AUTHENTICATING AND IDENTIFYING OBJECTS BY DETECTING MARKINGS THROUGH TURBID MATERIALS
Described herein are techniques for authenticating and identifying objects by detecting markings through turbid materials. In one embodiment, a container includes a substrate having an outer surface and an inner surface and including a turbid material. The container also includes a marking adjacent to the inner surface and including a luminescent material that exhibits photoluminescence in response to incident light directed on the outer surface. The photoluminescence has a quantum efficiency of at least 20 percent and a peak emission wavelength in the near infrared range.
1 . A container for an object, comprising:
a substrate having an outer surface and an inner surface and including a turbid material; and
a marking adjacent to the inner surface and including a luminescent material that exhibits photoluminescence in response to incident light directed on the outer surface, the photoluminescence having a quantum efficiency of at least 20 percent and a peak emission wavelength in the near infrared range.
2 . The container of claim 1 , wherein the substrate defines an internal compartment, and the inner surface faces the internal compartment.
3 . The container of claim 2 , wherein the internal compartment is sized to accommodate the object, and the marking is a security marking to authenticate the object.
4 . The container of claim 1 , wherein the marking includes a binder and a plurality of particles dispersed in the binder, the plurality of particles including the luminescent material.
5 . The container of claim 4 , wherein the plurality of particles have sizes in the nanometer range.
6 . The container of claim 5 , wherein the plurality of particles are monodisperse with respect to the sizes of the plurality of nanoparticles.
7 . The container of claim 1 , wherein the luminescent material has the formula:
[A a B b X x ],
wherein
A is selected from elements of Group IA;
B is selected from elements of Group VA, elements of Group IB, elements of Group IIB, elements of Group IIIB, elements of Group IVB, and elements of Group VB;
X is selected from elements of Group VIIB;
a is in the range of 1 to 5;
b is in the range of 1 to 3; and
x is in the range of 1 to 5.
8 . The container of claim 7 , wherein A is cesium, B is tin, and X is one of chlorine, bromine, and iodine.
9 . The container of claim 7 , wherein a is 1, b is 1, and x is 3.
10 . The container of claim 7 , wherein the luminescent material includes dopants.
11 . The container of claim 10 , wherein the dopants include electron acceptors and electron donors.
12 . The container of claim 1 , wherein the quantum efficiency is at least 30 percent.
13 . The container of claim 1 , wherein the photoluminescence has a spectral width that is no greater than 100 nm at Full Width at Half Maximum.
14 . The container of claim 1 , wherein the peak emission wavelength is in the range of 700 nm to 800 nm.
15 . The container of claim 1 , wherein the peak emission wavelength is in the range of 900 nm to 1 μm.
16 . The container of claim 1 , wherein the luminescent material produces emitted light in response to the incident light, and the container further comprises a reflective element adjacent to the marking to reflect at least a portion of the emitted light towards the outer surface.
17 . A label for an object, comprising:
a substrate; and
a coating adjacent to the substrate and including a set of luminescent materials to provide an optical signature, at least one of the set of luminescent materials having the formula:
[A a B b X x ],
wherein
A is selected from elements of Group IA;
B is selected from elements of Group VA, elements of Group IB, elements of Group IIB, elements of Group IIIB, elements of Group IVB, and elements of Group VB;
X is selected from elements of Group VIIB;
a is in the range of 1 to 9;
b is in the range of 1 to 5; and
x is in the range of 1 to 9.
18 . The label of claim 17 , wherein the coating is adjacent to the object when the label is coupled to the object.
19 . The label of claim 17 , wherein the substrate includes a turbid material, and at least one of the set of luminescent materials exhibits photoluminescence in response to incident light directed through the turbid material.
20 . The label of claim 19 , wherein the photoluminescence has: (a) a quantum efficiency of at least 20 percent; (b) a spectral width no greater than 100 nm at Full Width at Half Maximum; and (c) a peak emission wavelength in the near infrared range.
21 . The label of claim 19 , wherein the set of luminescent materials includes: (a) a first luminescent material having a first peak emission wavelength; and (b) a second luminescent material having a second peak emission wavelength that is different from the first peak emission wavelength.
22 . The label of claim 17 , wherein the coating includes a plurality of nanoparticles including the set of luminescent materials.
23 . The label of claim 17 , wherein B is selected from elements of Group IVB.
24 . The label of claim 17 , wherein A is cesium, B is tin, and X is one of chlorine, bromine, and iodine.
25 . The container of claim 17 , wherein a is in the range of 1 to 5, b is in the range of 1 to 3, and x is in the range of 1 to 5.
26 . The container of claim 25 , wherein a is 1, b is 1, and x is 3.