(under subclass 642) Subject matter where the lens or structure combined with the lens exhibits spectrally differential transmission.
(1) Note. In the lenses of this and the indented subclass the means which gives the lens its particular light-transmitting properties may be either an integral part of the lens, i.e., the particular material from which the lens and the components are made, or a separate plate having opposed parallel plane surface disposed transversely of the optical axis of the lens, such plate being formed of a material which favors or hinders light transmission in a selected area of the spectrum more than it does in any other area of the spectrum.
(2) Note. The term spectrum as employed in this definition refers to light having wavelengths between 3850 and 7600 angstrom units, that is, visible light.
SEE OR SEARCH THIS CLASS, SUBCLASS:
350+, for lenses having significant characteristics in the infrared or ultraviolet spectrum.
885+, for light filters, per se.
SEE OR SEARCH CLASS
351, Optics: Eye Examining, Vision Testing and Correction, 163, for spectacle lenses with light-filtering means.
362, Illumination,
317, for refractors in the form of lenses not otherwise classified.
