Today, the optical comparator is a reliable factory stalwart that workers find easy to understand and use, whether on the shop floor or in the inspection room. But they are a far cry from the basic shadowgraph. The transition from purely observational optical measurement to direct digital analyses began about 20 years ago. Modern comparators are equipped with better optics, readout devices, software interfaces, geometric measuring capabilities and screens that range in size from 12 inches to 40 inches.