Evaluation of optical systems designed using the 'concentric-aplanatic' method

After reviewing third-order aberration theory, three examples are given of the design of lenses by the concentric-aplanatic method. The performance of any optical system designed with this method can be improved by releasing all the constraints one by one. After correcting for third-order aberrations, the error function can be inspected to determine if the system is dominated by third- or higher-order aberrations.