Abstract: Guide for light or infrared wave beam in which a radial temperature gradient deflects towards the guide axis the light rays which tend to diverge therefrom. The isotherm pattern of two sets of four heater wires, each set being formed of pairs of wires diametrically opposite with respect to the guide axis, is calculated and it is shown that it comprises a particular isothermic curve which has the shape of a bean and separates the two sets of wires. The metal wall of the guide is given the shape of this particular isothermic curve and the set of heater wires outside this wall is omitted.

Abstract: A process for the manufacture of a circular helix waveguide comprising a helically wound insulated metallic wire covered with a barrier layer and forming a wound and wrapped structure itself covered by a metallic screen, wherein a metal band is shaped into a tube, the contiguous edges of the said band are welded by a high frequency current in such a way that after welding the internal diameter of the shaped tube is a few millimeters greater than the external diameter of the wound and wrapped structure, the said tube is placed around the said structure, then the said tube is shaped into a cylinder with a circular base on the said structure to constitute the said metallic screen.