Narrowband interference filter
Narrowband interference filter, one of five, type MD4 (peaks at the wavelengths 436, 546, 626, 672, and 766 n.m.), by Barr and Stroud Ltd., Glasgow, Scotland, 1973. (red)
Narrowband interference filter, one of five, type MD4 (peaks at the wavelengths 436, 546, 626, 672, and 766 n.m.), by Barr and Stroud Ltd., Glasgow, Scotland, 1973. (red)