OPTICS & OPTICAL PHENOMENA A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site filter An accessory used with an optical instrument or detector of electromagnetic radiation either to narrow down the wavelength band or to reduce the total intensity passing into the instrument. Filters are often valuable in improving contrast and delineating detail that would otherwise be less visible. Related entry    • nebula filter Related category    • OPTICS AND OPTICAL PHENOMENA Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP