Sensors and taggants utilizing scatter controlled emission

Abstract

Sensors and/or taggants feature high optical gain materials which are disposed in a high scattering environment. These materials, when adequately excited, emit intense and spectrally narrow light that is dependent on the chemical environment in which high gain materials are dispersed. When two materials are placed in the same high scattering environment, the spectal emission properties of each emitter will depend on the chemical composition of the surrounding medium. The switching or transferring of energy from one emitter to the other when the chemical environment is changed in a specific manner is enabled and a shift in the spectral emissions can be detected and/or predicted.

What is claimed is:  
     
         1 . A sensor arrangement comprising: 
 a source of photonic energy which emits photonic energy of a photonic level sufficient to induce stimulated emissions from irradiated materials;    a cell into which the photonic energy from said source is directed, the cell including a host material in which first and second photonically responsive materials, and scattering particles are dispersed, said first photonically responsive material being excited by exposure to photonic energy from said source to emit stimulated photonic energy in a first frequency range, said cell being adapted to have a mediating material introduced thereinto which causes the photonic energy in the first frequency range, to be transmitted to and absorbed by the second photonically responsive material which becomes sufficiently excited to emit photonic energy in a second frequency range; and    a photonically responsive device responsive to the stimulated photonic emissions from the cell for determining the frequency or frequency range of the photonic emissions emitted by the cell during excitement by the source of photonic energy.    
     
     
         2 . A sensor arrangement as set forth in  claim 1 , wherein the source of photonic energy comprises one of a continuous wave and a pulsed laser.  
     
     
         3 . A sensor arrangement as set forth in  claim 1 , wherein the first material is selected from the group consisting essentially of: rhodamine green, DCM, coumarin dyes, fluorescein, anthracene dicarboxaldahyde, napththalene dicarboxaldahyde.  
     
     
         4 . A sensor arrangement as set forth in  claim 1 , wherein the second material is selected from the group consisting essentially of: 
 seminaphthorhodfluor dyes, dimers of cyanine dyes, hydroxypyrene trisulfonic, magnesium orange, BODIPY, fluorescein, and carbazine.    
     
     
         5 . A sensor arrangement as set forth in  claim 1 , wherein the photonically responsive device comprises a photometer.  
     
     
         6 . A sensor arrangement as set forth in  claim 1 , wherein the photonically responsive device comprises a CCD camera.  
     
     
         7 . A sensing method comprising: 
 using a source of photonic energy to irradiate a mixture of first and second photonic excitable materials;    sensing a frequency or frequency range of photonic emissions from the mixture;    introducing a mediating material into the mixture; and    detecting a change in the frequency or frequency range on photonic emissions which occurs due to a presence-of the mediating material.    
     
     
         8 . A method as set forth in  claim 7 , further comprising the steps of: 
 sensing the intensity of photonic emissions from the mixture in the absence of the mediating material; and    sensing the intensity of photonic emissions from the mixture in the presence of the mediating material.    
     
     
         9 . A method as set forth in  claim 7 , further comprising the step of: 
 monitoring a decrease in photonic emissions in a first frequency range and a corresponding increase in photonic emissions in a second frequency range which occurs in response to a change in an amount of mediating material introduced into the mixture.    
     
     
         10 . A method of taggant examination comprising the steps of: 
 preparing a mixture of first and second photonically responsive materials, scattering particles and a mediating material, the first and second photonically responsive materials being excited by exposure to photonic energy to respectively emit photonic energy in first and second frequency ranges;    incorporating the mixture into a carrier;    disposing the carrier with a surface which is to be identified;    irradiating the surface with a beam selected to excite the first material to emit stimulated emissions;    detecting the frequency at which the stimulated emission occurs;    introducing a mediating analyte into the mixture; and    detecting a change in frequency which occurs as a result of the introduction of the mediating analyte.    
     
     
         11 . A method of a taggant examination as set forth in  claim 10 , further comprising the steps of: 
 sensing the intensity of the stimulated emission at a first frequency prior introduction of the mediating analyte;    sensing the change in intensity with a change in mediating analyte; and    sensing the increase of the intensity of the emission at a second frequency as the concentration of the analyte increases.    
     
     
         12 . A taggant comprising: 
 a fluid permeable host material exposable to beam of photonic energy from a source which is remotely located relative to the host material;    first and second photonically responsive materials which are dispersed through the host material; and    reflecting particles which are dispersed in the host material with the first and second photonically responsive materials to establish a high optical gain media through which photonic energy from the remotely located source can generate and detect stimulated emission.    
     
     
         13 . A taggant as set forth in  claim 12 , wherein the scattering particles are particles selected from the group consisting essentially of: silicon carbide, diamond, alumina, barium titanate, zinc oxide and titanium dioxide.  
     
     
         14 . A taggant as set forth in  claim 12 , wherein the first and second materials are photonically responsive dyes.  
     
     
         15 . A taggant as set forth in  claim 12 , wherein the first material is selected from the group consisting essentially of: rhodamine green, DCM, coumarin dyes, fluorescein, anthracene dicarboxaldahyde, napththalene dicarboxaldahyde.  
     
     
         16 . A taggant as set forth in  claim 12 , wherein the second material is selected from the group consisting essentially of: seminaphthorhodfluor dyes, dimers of cyanine dyes, hydroxypyrene trisulfonic, magnesium orange, BODIPY, fluorescein, and carbazine.  
     
     
         17 . A taggant as set forth in  claim 12  wherein the host material is a fluid permeable polymeric structure.