Abstract: In an automatic brightness control feedback loop for controlling the bias voltage of a microchannel plate of an image intensifier tube, there are provided a gas discharge tube and a photoconductor which is photoelectrically coupled with the gas discharge tube. The brightness of the gas discharge tube is controlled depending on the phosphor screen current. An ordinary automatic brightness control and also the blinking when the incident light is excessive can be made by having the bias voltage of the microchannel plate depend on the resistance of the photoconductor.

Abstract: A solar heat collector assembly includes a cylindrical transparent tube having an open end portion hermetically sealed by the use of a sealant and being held in vacuum state and a heat-collecting pipe secured in the transparent tube with its end portion extending outside the transparent tube through the sealant. The sealant of a transparent material, for example, is bowl-shaped and the heat-collecting pipe is secured to pass through the center of the bowl-shaped sealant. The pipe and the sealant are bonded together through the use of a proper adhesive metal material. The outer periphery of the sealant is further bonded to the open end portion of the transparent tube. The adhesive metal material is typically 426 alloy.

Abstract: A solar heat collector assembly includes a cylindrical transparent tube having an open end portion hermetically sealed by the use of a sealant and being held in vacuum state and a heat-collecting pipe secured in the transparent tube with its end portion extending outside the transparent tube through the sealant. The sealant is made of a thermally-nonconducting and anti-corrosion material with a softening point higher than that of the transparent tube. Especially, the sealant is made of ceramics or crystallized glass.