is resilient and deflectable in a radially inward direction when the upper flange portion 40 is inserted into the neck portion 36 the upper flange portion 40 bears against the collar portion 38 and is radially inwardly deflected until the flange portion 40 clears the collar portion 38 at which time the upper flange portion 40 due to its inherent resilience snaps back to its initial undeflected position and engages behind the collar portion with a snap type locking action to disengage the handle portion from the body portion the upper part of the handle portion is sufficiently deflected until the upper flange portion 40 again clears the collar portion and thereupon the handle portion can be withdrawn from the neck portion 36 in this manner handle portion 12 can be detachably snap mounted and de mounted from the body portion 14 and as explained below another handle portion from a set of interchangeable handle portions each containing different components of the laser scanning system may be mounted to the body portion to adapt the head 10 to different user requirements a plurality of components are mounted in the head and as explained below at least some of them are actuated by the trigger 32 either directly or indirectly by means of a control microprocessor one of the head components is an actuatable laser light source see fig4 e g a semiconductor laser diode 42 operative when actuated by the trigger 32 for propagating and generating an incident laser beam whose light as explained above is 34 invisible 34 or non readily visible to the user is highly divergent is non radially symmetrical is generally oval in cross section and has a wavelength above 7000 e g about 7800 angstrom units advantageously the diode 42 is commercially available from.