Abstract: An apparatus used directly on a flat sheet of transparent material, especially tempered glass, for simultaneous measurement of sign and amplitude of stress across the section of said glass sheet using scattered light. The apparatus allows reliable and repetitive measurements independently of the operator's subjective observations, since the data is read through an automatic system. The apparatus has a Helium-Neon (He-Ne) laser source of 1 to 5 mW, whose light beam is linearly polarized, then modulated with a series of wave plates (2,2', 2"), then passed through a collimator (3) and subsequently made to strike a prism (4) optically coupled with the glass sheet (V) being tested. Variation in intensity of the interference fringes is revealed by a TV camera (5) having a macrophotographic lens system (5') which focusses the scattered light on a solid-state array photodetector (5').

Abstract: A multiband aerial, especially suitable for a motor vehicle window, or for application to the window, which comprises a single conductor wire which starts from a signal pickup position, terminating in just the one free end, and which includes the FM aerial section and the AM aerial section, with such sections being connected in series, and therefore not requiring phasing, and being electrically isolated by means of an inductor, preferably of box rib pattern, which inductor can function as an open circuit in the FM band and as a short circuit in the AM band. The series of vertical and horizontal segments, forming the sole aerial conductor wire which contains in series such FM section and AM section, can be of variable, but always asymmetrical, geometry or configuration.