METHOD OF AUTHENTICATING AN OBJECT
A method of authenticating an object ( 12 ) includes applying indicia ( 14 ) to the object, wherein the indicia includes at least two different types of particles which fluoresce upon exposure to light ( 15 ) and which have different decay rates. The indicia is exposed to light from a lamp ( 32 ) causing the plurality of particles to fluoresce. At least a first image of the indicia is captured with a sensor ( 22 ) at a first time and a second image of the indicia at a second time different from the first time. The images are analyzed to determine decay rates of the at least two types of particles and object is authenticated if the decay rates match stored information.
1 . A method of authenticating an object comprising:
applying indicia to the object;
wherein the indicia comprises at least two different types of particles which fluoresce upon exposure to light and which have different decay rates;
exposing the indicia to light from a lamp causing the plurality of particles to fluoresce;
capturing at least a first image of the indicia with a sensor at a first time and a second image of the indicia at a second time different from the first time;
analyzing the images to determine decay rates of the at least two types of particles; and
authenticating the object if the decay rates match stored information.
2 . The method of claim 1 further comprising:
capturing a third image of the indicia with the sensor at a third time prior to analyzing the images to determine decay rates.
3 . The method of claim 2 wherein the first, second, and third times are regularly spaced in time.
4 . The method of claim 2 wherein the first, second, and third times are irregularly spaced in time.
5 . The method of claim 1 wherein the second time is dependent on the analysis of the first image.
6 . The method of claim 1 wherein the light is selected from a group comprising IR, UV, and visible light.
7 . The method of claim 1 further comprising:
exposing the indicia to light a second time so that at least one type of particle emits more light after the second exposure than the particle emits after the first exposure.
8 . The method of claim 1 , further including analyzing the images with a microprocessor.
9 . The method of claim 1 , further including displaying the images with a display and receiving an indication of authenticity responsive to the displayed images.
10 . The method of claim 1 , further including transmitting the images with a transmitter to a remote location and receiving with a receiver an indication of authenticity from the remote location.
11 . The method of claim 1 further including operating a camera flash to expose the particles.
12 . The method of claim 11 wherein the camera flash is a visible-light flash and the image sensor is a visible-light image sensor, and further comprising:
converting the emitted visible light to UV light with a conversion device mounted over the camera flash.
13 . The method of claim 12 wherein the conversion device comprises:
a photovoltaic device that converts the visible light emitted by the camera flash to electrical power; and
a UV lamp that converts the electric power to UV light.
14 . The method of claim 11 wherein the camera, camera flash, and image sensor are all components of a cell phone or smart phone.
15 . The method of claim 8 wherein the microprocessor is a component of a cell phone or smart phone.
16 . The method of claim 9 wherein the display is a component of a cell phone or smart phone.
17 . The method of claim 10 wherein the transmitter and receiver are components of a cell phone or smart phone.
18 . The method of claim 1 wherein the indicia changes color over time.