Official module comparison: 81636B at left and the different 81635A at right. This reference is not a two-module package; actual connector configuration and supplied unit must be confirmed.
Official Keysight 8162xB optical-head family reference for 81624B. Exact pictured variants are unverified; offered-unit configuration and accessories must be confirmed.
Supplier reference system photograph for the Agilent 81623A optical power head, shown connected through an 81618A interface in an 8163B lightwave mainframe with an installed 81689A tunable laser. Spare cables and a dust cap are also pictured. Confirm the offered optical head, mainframe, installed modules, connector interfaces and included accessories.
Official Keysight reference configuration: 81619A is the rear-left module with two inputs. The 81618A and optical head are illustrative companion components.