Printed LEDs and wavelength conversion area on objects to provide optical security feature

A method for authenticating an object comprising:

• providing a wavelength conversion material on or within a portable object, the wavelength conversion material for converting primary light to secondary light, the wavelength conversion material being selected to have a particular spectrum characteristic and/or a persistence characteristic;
• receiving power from a power source, external to the object and not permanently connected to the object, for supplying power to light emitting diodes (LEDs) on or within the object to illuminate the LEDs when the object is proximate to the power source, the LEDs emitting the primary light for energizing the wavelength conversion material;
• detecting light emitted by at least the wavelength conversion material on or within the object;
• detecting one or both of the spectrum characteristic of the wavelength conversion material or the persistence characteristic of the wavelength conversion material;
• and
• comparing the spectrum characteristic and/or the persistence characteristic of the wavelength conversion material to stored data in a data base for authenticating the object.