons. Want to design the experiment, Ivo?

From: Ivo Stutznegger <ics_ute@yahoo.com>

I would definitely agree with the first statement of your first post on this thread. -“I've discovered that powerrating is not in itself a foolproof indicator of brightness.”

However an indication that the laser operates at less than 100% duty cycle doesn’t necessarily mean that it is dimmer. There is a very good reason to operate a portable battery powered laser at less than 100% duty cycle.

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