The AQ6370D is the latest iteration of the most popular Telecom class OSA from Yokogawa. It offers a versatile wavelength range of 600 nm to 1700 nm ideally suited for both Telecommunications and general purpose applications. The unique free space input design allows testing of both DWDM class singlemode and VCSEL sourced multi-mode fibers in one single model. Newly added functions include data logging, gate sampling,resolution calibration, an advanced marker function and an enhanced auto-sweep mode.