DIFF Subgroup
G02B 27/40 Optical focusing aids
Introduced: September 1968
Full Title
Full titles differ between systems:
IPC:
Optical systems or apparatus not provided for by any of the groups , > Optical focusing aids
CPC:
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 > Optical focusing aids
No child classifications to compare. This is a leaf node in both IPC and CPC.