Power meter heads

[polishedball]

I understand how the 4 wire Ophir heads work, but can someone explain how the 2 wire power meter heads work? Looking at adding logging tommy meter that uses just a 2 wire head.

This is the meter and head info.

http://www.gkoe.com/products/laser_p...rgy_meters.php

http://www.meierlight.net/print_page_p1081

Thanks for any thoughts.

[helium]

I have a two wire Coherent head as well as an Ophir head. As you probably know two of the four wires in the Ophir head are used to power the internal amp. There is no amp in the Coherent head hence the two output wires (actually a coaxial cable).

[polishedball]

Thanks that actually explains it well. Ill just use a opamp as gain and cainration and be set.

Thanks