Optical comparators also referred to as optical projectors or contour projectors project the shadow of the work piece onto a glass screen. They offer the capability to measure difficult and special configurations.
The optical comparator is typically used with a chart overlay that has detailed cross hairs so that the movement of the part can be measured from one edge to another. Other overlays offer radius lines and thread angles.
Many optical comparators are equipped with a range of magnifying lenses so that images can be projected at 10 to 50 or more times the size of the original object.
The optical comparator plays a vital role in quality inspection.