Abstract: The solar blind ultraviolet filter includes in an intimate cascade relationship an ultraviolet grade quartz cell containing chlorine gas receiving light energy on an input face thereof, a first Jena UG5 glass cell containing potassium iodide doped with thallium, a second Jena UG5 glass cell containing a 2, 3-dihydro-5, 7-dimethyl-1H-1, 4-diazepine perchlorate and glycerol solution and a Jena UG5 glass and ultraviolet grade quartz cell containing nickel sulfate hexahydrate as the output element of the filter. A black anodized aluminum shell encloses the peripheral surface of all of the above cells. An extremely high viscosity interface coupling medium, such as dimethyl polysiloxane, is disposed at all interface surfaces of the various materials employed in the filter to minimize reflection losses at these interface surfaces.

Abstract: The improved reflection Fabry-Perot interferometer includes the conventional pair of spaced parallel mirrors have a predetermined angle with respect to an incident light beam. The improvement includes third and fourth mirrors each disposed at a different end of the first and second mirrors at a second predetermined angle with respect to a line parallel to the incident light beam so as to reduce the end losses in the two parallel conventional mirrors and to reinforce the light beam emanating from the two conventional mirrors.

Abstract: Solutions of 2,7-dimethyl-diaza-(3,6)-cycloheptadien-(1,6)- perchlorate are used as liquid band pass filters for the transmission of U-V.

Abstract: An ultraviolet optical filter is provided having a first filter element including a 2,7-dimethyl-diaza-(3,6)-cycloheptadien-(1,6)-perchlorate and second filter element including a crystal of thallium doped potassium iodide. A method for filtering light is also disclosed.

Abstract: A spectrometer for use with optical elements which pass both undispersed and dispersed irradiation onto detectors coupled to a transversal filter and a comparitor means which open gates said filter to receive dispersed signals when an initial undispersed threshold is exceeded, thereafter said comparitor inhibits signals exceeding the undispersed threshold during spectral analysis of the dispersed signals.