Using an Optical Comparator as a High Resolution Reduction Camera

This paper discusses a method of modifying certain optical comparators so that they may be used as both comparator and high resolution camera. The modifications are uncomplicated and inexpensive. They consist primarily of providing a new light source and a means to hold the photographic plates or film. Since the lenses of the comparator serve as the lenses of the camera, no lens modifications are needed. The system discussed has five discrete reduction capabilities ranging from 10X to 500X. Optical resolution in excess of 500 lines per millimeter has been obtained. A camera system of this type, when compared to the camera ordinarily used for integrated circuit work, has reduced flexibility in certain areas. As an example, one of these areas is the upper limit of the master size. However, in most instances, these limitations can be minimized or circumvented as described.