What are Optical Comparator?

Optical comparators, also called profile projectors or shadowgraphs, enlarge an image of a component and display it on a screen or sensor for inspection. The image thus obtained can be compared with a reference overlay or template to ascertain whether or not the component meets specifications. The manufacturing, aerospace, and automotive sectors all make extensive use of optical comparators.

Optical comparators use a projection system that includes a light source, lenses, mirrors, and a stage or table where the object to be measured is placed. The lenses and mirrors use the light source to illuminate the object and project the magnified image onto the screen. The viewing screen is a glass or translucent surface that displays a magnified image of the object. It usually features markings, grids, or scales for measuring purposes. 

Optical comparators come with a variety of magnification choices, allowing for a more precise analysis of minute features and details. Change the lenses or modify the distance between the lenses and the object to change the magnification.  Some optical comparators may include overlay charts or templates with predefined forms or contours. These overlays can be overlaid on the projected image to allow for easy comparison and identification of deviations from the norm.  

Optical comparators frequently contain measurement capabilities such as linear scales, angle measurements, and coordinate systems. These functions enable operators to measure the dimensions, distances, angles, and other geometrical attributes of the object under inspection.Dial comparators and mechanical comparators, both of which use mechanical amplification to compare a part’s dimensions to a standard, are two types of mechanical-optical comparators. Dial gauges and indicators, which are used to measure the part’s dimensions, are typically mounted on a mechanical frame. Machine shops frequently employ mechanical-optical comparators for use in quality control and inspection.

Video 01: Optical Comparators | Mechanical-Optical Comparators