Optical temperature measurement techniques
AssigneeLuxtron Corporation
InventorsKenneth A. Wickersheim, Mei H. Sun, Stanley O. Heinemann, Stanley O. Hinemann
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Abstract
An optical temperature measurement technique that utilizes the decaying luminescent intensity characteristic of a sensor composed of a luminescent material that is excited to luminescence by a light pulse or other periodic or other intermittent source of radiation. The luminescent emissions of a preferred sensor exhibit an approximately exponential decay with time that is the average of a distribution of chemically reproducible crystallites and are repeatable with a high degree of accuracy regardless of excitation level or prior temperature history of the sensor.
Claims38
A method of determining the temperature of an environment, comprising the steps of:
- positioning in thermal communication with said environment a luminescent material which contains a luminescent activator of tetravalent manganese and which is characterized by emitting, when excited with transient radiation, luminescent radiation having an intensity which decreases after termination of the excitation radiation in a manner that can be correlated with the temperature of the luminescent material,
- exposing said luminescent material to transient excitation radiation, thereby causing said luminescent material, after termination of the excitation radiation, to luminesce with a decreasing intensity function related to the temperature of the luminescent material, and
- detecting and measuring the decreasing luminescent intensity function, thereby to measure the temperature of the luminescent material, whereby the temperature of said environment is determined.
For use with a temperature measuring instrument that generates transient radiation to excite a luminescent material and then measures a decreasing intensity function of the luminescence after termination of the excitation radiation in order to determine the temperature of the the luminescent material, a sensor (1) comprising a length of optical fiber carrying at one end thereof a luminescent material having an activator component consisting essentially of tetravalent manganese and a host component, and (2) being characterized by emitting along the length of the optical fiber, when excited with transient radiation from along the optical fiber, luminescent radiation having an intensity that decreases after termination of the excitation radiation in a manner related to the temperature of the luminescent material.
For use with a temperature measuring instrument that generates transient radiation to excite a luminescent material and then measures a decreasing intensity function of the luminescence after termination of the excitation radiation in order to determine the temperature of the luminescent material, a sensor comprising a substrate adapted to be positioned against a surface whose temperature is to be measured, said substrate having a quantity of luminescent material carried thereby, said luminescent material having a an activator component consisting essentially of tetravalent manganese and a host component, the sensor being characterized by emitting, when excited with transient radiation, luminescent radiation having an intensity that decreases after termination of the excitation radiation in a manner related to the temperature of the luminescent material.
For use with a temperature measuring instrument that generates transient radiation to excite a liminescent material and then measures a decreasing intensity function of the luminescence after termination of the excitation radiation in order to determine the temperature of the luminescent material, a sensor comprising:
- an elongated hollow member being open at one end in a manner adapted to receive an end of an optical fiber therethrough, and
- a quantity of luminescent material being carried by another end of said hollow member in a manner to be in optical communication with said optical fiber through its said end, said luminescent material having a host compoenent and an activator component, the activator component consisting essentially of tetravalent manganese,
- the sensor being characterized by emitting along the length of the optical fiber, when excited with transient radiation along the optical fiber, liminescent radiation having an intensity that decreases after termination of the excitation radiation in a manner that is related to the temperature of the luminescent material.
A system for measuring the temperature of an environment, comprising:
- a quantity of luminescent material adapted to be positioned in thermal communication with said environment, said luminescent material (A) being characterized by emitting, when excited with transient radiation, luminescent radiation having an intensity which decreases after termination of the excitation radiation, and (B) including a luminescent composition having a host component and an activator component, the activator component consisting essentially of tetravalent manganese in a concentration effective to cause the decreasing lumination radiation to have a decay time of about one or a few milliseconds for temperatures of said luminescent material within a range of from about negative 200 degrees centigrade to about positive 400 degrees centigrade,
- means including a source of transient excitation radiation for exposing said luminescent material to an excitation radiation pulse, thereby causing said luminescent material to luminesce after termination of the pulse with a decreasing intensity function having a decay time that is related to the temperature of the luminescent material,
- means receiving luminescent radiation of the luminescent material for detecting said decreasing intensity of its luminescent radiation, thereby to generate an electrical signal proportional thereto, and
- means responsive to said electrical signal for measuring a decreasing characteristic of said electrical signal, thereby to determine a quantity that corresponds to the temperature of the luminescent material and thus also to the temperature of said environment.
A system for measuring the temperature of an environment, comprising:
- a quantity of luminescent material adapted to be positioned in thermal communication with said environment, said luminescent material being in a physical form of a powder held together with a binder and being characterized by emitting, when excited with transient radiation, luminescent radiation having an intensity function continuing in time after termination of the excitation radiation, said intensity function (A) approximating a single repeatable exponential decaying function for each temperature of the luminescent material desired to be measured within a range of temperatures, and (B) being substantially independent of the excitation radiation intensity and any prior illumination or temperature history of the luminescent material,
- means including a source of transient excitation radiation for exposing said luminescent material to an excitation pulse, thereby causing said luminescent material to luminesce with a decaying intensity function after the pulse that is related to the temperature of the luminescent material,
- means receiving luminescent radiation of the luminescent material for detecting the decaying intensity of said luminescent radiation, thereby to generate an electrical signal proportional thereto,
- means responsive to said electrical signal for determining a decay time constant of said electrical signal beginning a particular time after said radiation pulse, thereby to determine a quantity that corresponds to the temperature of the luminescent material and thus also the temperature of said environment, and
- said source of transient excitation radiation including means responsive to the magnitude of said electrical signal for adjusting the intensity of the excitation pulse in order to maintain said electrical signal within a desired magnitude range.
In a system for measuring the temperature of an environment by use of a quantity of luminescent material adapted to be positioned in thermal communication with said environment, said luminescent material being characterized by emitting, when excited with transient radiation, luminescent radiation having an intensity function which decreases with time, after termination of the excitation radiation, in a manner related to its temperature, an instrument comprising:
- means including a source of transient excitation radiation for exposing said luminescent material to a plurality of excitation pulses with time between pulses sufficient to allow said luminescent material to luminesce with a decreasing intensity function that is uniquely related to the temperature of the luminescent material,
- means receiving luminescent radiation of the luminescent material for detecting the decreasing intensity of said luminescent radiation, thereby to generate an electrical signal proportional thereto,
- means responsive to said electrical signal for determining a characteristic of the decreasing signal, thereby to determine a quantity that corresponds to the temperature of the luminescent material and thus also to the temperature of said environment, and
- means responsive to the magnitude of said electrical signal for adjusting the intensity of subsequent excitation pulses in order to maintain said electrical signal within a desired magnitude range.
Dependencies are inferred from the claim text.