GB264176A - Improvements in or relating to means for translating electrical variations into light variations - Google Patents

Abstract

264,176. Telefunken Ges. f³r Drahtlose Telegraphie. Jan. 9, 1926, [Convention date]. Photographic recorders; copying-telegraphs.- Light interference effects are utilized in arrangements for relaying or recording electric currents for picture telegraphy, high-speed telegraphy, or sound recording. In one arrangement, Fig. 1, current supplied to windings W<1>, W<2> controls electromagnetically movement of a diaphragm M carrying at each side a mirror surface Sp receiving light from a source L. Light from the source is incident obliquely on a glass plate J, one portion being reflected at the partially-silvered front face of the plate and another being refracted and reflected from the rear face. The directly reflected ray and the refracted ray, which are arranged to be of substantially equal intensity, are reflected by mirrors 2, 1 respectively on to the opposed mirror surfaces Sp, and after further reflection by mirrors 4, 3 respectively are focused by a lens O to a point F on a stationary or moving photographic surface or a light-sensitive cell S where they interfere to produce a record on the surface or to vary the current in the circuit of the cell. Alternatively, when using non- parallel rays, the interference bands produced are projected on a diaphragm provided with alternately opaque and transparent strips, and therays passing this diaphragm are focused on the sensitive surface or cell S. Fig. 2 shows another arrangement. A parallel beam from a, source 1 and lens 2 is incident obliquely on a glass plate 3 at the front face of which it is refracted with negligible reflection. The refracted beam is reflected partly at the rear face of the plate, and partly by a mirror surface 8 carried by a diaphragm 9 controlled by an electromagnet 10. An initial tension is imparted to the diaphragm as by a direct current supplied to the electromagnet coil or by polarized cores. The two reflected portions, which are arranged to be of substantially equal intensity, are focused by a lens 5 to a point 7 on a sensitive surface 6. The movements of the diaphragm may in all cases be effected through a moving-coil, nr electrostatically, or thermally, i.e. by bending of the diaphragm by expansion of a wire heated bv the controlling current. Specification 256,611 is referred to.