DIFF Subgroup
G02B 5/23 Photochromic filters
Introduced: July 1974
Full Title
Full titles differ between systems:
IPC:
Optical elements other than lenses > Filters > Absorbing filters > Photochromic filters
CPC:
Optical elements other than lenses (light guides G02B6/00; optical logic elements G02F3/00) > Filters (polarising elements G02B5/30) > Absorbing filters > Photochromic filters
No child classifications to compare. This is a leaf node in both IPC and CPC.