Since the laser power detection circuit 11 often has an abnormal emission slice level n1 of about 1.5 mW set relative to the signal m of {HEAD ~ about 1 mW}, the detector 11 detects this interval as the abnormal emission, thus producing the output signal p of H1 voltage by which the laser drive circuit 21 is controlled to stop the beam emission of {TAIL ~ the laser beam source} 1 
Since the laser power detection circuit 11 often has an abnormal emission slice level n1 of about 1.5 mW set relative to the signal m of { HEAD ~ about 1 mW } , the detector 11 detects this interval as the abnormal emission , thus producing the output signal p of H1 voltage by which the laser drive circuit 21 is controlled to stop the beam emission of { TAIL ~ the laser beam source } 1
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH