Design and fabrication of a prototype equipment to measure the refractive power of progressive ophthalmic lenses.*

An optical device designed and manufactured at the Universidad Nacional de Colombia to characterize the refraction of progressive addition ophthalmic lenses is described. The operating principle of the device is the modified Hartmann test. The device evaluates in-frame or uncut lenses. It includes a linear translation stage that allows to measure a wide dynamic range of the refractive power of the lenses, an Arduino module to control the equipment functions, a Raspberry pi module with an own made software for digital image processing and analysis of the refraction of the lenses, and a touch screen to operate the equipment and display the cylindrical and spherical refractive power maps of the lenses.