Ophir power meter heads that incorporate amplifiers into the head can be found from time to time on Ebay. They're a great way to get a reasonably accurate meter at an affordable price. Keep in mind that as these are usually surplus items, are often tuned to measure very specific laser wavelengths, and usually do not include any calibration documentation, you cannot rely on them to give you totally accurate power readings. For hobbyist purposes however, they work extremely well. Remember to exercise caution when measuring laser energy and ALWAYS WEAR LASER ATTENUATION EYE WEAR.
The following explains how to connect the Ophir 150C-A-xxx series power meters:
A photo that details the pins listed below can be seen [http://www.photonlexicon.com/forums/album.php?albumid=262&attachmentid=37435 here].
{| class=“wikitable”
! 'Pin' !! 'Connection'
| -V | |
| Gnd | |
| +V | |
| Out | |
* The connector used is a standard 4-pin Molex connector which is widely available.
* You’ll need a bipolar power supply, i.e. a supply that gives both a positive voltage and a negative voltage relative to its ground. The voltages can be anything from +/- 12V to +/- 24V. Common dual-output lab power supplies would work well.
* You can also used two standard “wall-wart” AC adapters – of the type that can be purchased for a few dollars at every electronics store. In the latter case, connect the positive of one of the wall-warts to the negative of the other – this junction will serve as the ground. The remaining two wires would connect to +V and –V.
* The output can be read using a standard voltmeter, connected as described in the table. The scaling factor can be determined from the model number of the meter – in the picture above “.1” stands for 0.1 Volt / Watt.
* The sensor has potentiometers inside for adjusting sensitivity, offset, and response speed.
* If you intend to let the laser hit the meter for prolonged periods (minutes or more), you should attach the meter body to a heat-sink.
* These meters are very sensitive. With the laser off, moving your finger or any source of radiant thermal energy in front of the sensor will generate a reading. It is important to let the meter come to equilibrium before testing any laser.