633 HeNe laser for lab demos

[steven t hand <hand@wam.umd.edu>]

A researcher would like to purchase a HeNe laser at 633 nm for 	
physics lecture demos.  The individual requested the limit at 
which they could purchase the laser, in mW.  They are interested	
in 20 mW.  This appears to be over the limit for the MPE for a HeNe
to keep it under class III.  It appears to be in the class IIIB
category because it has an output of > 5x the class II level of 
1mW/cm sq .  The MPE is 20mW/.385 cm sq resulting in 52 mW/cm sq
which is > than the 2.5 mW/cm sq MPE for this laser.


Please comment or advise on this determination.  Thank you.

steve at umcp.