This type of headlight that uses a trace of bromine or iodine vapor is the standard in auto manufacture
[DOC] [TLE] AUTOMOTIVE TECHNICAL TERMS F to P [PAR] The process of using a chemical to remove sludge, dirt, rust or metallic debris 
from ... On the plus side, the advantages go mostly to the vehicle manufacturers 
because it .... A type of headlight that produces more light than an ordinary 
headlight.