Multi-band optical fiber temperature sensor

Abstract

In particular, multi-band optical fiber temperature sensors configured to provide temperature measurements independent of changes in the optical path are described. The systems and devices described herein include phosphorescent time constant temperature sensors that use one or more portions of the emission spectrum to measure more than one time-dependent parameter (e.g., one or more time constants) from the emission spectrum of one or more phosphors. Accuracy and reproducibility can be improved by measuring the time-dependent parameter (e.g., the time decay or time constant of the intensity of the phosphorescent emission) in one portion of the emission spectrum or in more than one different portion of the emission spectrum. Limiting the measurement of the time-dependent parameter to a portion of the emission spectrum can reduce the dependency of the time-dependent value on the attenuation spectrum (or frequency response) of the optical path between the phosphor and the detector and / or the attenuation spectrum of the matrix in which the phosphor is disposed.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 383,727, filed November 15, 2022, the entire contents of which are incorporated herein by reference.

[0002] Technical Field The following relates generally to fiber optic temperature sensors, and more particularly to fiber optic temperature sensors configured to process multiple bands of an emission spectrum individually to measure multiple parameters from such an emission spectrum or to measure multiple point positions from the same type of sensor element. [Background technology]

[0003] background Existing thermographic phosphor temperature sensors utilize one or more properties that change with temperature, such as phosphorescence emission intensity or decay time. These sensors typically use a laser or light-emitting diode (LED) to excite the phosphor and measure the resulting emission intensity using, for example, a photodiode or the spectral power distribution (SPD) of the emission using, for example, a spectrometer or photodiode array. An optical fiber optically couples the LED and photodiode (or other measurement means) to the phosphor. The phosphor is placed near the target surface or submerged at the measurement location where temperature measurement is required. A filter can be placed in the optical path to reduce the amount of stray light in the environment that reaches the photodiode. This filter passes the emission spectrum and blocks other wavelengths.

[0004] For systems that utilize the temperature-dependent properties of phosphorescence emission, such as the time constant or time decay, these are considered bulk parameters in existing sensors. However, the time constant is known to vary across the emission wavelength spectrum, and considering it as a single parameter leads to a dependency on the attenuation spectrum of the optical path. Because certain portions of the emission spectrum are attenuated more by the optical path than others, extending the optical path length reduces the ability of these portions of light to reach the photodiode. Because the emission time constant varies across the emission spectrum, the measured bulk time constant varies with the optical path length and its attenuation spectrum. This leads to discrepancies in the measured time constants between optical paths.

[0005] The phosphor is typically fixed in a matrix, such as epoxy or silicone, the wavelength dependence of which can cause further discrepancies in the measured time constants. Summary of the Invention

[0006] overview In one aspect, there is provided a temperature measurement system comprising: a measurement module coupled to an optical path terminating at a phosphor sensing element, the measurement module having: a light source optically coupled to the optical path to generate an optical excitation signal to excite the phosphor sensing element and to generate an optical excitation response signal from the phosphor sensing element, the measurement module having: one or more optical elements configured to separate the optical emission spectrum into a plurality of bands of the emission spectrum; and a plurality of detector elements configured to detect each of the bands of the emission spectrum and thereby generate a detection signal for each of the plurality of bands of the emission spectrum; and a controller coupled to the light source generating the optical excitation signal and to the plurality of detector elements to enable the temperature measurement system to process each detection signal, the controller configured to calculate a temperature of the phosphor sensing element based on at least one time dependent parameter of at least one of the plurality of bands of the emission spectrum.

[0007] In an example embodiment, the at least one time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0008] In an example embodiment, the at least one time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0009] In an example embodiment, the controller is configured to modulate the optical excitation signal.

[0010] In some example embodiments, at least one of the one or more optical elements includes at least one dichroic mirror.

[0011] In some example embodiments, the measurement module further includes a plurality of channels, each of the plurality of channels including at least one of the one or more optical elements, a filter, and one of the plurality of detector elements.

[0012] In an example embodiment, the measurement module is configured to determine a time-dependent parameter of decay of the emission intensity of the emission spectrum in at least one of the plurality of channels and to use the time-dependent parameter in the at least one of the plurality of channels in determining a temperature of the phosphor sensing element.

[0013] In an example embodiment, the measurement module is configured to determine a time constant of decay of emission intensity of the emission spectrum in at least one of the plurality of channels and use the time constant in the at least one of the plurality of channels to determine a temperature of the phosphor sensing element.

[0014] In one example embodiment, the optical fiber includes a plurality of refractive index matching elements optically connected to a core of the optical fiber that provides the optical path, and each of the plurality of refractive index matching elements is optically connected to the controller through the optical path.

[0015] In some example embodiments, each of the plurality of index-matching elements includes at least one phosphor sensing element and at least one filter.

[0016] In some example embodiments, the at least one filter comprises at least one of a bandpass filter, a lowpass filter, or a highpass filter, and the at least one filter is characterized by a transmission spectrum.

[0017] In some example embodiments, (i) the optical path has a first refractive index, and (ii) the plurality of index-matching elements are index-matched to the first refractive index.

[0018] In one example embodiment, (i) the optical path includes an optical fiber having a core region and a cladding region, (ii) the core region has a first refractive index, and (iii) the plurality of index-matching elements are index-matched to the first refractive index.

[0019] In an example embodiment, each of the plurality of phosphor sensing elements is identical, and the filter in a first channel has a different transmission spectrum than the filter in a second channel, and the first channel is different from the second channel.

[0020] In an example embodiment, the phosphor sensing element associated with a first channel is different from the phosphor sensing element associated with a second channel that is different from the first channel, the filter in the first channel has a different transmission spectrum from the filter in the second channel, and the first channel is different from the second channel.

[0021] In an example embodiment, the system further comprises a computing device coupled to the controller.

[0022] In some example embodiments, the light source includes at least one of a light emitting diode (LED) and a laser.

[0023] In an example embodiment, the measurement module includes a spectrometer.

[0024] In one example embodiment, the spectrometer is a Czerny-Turner spectrometer.

[0025] In an example embodiment, the measurement module further includes a photodiode array coupled to the spectrometer via multiple optical paths.

[0026] In an example embodiment, the measurement module includes a photodiode array as part of the spectrometer.

[0027] In another aspect, a temperature measurement system includes a plurality of branches of a common optical path, each of the plurality of branches terminating at a sensing location, each sensing location including a filter disposed between one of the plurality of branches of the common optical path and a phosphor sensing element; and a measurement module coupled to the common optical path, the measurement module including a light source optically coupled to the common optical path to generate an optical excitation signal that excites a respective phosphor sensing element and to generate an optical excitation response signal from each of the phosphor sensing elements, the light source including an emission spectrum, the light excitation response signal including an emission spectrum, the light source configured to generate a plurality of filtered excitation response signals by passing a band of the emission spectrum, and the light source configured to generate a plurality of filtered excitation response signals from each of the phosphor sensing elements, the measurement module including a light source optically coupled to the common optical path to generate an optical excitation response signal from each of the phosphor sensing elements, the measurement module including a light source optically coupled to the common optical path to generate an optical excitation response signal from each of the phosphor sensing elements, the measurement module including a light source optically coupled to the common optical path to generate a plurality of filtered excitation response signals by passing a band of the emission spectrum, the measurement module configured to generate a plurality of filtered excitation response signals from each of the phosphor sensing elements ... a measurement module having a light source optically coupled to the common optical path, wherein each of the plurality of filtered optical excitation response signals is optically coupled to the common optical path; one or more optical elements separating the plurality of filtered optical excitation response signals into a plurality of detection channels; and a plurality of detector elements configured to detect each of the plurality of filtered optical excitation response signals and process each band of the emission spectrum; and a controller coupled to the light source generating the optical excitation signals and coupled to the plurality of detector elements, enabling the measurement system to process the plurality of filtered optical excitation response signals, the controller configured to calculate a temperature of the detector element based on at least one time-dependent parameter of the emission intensity within the band of the emission spectrum.

[0028] In an example embodiment, the time-dependent parameter comprises a measure of the decay of the emission intensity in at least one of the bands of the emission spectrum.

[0029] In an example embodiment, the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the bands of the emission spectrum.

[0030] In an example embodiment, the controller is configured to modulate the optical excitation signal.

[0031] In some example embodiments, the one or more optical elements include at least one dichroic mirror.

[0032] In an example embodiment, the measurement module further includes a plurality of channels, each channel including at least one of the optical element, a filter, and one of the plurality of detectors.

[0033] In an example embodiment, the measurement module is configured to determine a time-dependent parameter of decay of the emission intensity of the emission spectrum in at least one of the plurality of channels and use the time-dependent parameter in the at least one of the plurality of channels to determine the temperature of the sensing element.

[0034] In an example embodiment, the measurement module is configured to determine a time constant of decay of the emission intensity of the emission spectrum in at least one of the plurality of channels and use the time constant in the at least one of the plurality of channels to determine the temperature of the sensing element.

[0035] In some example embodiments, the at least one filter comprises at least one of a bandpass filter, a lowpass filter, or a highpass filter, and the at least one filter is characterized by a transmission spectrum.

[0036] In an example embodiment, the system further comprises a computing device coupled to the controller.

[0037] In some example embodiments, the light source includes a light emitting diode (LED) or a laser.

[0038] In an example embodiment, the measurement module includes a spectrometer.

[0039] In one example embodiment, the spectrometer is a Czerny-Turner spectrometer.

[0040] In an example embodiment, the measurement module further includes a photodiode array coupled to the spectrometer via multiple optical paths.

[0041] In an example embodiment, the measurement module includes a photodiode array as part of the spectrometer.

[0042] In one example embodiment, the measurement module includes a plurality of index matching elements optically connected to the core of the optical fiber providing the optical path, and each index matching element is optically connected to the controller through an optical path.

[0043] In some example embodiments, each of the plurality of index-matching elements includes at least one phosphor sensing element and at least one filter.

[0044] In some example embodiments, the at least one filter comprises at least one of a bandpass filter, a lowpass filter, or a highpass filter, and the at least one filter is characterized by a transmission spectrum.

[0045] In some example embodiments, (i) the optical path has a first refractive index, and (ii) each of the plurality of index-matching elements is index-matched to the first refractive index.

[0046] In one example embodiment, (i) the optical path includes an optical fiber having a core region and a cladding region, (ii) the core region has a first refractive index, and (iii) each of the plurality of index-matching elements is index-matched to the first refractive index.

[0047] In an example embodiment, each of the plurality of phosphor sensing elements is identical, and the filter in a first channel has a different transmission spectrum than the filter in a second channel, and the first channel is different from the second channel.

[0048] In an example embodiment, a phosphor sensing element associated with a first channel is different from a phosphor sensing element associated with a second channel that is different from the first channel, a filter in the first channel has a different transmission spectrum from the filter in the second channel, and the first channel is different from the second channel.

[0049] In some example embodiments, each phosphor element is positioned to make a measurement at a separate location on the object being measured or to measure multiple separate objects.

[0050] In another aspect, a method is provided that includes transmitting an optical signal along an optical path to excite a phosphor sensing element optically coupled to the optical path, receiving a return signal having an emission spectrum, splitting the return signal into a plurality of bands of the emission spectrum, directing each of the plurality of bands of the emission spectrum to a corresponding detector element, each detector element generating a detection signal, applying signal processing to each detection signal having a respective band of the emission spectrum, and determining a temperature of the phosphor sensing element based on at least one time-dependent parameter of at least one of the plurality of bands of the emission spectrum.

[0051] In an example embodiment, the time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0052] In an example embodiment, the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0053] In an example embodiment, the optical signal is modulated.

[0054] In another aspect, a method is provided that includes transmitting an optical signal along a common optical path coupled to a plurality of branches to excite a plurality of phosphor sensing elements, each of the plurality of phosphor sensing elements coupled to a respective branch of the common optical path and receiving a plurality of return signals via the common optical path, each of the plurality of return signals being filtered to provide one of a plurality of bands of an emission spectrum of a respective one of the phosphor sensing elements, directing each of the plurality of return signals to a respective measurement channel, each measurement channel including at least one detector, each of the at least one detector generating a respective detection signal and applying signal processing to the respective detection signal to obtain measurements for each of the plurality of phosphor sensing elements, and determining a temperature of the phosphor sensing element based on at least one time dependent parameter of the at least one band of the emission spectrum.

[0055] In an example embodiment, the time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0056] In an example embodiment, the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

[0057] In an example embodiment, the optical signal is modulated. [Brief explanation of the drawings]

[0058] BRIEF DESCRIPTION OF THE DRAWINGS Example embodiments will now be described with reference to the accompanying drawings.

[0059] [Figure 1] FIG. 1 is a schematic diagram of an example embodiment of a fiber optic temperature sensor configured to detect multiple bands of a phosphor emission spectrum.

[0060] [Figure 2A] FIG. 2A is a schematic diagram of an example embodiment of a fiber optic temperature sensor configured to measure temperature at multiple locations by filtering each measurement source and detecting within a selected band of the source-filtered phosphor emission spectrum.

[0061] [Figure 2B] FIG. 2B shows a spectrum that may be transmitted from a sensing element in the fiber optic temperature sensor shown in FIG.

[0062] [Figure 3] FIG. 3 is a schematic diagram illustrating an example embodiment for measuring signals in multiple bands of a phosphor emission spectrum.

[0063] [Figure 4] 4A and 4B are schematic diagrams illustrating example embodiments for measuring signals in multiple bands of a phosphor emission spectrum.

[0064] [Figure 5] FIG. 5 is a schematic diagram illustrating an example embodiment for measuring temperature at multiple locations.

[0065] [Figure 6] FIG. 6 is a schematic diagram illustrating an example embodiment for measuring temperature at multiple locations along an optical path using an index-matching element.

[0066] [Figure 7] FIG. 7 shows phosphor emission spectra in an example embodiment for resolving emission spectra.

[0067] [Figure 8] FIG. 8 shows the dichroic filter transmission spectrum applied to the phosphor emission spectrum of FIG.

[0068] [Figure 9]FIG. 9 shows the filter bandpasses applied to the phosphor emission spectra of FIG.

[0069] [Figure 10] FIG. 10 shows the spectra arriving at each of the two photodiodes based on the filter bandpass shown in FIG.

[0070] [Figure 11] FIG. 11 illustrates a decomposition process for improving parameter or variable prediction according to the example process illustrated in FIGS.

[0071] [Figure 12] FIG. 12 is a flowchart illustrating example operations that may be performed in decomposing an emission spectrum to improve parameter or variable prediction.

[0072] [Figure 13] FIG. 13 shows the phosphor emission spectra from a pair of sensors in a multiple sensor transmission embodiment.

[0073] [Figure 14] FIG. 14 shows the filter bandpass across the sensor emission spectrum shown in FIG.

[0074] [Figure 15] FIG. 15 shows a pair of signals obtained from the filter bandpass shown in FIG.

[0075] [Figure 16] FIG. 16 shows a pair of signals passing through a common optical fiber.

[0076] [Figure 17] FIG. 17 shows a dichroic filter applied to a pair of signals.

[0077] [Figure 18]FIG. 18 shows a filter bandpass applied to the signal shown in FIG.

[0078] [Figure 19] FIG. 19 shows a pair of signals with different attenuation rates.

[0079] [Figure 20] FIG. 20 illustrates an embodiment of multiple sensor transmissions over one optical path according to the example process shown in FIGS.

[0080] [Figure 21] FIG. 21 is a flowchart illustrating example operations that may be performed in acquiring multiple sensor signals over a single optical path. DETAILED DESCRIPTION OF THE INVENTION

[0081] Detailed Description Described below is a multi-band fiber optic temperature sensor that is specifically configured to provide independence of the temperature measurement from variations in the optical path.

[0082] In one aspect, the systems and devices described herein include a phosphorescent time constant temperature sensor that measures multiple time-dependent parameters (e.g., one or more time constants) from the emission spectrum of one or more phosphors using one or more portions of the emission spectrum. Measuring a time-dependent parameter, such as the time decay or time constant of the intensity of phosphorescent emission, in a portion of the emission spectrum or in multiple portions of the emission spectrum can improve accuracy and reproducibility. By limiting the measurement of the time-dependent parameter to a portion of the emission spectrum, the dependence of the time-dependent value on the attenuation spectrum (or frequency response) of the light path between the phosphor and the detector and / or the attenuation spectrum of the matrix in which the phosphor is located can be reduced. For example, one or more portions of the emission spectrum to be evaluated can be selected to overlap or match multiple regions of the attenuation spectrum of the light path or matrix that are relatively flat, i.e., have little or no variation in attenuation with wavelength.

[0083] Additionally, the example embodiments described herein may allow for relative changes in time-dependent parameters in different portions of the emission spectrum to be taken into account. Additionally, the example embodiments described herein may allow for the measurement of multiple phosphor elements of the same type using a single optical fiber by measuring different portions of the emission band from each phosphor element.

[0084] In one example embodiment, at least one phosphor or a combination of phosphors can be configured to measure temperature and can be connected via an optical path to an excitation light source and multiple emission photodetectors. The multiple emission photodetectors can be implemented using multiple photodiodes, a photodiode array, a complementary metal-oxide semiconductor (CMOS) detector, a charge-coupled device (CCD), or any other suitable set of photodetectors. Each of these photodetectors can measure a different band within the emission spectrum. Each photodetector can be connected to an electronic circuit that measures a parameter of the phosphorescence decay, such as a time constant.

[0085] The fiber optic temperature sensor embodiments described herein can be used to more accurately measure phosphorescence time decay. Because phosphorescence decay can be parameterized in other ways, such as phase shift, the example embodiments described herein can also be used to measure multiple parameters of phosphorescence decay and provide relative measurements of phosphorescence decay at different bands within the emission spectrum.

[0086] Additionally, the fiber optic temperature sensor configurations described herein can be used to measure multiple phosphors at different locations by considering one or more bands in the emission spectrum from each phosphor.

[0087] Advantages of the embodiments, configurations, and examples described herein include increased accuracy and increased independence from variations in attenuation of the optical path. Accuracy benefits come from measuring within narrow bands of the emission spectrum, which have less time constant variability than the bulk emission spectrum. Separating the emission spectrum into multiple bands allows each band to be considered independently while measuring the signal across the emission spectrum.

[0088] 1 illustrates an example embodiment of a fiber optic temperature sensing system 10 configured to detect one of multiple bands in the emission spectrum of a phosphor. In this example embodiment, the fiber optic temperature sensing system 10 includes a phosphor sensing element 12 (also referred to herein as sensing element 12″) supported by or optically coupled to a temperature probe or other structure (not shown) and connected to a measurement module 14 via an optical path 16. The measurement module 14 includes an optoelectronic circuit or subsystem that detects and generates a set of outputs 18, each indicative of a parameter, e.g., a time-dependent parameter, to be measured within the distinct bands of the emission spectrum. The optical path 16 may be provided as an optical fiber, a light guide, free space, or the like.

[0089] 2A illustrates an example embodiment of a fiber optic temperature sensing system 11 configured to utilize at least one of multiple bands of an emission spectrum to allow the same optical path 16 and measurement module 14 to couple to branch optical paths (22a, 22b, ... 22N) connected to the optical path 16 via a splitter or other optical connector (not shown in FIG. 2A for simplicity), and to obtain measurements from multiple sensing elements 112a, 112b, 112c, ... 112N using the same phosphorescent material (e.g., using standard elements such as splitters or couplers). Each phosphor element may be arranged to perform measurements at a separate location on the object being measured, or to measure multiple separate objects (which may or may not be different), and generate a set of outputs 18 each indicative of a measured parameter, e.g., a time-dependent parameter, in separate bands of the emission spectrum that may be associated with the different locations.

[0090] In the example embodiment shown in FIG. 2A , each measurement location includes a sensing element 112 and a filter element 20 (shown as filter elements 20 a, 20 b, 20 c, ..., 20 N) for isolating the corresponding band for that sensing location from the emission spectrum. In this manner, the measurement module 14 can detect and generate a set of outputs 118 indicative of measurements obtained from each of the sensing elements 112. The filter elements 20 are each configured to pass the corresponding band used for the respective sensing element 112. For example, in the example embodiment shown in FIG. 2A , sensing element 112 a uses a specific bandpass filter element 20 a so that the measurement module 14 can associate measurements in that band with the specific temperature sensing location where sensing element 112 a is used. Similarly, sensing element 112 b uses a specific bandpass filter element 20 b to utilize other specific bands of the emission spectrum for the other sensing locations, and so on for the remaining elements 112 c, ..., 112 N.

[0091] While the sensing elements 112a, 112b, 112c, ..., 112N are described as utilizing the same type of phosphorescent material, this is not intended to be a limitation of the present invention, and in other embodiments, different sensing elements may utilize different phosphorescent materials. In various embodiments, multiple phosphorescent materials may be used for various reasons. For example, in various embodiments, different phosphorescent materials (or phosphors) may be used when one or more locations may have a different measurement temperature range than one or more other locations. The type of phosphor may be selected or optimized to best match the temperature range of each location. For example, the phosphor may be selected based on the emission intensity, time decay value, or other parameters (both time-dependent and time-dependent) for each temperature range. In various embodiments, one or more phosphors may be selected so that their spectral power distributions at least partially do not overlap. This may increase the total wavelength range accessible to the system, thereby increasing the number of locations that can be measured.

[0092] 2B shows an example spectrum that may be transmitted from a sensing element to measurement module 14. The spectrum shown in FIG. 2B includes emission spectra of two different phosphors, identified as 23 and 24, but this is not intended to be a limitation of the present disclosure, and other embodiments may include emission spectra of a single phosphor or more than two phosphors.

[0093] 1, sensing element 12 may have an emission spectrum as illustrated by spectrum 23 in FIG. 2B. In various embodiments, emission spectrum 23 may be divided into multiple bands, such as bands 23′, 23″, and 23′″. In various embodiments, the multiple bands may be adjacent to one another, as illustrated by bands 23′ and 23″, and / or separated from one another, as illustrated by bands 23″ and 23′″.

[0094] Referring to FIG. 1 , sensing element 12 may have an emission spectrum as illustrated by spectrum 23 in FIG. 2B . In various embodiments, emission spectrum 23 may be divided into multiple bands, such as bands 23′, 23″, and 23′″. In various embodiments, one or more time-dependent parameters, such as time decay or time constant, and / or time-independent parameters, such as integrated intensity over the band, may be determined in each band. These may be used individually or collectively to determine or calculate the temperature of phosphor sensing element 12. In various embodiments, the value of one or more parameters may be used in this determination, while in other embodiments, a ratio of such values ​​may be used.

[0095] 2A, sensing elements 112a, 112b, 112c, ..., 112N may be identical or substantially identical, and sensing elements 112a, 112b, and 112c (only three sensing elements are described with reference to FIG. 2B) may each have an emission spectrum, as illustrated by spectrum 23 in FIG. 2B. In various embodiments, emission spectrum 23 may be divided into multiple bands, e.g., bands 23', 23'', and 23''', corresponding to the filtered emission spectra in light paths 22a, 22b, and 22c in FIG. 2A, respectively. In various embodiments, one or more time-dependent parameters, e.g., time decay or time constant, and / or time-independent parameters, e.g., integrated intensity over the band, may be determined for each band. These may be used individually or collectively to determine or calculate the temperature of sensing elements 112a, 112b, and 112c. In various embodiments, the value of one or more time parameters may be used in this determination, while in other embodiments, a ratio of such values ​​may be used.

[0096] 2B shows the spectra of two sensing elements or phosphors 23 and 24. In various embodiments, sensing element 12 of FIG. 1 can include multiple phosphors, for example, to extend the temperature range of the sensing system. For example, in various embodiments, one phosphor may provide more accurate temperature determinations at lower temperatures, while a different phosphor may provide more accurate temperature determinations at higher temperatures. In various embodiments, parameters determined from each zone (23′, 23″, and 23′″ from phosphor 23 and 24′, 24″ from phosphor 24) can be used to calculate or determine temperature and can be used collectively to determine a more accurate temperature value, or one or more parameters from each zone can be evaluated and the temperature can be calculated using one or more parameters from a zone or portion of a zone.

[0097] In various embodiments, the spectrum of a single sensing element or phosphor may not provide sufficiently distinct temperature-dependent values ​​to satisfy the desired number of locations to be measured, and two or more phosphors may be used to expand the number of distinct locations. For example, in various embodiments, some of the sensing elements 112a, 112b, 112c, ..., 112N may include one phosphor, and different portions of the sensing elements 112a, 112b, 112c, ..., 112N may include different phosphors. While Figure 2B shows the spectra of two different phosphors, this is not limiting, and in other embodiments, more than two different phosphors may be utilized.

[0098] Referring now to FIG. 3, an example embodiment of measurement module 14 is shown and generally designated 114. In this example, measurement module 114 includes a casing or housing 30 for containing optical elements. Housing 30 houses or is attached to a printed circuit board assembly (PCBA) 32 that includes a laser or light-emitting diode (LED) 34 provided as a light source for emitting an optical excitation signal that excites phosphor sensing element 12 via optical path 16, and a plurality of photodiodes (e.g., 46a, 46b, also referred to herein as "detector devices" or "detector elements"). The phosphor sensing element is configured to emit at least one optical excitation response signal having an emission spectrum. While the example of FIG. 3 illustrates a pair of photodiodes 46a, 46b, it will be appreciated that more photodiodes can be included within module 114 (N is generally referred to herein as the number of multiple channels 1, 2, ... N) to, for example, isolate additional bands of the emission spectrum. Module 114 also includes lens 38 and dichroic mirror 36 positioned to reflect and focus light emitted by LED 34 into an optical fiber (or other optical element) providing light path 16 while allowing light emitted by phosphor 12 to pass therethrough toward dichroic mirror 40 aligned with first photodiode 46a, and mirror 42 aligned with second photodiode 46b. Dichroic mirror 40 reflects light of shorter wavelengths toward filter 44a and photodiode 46a and transmits light of longer wavelengths toward mirror 42, filter 44b, and photodiode 46b. It will be appreciated that filters 44a and 44b may be omitted since dichroic mirror 40 performs the filtering function. However, in this example, filters 44a and 44b are used to further limit the wavelength range reaching each photodiode 46a and 46b. For example, if it is found that there are wavelength ranges where dichroic mirror 40 varies from very low transmittance to very high transmittance and / or if it is found that there is variability in angular placement between dichroic filters, filters 44a, 44b can be positioned as shown in this example.A first photodiode 46a detects light that is allowed to pass through the first filter 44a, which filters the reflected light to allow processing of a band of the emission spectrum for that photodiode 46a. Similarly, a second photodiode 46b detects light that is allowed to pass through the second filter 44b, which filters the reflected light to allow processing of another band of the emission spectrum for that photodiode 46b.

[0099] Signals detected by the photodiodes 46a, 46b can be provided to a controller 50. The controller 50 may be coupled to the PCBA 32 to enable the controller 50 to control the operation of the LED 34. In this example embodiment, the controller 50 may be operated by another computing device 52, such as a computing workstation in a measurement, test, or manufacturing environment, or may be operated in a stand-alone configuration. The controller 50 may be used for a variety of functions and operations. For example, the controller 50 may be used to adjust the gain of a transimpedance amplifier (not shown) that converts the current signal from the photodiodes 46a, 46b into a voltage signal. The controller 50 may also be used to control the on / off time duration or current of the LED 34. In various embodiments, the LED 34 may be modulated, for example, by a square wave, to turn on and off, and a temperature-dependent value, such as a time decay value or time constant, may be determined after the LED turns off. In various embodiments, the phosphor 12 may be excited by a sine wave. The emission of the phosphor 12 will be a sine wave that is phase-shifted from the excitation wave. The phase shift and amplitude change can be used to measure temperature. The decay length can also be controlled. Furthermore, in alternative methods of exciting the phosphor, the period, amplitude, and offset of the sine wave (used instead of a square wave) can also be controlled. While a computing workstation is shown in FIG. 3, it is understood that various other computing devices 52 can be used. For example, a typical control system used to control the photodiodes 46a, 46b and the LED 34 may interface with other communication interfaces (not shown) that communicate via communication protocols such as RS232, RS485 (or other serial protocols), TCP / IP, EtherCAT, analog 4-20 mA, and analog 0-10 V, to name a few. In such example embodiments, an external programmable logic controller (PLC), readout, or master device may be provided, which may or may not utilize a computing workstation to communicate with the communication module.

[0100] FIG. 4A shows another example embodiment of measurement module 14, designated by the numeral 214. In this example, measurement module 214 includes a Czerny-Turner spectrometer 60, a dichroic mirror 36, and a light source 134. Light source 134 is aligned with dichroic mirror 36 to direct a light beam into an optical fiber that provides a light path 16 toward phosphor element 12. Light emitted by phosphor element 12 passes through the dichroic mirror into spectrometer 60 and toward collimating mirror 62, which collimates the returning light toward diffraction grating 64. Diffraction grating 64 disperses the returning light so that its spectrum is focused by collection mirror 66 along a line corresponding to its wavelength. Linear optical elements can be implemented using a series of optical fibers 68, which connect each wavelength band to a separate photodiode element or to a separate pixel on a CCD or CMOS device. Photodiode module 146, which includes multiple photodiodes 46a, 46b, ... 46N, may be coupled to controller 50 and computing device 52, as in the example embodiment shown in Figure 3. Additionally, Figure 4B illustrates another example embodiment of measurement module 14, designated by the reference numeral 215 in Figure 4B. Photodiode array 246 of photodiodes 46a, 46b, ... 46N may be located within spectrometer 60 in such other devices.

[0101] FIG. 5 illustrates another example embodiment in which the measurement module 114 shown in FIG. 3 is used with a branching optical path 16, as shown in FIG. 2A. The optical path 16 shown in FIG. 5 can be combined into paths 22a and 22b in this example using a splitter or coupler, which may be available off-the-shelf. To separately distinguish the temperatures of each phosphor element 112a, 112b, etc., filters 20a and 20b adjacent to the phosphors 112a and 112b are used in conjunction with filters 44a and 44b (see also FIG. 3) in the module 114. That is, filter 20a corresponds to (i.e., is the same filter as) filter 44a, and filter 20b corresponds to (i.e., is the same filter as) filter 44b, allowing light to propagate only between corresponding phosphor-photodiode pairs. For example, this would mean that light from phosphor 112a cannot reach photodiode 46b. The embodiment shown in FIG. 5 may, in other example embodiments, use identical or similar phosphor elements 112a, 112b, and the emission of each element 112a, 112b may be filtered to transmit specific bands to allow module 114 to distinguish between different detection points.

[0102] FIG. 6 illustrates yet another example embodiment in which the optical path 16 includes multiple optical elements 70 (also referred to herein as “index-matching elements 70”) comprising a material selected to match the refractive index of the optical path 16 along its length. Each index-matching element 70 can be integrated with the optical path 16 by placing the sensor of element 70 in optical contact with the core of the fiber used in the optical path 16, for example, by cutting away the cladding around the core to provide such optical contact when the index-matching element 70 is coupled to the optical path 16. Each index-matching element 70 matches the refractive index of the optical fiber. Optical fibers contain light by having cladding with a different refractive index. This cladding reflects light within the fiber back into the fiber when it encounters a cladding with a different refractive index. If the fiber cladding has the same refractive index as the optical fiber core over a short length, some light will exit the fiber and reach the sensor element. This allows multiple index-matching elements 70 to be placed along the length of the optical fiber 16, rather than just one at the end of each optical fiber 16.

[0103] In various embodiments, the index-matching element 70 may include the filter 20 and phosphor sensing element 12 shown in FIG. 6 . In various embodiments, the multiple index-matching elements 70 may have the same or essentially the same filters 20 (e.g., the same transmission spectrum) and the same or essentially the same phosphor elements (e.g., the same emission spectrum). In these embodiments, the temperatures at the locations of these multiple index-matching elements 70 may be measured together. In various embodiments, this may be referred to as bulk temperature, which refers to a single temperature value reported for measurements at more than one location. In various embodiments, this may refer to the average of the temperatures measured at each location, while in other embodiments, bulk temperature may be determined in different ways. However, in other embodiments, different sensing elements may have different filters 20 (e.g., different transmission spectra) and the same or essentially the same phosphor elements (e.g., the same emission spectrum) and / or different phosphor elements (e.g., different emission spectra). In these embodiments, the system may be able to distinguish between temperatures at different locations of different index-matching elements.

[0104] Waveform 80 in FIG. 6 illustrates the cutoff or bandpass filters applied by different index-matching elements 70, corresponding to different sensor locations. Multiple identical bandpass filters or combinations of different bandpass filters, some with the same wavelength and some with different wavelengths, can be positioned along optical path 16 to obtain bulk temperature measurements across one set of sensing locations and different bulk temperature measurements from another set of sensing locations. It will be understood that index-matching element 70 (e.g., as shown in FIGS. 3, 4A, and 4B) can be coupled to measurement module 14 or other systems, and may or may not include a computing device. For example, time constant calculations can be performed on a PCBA in a microcontroller or using other forms of signal processing. The temperature signal is then passed to controller 50 or a computer. For this reason, FIG. 6 is shown in isolation for simplicity and simplicity of explanation.

[0105] 7-11 show decompositions of the emission spectra to improve accuracy and reduce the effect of changes in cable length on accuracy. Figure 7 shows an example of a phosphor emission spectrum 101 plotted as emission intensity as a function of wavelength. One band of spectrum 101 exhibits a first decay rate 100, and another band of spectrum 101 exhibits a second decay rate 102.

[0106] FIG. 8 shows an example dichroic mirror transmission spectrum 104 along with the example phosphor emission spectrum 101 shown in FIG. 7 to illustrate filtering to obtain the second attenuation factor 102, or in other words, to separate the second attenuation factor 102 from the first attenuation factor 100. The example transmission spectrum 104 can represent the transmittance or reflectance of a dichroic mirror, depending on its type, i.e., long-pass (reflecting short wavelengths) or short-pass (reflecting long wavelengths) type. The dichroic mirror (e.g., mirror 36 or 40 described with reference to FIG. 5) acts as a filter, splitting different portions of the emission spectrum 101 into two bands (or more, up to N as shown herein), in this example, so that the signals can be processed separately.

[0107] Figure 9 shows an example pair of transmission curves 106 and 108 for a pair of bandpass filters superimposed on an emission spectrum 101 as described with reference to Figures 7 and 8. Figure 10 shows example spectra 110, 112 arriving at each of two photodiodes (e.g., 46a, 46b in Figure 3) after being filtered through bandpass filters with the example transmission curves 106 and 108 shown in Figure 9. Thus, a first decay rate 100 is associated with a first portion of the emission spectrum 110, and a second decay rate 102 is associated with a second portion of the emission spectrum 112.

[0108] FIG. 11 shows a flowchart of a decomposition process, such as that shown in FIGS. 7-10, for example, to improve accuracy and mitigate variations in cable length. The phosphor emission spectrum at block 200 reaches a dichroic filter at block 202. The dichroic filter separates the light into transmitted light at block 204 and reflected light at block 210. The transmitted light (e.g., long wavelengths) is filtered to produce filtered transmitted light at block 206. This filtered transmitted light is incident on a first photodetector, and signal processing is performed at block 208, e.g., to calculate a time constant. The reflected light (e.g., short wavelengths) is filtered to produce filtered reflected light at block 212. This filtered reflected light is incident on a second photodetector, and processed at block 218, e.g., to calculate a time constant for a band of the emission spectrum associated with the reflected light. At block 216, the calculations performed at blocks 208 and 218 are used to predict temperature or other parameters and / or predict cable length or other variables.

[0109] A method for performing the decomposition process in FIG. 11 is shown in FIG. 12, which illustrates operations that can be performed when decomposing an emission spectrum into multiple bands, for example, to improve the accuracy of parameter or variable prediction. In step 220, module 14 sends an optical signal to excite phosphor 12. In step 222, the phosphor emission spectrum is received by measurement module 14. Measurement module 14 uses dichroic mirrors and / or other elements (e.g., as illustrated in FIGS. 3, 4A, and 4B) to divide the emission spectrum into N portions or bands to be processed, i.e., first band, second band, ..., Nth band. In step 224, each measurement subsystem receives filtered light from first portion, second portion, ..., Nth band, and signal processing is performed for each measurement band in step 226. The processed signals can then be simultaneously combined, compared, or considered to obtain processed signals from portions of the emission spectrum in step 228 and make predictions using the processed signals in step 230.

[0110] 13-21, multiple sensor transmissions across one optical path 16 are shown using example embodiments such as those shown in FIGS. 2 and 5. In FIG. 13, an example emission spectrum 301 may have a first attenuation rate 300 and a second attenuation rate 302. In various embodiments, a bandpass filter (e.g., bandpass filters 20a, 20b, 20c, ..., 20N as described with reference to FIG. 2A) may have example transmission curves 304, 306 superimposed on the emission spectrum 301 of FIG. 14. FIG. 15 shows example spectra 310, 312 after filtering through example bandpass filter transmission curves 304, 306, illustrating the separation of the first signal 310 (FIG. 14) and the second signal 312 relative to the signal 301 that has passed through the common optical path 16, as shown in FIG. 16.

[0111] Figure 17 shows an example transmission spectrum 314 for a dichroic filter together with the example phosphor emission spectrum 301 shown in Figure 16, illustrating the filtering to obtain the second attenuation factor 302. Example transmission spectra 304 and 306 of bandpass filters are again shown in Figure 18 to illustrate the further filtering within module 14 to allow separation of the first attenuation factor 300 and the second attenuation factor 302, respectively. Figure 19 shows the resulting first and second attenuation factors 300 and 302.

[0112] 20 illustrates an embodiment of multiple sensor transmissions on a single optical path 16. The phosphor emission spectrum from the first phosphor element 12a in block 400 is filtered in block 402 to produce a first filtered spectrum, referred to as Filtered Spectrum 1. Similarly, the phosphor emission spectrum from the second phosphor element 12b in block 404 is filtered in block 406 to produce Filtered Spectrum 2. A coupler or splitter along the optical path 16 is used in block 408 to direct the filtered spectrum into an optical fiber in block 410. The signal then reaches a dichroic filter in block 412 to produce transmitted light (e.g., longer wavelengths) in block 414 and reflected light (e.g., shorter wavelengths) in block 420. The transmitted light in block 414 is filtered to produce filtered transmitted light in block 416, and a first signal processing stage (Signal Processing 1) is performed in block 418 to determine, for example, a time constant and temperature calculations for the first phosphor element 12a. Similarly, the reflected light is filtered in block 422 to produce filtered reflected light, which is used to perform a second signal processing stage (Signal Processing 2) in block 424 .

[0113] A method for performing the decomposition process of FIG. 20 is shown in FIG. 21, which illustrates the operations that may be performed when processing multiple sensors.

[0114] Returning to Figure 20, Figure 20 illustrates the decomposition process. Phosphor emission spectra 1 and 2 are generated in blocks 400 and 404, respectively (more than two emission spectra are within the scope of the present invention). The different phosphor emission spectra 1 and 2 are filtered in blocks 402 and 406, respectively, before being optically combined into a single optical path in block 434, passing through an optical path in block 410, and separated by dichroic filters into a long wavelength portion in block 414 and a short wavelength portion in block 420. The short wavelength and long wavelength portions are then filtered in blocks 416 and 422, respectively, and directed to a photodetector, which generates a signal from which a time calculation or time constant can be calculated in blocks 418 and 424.

[0115] 21 , in step 430, the system transmits optical signals to excite the phosphors 112a, 112b, ... 112N. In step 432, filtered signals are received from each emission spectrum, i.e., in this example, from the first portion of the emission spectrum, the second portion of the emission spectrum, etc., up to the Nth portion of the emission spectrum. That is, each phosphor element 112a, 112b, ... 112N uses a band of its emission spectrum so that the measurement module 224 can distinguish each measurement point. The signals are combined onto a single optical path 16 in step 434, and the signals are received by the measurement module 214 in step 436. Using dichroic mirrors and / or other elements as described herein, the measurement module 214 acquires signals from each phosphor element 112a, 112b, ... 112N in step 438, i.e., in this example, from the first portion of the emission spectrum, the second portion of the emission spectrum, etc., up to the Nth portion of the emission spectrum. This allows the measurement module 214 to apply signal processing to each band individually in step 440 and obtain measurements for, in this example, the first phosphor element 112a, the second phosphor element 112b, and so on up to the Nth phosphor element 112N.

[0116] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Additionally, numerous specific details have been set forth in order to provide a thorough understanding of the examples described herein. However, it will be understood by those skilled in the art that the examples described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the examples described herein. Additionally, the above description should not be considered as limiting the scope of the examples described herein.

[0117] It will be understood that the examples and corresponding figures used herein are for illustrative purposes only. Different embodiments, configurations, and terminology can be used without departing from the principles expressed herein. For example, components and modules can be added, removed, modified, or arranged with different connections without departing from these principles.

[0118] It will also be understood that any module or component illustrated herein that executes instructions may include or have access to a storage medium, computer storage medium, or data storage device (removable and / or non-removable), such as a magnetic disk, optical disk, or tape. Computer storage media may include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and that can be accessed by an application, module, or both. Such computer storage media may be part of a system, any component of a system, or any component associated with a system, or any component accessible or connectable to a system. Any application or module described herein may be implemented using computer-readable / executable instructions that may be stored or carried by such computer-readable media.

[0119] The steps or operations in the flowcharts and diagrams described herein are provided as examples. There may be many variations to these steps or operations without departing from the principles described above. For example, steps may be performed in a different order, or steps may be added, deleted, or modified.

[0120] While the above principles have been described with reference to certain specific examples, various modifications thereof will become apparent to those skilled in the art in light of the entire specification and the appended claims.

Claims

1. 1. A temperature measurement system comprising: a measurement module coupled to an optical path terminating in the phosphor sensing element, a light source optically coupled to the optical path to generate a photoexcitation signal that excites the phosphor sensing element and to generate a photoexcitation response signal from the phosphor sensing element, the photoexcitation response signal including an emission spectrum; one or more optical elements configured to separate the emission spectrum into a plurality of bands of the emission spectrum; a plurality of detector elements that detect each of the bands of the emission spectrum, thereby generating a detection signal for each of the plurality of bands of the emission spectrum; a measurement module having a controller coupled to the light source generating the optical excitation signal and coupled to the plurality of detector elements, enabling the temperature measurement system to process respective detection signals, the controller being configured to calculate a temperature of the phosphor detector element based on at least one time-dependent parameter of at least one of the plurality of bands of the emission spectrum; A temperature measurement system comprising:

2. The temperature measurement system of claim 1 , wherein the at least one time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

3. The temperature measurement system of claim 1 , wherein the at least one time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

4. The temperature measurement system of claim 1 , wherein the controller is configured to modulate the optical excitation signal.

5. The temperature measurement system of claim 1 , wherein at least one of the one or more optical elements includes at least one dichroic mirror.

6. 2. The temperature measurement system of claim 1, wherein the measurement module further includes a plurality of channels, each of the plurality of channels including at least one of the one or more optical elements, a filter, and one of the plurality of detector elements.

7. 7. The temperature measurement system of claim 6, wherein the measurement module is configured to determine a time-dependent parameter of decay of an emission intensity of the emission spectrum in at least one of the plurality of channels and to use the time-dependent parameter in the at least one of the plurality of channels to determine a temperature of the phosphor sensing element.

8. 7. The temperature measurement system of claim 6, wherein the measurement module is configured to determine a time constant of decay of an emission intensity of the emission spectrum in at least one of the plurality of channels and use the time constant in the at least one of the plurality of channels to determine a temperature of the phosphor sensing element.

9. 2. The temperature measurement system of claim 1, wherein the measurement module includes a plurality of index matching elements optically connected to a core of an optical fiber providing the optical path, and each of the plurality of index matching elements is optically connected to the controller through the optical path.

10. 10. The temperature measurement system of claim 9, wherein each of the plurality of index-matching elements includes at least one phosphor sensing element and at least one filter.

11. The temperature measurement system of claim 10 , wherein the at least one filter comprises at least one of a band-pass filter, a low-pass filter, or a high-pass filter, and the at least one filter is characterized by a transmission spectrum.

12. 11. The temperature measurement system of claim 10, wherein (i) the optical path has a first refractive index, and (ii) the plurality of index-matching elements are index-matched to the first refractive index.

13. 11. The temperature measurement system of claim 10, wherein (i) the optical path includes an optical fiber having a core region and a cladding region, (ii) the core region has a first refractive index, and (iii) the plurality of index-matching elements are index-matched to the first refractive index.

14. 12. The temperature measurement system of claim 11 , wherein each of the plurality of phosphor sensing elements is identical, a filter in a first channel has a different transmission spectrum than a filter in a second channel, and the first channel is different from the second channel.

15. 12. The temperature measurement system of claim 11 , wherein the phosphor sensing element associated with a first channel is different from the phosphor sensing element associated with a second channel that is different from the first channel, a filter in the first channel has a different transmission spectrum than the filter in the second channel, and the first channel is different from the second channel.

16. The system of claim 1 , further comprising a computing device coupled to the controller.

17. The system of claim 1 , wherein the light source comprises at least one of a light emitting diode (LED) and a laser.

18. The system of claim 1 , wherein the measurement module includes a spectrometer.

19. 20. The system of claim 18, wherein the spectrometer is a Czerny-Turner spectrometer.

20. 20. The system of claim 18, wherein the measurement module further comprises a photodiode array coupled to the spectrometer via a plurality of optical paths.

21. 20. The system of claim 18, wherein the measurement module includes a photodiode array as part of the spectrometer.

22. 1. A temperature measurement system comprising: a plurality of branches of a common optical path, each of the plurality of branches terminating in a sensing location, each sensing location including a filter disposed between one of the plurality of branches of the common optical path and a phosphor sensing element; a measurement module coupled to the common optical path, a light source optically coupled to the common optical path to generate an optical excitation signal that excites each phosphor sensing element and to generate an optical excitation response signal from each of the phosphor sensing elements, wherein (i) the optical excitation response signal includes an emission spectrum, (ii) each filter is configured to pass a band of the emission spectrum to generate a plurality of filtered excitation response signals, and (iii) each of the plurality of filtered optical excitation response signals is optically coupled to the common optical path; one or more optical elements that separate the plurality of filtered optical excitation response signals into a plurality of detection channels; a plurality of detector elements configured to detect each of the plurality of filtered photoexcitation response signals to process respective bands of the emission spectrum; a measurement module having a controller coupled to the light source generating the optical excitation signal and coupled to the plurality of detector elements, the controller enabling the measurement system to process the plurality of filtered optical excitation response signals, the controller configured to calculate a temperature of the detector elements based on at least one time-dependent parameter of the emission intensity within the band of the emission spectrum; A temperature measurement system comprising:

23. 23. The temperature measurement system of claim 22, wherein the time-dependent parameter comprises a measure of decay of the emission intensity in at least one of the bands of the emission spectrum.

24. 23. The temperature measurement system of claim 22, wherein the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the bands of the emission spectrum.

25. 23. The temperature measurement system of claim 22, wherein the controller is configured to modulate the optical excitation signal.

26. 23. The temperature measurement system of claim 22, wherein the one or more optical elements include at least one dichroic mirror.

27. 23. The temperature measurement system of claim 22, wherein the measurement module further includes a plurality of channels, each channel including at least one of the optical element, a filter, and one of the plurality of detectors.

28. 28. The temperature measurement system of claim 27, wherein the measurement module is configured to determine a time-dependent parameter of decay of an emission intensity of the emission spectrum in at least one of the plurality of channels and use the time-dependent parameter in the at least one of the plurality of channels to determine a temperature of the sensing element.

29. 28. The temperature measurement system of claim 27, wherein the measurement module is configured to determine a time constant of decay of emission intensity of the emission spectrum in at least one of the plurality of channels and use the time constant in the at least one of the plurality of channels to determine a temperature of the sensing element.

30. 23. The temperature measurement system of claim 22, wherein the at least one filter comprises at least one of a bandpass filter, a lowpass filter, or a highpass filter, and the at least one filter is characterized by a transmission spectrum.

31. The temperature measurement system of claim 22 further comprising a computing device coupled to the controller.

32. 23. The temperature measurement system of claim 22, wherein the light source comprises a light emitting diode (LED) or a laser.

33. 23. The temperature measurement system of claim 22, wherein the measurement module includes a spectrometer.

34. 34. The temperature measurement system of claim 33, wherein the spectrometer is a Czerny-Turner spectrometer.

35. 34. The temperature measurement system of claim 33, wherein the measurement module further includes a photodiode array coupled to the spectrometer via a plurality of optical paths.

36. 34. The system of claim 33, wherein the measurement module includes a photodiode array as part of the spectrometer.

37. 23. The temperature measurement system of claim 22, wherein the measurement module includes a plurality of index matching elements optically connected to cores of optical fibers providing the optical paths, each index matching element optically connected to the controller through an optical path.

38. 38. The temperature measurement system of claim 37, wherein each of the plurality of index-matching elements includes at least one phosphor sensing element and at least one filter.

39. 39. The temperature measurement system of claim 38, wherein the at least one filter comprises at least one of a bandpass filter, a lowpass filter, or a highpass filter, and wherein the at least one filter is characterized by a transmission spectrum.

40. 39. The temperature measurement system of claim 38, wherein (i) the optical path has a first refractive index, and (ii) each of the plurality of index-matching elements is index-matched to the first refractive index.

41. 39. The temperature measurement system of claim 38, wherein (i) the optical path includes an optical fiber having a core region and a cladding region, (ii) the core region has a first refractive index, and (iii) each of the plurality of index-matching elements is index-matched to the first refractive index.

42. 40. The temperature measurement system of claim 39, wherein each of the plurality of phosphor sensing elements is identical, a filter in a first channel has a different transmission spectrum than a filter in a second channel, and the first channel is different from the second channel.

43. 23. The temperature measurement system of claim 22, wherein a phosphor sensing element associated with a first channel is different from a phosphor sensing element associated with a second channel that is different from the first channel, a filter in the first channel has a different transmission spectrum than the filter in the second channel, and the first channel is different from the second channel.

44. 23. The system of claim 22, wherein each phosphor element is positioned to make a measurement at a distinct location on the object being measured or to measure a plurality of distinct objects.

45. transmitting an optical signal along an optical path to excite a phosphor sensing element optically coupled to the optical path; receiving a return signal having an emission spectrum; splitting the return signal into a plurality of bands of the emission spectrum; directing each of the plurality of bands of the emission spectrum to a corresponding detector element, each detector element generating a detection signal; applying signal processing to each detection signal having each band of the emission spectrum; determining a temperature of the phosphor sensing element based on at least one time-dependent parameter of at least one of the plurality of bands of the emission spectrum; method.

46. 46. ​​The method of claim 45, wherein the time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

47. 46. ​​The method of claim 45, wherein the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

48. 46. ​​The method of claim 45, wherein the optical signal is modulated.

49. transmitting an optical signal along a common optical path coupled to a plurality of branches to excite a plurality of phosphor sensing elements, each of the plurality of phosphor sensing elements being coupled to a respective branch of the common optical path; receiving a plurality of return signals via the common optical path, each of the plurality of return signals being filtered to provide one of a plurality of bands of the emission spectrum of a respective one of the phosphor sensing elements; directing each of the plurality of return signals to a respective measurement channel, each measurement channel including at least one detector, each of the at least one detector generating a respective detection signal; applying signal processing to each detected signal to obtain a measurement for each of the plurality of phosphor sensing elements; determining a temperature of the phosphor sensing element based on at least one time-dependent parameter of at least one band of the emission spectrum; method.

50. 50. The method of claim 49, wherein the time-dependent parameter comprises a measure of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

51. 50. The method of claim 49, wherein the time-dependent parameter comprises a time constant of decay of emission intensity in at least one of the plurality of bands of the emission spectrum.

52. 50. The method of claim 49, wherein the optical signal is modulated.

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