Patents by Inventor John K Drinkwater

John K Drinkwater has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20040032659
    Abstract: The invention provides in particular for an achromatic diffractive diffuser comprising a surface relief diffractive device arranged such that, under illumination by ambient light, the diffractive effect serves to provide a uniform achromatic diffuser reflection into a defined viewing zone for observation by an observer, and also such that the achromatic diffractive replay of the device has a non-symmetric distribution of diffractive light intensity between positive and negative diffractive order such that the diffractive efficiency in the desired diffractive order is enhanced over that of the undesired order to provide an enhanced brightness achromatic device.
    Type: Application
    Filed: June 20, 2003
    Publication date: February 19, 2004
    Inventor: John K Drinkwater
  • Publication number: 20030161017
    Abstract: An optical device for security and anti-counterfeit applications comprises a holographic diffractive structure comprising a discrete region that in response to white light illumination generates a holographic image by a process of diffraction of light in one embodiment combined with a paper substrate which also contains a secure mark produced by laser ablation of the structure, the mark being characterised by various attributes: variable cut width and pattern, being visible both in reflected light and also in transmitted light, variable depth of cut, variable perforation visible in transmission, variable reflection characteristics. In one embodiment when combined with paper based laser mark has elements in both metallised diffractive region and paper region, the marks on different regions showing different characteristics and thereby securely linking diffractive structure and paper substrate and also showing different characteristics of marking pattern on the different materials.
    Type: Application
    Filed: April 7, 2003
    Publication date: August 28, 2003
    Inventors: Philip Hudson, John K Drinkwater