The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 12, 1991
Filed:
Aug. 01, 1988
William A Crossland, Harlow, GB;
Neil Collings, Epping, GB;
STC PLC, London, GB;
Abstract
An optical logic device consists of a bistable liquid crystal layer (BOD 1) of the thermally-induced birefringent (TIB) type settable by one or more write beams and rfead by a beam of a different wavelength or different light polarization. Thus the read and write beams are optically decoupled. Two such devices (BOD 1 and BOD 2) in tandem form a 3-input AND gate. Here beams A and B are write beams for the first device, (BOD 1), and beam C is the read beam for the first device. For the second device (BOD 2) the write beams are the output of the first device (BOD 1) and beam D, the read beam being beam E. The two read beams have different wavelengths from the write beam. In a second version, the liquid crystal layer is on the base of a prism via which the beams reads it. Write beams go right through the layer, while a read beam is 'reflected' from the layer but is modulated by the state thereof. This is an OR gate. Logic assemblies can use combinations of such AND or OR gates.