Temperature probe

Abstract

A temperature probe measures temperature changes within biological material while the tissue is being irradiated with microwaves. In order to measure tissue temperatures accurately a probe must be designed to function in a microwave field while causing minimum perturbation to the microwave field. This generally requires a probe being constructed of dielectric (non-metallic) material which utilizes physical phenomena which are thermally dependent yet unaffected by electromagnetic fields at the field strength and frequencies of interest. In one embodiment the structure of the probe basically includes an optical fiber bundle for conducting light both toward and away from a temperature sensitive luminescent element located at one end of the optical fiber bundle, the source for exciting the temperature sensitive element and a light responsive detection element located at the output end of the optical fiber bundle for detecting light emitted from the temperature sensitive element which is temperature dependent. The light received by the light responsive detection element can be analyzed with regard to several parameters (intensity, frequency and phase) and thereby used for indicating the temperature of the biological sample or tissue.

I claim: .[.1. A temperature probe adapted to be implanted in a material whose temperature is to be measured, said temperature probe comprising: 
     
        element..]. .Iadd.25.  A method of measuring temperature of an environment, comprising the steps of: positioning luminescent material in thermal communication with said environment, said luminescent material being characterized by emitting, when excited with transient illumination radiation, luminescent radiation that continues in time beyond termination of the excitation radiation and with a rate of intensity decay that is related to the temperature of the luminescent material,   exposing said luminescent material to transient excitation radiation, thereby causing said luminescent material to luminesce with a decaying intensity extending beyond the termination of said excitation radiation, and   detecting the rate of decay of said luminescence, thereby to detect the temperature of the luminescent material and that of said environment. .Iaddend. .Iadd.26. A method according to claim 25 wherein said luminescent material is further characterized by comprising zinc sulfide activated with cadmium. .Iaddend. .Iadd.27. A method according to claim 25 wherein said luminescent material is further characterized by comprising   
     
     
        calcium sulfide activated with europium and tin. .Iaddend. .Iadd.28.  The method according to claim 25 wherein the exposing step comprises exposing said luminescent material to a periodically recurring illumination intensity variation, thereby to cause said luminescent material to luminesce with a periodically recurring intensity variation, and further wherein the step of detecting the luminescence comprises the steps of detecting the periodic luminescence intensity variations and comparing the phase of those variations with the phase of the periodically recurring excitation intensity variation, whereby the phase difference is related to the rate of decay of the luminescent material emission and the temperature of the luminescent material. .Iaddend. .Iadd.29. A method of measuring temperature of an environment, comprising the steps of: positioning luminescent material in thermal communication with said environment, said luminescent material being characterized by emitting, when excited with transient illumination radiation, luminescent radiation that continues in time beyond termination of the excitation radiation and with a rate of intensity decay that is related to the temperature of the luminescent material,   exposing said luminescent material to transient excitation radiation, thereby causing said luminescent material to luminesce with a decaying intensity extending beyond the termination of said excitation radiation,   detecting the rate of decay of said luminescence, and   determining from said rate of decay the temperature of the luminescent material, thereby to determine the temperature of said environment.   
     
     
        .Iaddend. .Iadd.30.  The method according to claim 29 wherein the exposing step comprises exposing said luminescent material to a periodically recurring illumination intensity variation, thereby to cause said luminescent material to luminesce with a periodically recurring intensity variation, and further wherein the step of detecting the luminescence comprises the steps of detecting the periodic luminescence intensity variations and comparing the phase of those variations with the phase of the periodically recurring excitation intensity variation, whereby the phase difference is related to the rate of decay of the luminescent material emission and the temperature of the luminescent material. .Iaddend. .Iadd.31. A system for measuring temperature of an environment, comprising: a quantity of luminescent material positionable in thermal communication with said environment, said luminescent material characterized by emitting, when excited with transient radiation, luminescent radiation that continues in time beyond the termination of the excitation radiation and with a rate of decay that is related to the temperature of the luminescent material,   means for exposing said luminescent material to such transient excitation radiation, thereby to cause said luminescent material to luminesce with a decaying intensity extending beyond the termination of said excitation radiation, and   means receiving the luminescent material luminescence for measuring the rate of decay of said luminescence pulse, thereby to measure the   
     
     
        temperature of the luminescent material. .Iaddend. .Iadd.32.  The system according to claim 31 wherein said luminescent material comprises zinc sulfide activated with cadmium. .Iaddend. .Iadd.33. The system according to claim 31 wherein said luminescent material comprises calcium sulfide activated with europium and tin. .Iaddend. .Iadd.34. The system according to claim 31 wherein said exposing means includes means for directing toward said luminescent material excitation radiation having a periodically recurring intensity variation, thereby to cause said luminescent material to luminesce with a periodically recurring intensity variation, and further wherein said measuring means includes means receiving the periodically recurring luminescent intensity variation and a signal corresponding to the periodically recurring excitation radiation for comparing the phase therebetween, said phase difference being related to the rate of decay of the luminescent material, whereby this phase difference is related to the temperature of the luminescent material. 
     
     
        .Iaddend. .Iadd.35.  A system for measuring temperature of an environment, comprising: a quantity of luminescent material attached to one end of an optical fiber communication medium, said luminescent material characterized by emitting, when excited with transient radiation, luminescent radiation that continues in time beyond the termination of the excitation radiation and with a rate of decay that is related to the temperature of the luminescent material,   means positioned at another end of said optical fiber communication medium for exposing said luminescent material to such transient excitation radiation, thereby to cause said luminescent material to luminesce with a decaying intensity extending beyond the termination of said excitation radiation, and   means positioned at said another end of said optical fiber communication medium to receive the luminescent material luminescence for measuring the rate of decay of said luminescence pulse, thereby to measure the   
     
     
        temperature of the luminescent material. .Iaddend. .Iadd.36.  The system according to claim 35 wherein said luminescent material comprises zinc sulfide activated with cadmium. .Iaddend. .Iadd.37. The system according to claim 35 wherein said luminescent material comprises calcium sulfide activated with europium and tin. .Iaddend. .Iadd.38. The system according to claim 35 wherein said exposing means includes means for directing toward said luminescent material excitation radiation having a periodically recurring intensity variation, thereby to cause said luminescent material to luminesce with a periodically recurring intensity variation, and further wherein said measuring means includes means receiving the periodically recurring luminescent intensity variation and a signal corresponding to the periodically recurring excitation radiation for comparing the phase there between, said phase difference being related to the rate of decay of the luminescent material, whereby this phase difference is related to the temperature of the luminescent material. .Iaddend. .Iadd.39. The method according to claim 25 wherein the environment whose temperature is being measured is biological tissue, and further wherein the step of positioning luminescent material within this environment includes positioning said material at the end of an optical fiber that is implanted into said tissue. .Iaddend. .Iadd.40. The method according to claim 29 wherein the environment whose temperature is being measured is biological tissue, and further wherein the step of positioning luminescent material within this environment includes positioning said material at the end of an optical fiber that is implanted into said tissue. .Iaddend.