A Gillette (as in the razor
blade) was once a standard measurement tool for determining the strength of a ruby laser beam (used in the late '60's), until calorimiters were developed for energy measurement. If you could focus your laser output sufficiently to blow a
hole through a double-edge Gillette razor
blade, you were the proud owner of a
One Gillette Laser. Gillette blades were found world-wide with standard thickness, so any researcher, anywhere, could compare apples to apples with other researchers for determining their own laser's power