... Linear and logarithmic display. Absolute measurement and relative measurement. Compact design, portable , light weight. Long battery operating period ... series include the following three types of Optical Power Meter, which divided by different measuring range. ... 780,850,980,1060nm850,980,1310,1490,1550nmOptical Power Range+3~-70dBm or+10~-70dBm(Optional)+ ...