Rough dual lens design

design_doublets.py

import argparse as ap

if __name__ == "__main__":
    parser = ap.ArgumentParser()
    parser.add_argument('f', type=float, help="Overall focal length")
    parser.add_argument('library', type=int, nargs='+', help="Focal length of available lenses")
    args = parser.parse_args()
    
    f = args.f
    fs = args.library
    
    design_tbl = []
    for f1 in fs:                           
        for f2 in fs:
            if f1 <= f2:
                d = (1/f1 + 1/f2 - 1/f) * f1 * f2
                design_tbl.append({'d':d, 'f1':f1, 'f2':f2})
                
    design_tbl = [x for x in design_tbl if x['d'] <= 0]
    design_tbl = sorted(design_tbl, key=lambda x: x['d'])
    for entry in design_tbl:
        print("{f1:d}, {f2:d} --> {d:0.3f}mm")