When using a Fiber Adapter accessory together with one of Ophir's sensors, it is important to be aware of the power/energy density that is going to reach the sensor's surface.In most cases, the fiber adapter locates the fiber tip far enough away from the absorber surface that the spot diameter on the surface will be large, and problems of damage avoided. However, that is not always a certainty! For example, when using a sensor from the PD300 series, especially with filter IN, this distance could be quite small. A power level that is within spec limits could still result in a power density on the filter that is too high, and the result could be damage to the filter. In most cases, as noted, this is not a concern, but in cases where any one parameter seems like it is going to be near a limit, a quick sanity check is a good idea.