THERMAL RADIATION SOURCE AND METHOD FOR MEASURING THE EXACT TEMPERATURE AND / OR RADIANT POWER OF THE THERMAL RADIATION SOURCE

Description

[0001] The invention relates to a thermal radiation source comprising the features according to claim 1.

[0002] The invention also comprises two methods for measuring the temperature of an exit window of the thermal radiation source according to the invention and the radiant power of emitted radiation from the thermal radiation source according to the invention through an exit window, each defined by the features of claims 17 and 18.

[0003] Thermal radiation sources are primarily used in analytical and measurement technology, for example, to detect the concentration of substances (gases, liquids, solids). Another major area of ​​application is medical technology for the treatment and alleviation of illnesses and injuries. In all applications, precise knowledge of the emitted radiation power or radiation dose of the thermal radiation source's radiation element is necessary to perform accurate, reproducible, and long-term stable measurements or defined treatments. The radiation power PS The effectiveness of a thermal radiation source depends essentially on its temperature. T from and is described by the Stefan-Boltzmann law: P S = σ ⋅ ε ⋅ A ⋅ T 4 with the Stefan-Boltzmann constant σ as well as the emission level ε and the area A the radiation source.

[0004] The wavelength λThe maximum temperature T, at which the maximum emission lies and which determines the spectral distribution, also depends on the temperature T of the radiation source and is described by Wien's displacement law: λ max = 2897 , 8 μm ⋅ K T .

[0005] Moreover, especially in medical and therapeutic applications, it is of great importance to know not only the radiation dose but also the temperature of the exit window, so that direct skin contact does not cause skin burns.

[0006] A thermal radiation source 1 essentially consists of an electrically operated radiation element 2, e.g. a heating conductor element, which is arranged in a housing 3, wherein the radiation of the radiation element is emitted from the housing 3 through an exit window 4 ( Fig. 1The radiation or heating element 2 is typically heated to a temperature > 500 °C to generate a broad emission spectrum in the infrared spectral range. For applications in the visible and near-infrared range, significantly higher temperatures of > 1000 °C are necessary. This means that the temperature is adjustable depending on the application and operating range to achieve a desired emission spectrum with the thermal radiation source.

[0007] Silicon-based MEMS devices with integrated temperature sensors are known from the prior art, e.g., from US 5,391,875 A, which allows the temperature of the silicon chip to be measured. This is described, for example, in US 8,859,303 B2 for a thermal infrared radiation source. The integrated temperature sensor measures the temperature of the radiation source, thus enabling temperature control. Based on the laws of radiation, the emitted radiation power is estimated and attempts are made to keep it constant. However, this does not allow for an exact determination of the actual radiation power emitted from the radiation source's housing, nor does it enable monitoring of aging of the radiation source. For example, the spatial radiation pattern of thermal radiation sources means that some of the emitted radiation remains trapped within the housing.Similarly, changes in emissivity, e.g. due to oxidation or aging, lead to a change in radiant power.

[0008] US Patent 2016 / 0361449 A1 discloses an electron beam sterilization device for sterilizing a packaging container by irradiation with electrons from an electron beam source. For reliable sterilization, a minimum electron energy or beam intensity of the electrons from the electron beam source must be ensured, with the emitted electrons generating temperatures in the range of 300°C to 400°C at the device's exit window. The emitted energy or beam intensity of the electrons from the electron beam source is determined by measuring the temperature inside the housing or at the device's exit window. A disadvantage is the complex construction of the exit window, consisting of copper fins and a metal foil spanning the copper fins, which is permeable to electrons but not to electromagnetic radiation.The thermocouples used for temperature measurement are arranged on copper fins or metal foil and covered with a material capable of generating heat when exposed to electrons. The temperature detected by the thermocouples is used to determine the intensity of the electrons emitted by the electron beam source; therefore, the thermocouples must be positioned within the electron beam. Due to the higher heat capacity of the thermocouples used compared to the heat capacity of the metal foil, which is only 4 to 12 µm thick, the temperature of the exit window cannot be measured directly. The radiation intensity of a thermal radiation source cannot be measured with the device described in US 2016 / 0361449 A1, as the thermal radiation would be reflected at the (metallic) exit window.

[0009] German patent application DE 198 07 453 A1 describes a device for generating thermal radiation for medical and therapeutic applications, such as the treatment of insect bites. In this device, a sliding protective sheath is used to maintain a safe distance, thus creating a burn on the skin. The radiation output or dose and / or the temperature of the contact surface, i.e., an exit window, are not measured. Optimal and precisely dosed treatment is not possible with this design. Furthermore, there is a risk of burns if the safety distance is incorrectly set. A similar, but miniaturized, heat transfer device for non-contact thermal treatment is disclosed in German patent application DE 10 2019 109 842 A1, but without the capability to determine the temperature at the exit window.

[0010] US2004133084 A1 discloses an infrared measuring device for the determination of analytes in tissues / liquids, both non-invasively (skin) and in vitro. The device comprises a window assembly made of CVD diamond, a heating layer with conductive traces as a heating element mounted thereon, and integrated resistance thermometers in the heating layer for precise temperature control of the window. Radiation detectors are positioned in the optical path behind the window.

[0011] In summary, to date no device for an integrated solution is known that enables the measurement of the radiation power or radiation dose emitted by a thermal radiation source and the measurement of the surface temperature of the exit window of a thermal radiation source.

[0012] It is therefore an object of the present invention to provide a means of measuring the emitted radiation power or radiation dose and the surface temperature of the exit window of a thermal radiation source.

[0013] The problem is solved by a thermal radiation source according to independent claim 1.

[0014] The thermal radiation source according to the invention comprises the features of claim 1. Further embodiments are defined by dependent claims 2-16.

[0015] A homogeneous exit window is understood to be an exit window which has a homogeneous thickness in the range of 200µm to 2mm and has a significantly higher heat capacity compared to a temperature sensor and radiation sensor used.

[0016] The advantage over previously known solutions lies particularly in the fact that the actual radiation power emitted from the housing of the radiation source or the temperature of the exit window is measured and can therefore be regulated and monitored.

[0017] This is achieved in particular by dividing the output window of the thermal radiation source according to the invention into three different functional areas: a transmission area, a contact area, and a measuring area. The transmission area defines the functional area of ​​the output window from which the radiation emitted by the radiation element of the thermal radiation source is radiated from the housing into the environment. The transmission area should preferably correspond to the size of the radiation element. The measuring area defines the functional area of ​​the output window within which the temperature sensor and the radiation sensor are arranged.The contact area defines the functional area of ​​the exit window where the temperature and radiation sensors make contact. The contact area is located at the edge of the exit window where it contacts the housing of the thermal radiation source. Looking at its cross-section from the inside out, the exit window comprises a transmission area, a subsequent measuring area, and a subsequent contact area. However, the transmission area and the measuring area can be separate and partially overlapping. Partially overlapping, as defined in the invention, means that the measuring area can also be located within the transmission area of ​​the exit window, for example.by arranging a temperature sensor and a radiation sensor in the center of the transmission area, which is contacted via narrow connecting tracks that lead through the transmission area to the contacting area.

[0018] According to the invention, the material of the exit window is sapphire, since sapphire is transparent over a wide wavelength range, very robust, chemically inert, and therefore biocompatible. Alternatively, other infrared-transmitting materials, such as silicon, germanium, calcium fluoride, barium fluoride, or zinc selenide, can also be used.

[0019] A platinum thin-film resistor is preferably used as the temperature and radiation sensor in the measuring area of ​​the exit window because it exhibits a nearly temperature-linear resistance curve, a wide temperature measuring range, and can be manufactured cost-effectively. However, any other type of temperature or radiation sensor can also be used, such as semiconductor sensors or thermocouples. For contacting the temperature and radiation sensors in the measuring area, indium tin oxide (ITO), as used, for example, as a transparent thin-film conductor in OLEDs, can be used. If ITO is used as the material for the conductors on the exit window, the measuring area can be positioned in the center (or at any spatial location) on the exit window, i.e., partially overlapping with the passband.Furthermore, if the temperature sensor and radiation sensor are transparent to radiation, then the measuring range and the transmission range can be identical in one variant.

[0020] By applying a temperature and radiation sensor to the emission window of a thermal radiation source, the quality and reliability of measurements, for example in materials analysis, can be improved. For the purposes of this invention, applying a temperature and radiation sensor within the measuring range of the emission window means that the sensor is applied directly to the surface of the emission window, for example using thin-film technology or stencil / screen printing, or is attached to or arranged on the emission window, for example by adhesive. This also allows for better monitoring of aging of the radiation source. In medical and therapeutic applications, the radiation dose can be measured precisely and adjusted to the treatment.Measuring the surface temperature of the outlet window helps prevent burns in applications involving skin contact, or even makes such applications feasible in the first place. This increases the reliability of medical devices and ensures optimal treatment. Furthermore, in analytical and metrological applications, such as gas analysis, temperature-dependent spectral shifts in the transmission properties of the outlet window, particularly at filter edges, can be determined, quantified, and corrected during measurement. This improves measurement accuracy and reliability.

[0021] The combination of the thermal radiation source according to the invention with a housing for surface mounting, a so-called SMD housing (Surface Mount Device housing), is particularly advantageous because it allows for a highly integrated component without external contacting, a very flat design and the possibility of fully automated manufacturing.

[0022] In one embodiment of the thermal radiation source according to the invention, the measuring range is comprised of the transmission area and the contact area. That is, the measuring range is delimited by the transmission area and the contact area. The temperature and radiation sensor(s) are arranged within the measuring range. This has the advantage that the temperature or the radiation power can be measured directly in the immediate vicinity of the transmission area of ​​the exit window, where the radiation passes through.

[0023] In another embodiment of the thermal radiation source according to the invention, the measuring range is congruent with the transmission range. This has the advantage that the temperature or the radiation power can be measured directly in the exit window, for example in the middle of the exit window, where the radiation passes through.

[0024] In a further embodiment of the thermal radiation source according to the invention, the output window has a rectangular, square, or round shape. A rectangular or square output window is particularly suitable for surface-mount devices (SMDs), but also for square through-hole mounting devices. A round output window is preferably used for round housings, such as TO packages.

[0025] In a preferred embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor is designed to be congruent with the measuring area of ​​the exit window. Congruent, in the context of the invention, means that the temperature and radiation sensor is advantageously designed to be circumferential or to have the same area as the measuring area of ​​the exit window, so that temperature and radiation power can be measured as precisely as possible; that is, the temperature and radiation power can be detected throughout the entire measuring area of ​​the exit window by means of the temperature and radiation sensor.

[0026] In another advantageous embodiment of the thermal radiation source according to the invention, more than one temperature and radiation sensor is arranged within the measuring range of the exit window. By arranging more than one temperature and radiation sensor, preferably a plurality of temperature and radiation sensors, it is possible to measure the temperature and radiation power with spatial resolution.

[0027] In another embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor located in the measuring area of ​​the exit window is arranged inside the housing, with an electrical wire connection of the temperature and radiation sensor also being formed inside the housing. An internal arrangement of the temperature and radiation sensor in the measuring area of ​​the exit window and its wire connection in the contact area has, among other advantages, that all components are well protected from external influences, e.g., damage.Although in this arrangement the temperature sensor does not directly measure the surface temperature of the outer side of the exit window facing a (measurement) object, and the radiation sensor does not directly detect the radiant power emitted by the thermal radiation source that passes through the exit window, both can be corrected in the system's signal processing by calibrating the system and by knowing the material properties, such as the transmission and thermal conductivity of the exit window.

[0028] In a further embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor located in the measuring area of ​​the exit window is arranged outside the housing, with an electrical wire connection of the temperature and radiation sensor also being formed outside the housing. In this arrangement, the radiation power emitted by the radiation source and passing through the exit window is advantageously detected directly, and the surface temperature of the side of the exit window facing a (measurement) object is also measured. The temperature and radiation sensor in the measuring area of ​​the exit window and its contact wires can be protected from external influences by applying an additional thin passivation and protective layer, e.g., made of glass.

[0029] In another embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor located in the measuring area of ​​the output window is arranged inside the housing, with an electrical wire connection of the temperature and radiation sensor being formed outside the housing. If, when arranging the temperature and radiation sensor in the measuring area of ​​the output window inside the housing, there is no space for contact wires or this is technologically incompatible, an external wire connection can be made such that the output window projects beyond the housing and the contact area also extends to the outside, so that the contact is located outside the housing.

[0030] In a particularly preferred embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor is contacted via contact surfaces mounted externally on the housing by soldering a metallic solder paste and / or by means of a conductive adhesive. This variant enables the realization of a highly integrated and long-term stable component for automated mass production, with the wireless contacting of the temperature and radiation sensor, e.g., by bonding with a conductive adhesive or soldering with a metallic solder paste, as well as a housing for surface mounting, being particularly advantageous. The electrical contacting of the temperature and radiation sensors is achieved via suitable contact surfaces on the housing for surface mounting.

[0031] In a further preferred embodiment of the thermal radiation source according to the invention, the temperature and radiation sensor located in the measuring area of ​​the exit window is arranged outside the housing. Electrical contact between the temperature and radiation sensor is made via contact surfaces on a mount connected to the thermal radiation source. The thermal radiation source is attached to a mount or installation device with solderable contact surfaces and electrically contacted in the contact area using solder paste or conductive adhesive. The mount can be, for example, a printed circuit board, another housing, or something similar. This has the advantage that the electrical contacts are protected from damage and other external environmental influences, and only the measuring area of ​​the exit window would need to be covered with a passivation and protective layer.

[0032] In another embodiment of the thermal radiation source according to the invention, a temperature and radiation sensor is arranged inside the housing in the measuring area of ​​the exit window, and a further temperature and radiation sensor is arranged outside the housing in the measuring area of ​​the exit window. The temperature and radiation sensors are electrically connected by means of a wire connection and / or via contact surfaces attached to the outside of the housing by soldering a metallic solder paste and / or by means of a conductive adhesive. The arrangement on both sides...Integrating temperature and radiation sensors into the emission window—specifically on the inward-facing surface of the window as well as on the outward-facing surface—offers the advantage of measuring temperature differences between the inside and outside of the window, thereby increasing measurement accuracy. Furthermore, this allows for the integration of numerous sensor elements on the emission window, enabling spatially resolved measurements of temperature and radiation power, for example.

[0033] In one embodiment of the thermal radiation source according to the invention, the exit window is made of silicon or germanium, and the temperature and radiation sensor is integrated within the measuring area of ​​the exit window. "Integrated" in this sense means that the temperature and radiation sensor is formed, i.e., integrated, in the plane of the exit window using semiconductor technology methods.

[0034] In a further preferred embodiment of the thermal radiation source according to the invention, the electrical radiation element is self-supporting, with a reflective layer preferably formed below the radiation element. Due to its self-supporting design, the radiation element exhibits very good thermal insulation. In combination with the very low thermal mass of the radiation element, which makes it easily modulated electrically, maximum efficiency can be achieved. The reflective layer serves to reflect the radiation emitted from the rear and direct it through the exit window.

[0035] The problem is also solved by a method according to independent claim 17.

[0036] The method according to the invention is defined by the features of claim 17.

[0037] In the first step, the temperature can be measured using the temperature sensor, which does not detect radiation (i.e., it "sees"). The radiation sensor detects the emitted radiation but can also simultaneously measure the temperature of the exit window. To determine the radiant power from the two sensor signals, which are acquired either by the temperature sensor and the radiation sensor or by the radiation sensor alone, calibration of the thermal radiation source, as described below, is mandatory. This calibration is performed once after the component is manufactured; therefore, it is not necessary before each measurement. The determination and evaluation of the radiant power is achieved through a mathematical combination of the acquired sensor signals. This mathematical combination can, for example, involve calculating the difference between the signals.

[0038] The problem is also solved by a method according to independent claim 18.

[0039] The method according to the invention is defined by the features of claim 18.

[0040] The calibration process includes, firstly, recording the sensor signals at defined temperature values ​​with the radiation element switched off, and secondly, an external, non-contact temperature measurement of the exit window with the radiation element switched on and defined power parameters. Additionally, an external measurement of the emitted radiation power can be performed at defined power parameters of the radiation element.

[0041] The thermal radiation source according to the invention is particularly intended for use in measuring instruments for material and spectral analysis as well as medical and therapeutic devices for the treatment of diseases and injuries, and is suitable and designed for this purpose.

[0042] The invention will now be explained in more detail using exemplary embodiments.

[0043] The accompanying drawings show Fig. 1 Basic structure of a thermal radiation source according to the prior art; Fig. 2 Preferred embodiments of the outlet window of the thermal radiation source according to the invention: (a) rectangular / square shape and (b) round shape; Fig. 3 Exemplary embodiments of the thermal radiation source according to the invention with a temperature sensor and radiation sensor mounted in the measuring area of ​​the outlet window: (a) internal arrangement of the temperature sensor and radiation sensor and their wire contacting, (b) external arrangement of the temperature sensor and radiation sensor and their wire contacting, and (c) internal arrangement of the temperature sensor and radiation sensor with external wire contacting of the temperature sensor and radiation sensor; Fig.4 Preferred embodiment of the thermal radiation source according to the invention with wireless contacting of the temperature sensor and radiation sensor via contact surfaces in a housing for surface mounting; Fig. 5 Embodiment of the thermal radiation source according to the invention with external arrangement of the temperature sensor and radiation sensor and contacting via contact surfaces formed on a holder; Fig. 6 Preferred embodiments of the thermal radiation source according to the invention with a temperature sensor and radiation sensor arranged on both sides inside and outside the housing in the measuring area of ​​the exit window: (a) With external wire contacting as well as contacting via contact surfaces on the housing; (b) With contacting via contact surfaces on the housing as well as contact surfaces formed on a holder that is connected to the thermal radiation source; Fig.7Preferred embodiment of the thermal radiation source according to the invention with a thin, self-supporting radiation element of the thermal radiation source.

[0044] Figure 2Figure 1 shows preferred embodiments of the output window 4 of the thermal radiation source 1 according to the invention. The output window 4 of the thermal radiation source 1 according to the invention is divided into three different functional areas. In one embodiment, the homogeneous output window 4, viewed from the inside out, has a transmission area 5, an adjoining measuring area 6, and a subsequent contacting area 7. The transmission area 5 identifies the functional area of ​​the output window 4 from which the radiation emitted by the radiation element 2 of the thermal radiation source 1 is radiated from the housing 3 into the surroundings. The transmission area 5 should preferably correspond to the size of the radiating surface of the radiation element.The measuring area 6 defines the functional area of ​​the outlet window 4, within which the temperature sensor and radiation sensor are mounted and / or integrated, wherein the measuring area 6 is configured between the passage area 5 and the contacting area 7. The contacting area 7 defines the functional area of ​​the outlet window 4 in which the temperature sensor and radiation sensor make contact, wherein the contacting area 7 is configured in the edge region of the outlet window 4, where the outlet window 4 is in contact with the housing 3 of the thermal radiation source 1. The outlet window 4 may have a rectangular or square shape, as shown in [reference]. Fig. 2(a) As shown, it is particularly suitable for surface-mount devices (SMD packages), but also for square through-hole mounting packages. A round exit window 4, as shown in Fig. 2(b)The device shown is preferably used in round housing shapes, such as TO packages. The temperature sensor and radiation sensor are positioned in the measuring area 6 on the exit window 4 such that a preferably round or rectangular passage area 5 is created in the center of the exit window 4 for the transmission of radiation. The temperature sensor and radiation sensor are contacted in the contact area 7, which is located at the edge of the exit window 4 where it contacts the housing 3. The temperature and / or radiation sensor is preferably arranged circumferentially within the measuring area 6 of the exit window 4, so that temperature and radiation power can be measured precisely. However, it is also possible to arrange a plurality of temperature sensors and radiation sensors in the measuring area 6 of the exit window 4 to achieve spatially resolved temperature or radiation power measurement.

[0045] In another embodiment, the temperature and radiation sensor, for example in the form of a platinum (Pt) resistor, is arranged in the center of the exit window. Electrical contact is made, for example, via ITO conductors that run from the Pt resistor to the contact area at the edge of the exit window. A Pt resistor can be made very small compared to the transmission area of ​​the exit window, so that it does not affect the emitted radiation of the radiation element. This allows the temperature or radiation power to be measured directly in the center of the exit window.

[0046] Figure 3Figure 1 shows possible embodiments of the thermal radiation source 1 according to the invention, with a temperature sensor and a radiation sensor mounted in the output window 4 in the measuring area 6 of the output window 4 and a wire contact 8 in the contact area 7 of the output window 4. An internal arrangement of the temperature sensor and radiation sensor in the measuring area 6 of the output window 4 and their wire contact 8 in the contact area 7 of the output window 4, as shown in Figure 1, is also shown. Fig. 3(a)As shown, this arrangement has the advantage that all components are well protected from external influences, such as damage. Due to the internal placement of the temperature sensor, it cannot directly measure the surface temperature of the outer side of the outlet window 4 facing a (measurement) object, and the radiation sensor cannot directly detect the radiant power emitted by the thermal radiation source 1. However, both of these limitations can be corrected in the system's signal processing by calibrating the system and by understanding the material properties, such as the transmission and thermal conductivity of the outlet window 4.

[0047] Alternatively, the temperature sensor and radiation sensor can be located in the measuring area 6 of the exit window 4 and their contact wires 8 in the contact area 7 outside the housing 3, as shown in Fig. 3(b)As shown. In this arrangement, the radiation power emitted by the thermal radiation source 1 is advantageously measured directly, as is the surface temperature of the side of the exit window 4 facing a (measurement) object. The temperature sensor and radiation sensor in the measuring area 6 of the exit window 4 and their contact wires 8 can be protected from external influences by applying an additional thin passivation and protective layer, e.g., made of glass.

[0048] If, in the case of an internal arrangement of the temperature sensor and radiation sensor in the measuring area 6 of the exit window 4 within the housing 3, there is no space for contact wires 8 or this is technologically incompatible, then external wire contact 8 can be provided such that the exit window 4 projects beyond the housing 3 and the contact area 7 also extends to the outside, as shown in Fig. 3(c) shown.

[0049] A particularly preferred embodiment of the thermal radiation source 1 according to the invention is in Figure 4 As shown, to realize a highly integrated and long-term stable component for automated high-volume production, wireless contacting of the temperature and radiation sensors, e.g., by bonding with a conductive adhesive or by soldering with a metallic solder paste, as well as a housing 3 for surface mounting, are advantageous. The electrical contacting of the temperature and radiation sensors is achieved via suitable contact surfaces 9 on the housing 3 for surface mounting.

[0050] Figure 5Figure 1 shows a further preferred embodiment of the thermal radiation source 1 according to the invention with wireless contacting of an external temperature sensor and radiation sensor located outside the housing 3 in the measuring area 6 of the output window 4. Here, the thermal radiation source 1 is attached to a holder 10 with solderable contact surfaces 9 and electrically contacted in the contact area 7 of the output window 4 by means of solder or conductive adhesive. The holder can be, for example, a printed circuit board, another housing, or something similar. This embodiment has the advantage that the electrical contacts are protected from damage and other external environmental influences, and only the measuring area 6 of the output window 4 needs to be covered with a passivation and protective layer.

[0051] Figure 6Figure 1 shows a further embodiment of the thermal radiation source 1 according to the invention with temperature sensors and radiation sensors arranged on both sides of or within the measuring area 6 of the exit window 4. The sensors can be contacted either wirelessly via contact surfaces 9 ( Fig. 6(b) ), by means of contact wires 8 or combined ( Fig. 6(a) This has the advantage that temperature differences between the inside and outside of the exit window 4 can be measured, thereby increasing, for example, the measurement accuracy. Furthermore, it makes it possible to accommodate a large number of sensor elements in the measuring area 6 of the exit window 4 in order to measure, for example, the temperature and the radiant power with spatial resolution.

[0052] Figure 7Figure 1 shows a further preferred embodiment of the thermal radiation source 1 according to the invention, wherein the radiation element or heating element 2 has a very low thermal mass so that it can be easily electrically modulated, and has very good thermal insulation due to a self-supporting structure so that maximum efficiency is achieved.

[0053] The temperature sensor and radiation sensor can be used to measure the actual temperature of the outlet window. A platinum measuring resistor in thin-film technology is preferably used as both the temperature and radiation sensor. Since both sensors, the temperature sensor and the radiation sensor, are applied to and / or integrated within the measuring area of ​​the outlet window, the temperature of the outlet window can be measured with either sensor.

[0054] According to the invention, two method variants are available for determining the emitted radiation power.

[0055] In one method variant, a temperature sensor and a radiation sensor are used to determine the radiant power. The temperature sensor is designed with a mirrored surface, for example, by applying a thin metal layer. This has the advantage that the radiation incident on the temperature sensor is reflected and not detected by the sensor, so that the sensor only measures the temperature of the exit window. If the temperature sensor is designed as a platinum measuring resistor, the platinum acts as a mirror layer and fulfills this purpose. Sometimes it is advantageous to protect the temperature sensor with a passivation and protective layer, in which case a reflective layer must be applied on top of the passivation and protective layer, as the passivation and protective layer might otherwise absorb the radiation. The temperature sensor provides an initial sensor signal.The radiation sensor, which may also be made of platinum, is designed to be highly absorbent, for example, by applying an absorption layer. The radiation sensor detects the emitted radiation from the thermal radiation element, generating a second sensor signal. A mathematical relationship, such as a difference, is established between the two detected sensor signals, which ultimately serves as a measure of the emitted radiation power of the thermal radiation source. Using the initial calibration described above, a correlation is established between the (uncalibrated) measured temperature and the actual (true) temperature of the exit window or the emitted radiation power. This correlation is then stored in the signal processing system and corrected to enable precise control.

[0056] In a second method variant, a temperature sensor or a radiation sensor is used to determine the radiant power. Electrical modulation of the radiation element, which causes a change in radiation over time, leads to a corresponding temperature change in the absorbing radiation sensor or the temperature sensor. Both can be provided with a passivation and protective layer. This temperature change is detectable, and thus the radiant power can be determined after calibration. This method variant requires only one sensor element, either a temperature sensor or a radiation sensor, enabling the simultaneous measurement of the temperature of the exit window and the radiant power. This second method variant is advantageous in terms of its simple and cost-effective design. However, this second method variant requires system calibration. Reference symbol list

[0057] 1 Thermal radiation source 2 Radiating element or heating element / heating element chip 3 Housing of the radiation source 4 Emission window 5 Passage area of ​​the emission window 6 Measuring area of ​​the emission window in which the temperature sensor and radiation sensor are located 7 Contacting area of ​​the emission window 8 Wire contact / contact wires 9 Contact surface for soldering and / or gluing, wireless contacting 10 Mounting bracket for thermal radiation source

Claims

1. Thermal radiation source (1) comprising a housing (3), an electrically operated radiation element (2) arranged in the housing (3), and a homogeneous exit window (4) designed for skin contact, through which electromagnetic radiation emitted by the radiation element (2) is radiated from the housing (3), wherein the exit window is spaced apart from the radiation element, wherein the exit window (4) has a transmission region (5), a contact region (7), and a measuring region (6), wherein the measuring region (6) and the transmission region (5) are separate from one another or partially overlap, wherein a temperature sensor and a radiation sensor are arranged inside the measuring region (6) of the exit window (4), the temperature sensor is designed to generate a first signal for measuring a temperature of the exit window, and the radiation sensor is designed to generate a second signal for measuring the radiated radiant power of the radiation element, wherein the temperature sensor and the radiation sensor are electrically contacted via the contact region (7), wherein the exit window (4) is made of one of the materials sapphire or calcium fluoride or barium fluoride or zinc selenide or silicon or germanium.

2. Thermal radiation source (1) according to claim 1, characterized in that the measuring region (6) is bordered by the transmission region (4) and the contact region (7).

3. Thermal radiation source (1) according to claim 1, characterized in that the measuring region (6) is congruent with the transmission region (5).

4. Thermal radiation source (1) according to any of claims 1 to 3, characterized in that the exit window (4) is a rectangular, square or round shape having a thickness in the range from preferably 200 µm to 2 mm.

5. Thermal radiation source (1) according to either claim 1 or claim 2, characterized in that the temperature sensor and the radiation sensor are congruent with the measuring region (6) of the exit window (4).

6. Thermal radiation source (1) according to any of the preceding claims, characterized in that more than one temperature sensor and more than one radiation sensor are arranged inside the measuring region (6) of the exit window (4).

7. Thermal radiation source (1) according to any of the preceding claims, characterized in that the temperature sensor and the radiation sensor are platinum resistors.

8. Thermal radiation source (1) according to claim 7, characterized in that the temperature sensor has a reflective layer and the radiation sensor has an absorbing layer and / or the temperature sensor and the radiation sensor have a protecting and passivating layer.

9. Thermal radiation source (1) according to claim 1, characterized in that the temperature sensors and radiation sensors attached in the measuring region (6) of the exit window (4) are arranged inside the housing (3), an electrical wire contact (8) of the temperature sensor and of the radiation sensor also being formed inside the housing (3).

10. Thermal radiation source (1) according to claim 1, characterized in that the temperature sensors and radiation sensors attached in the measuring region (6) of the exit window (4) are arranged outside the housing (3), an electrical wire contact (9) of the temperature sensor and of the radiation sensor also being formed outside the housing (4).

11. Thermal radiation source (1) according to claim 1, characterized in that the temperature sensors and radiation sensors attached in the measuring region (6) of the exit window (4) are arranged inside the housing (3), an electrical wire contact (9) of the temperature and radiation sensor being formed outside the housing (3).

12. Thermal radiation source (1) according to claim 1, characterized in that a contact of the temperature sensor and of the radiation sensor is formed using contact surfaces (9) attached to the housing on the inside or outside, by means of soldering a metal soldering paste and / or by means of conductive adhesive.

13. Thermal radiation source (1) according to claim 1, characterized in that the temperature sensors and radiation sensors attached in the measuring region (6) of the exit window (4) are arranged outside the housing (3), whereas an electrical contact of the temperature sensor and of the radiation sensor being formed using contact surfaces (9) is formed on a support (10) which is connected to the thermal radiation source (1).

14. Thermal radiation source (1) according to claim 1, characterized in that the temperature sensor and the radiation sensor are attached inside the housing (3) in the measuring region (6) of the exit window (4), and a further temperature sensor and a further radiation sensor are attached outside the housing (3) in the measuring region (6) of the exit window (4), an electrical contact of the temperature sensors and of the radiation sensors being formed by means of a wire contact (8) and / or using contact surfaces (9) attached to the housing (3) on the outside, by means of soldering a metal soldering paste and / or by means of conductive adhesive.

15. Thermal radiation source (1) according to any of claims 1 to 6 or 9 to 14, characterized in that the exit window (4) is made of silicon or germanium, the temperature sensor and the radiation sensor being integrated in the measuring region (6) of the exit window (4).

16. Thermal radiation source (1) according to any of the preceding claims, characterized in that the electrical radiation element (2) is self-supporting, a reflective layer being formed below the radiation element (4).

17. Method for measuring the temperature of an exit window (4) of a thermal radiation source (1) and for measuring the radiant power of radiation emitted by the thermal radiation source (1) through the homogeneous exit window (4), wherein the thermal radiation source (1) according to any of claims 1 to 14 or 16 is used, wherein the method comprises the method steps of: - measuring the temperature of the exit window (4) by means of the temperature sensor, which is attached in the measuring region (6) of the exit window (4), wherein the first sensor signal is generated; - detecting the emitted radiation of the radiation element (2) which is absorbed by the radiation sensor, which is attached in a measuring region (6) of the exit window (4), wherein a second sensor signal is generated; - evaluating the sensor signals by forming a mathematical operation from the first sensor signal of the temperature sensor and the second sensor signal of the radiation sensor using a calibration, wherein the mathematical operation indicates the radiant power.

18. Method for measuring the temperature of an exit window (4) of a thermal radiation source (1) by means of a temperature sensor, and for measuring the radiant power of radiation, emitted by the thermal radiation source (1) through the exit window (4), by means of the radiation sensor, wherein the thermal radiation source (1) according to any of claims 1 to 14 or 16 is used, wherein either the temperature sensor or the radiation sensor is used as a sensor element, and a radiation change over time is generated by means of an electrical modulation of the radiation element (2) of the thermal radiation source (1), which change causes a temperature change over time in the sensor element used, and wherein the radiant power is ascertained therefrom by means of a calibration.