Patent GB-431958-A (GB)
Title: Improvements in and relating to optical valves
IPC: G02F1/07
Filed: 1933-11-20
Abstract: 431,958. Light-valves. WALTON, G. W., 2, Dean Street, Soho, London. Nov. 20, 1933, No. 25919. [Class 40 (iii)] Optical valves such as those using the Kerr or Faraday effects, have the solid polarizing and analyzing devices wholly immersed in a transparent liquid. Figs. 1 and 2 show a construction in which the polarizing and analyzing prisms 1, 2 are arranged within metal end plates 3, 4. One set of controlling plates 6 bear at their upper ends through soft metal 7 on the plate 3 and at their lower ends through soft metal 8 on a tension plate 9 provided with adjusting screws 10 bearing through glass plates 11 on the plate 4. A second set of controlling plates 14 are interleaved with the set 6 and are supported in a similar manner, the tension plate 15 being drawn upwards by screws 16 bearing through glass plates 17 on plate 3. If desired, glass spacers 18 may be provided between adjacent plates. The cell assembly 23 above described is arranged in a bulb 22, Fig. 4, or in a container of the form shown in Figs. 5 or 6, the bulb or container being filled with a suitable working liquid, such as nitrobcnzene, having approximately the same refractive index as the prisms 1, 2. According to a modification, the prisms together with suitable covers may be arranged to constitute a container for the working liquid which is then only in contact with the inner faces of the prisms. The assembly is then mounted within a container as shown in Figs. 4-6 which is filled with the same or a different liquid. A construction employing four units of the kind shown in Figs. 1 and 2 is also described, Figs. 8-10 (not shown), the plates of the first two units being located side by side and those of the other two units being also located side by side but displaced along the light path relatively to the first two units and arranged in planes at right angles to those of the first two units. A construction of double cell is also referred to and in the case in which a cell unit comprises two pairs of sets of plates with the plates of one pair arranged at right angles to the plates of the other pair, the unit may be connected in pushpull, Fig. 14 (not shown). In a construction employing two control systems each comprising a pair of control electrodes, the electrodes may be associated with electric circuits so arranged that both systems operate upon curved parts of their characteristic but so that the curvatures tends to cancel one another whereby the overall characteristic of the valve is made more nearly straight. Fig. 13 shows a still further modification in which the plates 6 of Fig. 1 are each replaced by two plates 6a, 6b and the plates 14 by two plates 14<a>, 14<b>, the plates 6a, 14a co-operating to form one control system and the plates 6b, 14b co-operating to form another control system. The plates 6a, 6b may be connected together by common end plate 3 and tension plate 9 whilst plates 14<a>, 14b may be insulated from one another and from plates 6<a>, 6b, by making the tension plate 15 and end plate 4 of insulating material or with suitable insulating insets. If desired, the plates 6a, 14a may be displaced in a direction perpendicular to the plane of the paper with respect to plates 6b, 14b by an amount approximately equal to one half the gap between two adjacent plates in either unit. The invention may be applied to cells of the kind described in Specification 407,385 in which the Nicol prisms are replaced by double image prisms. The Provisional Specification also describes constructions of Kerr cells comprising special arrangements of controlling plates.