Abstract: Conventional fluorescent solar collectors are utilized as external surfaces for building units. Since fluorescent solar collectors need not be aligned with the sun to obtain a high degree of efficiency, they are utilized as wall units or wall elements, as well as roof units or roof elements.

Abstract: A method of increasing the contrast when photographing a transparent object, such as a glass object through the use of a television camera, is provided. The transparent object is illuminated with radiation in a region of the spectrum to which the transparent object is impermeable. A filter which suppresses the radiation in the region of the spectrum to which the transparent object is permeable and transmits radiation in the region of the spectrum to which the transparent object is impermeable is used between the light source and the transparent object. An electronic pick-up camera which is sensitive, i.e., capable of detecting radiation, in the region of the spectrum to which the filter is permeable, is used for taking photographs of the object.

Abstract: Glass composition ranges are described which permit the introduction of laser activators into fluorphosphate glass with exceptionally high fluorine content while forming glasses of high crystallization stability and permitting the realization of large melt volumes. The high fluorine content imparts to the glasses an exceptionally low nonlinear refractive index n.sub.2 down to O,4 .times.10.sup.-13 esu.

Abstract: A glass when in the form of an optical fiber having an optical loss of not more than 150 dB/km, high transparency, a high numerical aperture, and a high flexural strength, said glass being especially suitable for optical fibers and consisting essentially of:SiO.sub.2 : 65 - 75 mol-%; (38 - 46% by weight);R.sub.2 o: 4 - 17 mol-%; (4 - 13% by weight);PbO: 16 - 25 mol-%; (42 - 55% by weight); wherein R.sub.2 O is Na.sub.2 O, K.sub.2 O or Cs.sub.2 O or mixtures thereof, preferably not more than 3.0 mol % Na.sub.2 O, and with the provision that the molar ratio of SiO.sub.2 : PbO is 2.5 - 4.0.

Abstract: A neodymium-doped phosphate laser glass composition having a low threshold for stimulated emission, a negative temperature coefficient of refractive index, high acid resistence and homogeneity even in large structures comprises P.sub.2 O.sub.5, Na.sub.2 O or K.sub.2 O, Al.sub.2 O.sub.3, Nd.sub.2 O.sub.3, and optionally, F or RO, wherein R is Mg, Ba, Ca, Sr or Zn.