Patent Publication Number: US-2021161704-A1

Title: Laser dosage determination by temperature monitoring

Description:
CROSS-REFERENCE 
     This patent application is section 371 nationalization of PCT Application No. PCT/US2017/058331 filed Oct. 25, 2017, which application is incorporated herein by specific reference in its entirety. 
    
    
     BACKGROUND 
     Unless otherwise indicated herein, the materials described herein are not prior art to the claims in the present application and are not admitted to be prior art by inclusion in this section. 
     Therapeutic radiation may be administered to an eye of a patient to treat various conditions of the eye that may negatively affect vision. It may be difficult to accurately measure an exposure level of the eye to the therapeutic radiation, which can damage the eye at excess exposure levels. 
     SUMMARY 
     Techniques described herein generally relate to laser dosage determination by temperature monitoring. 
     In an example embodiment, a laser-based ophthalmological surgical system includes a therapeutic radiation source, one or more optical elements, and a detector system. The therapeutic radiation source may be configured to emit therapeutic radiation. The one or more optical elements may be configured to direct the therapeutic radiation to a targeted area of an eye of a patient. A temperature of the targeted area may depend on a dosage of the therapeutic radiation. The detector system may be configured to measure thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation. The one or more optical elements may be configured to optically couple the detector system to the targeted area. 
     In another example embodiment, a method to measure therapeutic radiation dosimetry may include irradiating a targeted area of an eye of a patient with therapeutic radiation. A temperature of the targeted area may depend on a dosage of the therapeutic radiation. The method may also include measuring thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation to generate a measurement of the thermal radiation. The measurement of the thermal radiation may be indicative of the temperature of the targeted area and the dosage of the therapeutic radiation. 
     In some embodiments, a laser-based ophthalmological surgical system can include: a therapeutic radiation source configured to emit therapeutic radiation; one or more optical elements configured to direct the therapeutic radiation to a targeted area of an eye of a patient, wherein a temperature of the targeted area depends on a dosage of the therapeutic radiation; and a detector system configured to measure thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation, wherein the detector system includes a first detector configured to detect radiation at a first wavelength and a second detector configured to detect radiation at a second wavelength shorter than the first wavelength, wherein the one or more optical elements are configured to optically couple the detector system to the targeted area. In some aspects, at least one of the first detector or second detector includes: a detector with a quantum efficiency, the detector configured to detect an intensity of the thermal radiation; and a processor device communicatively coupled to the detector and configured to receive the detected intensity from the detector, and calculate the temperature of the targeted area based on the detected intensity, the quantum efficiency of the detector, and a blackbody spectrum associated with a target temperature threshold of the targeted area. In some aspects, at least one of the first detector or second detector includes an infrared (IR) detector. In some aspects, at least one of the first detector or second detector comprises an infrared (IR) detector, wherein the IR detector includes an indium gallium sulfide (InGaS) IR detector, a mercury cadmium telluride (MCT) IR detector, or an indium phosphide (InP) IR detector. In some aspects, at least one of the first detector or second detector includes a bandwidth greater than 10 megahertz (MHz) and configured to measure the thermal radiation at sub microsecond temporal resolution. 
     In some embodiments, the one or more optical elements includes at least one filter positioned in an optical path between the targeted area and the detector system and wherein the filter is configured to block radiation with a wavelength less than one micrometer. 
     In some embodiments, the one or more optical elements includes at least one beam splitter. In some aspects, the at least one beam splitter is configured to provide the first wavelength to the first detector and provide the second wavelength to the second detector. 
     In some embodiments, the one or more optical elements includes a first filter positioned in a first optical path between the targeted area and the first detector, wherein the first filter is configured to pass radiation at the first wavelength to the first detector. Also, a second filter can be positioned in a second optical path between the targeted area and the second detector, wherein the second filter is configured to pass radiation at the second wavelength to the second detector. In some embodiments, a processor device can be communicatively coupled to the therapeutic radiation source and the detector system, wherein the processor device is configured to terminate exposure of the targeted area of the eye of the patient to the therapeutic radiation responsive to a measurement of the thermal radiation generated by the detector system meeting or exceeding a target temperature threshold. 
     In some embodiments, a method to measure therapeutic radiation dosimetry can include: irradiating a targeted area of an eye of a patient with therapeutic radiation, wherein a temperature of the targeted area depends on a dosage of the therapeutic radiation; and measuring thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation to generate a measurement of the thermal radiation. In some aspects, the protocol for measuring thermal radiation can include: measuring thermal radiation in a first spectral band associated with a first temperature lower than a target temperature threshold to generate a first measurement of the thermal radiation; and measuring thermal radiation in a second spectral band associated with the target temperature threshold to generate a second measurement of the thermal radiation. In some aspects, a relationship between the first measurement and second measurement is indicative of the temperature of the targeted area and the dosage of the therapeutic radiation. 
     In some embodiments, the measuring of the thermal radiation to generate the measurement can include detecting an intensity of the thermal radiation to generate detected intensity, the method further comprising calculating the temperature of the targeted area based on the detected intensity, a quantum efficiency of at least one detector that generates the detected intensity, and a blackbody spectrum associated with a target temperature. 
     In some embodiments, the method can include filtering an optical path between the targeted area and a detector system that measures the thermal radiation to block radiation with wavelengths associated with temperatures less than a target temperature threshold. 
     In some embodiments, the method can include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the measurement of the thermal radiation meeting or exceeding a target temperature threshold. 
     In some embodiments, irradiating the targeted area with the therapeutic radiation can include irradiating the targeted area with discrete pulses of the therapeutic radiation, wherein the discrete pulses of therapeutic radiation have different amounts of pulse energy. 
     In some embodiments, the method can include: determining a current dosage of the therapeutic radiation based on the first measurement responsive to the first measurement exceeding a first threshold and the second measurement being below a second threshold that is lower than the first threshold; determining a target dosage of the therapeutic radiation based on at least one of the current dosage, the first measurement, and the second measurement; and controlling the therapeutic radiation source to emit a discrete pulse with an amount of energy that corresponds to the target dosage. In some aspects, the method can include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the therapeutic radiation source emitting a target dosage. 
     In some embodiments, the method can include synchronizing the measurement of the thermal radiation to discrete pulses of the therapeutic radiation. 
     In some embodiments, the measurement of thermal radiation comprises one or more measurements of the temperature of the targeted area, each of the one or more measurements is associated with a corresponding discrete pulse of the therapeutic radiation having a corresponding known amount of pulse energy. In some embodiments, the method can include: determining a target dosage of the therapeutic radiation based on the one or more measurements and the corresponding known amount of pulse energy; and controlling the therapeutic radiation source to emit a discrete pulse with an amount of pulse energy that corresponds to the target dosage. 
     In some embodiments, the method can include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the therapeutic radiation source emitting the discrete pulse with the amount of pulse energy that corresponds to the target dosage. 
     In some embodiments, measuring the thermal radiation includes measuring the thermal radiation using at least one detector with a bandwidth greater than 10 megahertz (MHz) at sub microsecond temporal resolution. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The foregoing and following information, as well as other features of this disclosure, will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings: 
         FIG. 1A  is a cross-sectional view of an example human eye (hereinafter “eye”); 
         FIG. 1B  is a cross-sectional perspective view of a portion of a retina and macula of  FIG. 1B ; 
         FIG. 1C  is a cross-sectional perspective view of a portion of the macula of  FIG. 1B ; 
         FIG. 2  is a graphical representation of an example feedback response to therapeutic radiation that may be generated by a laser-based ophthalmological surgical system; 
         FIGS. 3A and 3B  are graphical representations of various blackbody spectra at different temperatures; 
         FIG. 4  is a perspective view of an example laser-based ophthalmological surgical system in which thermal radiation detection may be implemented; 
         FIG. 5A  is a block diagram of an example laser-based ophthalmological surgical system; 
         FIG. 5B  is a block diagram of another example laser-based ophthalmological surgical system; 
         FIG. 6  illustrates a flow diagram of an example method to measure therapeutic radiation dosimetry; and 
         FIG. 7  illustrates a block diagram of an example computing device, 
     
    
    
     all arranged in accordance with at least one embodiment of the present disclosure. 
     DETAILED DESCRIPTION 
     This disclosure is generally drawn to methods, apparatus, systems, devices, and computer program products related to laser dosage determination by temperature monitoring. 
     In this detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. The aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. 
       FIG. 1A  is a cross-sectional view of an example human eye (hereinafter “eye”)  100 , arranged in accordance with at least one embodiment described herein. The eye  100  may include a cornea  102 , an iris  104 , a pupil  106 , a ciliary body  108 , a lens  110 , a retina  112 , and an optic nerve  114 . The retina  112  generally includes a light-sensitive layer of tissue upon which optics of the eye  100  project an image of the visual world external to the eye  100 . Through a series of chemical and electrical events, nerve impulses may be triggered in response to light striking the retina  112 . The nerve impulses may be processed in vision centers of the brain such that the visual world may be perceived by a person. 
     As illustrated in  FIG. 1A , the retina  112  includes an optic disc  116 , sometimes referred to as the “blind spot”, and a macula  118  temporal to the optic disc  116 . 
       FIG. 1B  is a cross-sectional perspective view of a portion of the retina  112  and the macula  118  of  FIG. 1A , arranged in accordance with at least one embodiment described herein. 
       FIG. 1C  is a cross-sectional perspective view of a portion of the macula  118  of  FIG. 1B , arranged in accordance with at least one embodiment described herein.  FIG. 1C  depicts various layers that may make up the macula  118 , including photoreceptors  120 , retinal pigment epithelial (RPE) cells  122 , Bruch&#39;s membrane  124 , and choroid  126 . The macula  118  may have a relatively high concentration of photoreceptors  120  compared to the rest of the retina  112  and without blood vessels, for central and/or high resolution vision. The RPE cells  122  may nourish the photoreceptors  120  by supplying nutrients from the choroid  126  and transporting extracellular material out through the Bruch&#39;s membrane  124 . 
     Various conditions may adversely affect vision in the eye  100 . For instance, with reference to  FIGS. 1A-1C , age-related macular degeneration (AMD) may involve degradation of the RPE cells  122  in the macula  118 . In dry AMD, degraded RPE cells  122  may fail to transport extracellular material which may then begin to build up (“Drusen”) in between the Bruch&#39;s membrane  124  and the RPE cells  122 . The Drusen may interfere with the supply of nutrients to the photoreceptors  120 , which can lead to vision loss. In wet AMD, new blood vessels (neovascularization) may grow from the choroid  126  and penetrate the Bruch&#39;s membrane  124  and the RPE cells  122  to supply nutrients to the photoreceptors  120 . The new blood vessels may be weak and prone to bleeding and leakage, which may result in blood and protein leakages, which in turn may damage the photoreceptors  120  and fuel rapid vision loss. 
     Another condition that may adversely affect vision in the eye  100  may be diabetic macular edema (DME). In more detail, persons with diabetes may experience a slowing of metabolism over time, which may reduce the ability of retinal vessels to deliver enough nutrients, which in turn may induce neovascularization. Fluid leakage from the neovascularization may cause the retina  112  to swell, causing vision loss. 
     Another condition that may adversely affect vision in the eye  100  may be central serous chorioretinopathy (CSC). In CSC, leakage of fluid accumulates under the central macula  118 , resulting in blurred or distorted vision which may progressively decline with each recurrence. 
     Some embodiments described herein include a laser-based ophthalmological surgical system that includes a therapeutic radiation source configured to emit therapeutic radiation to treat AMD, DME, CSC, and/or other conditions of the eye  100 . In general, the therapeutic radiation may be absorbed by RPE cells  122  targeted with the therapeutic radiation. Specifically, the therapeutic radiation may be absorbed by melanin or other chromophore in the RPE cells  122 . The absorbed therapeutic radiation may be converted to heat, which may lead to formation of microbubbles in the RPE cells  122 . The microbubbles may burst or otherwise destroy RPE cells  122 . By targeting degraded RPE cells included in the RPE cells  122 , the degraded RPE cells can be destroyed to prevent them from causing further damage. 
     According to some embodiments, such laser-based ophthalmological surgical systems may use real-time feedback to detect RPE damage and stop therapeutic radiation automatically based on the feedback prior to excessively damaging the targeted RPE cells  122 . In an example embodiment, the therapeutic radiation may be administered to the targeted RPE cells  122  in pulses that may have an energy per pulse (hereinafter “pulse energy”) that may vary from one pulse to the next. The administration of pulses may be terminated in response to the feedback indicating a maximum, or at least target, exposure to the therapeutic radiation. 
     The therapeutic radiation may, in some embodiments, be generally more effective at treating conditions of the eye at higher exposure levels. However, at a particular level of exposure, e.g., pulse energy, to the therapeutic radiation, therapeutic radiation may cause excessive damage to the eye that may result in vision loss. To avoid or reduce the likelihood of vision loss due to excessive exposure to the therapeutic radiation while permitting exposure up to a sufficiently high level to be effective, some embodiments described herein may start administration of the therapeutic radiation at a relatively low exposure that ramps up with each successive pulse until real-time feedback indicates a threshold exposure has been reached. In an example, the first pulse of therapeutic radiation may be at about 50% of a relatively high energy level, such as a maximum energy level. More generally, the first pulse may be at a relatively low energy level, and each successively administered pulse of therapeutic radiation may be increased compared to the preceding pulse. The amount of increase from pulse to pulse may be fixed or variable. For instance, in an example embodiment, the amount of increase from pulse to pulse may be fixed at 5% of the relatively high energy level. 
     In another example, a relatively small number of successive pulses, such as two, may be administered, each with relatively low but different pulse energy. Real-time feedback for each of the relatively small number of successive pulses may be used to calculate or otherwise determine a particular pulse energy that will result in the maximum, or at least target, exposure to the therapeutic radiation. In this and other embodiments, rather than ramping up the pulse energy by the fixed amount over a series of successive pulses, the therapeutic radiation may be increased from the pulse energy for the last one of the relatively small number of successive pulses directly to the particular pulse energy that will result in the maximum, or at least target, exposure to the therapeutic radiation. Such an approach may reduce a total amount of treatment time. 
     In these and other embodiments, the real-time feedback may measure exposure of the targeted RPE cells to the therapeutic radiation by measuring the formation and/or bursting of microbubbles that form on melanosomes of the targeted RPE cells in response to exposure to the therapeutic radiation, and/or by measuring thermal radiation emitted by the targeted RPE cells responsive to absorbing the therapeutic radiation. In an example embodiment, the formation and/or bursting of the microbubbles may be measured with optical feedback and/or acoustic feedback. In particular, the targeted RPE cells may reflect and/or emit optical and/or acoustic signals that may vary depending on the presence, absence, and/or characteristics (e.g., size, velocity) of the microbubbles. Excessive exposure to the therapeutic radiation after microbubble formation and RPE damage could damage other retinal structures, which may lead to formation of scotoma on the retina. 
       FIG. 2  is a graphical representation  200  of an example feedback response to therapeutic radiation that may be generated by a laser-based ophthalmological surgical system, arranged in accordance with at least one embodiment described herein. The horizontal axis is radiant exposure to the therapeutic radiation in millijoules per square centimeter (mJ/cm2), the left vertical axis is optical feedback value in microwatts, and the right axis is acoustic feedback value in volts.  FIG. 2  includes data points representing the measured optical feedback (diamonds in  FIG. 2 ) and acoustic feedback (circles in  FIG. 2 ) as a function of therapeutic radiation exposure level. Each data point may represent a measurement of the optical or acoustic feedback from the targeted RPE cells and/or from microbubbles thereon after exposure to a pulse of the therapeutic radiation at a corresponding exposure level. All of the optical feedback data points may be collectively referred to as an optical signal and all of the acoustic feedback data points may be collectively referred to as an acoustic signal. 
       FIG. 2  additionally includes a vertical reference zone  202 , at around 280 mJ/cm2 in the example of  FIG. 2 , that represents a microbubble threshold area at a therapeutic radiation exposure level that may be known or expected to cause excessive damage to the targeted RPE cells.  FIG. 2  additionally includes a horizontal reference line  204  at a threshold optical feedback value, at 10 arbitrary units (a.u.) in the example of  FIG. 2 , which may be selected as an optical feedback value after which irradiation with the therapeutic radiation may be terminated to avoid or reduce the likelihood of excessive damage to the targeted RPE cells. 
     The optical signal in the example of  FIG. 2  may be generated by measuring reflected therapeutic radiation or other reflected radiation from the targeted RPE cells and/or from microbubbles that form thereon. 
     The acoustic signal in the example of  FIG. 2  may be generated by measuring the acoustic response of the targeted RPE cells and/or the microbubbles that form thereon. 
     As illustrated in  FIG. 2 , the optical signal and the acoustic signal in this example may both be somewhat noisy and may exhibit substantial fluctuations, particularly around the vertical reference zone  202 . This strong fluctuation in the optical signal and the acoustic signal may impose a difficulty in accurately determining when the optical signal and the acoustic signal is at or near a corresponding threshold feedback value indicative of a therapeutic radiation threshold exposure level. 
     Embodiments described herein may alternatively or additionally measure thermal radiation emitted by the targeted RPE cells exposed to the therapeutic radiation. The thermal radiation may be emitted by the targeted RPE cells responsive to absorption by the targeted RPE cells of some or all of the therapeutic radiation. The measured thermal radiation may be used as the real-time feedback to measure exposure of the targeted RPE cells to the therapeutic radiation. In these and other embodiments, the thermal radiation may be less dependent on bubble dynamics (e.g., formation and/or bursting) of the microbubbles than the optical and/or acoustic signals of  FIG. 2 . Alternatively or additionally, the targeted RPE cells may absorb the thermal radiation, which may then be converted to heat in proportion to the thermal radiation exposure level. As such, measuring the thermal radiation emitted by the targeted RPE cells may provide a more direct measure of the thermal radiation exposure level than the optical and/or acoustic signals of  FIG. 2 . 
     In these and other embodiments, the measured thermal radiation may be less noisy and/or may have fewer fluctuations than the optical and/or acoustic signals of  FIG. 2 . Accordingly, one or more measurements of thermal radiation emitted by the targeted RPE cells may be used as the real-time feedback instead of or in addition to one or both of the optical signal or the acoustic signal of  FIG. 2 . The one or more measurements may include an intensity of the thermal radiation and/or a temperature of the targeted RPE cells derived from the intensity. 
     In this and other embodiments, a laser-based ophthalmological surgical system may include a therapeutic radiation source, one or more optical elements, and a detector system. The therapeutic radiation source may be configured to emit therapeutic radiation. The one or more optical elements may be configured to direct the therapeutic radiation to one or more targeted RPE cells included in a targeted area of an eye of a patient. A temperature of the targeted area and/or of the targeted RPE cells may depend on a dosage of the therapeutic radiation, or exposure level of the targeted area to the therapeutic radiation. The detector system may be configured to measure thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation and may include, e.g., an infrared (IR) detector. The one or more optical elements may be configured to optically couple the detector system to the targeted area. Various detection approaches may be implemented, some of which are described in more detail elsewhere herein. 
     In some embodiments, a temperature at which excess damage may occur to an eye of a patient in response to exposure to therapeutic radiation may be known and/or estimated. This temperature may be referred to as a damage temperature threshold. The damage temperature threshold may be known and/or estimated based on experimental results and/or simulations that may demonstrate a temperature at and/or above which the RPE cells in the targeted area and/or other portions of the eye of the patient are subjected to excessive damage, e.g., in the form of scotoma formation. 
     A target temperature threshold may be selected to be equal to or less than the damage temperature threshold. In some embodiments, the target temperature threshold may be in a range from 340-360 Kelvin (K) or in a range from 350-355 K. Alternatively or additionally, the targeted area of the eye of the patient may be exposed to the therapeutic radiation until and/or such that measured thermal radiation indicates the targeted area has reached the target temperature threshold. The target temperature threshold may be selected to be less than the damage temperature threshold to provide some margin for error. Alternatively, the target temperature threshold may be selected to be equal to the damage temperature threshold. In these and other embodiments, the targeted area may be assumed to be and/or may be approximated as a black body and thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation may be measured to determine the temperature of the targeted area, as described in more detail elsewhere. 
       FIGS. 3A and 3B  are graphical representations  300 A and  300 B of various blackbody spectra at different temperatures, arranged in accordance with at least one embodiment described herein. In  FIG. 3A , each blackbody spectrum is labeled with a temperature in Kelvin (K) at which the blackbody spectrum may be emitted by a black body. The horizontal axis and the vertical axis in  FIG. 3A  both have a logarithmic scale. The horizontal axis is wavelength in micrometers (μm), and the left and right vertical axes are, in effect, thermal radiation intensity. More specifically, the left vertical axis is spectral radiant emittance in W/(m2 μm) and the right vertical axis is spectral radiance in W/(m2 μm sr). Thus,  FIG. 3A  illustrates various blackbody spectra at different temperatures in terms of thermal radiation intensity as a function of wavelength. 
     It can be inferred from  FIG. 3A , in particular at least from the black body spectrum at 300 K and the black body spectrum at 500 K, that a black body at a temperature in a range from 300-380 K may have a blackbody spectrum with at least some spectral components at wavelengths of about 2 μm or less, with the intensity at any given spectral component in this range increasing with increasing temperature. For instance, the intensity of the blackbody spectra at a wavelength of 2 μm may be greater at 350 K than at 300 K, and still greater at 380 K. A graph (such as the graph of  FIG. 3A ), table, equation, or other information may relate thermal radiation intensities, wavelengths, and/or temperatures of black bodies such that one or more of the foregoing parameters may be calculated, estimated, or otherwise determined when one or more others of the foregoing parameters are known. Thus, the thermal radiation intensity at a given wavelength, when measured, may be used to determine a temperature of a black body. Alternatively or additionally, the thermal radiation intensities at two or more different wavelengths, a ratio thereof, or some other relationship therebetween, may be used to determine the temperature of the black body. 
     The targeted area in the eye of the patient may be assumed to be and/or may be approximated as a black body. As such, the thermal radiation emitted by the targeted area may be measured and used to determine the temperature of the targeted area, which in turn may be used to determine the therapeutic radiation dosage of the targeted area. For instance, the temperature of and thus the thermal radiation emitted by the targeted area may be directly proportional to and/or may have some other relationship to the therapeutic radiation dosage. 
     The temperature range 300-380 K may be and/or may include a range of temperatures that the targeted area of the eye may be expected to reach responsive to an expected range of therapeutic radiation dosages. Because the blackbody spectra associated with the temperature range from 300-380 K may each have at least some spectral components at wavelengths of about 2 μm or less, some embodiments described herein may be implemented with detector systems and/or optical components that are suitable for wavelengths of about 2 μm or less. Some laser-based ophthalmological surgical systems may already include and/or may already be designed with detector systems and/or optical components suitable for such wavelengths such that implementing one or more embodiments described herein in such laser-based ophthalmological surgical systems may be relatively simple and straightforward with relatively few modifications. 
     In  FIG. 3B , each blackbody spectrum is labeled with a temperature in Kelvin (K) at which the blackbody spectrum may be emitted by a black body, with three spectra at, respectively, 340 K, 350 K, and 360 K. The horizontal axis and the vertical axis in  FIG. 3B  both have a linear scale. The horizontal axis is wavelength in μm and the left vertical axis is, in effect, thermal radiation intensity. More specifically, the left vertical axis is radiant power. Thus,  FIG. 3B  illustrates various blackbody spectra at different temperatures in terms of thermal radiation intensity as a function of wavelength. 
     Based on the spectra of  FIG. 3B , measurements of thermal radiation for blackbody spectra in the range of 340-360 K at a wavelength of about 2 μm or less may be difficult. Accordingly, some embodiments may measure blackbody spectra in the range of 340-360 K at higher wavelengths than 2 μm or less, such as at least 3 μm, or at least 4 μm. In an example implementation, some embodiments may measure blackbody spectra at 4 μm or 5 μm. 
     In particular, some embodiments described herein may be implemented with detector systems and/or optical components that are suitable for wavelengths of about 4 and/or 5 μm. For each of the 340 K, 350 K, and 360 K spectra in  FIG. 3B , it can be seen that the thermal radiation intensity is much greater at 4 and 5 μm than at 2 μm. 
     In some embodiments, the thermal radiation intensity may be detected at both 4 and 5 μm and the ratio of the two measurements may be used to determine the temperature and thus the thermal radiation exposure at the eye of the patient. For instance, the ratio of the thermal radiation measured at 4 μm to the thermal radiation measured at 5 μm for the 360 K blackbody spectrum is about 2.41803. The same ratio for the 350 K blackbody spectrum is about 2.55996 and for the 340 K blackbody spectrum is about 2.71936. This ratio monotonically decreases as temperature increases near an example target temperature threshold of 353 K. Accordingly, by measuring the thermal radiation intensity at both 4 and 5 μm, and determining the ratio of the two, the temperature and thus the thermal radiation exposure at the eye of the patient may be determined in some embodiments. 
       FIG. 4  is a perspective view of an example laser-based ophthalmological surgical system (hereinafter “system”)  400  in which thermal radiation detection may be implemented, arranged in accordance with at least one embodiment described herein. As illustrated, the system  400  may include one or more of a console  402 , a head fixation assembly  404 , a microscope  406 , a graphical user interface (GUI)  408 , and one or more input devices  410 . 
     The console  402  may include a therapeutic radiation source configured to emit therapeutic radiation. The console  402  may also include one or more control systems (e.g., one or more processors, drivers, or other circuits), a cooling system, or other systems or components. Additional details regarding an example therapeutic radiation source are described elsewhere herein. 
     The therapeutic radiation may be directed by one or more optical elements of the system  400  from the therapeutic radiation source in the console  402  into an eye of a patient during treatment of the eye of the patient with the system  400 . The one or more optical elements may be included in one or more of the console  402 , the microscope  406 , and/or other components of the system  400  and/or may be provided as discrete components within the system  400 . 
     The head fixation assembly  404  may be configured to position and retain a head of the patient during treatment of the eye of the patient with the therapeutic radiation. For instance, the head fixation assembly  404  may be configured to position and retain the head of the patient with the eye of the patient aligned to receive the therapeutic radiation. 
     The microscope  406  may be used by a treatment provider to observe the patient&#39;s eye during treatment. Alternatively or additionally, the microscope  406  or other component of the system  400  may include a targeting radiation source that may be optically aligned to target a same location as the therapeutic radiation. The targeting radiation source may emit targeting radiation to identify a specific location within the patient&#39;s eye currently targeted to receive therapeutic radiation. In this and other embodiments, the treatment provider may operate the input device  410 , the GUI  408 , and/or other elements of the system  400  to adjust the particular location within the patient&#39;s eye that is targeted by the targeting radiation and/or the therapeutic radiation. 
       FIG. 5A  is a block diagram of an example laser-based ophthalmological surgical system (hereinafter “system”)  500 A, arranged in accordance with at least one embodiment described herein. The system  500 A may include or correspond to the system  400  of  FIG. 4 . The system  500 A may include a therapeutic radiation source  502 , one or more optical elements  504 , and a detector  506 . Alternatively or additionally, the system  500 A may include a processor device  508 . The detector  506  and the processor device  508  combined may form a detector system. The system  500 A may include one or more other elements not depicted in  FIG. 5A  for simplicity. 
     The therapeutic radiation source  502  may be configured to emit therapeutic radiation  510  with a center wavelength. For instance, the therapeutic radiation  510  may have a center wavelength in a range from 440-500 nanometers (nm), or in a range from 520 nm to about 540 nm, such as 527 nm, or in a range from 575 nm or higher, such as 577 nm, or in some other range. The therapeutic radiation  510  in some embodiments may be pulsed, meaning the therapeutic radiation source  502  may emit the therapeutic radiation  510  as discrete pulses. The pulses of therapeutic radiation  510  may each have a pulse duration in a range from 1.6 microseconds to 1.8 microseconds, and may be administered periodically in some embodiments, with a pulse frequency in a range of 50 hertz (Hz) to 200 Hz or higher (e.g., 500 Hz), such as 100 Hz. As used herein, “pulse frequency” may refer to a frequency at which the discrete pulses of therapeutic radiation  510  are emitted by the therapeutic radiation source  502 , e.g., a repetition rate of the discrete pulses of therapeutic radiation  510 . The pulses of therapeutic radiation  510  may be substantially flat-topped or may have some other shape. 
     In some embodiments, the therapeutic radiation  510  emitted by the therapeutic radiation source  502  may have up to a maximum energy of at least 0.4 millijoules (mJ). The therapeutic radiation source  502  may be controlled to emit discrete pulses of the therapeutic radiation  510  that have a pulse energy in a range between 0 mJ up to the maximum energy. For instance, the discrete pulses of therapeutic radiation  510  may be sequentially ramped up beginning at a relatively low pulse energy (e.g., 50% of the maximum energy) and successively ramping up in pulse energy by a fixed or variable amount (e.g., 5% of the maximum energy) until optical feedback, acoustic feedback, or thermal radiation feedback indicates a threshold exposure level of the eye  100  to the therapeutic radiation  510  has been reached. Alternatively, successive discrete pulses may have their pulse energy changed from one pulse to the next according to some other scheme. 
     The optical elements  504  may be configured to direct the therapeutic radiation  510  to the targeted area of the eye  100 , and in particular to targeted RPE cells within the targeted area. A temperature of the targeted area of the eye  100  may depend on the dosage, or pulse energy, of the therapeutic radiation  510 . The optical elements  504  may additionally be configured to optically couple the detector  506  to the targeted area of the eye  100  such that the detector  506  may receive and measure thermal radiation  512  emitted by the targeted area responsive to exposure to the therapeutic radiation. 
     The optical elements  504  in  FIG. 5A  include a microscope objective lens  504 A (hereinafter “lens  504 A”) and a beam splitter  504 B. In  FIG. 5A , the lens  504 A and the beam splitter  504 B are both common to optical paths of the therapeutic radiation  510  and the thermal radiation  512 . Alternatively or additionally, the optical elements  504  may include other components not illustrated in  FIG. 5A , some of which may be common to both optical paths, others of which may be in the optical path of the therapeutic radiation  510  but not in the optical path of the thermal radiation  512 , and/or others of which may be in the optical path of the thermal radiation  512  but not in the optical path of the therapeutic radiation  510 . 
     The lens  504 A may be configured to collect the thermal radiation  512  emitted from the eye  100  responsive to exposure to the therapeutic radiation  510 . The lens  504 A may be included in, e.g., the microscope  406  of  FIG. 4 . 
     The beam splitter  504 B may be configured to pass the thermal radiation  512  from the therapeutic radiation source  502  to the eye  100 . The beam splitter  504 B may also be configured to redirect the thermal radiation  512  collected from the eye  100  toward the detector  506 . 
     In an example, the beam splitter  504 B may include a dichroic beam splitter with a cutoff wavelength of 1 μm such that radiation incident on the beam splitter  504 B with a wavelength of at least 1 μm may be redirected to the detector  506 . In this and other embodiments, the beam splitter  504 B may function as a filter insofar as it may effectively block radiation with wavelengths less than 1 μm from being directed to the detector  506 . 
     The detector  506  may have a quantum efficiency which may be associated with a particular wavelength or wavelength range. In at least one embodiment, the detector  506  may be configured detect radiation with wavelengths up to 2 μm. In other embodiments, the detector  506  may be configured to detect radiation with wavelengths greater than 2 μm, such as radiation with wavelengths of 3 μm, 4 μm, 5 μm, and/or other wavelengths. The detector  506  may be configured to receive the thermal radiation  512  and detect its intensity or other parameter as a measure of the thermal radiation  512 . Alternatively or additionally, the detector  506  may include an IR detector, such as an indium gallium sulfide (InGaS) IR detector, a mercury cadmium telluride (MCT) IR detector, or an indium phosphide (InP) IR detector. In at least one embodiment, the detector  506  may have a bandwidth greater than 10 megahertz (MHz) and may be configured to measure the thermal radiation  512  at sub microsecond temporal resolution. 
     The processor device  508  may be communicatively coupled to the detector  506  and/or to the therapeutic radiation source  502 . The processor device  508  may be configured to receive the detected intensity from the detector  506 . Alternatively or additionally, the processor device  508  may be configured to calculate the temperature of the targeted area of the eye  100  based on the detected intensity, the quantum efficiency of the detector, and a blackbody spectrum. The blackbody spectrum may be associated with the target temperature threshold. Alternatively or additionally, the blackbody spectrum may include one or more of the blackbody spectra of  FIG. 3A , or one or more similar blackbody spectra at different temperatures than those of  FIG. 3A . 
     In an example embodiment, the processor device  508  may control the therapeutic radiation source  502  to emit discrete pulses of the therapeutic radiation  510  at a particular pulse frequency, pulse duration, and/or pulse energy. For instance, the therapeutic radiation source  502  may be controlled to emit a first discrete pulse with a first pulse energy and a second discrete pulse with a second pulse energy. The detector  506  may detect the intensity of the thermal radiation  512  emitted from the eye  100  after exposure of the eye  100  to each of the first and second discrete pulses. The processor device  508  may determine, based on the detected intensities, a first temperature of the eye  100  responsive to exposure to the first discrete pulse with the first pulse energy and a second temperature of the eye  100  responsive to exposure to the second discrete pulse with the second pulse energy. From the foregoing, the processor device  508  may then determine a third pulse energy for a third discrete pulse of the therapeutic radiation  510  that may cause the eye  100  to reach a third temperature, such as the target temperature threshold, and may control the therapeutic radiation source  502  to emit the third discrete pulse with the third pulse energy. 
     Alternatively or additionally, the beam splitter  504 B and/or another filter included in the optical elements  504  and in an optical path between the eye  100  and the detector  506  may be configured to block wavelengths associated with temperatures less than the target temperature threshold. For instance, referring to  FIG. 3A , if the target temperature threshold is in the range 350-355 K, such as 353 K, the filter may be configured to block relatively longer wavelengths associated with blackbody spectra at temperatures less than 353 K or other suitable target temperature threshold. In such embodiments, the therapeutic radiation  510  may be determined to be at or in excess of a target therapeutic radiation exposure level responsive to the detected intensity of the thermal radiation  512  being at or in excess of a detection threshold. 
       FIG. 5B  is a block diagram of another example laser-based ophthalmological surgical system (hereinafter “system”)  500 B, arranged in accordance with at least one embodiment described herein. The system  500 B may include or correspond to the system  400  of  FIG. 4 . The system  500 B may be similar in some respects to the system  500 A of  FIG. 5A  and may include the same or similar components. For instance, the system  500 B may include the therapeutic radiation source  502 , one or more optical elements  504 , a first detector  506 A, a second detector  506 B, and the processor device  508 . 
     The first and second detectors  506 A,  506 B may be the same or similar to the detector  506  of  FIG. 5A . Alternatively or additionally, the first detector  506 A may be configured to detect radiation, e.g., thermal radiation  512 , at a first wavelength while the second detector  506 B may be configured to detect radiation at a second wavelength different than the first wavelength. Additional aspects of the first and second detectors  506 A,  506 B according to at least one embodiment are described below. 
     The one or more optical elements  504  of  FIG. 5B  may include the lens  504 A and the beam splitter  504 B of  FIG. 5A  and may additionally include other components, such as a second beam splitter  504 C, a first bandpass filter  504 D, and a second bandpass filter  504 E. 
     The second beam splitter  504 C may generally be configured to split the thermal radiation  512  such that a first portion  512 A of the thermal radiation  512  may be directed toward the first detector  506 A and a second portion  512 B of the thermal radiation  512  may be directed toward the second detector  506 B. In this and other embodiments, the second beam splitter  504 C may include a 50/50 beam splitter or other suitable beam splitter. 
     Each of the first and second bandpass filters  504 D,  504 E may have a center wavelength and a bandwidth, where the center wavelengths of the first and second bandpass filters  504 D,  504 E may be different from each other. The bandwidths of the first and second bandpass filters  504 D,  504 E may be the same or different. In an example, each of the first and second bandpass filters  504 D,  504 E may have a 10 nm bandwidth. The center wavelengths of the first and second bandpass filters  504 D,  504 E may both be in a range from, e.g., 1 to 2 μm, but may be offset from each other, e.g., by 50 nm or more. For instance, the center wavelength of the first bandpass filter  504 D may be 1.15 μm (or 1150 nm), while the center wavelength of the second bandpass filter  504 E may be 1.10 μm (or 1100 nm). 
     The inclusion of the first and second bandpass filters  504 D,  504 E in the optical elements  504  may configure the first and second detectors  506 A,  506 B to detect different spectral components of the thermal radiation  512 . Such an arrangement may provide a more accurate determination of blackbody radiation and/or temperature of the eye  100  responsive to exposure to the therapeutic radiation  510 . For instance, the discrete pulses of therapeutic radiation  510  may be administered beginning at a relatively low pulse energy that increases from one discrete pulse to the next. Where the first bandpass filter  504 D has a higher center wavelength (e.g., 1.15 μm) than the second bandpass filter  504 E (e.g., 1.10 μm), the first detector  506 A may detect the thermal radiation  512  and output a corresponding signal before the second detector  506 B since the shorter wavelengths permitted by the second bandpass filter  504 E may be associated with higher temperatures resulting from higher pulse energies of the therapeutic radiation  510 . Accordingly, detection signals output by the first and second detectors  506 A,  506 B that each represents the intensity of a given wavelength band of the thermal radiation  512 , and/or the ratios of the intensities or other relationships therebetween may be used to determine the temperature of the eye  100 . 
     In the systems  500 A,  500 B (hereinafter “systems  500 ”), detector efficiency of each of the detectors  506 ,  506 A,  506 B may vary with wavelength, which may be corrected and/or calibrated for. Alternatively or additionally, there may be some IR absorption, e.g., absorption of at least some spectral components of the thermal radiation  512 , by parts of the eye  100  such as the aqueous humor which may be corrected and/or calibrated for. In some embodiments, IR absorption by parts of the eye  100  may be avoided, or at least reduced, by detecting predetermined wavelengths or wavelength ranges of the thermal radiation  512  that do not experience significant absorption by any parts of the eye  100 . 
     For any given discrete pulse of therapeutic radiation  510  that is absorbed by and causes the eye  100  to emit thermal radiation  512 , the detectors  506 ,  506 A, and/or  506 B may in some embodiments detect and/or compare relative intensities of the thermal radiation  512  at multiple different wavelengths to determine the temperature of the eye  100 .  FIG. 5B  illustrates one arrangement involving two detectors that can be implemented to detect multiple different wavelengths of the thermal radiation  512  emitted responsive to a single discrete pulse of the therapeutic radiation  510 , but other arrangements can alternatively or additionally be implemented. For instance, the system  500 A of  FIG. 5A  may be modified to include, e.g., a split signal path for the thermal radiation  512  with an optical delay line in one of two branches and a different bandpass filter in each of the two branches to allow a single detector such as the detector  506  to detect multiple different wavelengths of the thermal radiation  512  emitted responsive to a single discrete pulse of the therapeutic radiation  510 . 
     Alternatively or additionally, the detectors  506 ,  506 A, and/or  506 B of  FIGS. 5A and 5B  may each generate absolute measurements at a single wavelength or wavelength band, in which case quantum efficiency of the detectors  506 ,  506 A, and/or  506 B may be used together with the measurements to determine the temperature of the eye  100 . 
     Alternatively or additionally, thermal radiation  512  intensity may be determined as a ratio with therapeutic radiation  512  pulse energy and/or as a ratio with an initial reference temperature (e.g., initial body temperature and/or initial temperature of the eye  100 ). 
     Alternatively or additionally, black body radiation, e.g., the thermal radiation  512 , may be detected and/or measured as a relative reading. In one example, a baseline blackbody radiation level is measured prior to exposure to the therapeutic radiation  510 . Measurement of the baseline blackbody radiation level may be determined to correspond to a body temperature of 310.15 K (37 C). A change in the response of the detector  506 ,  506 A, and/or  506 B after exposure of the eye  100  to the therapeutic radiation  510  may provide a calibrated indication of the treated tissue temperature. 
     In a further example, a readout of the detector  506 ,  506 A, and/or  506 B may be synchronized to pulses of the therapeutic radiation  510 . In this case for each pulse of the therapeutic radiation  510  the detector  506 ,  506 A, and/or  506 B may provide a reading at a defined time delay corresponding to body temperature constants as well as the therapeutic and measurement system dynamics. The reference may be taken from the thermal radiation  512  prior to the first pulse of the therapeutic radiation  510 . The rise of temperature due to each pulse of the therapeutic radiation  510  may be monitored and the system  500 A and/or  500 B can stop after a pulse of the therapeutic radiation  510  has provided the required and/or desired temperature at the eye  100 . 
       FIG. 6  illustrates a flow diagram of an example method  600  to measure therapeutic radiation dosimetry, arranged in accordance with at least some embodiments described herein. The method  600  may be performed, in whole or in part, in the systems  400 ,  500  and/or in other systems and configurations. Alternatively or additionally, the method  600  may be implemented by a processor device, such as the processor device  508 , that performs or controls performance of one or more of the operations of the method  600 . For instance, a computer (such as the computing device  700  of  FIG. 7 ) or other processor device may be included in and/or communicatively coupled to the system  400 ,  500 A, or  500 B and may execute software or other computer-readable instructions accessible to the computer, e.g., stored on a non-transitory computer-readable medium accessible to the computer, to perform or control the system  400 ,  500 A, or  500 B to perform the method  600  of  FIG. 6 . 
     The method  600  may include one or more of blocks  602  and/or  604 . Although illustrated as discrete blocks, various blocks may be divided into additional blocks, supplemented with additional blocks, combined into fewer blocks, or eliminated, depending on the particular implementation. The method  600  may begin at block  602 . 
     In block  602  (“Illuminate A Targeted Area Of An Eye Of A Patient With Therapeutic Radiation”), a targeted area of an eye of a patient may be irradiated with therapeutic radiation. A temperature of the targeted area may depend on a dosage of the therapeutic radiation. Block  602  may be followed by block  604 . 
     In block  604  (“Measure Thermal Radiation Emitted By The Targeted Area Responsive To Exposure To The Therapeutic Radiation To Generate A Measurement Of The Thermal Radiation”), thermal radiation emitted by the targeted area responsive to exposure to the therapeutic radiation may be measured to generate a measurement of the thermal radiation. The measurement of the thermal radiation may be indicative of and/or may include the temperature of the targeted area and/or the dosage of the therapeutic radiation. 
     Measuring the thermal radiation to generate the measurement may include detecting an intensity of the thermal radiation to generate detected intensity. In these and other embodiments, the method  600  may further include calculating the temperature of the targeted area based on the detected intensity, a quantum efficiency of a detector that generates the detected intensity. Alternatively or additionally, the calculation of the temperature of the targeted area may be based on a blackbody spectrum associated with a target temperature or other temperature. 
     For this and other procedures and methods disclosed herein, the functions or operations performed in the processes and methods may be implemented in differing order. Furthermore, the outlined operations are only provided as examples, and some of the operations may be optional, combined into fewer operations, supplemented with other operations, or expanded into additional operations without detracting from the disclosed embodiments. 
     For instance, the method  600  may further include filtering an optical path between the targeted area and a detector system that measures the thermal radiation to block radiation with wavelengths associated with temperatures less than a target temperature threshold. In these and other embodiments, the method  600  may further include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the measurement of the thermal radiation meeting or exceeding the target temperature threshold. 
     In some embodiments, irradiating the targeted area with the therapeutic radiation in the method  600  may include irradiating the targeted area with discrete pulses of the therapeutic radiation, where the discrete pulses of therapeutic radiation have different amounts of pulse energy. In these and other embodiments, measuring the thermal radiation to generate the measurement may include measuring thermal radiation in a first spectral band associated with a first temperature lower than the target temperature threshold to generate a first measurement of the thermal radiation; and measuring thermal radiation in a second spectral band associated with the target temperature threshold to generate a second measurement of the thermal radiation. Alternatively or additionally, the method  600  may further include determining a current dosage of the therapeutic radiation based on the first measurement responsive to the first measurement exceeding a first threshold and the second measurement being below a second threshold that is lower than the first threshold; determining a target dosage of the therapeutic radiation based on at least one of the current dosage, the first measurement, and the second measurement; and controlling the therapeutic radiation source to emit a discrete pulse with an amount of pulse energy that corresponds to the target dosage. In some embodiments, the method  600  may further include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the therapeutic radiation source emitting the discrete pulse with the amount of pulse energy that corresponds to the target dosage. 
     Alternatively or additionally, the method  600  may further include synchronizing the measurement of the thermal radiation to the discrete pulses of therapeutic radiation. For instance, in the context of  FIGS. 5A and/or 5B , one or more of the detectors  506 ,  506 A, and/or  506 B may be synched to the discrete pulses of the therapeutic radiation  510  such that they detect the thermal radiation  512  during time periods that include a thermal response of the targeted area of the eye  100  to the discrete pulses of therapeutic radiation  510 . The time periods that include the thermal response may include time periods at which the targeted area of the eye  100  is irradiated with the discrete pulses. At other times, one or more of the detectors  506 ,  506 A, and/or  506 B may be turned off or otherwise operated to not detect the thermal radiation  512 . Such a detection scheme may reduce noise in the detection signal(s) generated by the detectors  506 ,  506 A, and/or  506 B. 
     In at least one embodiment of the method  600 , measuring the thermal radiation may include measuring the thermal radiation using a detector with a bandwidth greater than 10 megahertz (MHz) at sub microsecond temporal resolution. 
     Alternatively or additionally, the measurement of the thermal radiation may include one or more measurements of a temperature of the targeted area. Each of the one or more measurements may be associated with a corresponding discrete pulse of the discrete pulses of therapeutic radiation. Each of the one or more measurements may have a corresponding known amount of pulse energy. In these and other embodiments, the method  600  may further include determining a target dosage or target pulse energy of the therapeutic radiation based on the one or more measurements and the corresponding known amount of pulse energy; and controlling the therapeutic radiation source to emit a discrete pulse with an amount of pulse energy that corresponds to the target dosage. The target dosage or target pulse energy may be calculated or otherwise determined as a pulse energy of one of the discrete pulses of the therapeutic radiation effective to cause the targeted area of the eye to be heated to the target temperature threshold. The method  600  may further include terminating exposure of the eye of the patient to the therapeutic radiation responsive to the therapeutic radiation source emitting the discrete pulse with the amount of pulse energy that corresponds to the target dosage. 
       FIG. 7  illustrates a block diagram of an example computing device  700 , in accordance with at least one embodiment of the present disclosure. The computing device  700  may be used in some embodiments to perform or control performance of one or more of the methods and/or operations described herein. For instance, the computing device may be communicatively coupled to and/or included in the systems  400 ,  500  to perform or control performance of the method  600  of  FIG. 6  or other methods or processes described herein. In a basic configuration  702 , the computing device  700  typically includes one or more processors  704  and a system memory  706 . A memory bus  708  may be used for communicating between the processor  704  and the system memory  706 . 
     Depending on the desired configuration, the processor  704  may be of any type including, such as a microprocessor (μP), a microcontroller (μC), a digital signal processor (DSP), or any combination thereof. The processor  704  may include one or more levels of caching, such as a level one cache  710  and a level two cache  712 , a processor core  714 , and registers  716 . The processor core  714  may include an arithmetic logic unit (ALU), a floating point unit (FPU), a digital signal processing core (DSP Core), or any combination thereof. An example memory controller  718  may also be used with the processor  704 , or in some implementations, the memory controller  718  may be an internal part of the processor  704 . 
     Depending on the desired configuration, the system memory  706  may be of any type, such as volatile memory (such as RAM), non-volatile memory (such as ROM, flash memory, or the like), or any combination thereof. The system memory  706  may include an operating system  720 , one or more applications  722 , and program data  724 . The application  722  may include a dosimetry algorithm  726  that is arranged to measure therapeutic radiation dosimetry. The program data  724  may include dosimetry data  728  such as values included in or derived from detection signals generated as a measurement of detected thermal radiation and/or a graph, table, equation(s), or other information that relates thermal radiation intensities, wavelengths, and/or temperatures of black bodies. In some embodiments, the application  722  may be arranged to operate with the program data  724  on the operating system  720  to perform one or more of the methods and/or operations described herein, including those described with respect to  FIG. 6 . 
     The computing device  700  may include additional features or functionality, and additional interfaces to facilitate communications between the basic configuration  702  and any other devices and interfaces. For example, a bus/interface controller  730  may be used to facilitate communications between the basic configuration  702  and one or more data storage devices  732  via a storage interface bus  734 . The data storage devices  732  may include removable storage devices  736 , non-removable storage devices  738 , or a combination thereof. Examples of removable storage and non-removable storage devices include magnetic disk devices such as flexible disk drives and hard-disk drives (HDDs), optical disk drives such as compact disk (CD) drives or digital versatile disk (DVD) drives, solid state drives (SSDs), and tape drives to name a few. Example 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. 
     The system memory  706 , the removable storage devices  736 , and the non-removable storage devices  738  are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which may be used to store the desired information and which may be accessed by the computing device  700 . Any such computer storage media may be part of the computing device  700 . 
     The computing device  700  may also include an interface bus  740  for facilitating communication from various interface devices (e.g., output devices  742 , peripheral interfaces  744 , and communication devices  746 ) to the basic configuration  702  via the bus/interface controller  730 . The output devices  742  include a graphics processing unit  748  and an audio processing unit  750 , which may be configured to communicate to various external devices such as a display or speakers via one or more A/V ports  752 . The peripheral interfaces  744  include a serial interface controller  754  or a parallel interface controller  756 , which may be configured to communicate with external devices such as input devices (e.g., keyboard, mouse, pen, voice input device, touch input device, and/or others), sensors, or other peripheral devices (e.g., printer, scanner, and/or others) via one or more I/O ports  758 . The communication devices  746  include a network controller  760 , which may be arranged to facilitate communications with one or more other computing devices  762  over a network communication link via one or more communication ports  764 . 
     The network communication link may be one example of a communication media. Communication media may typically be embodied by computer-readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and may include any information delivery media. A “modulated data signal” may be a signal that includes one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media may include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency (RF), microwave, infrared (IR), and other wireless media. The term “computer-readable media” as used herein may include both storage media and communication media. 
     The computing device  700  may be implemented as a portion of a small-form factor portable (or mobile) electronic device such as a cell phone, a personal data assistant (PDA), a personal media player device, a wireless web-watch device, a personal headset device, an application-specific device, or a hybrid device that include any of the above functions. The computing device  700  may also be implemented as a personal computer including both laptop computer and non-laptop computer configurations. 
     The present disclosure is not to be limited in terms of the particular embodiments described herein, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, are possible from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of this disclosure. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. 
     The present disclosure is not to be limited in terms of the particular embodiments described herein, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, are possible from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of this disclosure. Also, the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. 
     With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
     In general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general, such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that include A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general, such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that include A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
     In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. 
     For any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible sub ranges and combinations of sub ranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, and/or others. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. All language such as “up to,” “at least,” and the like include the number recited and refer to ranges which can be subsequently broken down into sub ranges as discussed above. Finally, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth. 
     From the foregoing, various embodiments of the present disclosure have been described herein for purposes of illustration, and various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting.