For measuring power of a scanned beam we recommend using the BC20, and not the PD300. Since a scanned beam will spend only a fraction of the time of each scan on the detector, the average power measured by the detector will correspondingly be only a fraction of the actual power of the beam. The BC20 is specially designed for such applications by having a peak-hold circuit integrated in its electronics.

It's +/-3% of the reading from full scale down to 5% of full scale. Below 5% of full scale one should switch to next range down for the best accurate linear results.

All Ophir power meters, including photodiode power meters, have an air gap between the fiber tip and the sensor. Therefore they measure the power emitted by the fiber into the air and do not take into account any reflection losses there are in the fiber. Therefore, if in actual use, the fiber will be coupled with no loss to another element, then the losses should be added to the reading. These losses are usually about 4%. Thus if the reading on the Ophir meter is say 100 mW, then in lossless use, the real power will be 104 mW.

Yes, the adapter is arranged so the user can use it either with filter out or in.

Unless otherwise indicated, Ophir sensors and meters should be recalibrated within 18 months after initial purchase, and then once a year after that.

It should be okay, as long as:

• the wavelength is not near the long wavelength limit where the PD300 has a large temperature dependence;
• there is no condensation on the window of the detector which could interfere with the beam and affect the reading.

We suggest the customer does an experiment with a stable laser source (such as a pointer laser) shining in through a window onto the detector while the unit is temperature cycled to see if the reading changes. The final measurement should be back at the original temperature so as to make sure the laser hasn’t changed.

The PD300 sensors are not designed to measure with the fiber pushed up right against the detector surface. It may be reading lower in such a case due to saturation of the detector from the concentrated beam or higher due to back reflections off the detector and back again from the fiber tip. The optimal reading will be where the beam is expanded to a size of 2-5mm diameter. Therefore, you should back off the fiber to a distance where the beam has expanded somewhat. Do not back off too far, otherwise if the nominal beam size is larger than given above, you may lose some of the beam off the edges of the detector.

Although these sensors measure average power (of both CW and repetitively pulsed beams), not pulse energy, it is possible for a pulsed beam to have average power within the sensor’s rated limits and yet have the energy of the pulses themselves be high enough to cause a momentary saturation of the sensor. It is important to be sure that pulse energy is also within sensor spec – not just the average power. This is explained in detail in this White Paper.