US Patent 7251898 Transparent measuring device with enhanced visibility lines

A transparent measuring device with enhanced visibility lines formed on a transparent substrate having opposing planar front and back surfaces and with at least one opaque line formed on one of the front and back surfaces and at least one transparent line formed on one of the front and back surfaces to be colinear with the at least one opaque line to present a composite line where the transparent line permits viewing of material on which the device is placed while highlighting the at least one opaque line for enhanced visibility. The transparent line may be formed of excitable pigment that reacts to light, such as a black light, or that retains luminance after exposure to light.