Reverse engineering the inner parameters of a cemented doublet has always presented a significant challenge to optical engineers. However, new advances in technology have enabled a greatly simplified method to determining these inner parameters. Of the seven design parameters of a cemented doublet, two are conventionally accessible for measurement (the two outer radii of curvature). Newly available commercial measurement devices allow for center thickness measurements of the two individual components. The three remaining design parameters (the inner radius of curvature and the two indices of refraction) are unknown and are the focus of the method in this paper. Adding measurements of the doublet’s focal length and of the front and rear focal point locations, Mikš and Pokorný derive from the paraxial ray trace equations a set of equations containing only measured quantities. The authors provide an example using a real doublet and are able to show very close agreement between calculated and nominal parameters.

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