Keysight / Agilent 81531A Optical Power Sensor

The Agilent 81531A optical power sensor is designed for power measurements of optical components. Here is an answer to a common question asked about installing 815xx modules into 816x mainframes (from Agilent faq):

Can I use the 815xx Modules with the newer 816x mainframes? What are the trade-offs?
The 815xx modules will operate in the 8163 and 8164 mainframe. However, the 815xx modules will NOT operate in the 8166 mainframe.
The new series power modules 816xx have a number of advantages: 1) a minimum integration time of 100 microsecond vs. 20 ms integration time for 815xx, 2) advanced triggering capability, 3) 12,000 points can be acquired per channel in remote operate vs. only 4000 points for the 815xx.