In the 1930' s, many symmetrical double Gaussian structures, such as plane structures, were changed to asymmetric designs one after another, mainly to correct the aberration caused by large aperture. There are many variants of asymmetric double Gaussian, but the overall structure is still double Gaussian. Some separate the original bonded lenses, and some divide the original positive convex mirror into two positive convex mirrors, which have various uses. The most famous systems are summary 50/2, summary t 50/ 1.5, summary 50/2, Summitron 50/2, 90/2 and so on of LEITZ. The deformed double Gaussian has a long history, and these asymmetric double Gaussian structures are all designed to improve the quality at the maximum aperture.
Today, in the 2 1 century, there are more than 300 registered patents of optical manufacturers on the design of double Gaussian lenses, and there may be more variants of other unregistered patents, which shows that there are many grandchildren. Most of the large aperture lenses we see now are asymmetric double Gaussian structures, and some of them, such as f/ 1 or even 0.95, are of this design.