An eye diagram is a pattern displayed on an oscilloscope by accumulating a series of digital signals. It is vividly named so because its shape resembles an open eye. To generate an eye diagram, an oscilloscope needs to measure a large volume of data and then recover the diagram. Optical module eye diagram: opening the door to optical communication signals When we try to explore the performance of optical modules in depth, the eye diagram becomes the key “password lock”. Every slight fluctuation and. Graphical eye pattern showing an example of two power levels in an OOK modulation scheme. Constant binary 1 and 0 levels are shown, as well as transitions from 0 to 1, 1 to 0, 0 to 1 to 0, and 1 to 0 to 1.