A plastic aspheric eyepieceDave shaferDavid Shafer Optical DesignFairfield,CT 06824#203-259-1431shaferlens@sbcglobal.netf/5 and 60 degree fieldUNITS:MMFOCAL LENGTH 25.02 NA 0.09992DES:Shafer入The best 5 element design that combines fast speedand a wide angle looks like this,below.With just these5 lenses it can be corrected for axial and lateral color.The aperture stop is on the front lens.No nameUNITS:MMFOCAL LENGTH -4 NA 0.25DES:Shafer0.928By putting aspherics on all the surfaces it is possible to correctto zero all the five 3rd order aberrations and all of the twelveBuchdahl 5th order aberrations (only 9 of the 12 are actuallyindependent).This is more aspherics than are needed and whatwe eventually want is simply control over all these aberrations,not that they necessarily be zero.One solution looks like this.Only 4 lenses are needed because of the number of aspherics.f/2.0 and 40 degree fieldUNITS:MMFOCAL LENGTH 4 NA =0.25DES:Shafer.646人To get an eyepiece we need to move the entrance pupil out infront of the design.This will have no effect on the 3rd and 5thorder aberrations if they are zero but it does affect the rays.