Observatorio de I+D+i UPM

Memorias de investigación
Research Publications in journals:
Security devices based on liquid crystals doped with a colour dye
Year:2011
Research Areas
  • Electronic technology and of the communications
Information
Abstract
Liquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices. Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multi? ple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC cell. By rub? bing the polyimide in different directions in each substrate it is possible to create any kind of symbols, drawings or motifs with a greyscale; the more complex the created device is, the more difficult is to fake it. To identify the motifs it is necessary to use polarized light. Depending on whether the polarizer is located in front of the LC cell or behind it, different motifs from one or the other substrate are shown. The effect arises from the dopant colour dye added to the liquid crystal, the induced orientation and the twist structure. In practice, a grazing reflection on a dielectric surface is polarized enough to see the effect. Any LC flat panel display can obviously be used as backlight as well.
International
Si
JCR
Si
Title
OPTO?ELECTRONICS REVIEW
ISBN
1896-3757
Impact factor JCR
1,027
Impact info
Volume
19
Journal number
4
From page
92
To page
96
Month
SEPTIEMBRE
Ranking
Participants
  • Autor: Carlos Carrasco Vela (UPM)
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Grupo de Fotónica Aplicada
  • Centro o Instituto I+D+i: Centro de Materiales y Dispositivos Avanzados para Tecnologías de Información y Comunicaciones
  • Departamento: Tecnología Fotónica y Bioingeniería
S2i 2020 Observatorio de investigación @ UPM con la colaboración del Consejo Social UPM
Cofinanciación del MINECO en el marco del Programa INNCIDE 2011 (OTR-2011-0236)
Cofinanciación del MINECO en el marco del Programa INNPACTO (IPT-020000-2010-22)