Measurement of Progressive Addition Lenses

Methods on the measurement of progressive addition lenses (PALs) are summarized. Principles and characteristics of several comparatively promising kinds of methods based on Computer-aided Focimeters, optical sampling (Hartmann Testing, Ronchi Inspecting etc.) and Moire Deflection Technology (MDT) are described. Corresponding typical arrangements of the measurement devices used in these methods are provided too. After being compared with each other in their features, their respective advantages and application limitations are analyzed. Also, the new development tendencies of these methods are discussed. Based on foregoing comparison and analysis, key problems and difficulties on the measurement of progressive addition lenses are put forward. In the end, the future of the inspection of progressive addition lenses is proposed.