Early oscilloscope graticules were on a clear plastic screen in front of the CRT which could cause measurement errors due to parallax. This photo shows the process of scribing a graticule on a clear piece of plastic.

By the 1960s, parallax was eliminated as graticules were screened onto the faceplate of the CRT prior to depositing the phosphor.

Before this, Bob Anderson worked on a virtual oscilloscope graticule to eliminate parallax. Although this scheme never went into production, the museum has one of his prototypes installed on an oscilloscope. This video demonstrates how it operates.