DE102023106003A1 - Device and method for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation - Google Patents

Abstract

Device (1) for determining a temperature and a spectral emissivity of a surface (100) irradiated with solar radiation, with an infrared camera (2) and with a first bandpass filter (4) and a second bandpass filter (5), the first bandpass filter (4) is centered on a first wavelength range of atmospheric absorption bands for solar radiation and the second bandpass filter (5) is centered on a second wavelength range of atmospheric absorption bands for solar radiation, wherein the first wavelength range differs from the second wavelength range, wherein the infrared camera (2) has a spectral sensitivity that the first and the second wavelength range, wherein the infrared camera (2) receives a first measurement signal via the measurement channel formed with the first bandpass filter (4) and receives a second measurement signal via the measurement channel formed with the second bandpass filter (5) and a calculation device via a Ratio of the measurement signals determines the temperature and the spectral emissivity of the irradiated surface (100).

Description

The present invention relates to a device for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation and a corresponding method.

The recording of temperature and emissivity plays an important role in process monitoring, especially in solar thermal applications. For example, in solar thermal tower power plants, solar radiation is concentrated via a heliostat field onto a thermal receiver that is arranged on a tower. The receiver converts the concentrated direct radiation into heat and couples it into a thermodynamic cycle. In order to ensure optimal operation of such a solar thermal tower power plant, monitoring the temperature and emissivity of the receiver surface is important.

Surface temperature monitoring can be done using multiple high-resolution long-wave infrared (LWIR) cameras.

By measuring the temperature in real time, it is possible to regulate the heliostat field and thus ensure safe operation of the thermal receiver. This avoids local hotspots, places where locally elevated temperatures occur that lead to damage to the receiver, and increases the service life of the receiver and the durability of the receiver coating.

The accuracy of temperature measurement with an LWIR camera is influenced, for example, by the local emissivity of the receiver coating, the atmospheric transmittance between the receiver and camera and by the temperature of the LWIR camera and the temperature of the protective housing. In order to carry out the most accurate temperature measurement possible, these influencing factors must be corrected in a complex manner, for example through model-based simulations or through additional reference measurements on a heated reference surface.

When calibrating the camera, it can only be carried out in certain time windows, for example in a short time window after solar operation and therefore comparatively rarely. Possible deviations in emissivity during power plant operation (aging or overheating of the receiver coating) are difficult to take into account in real time for accurate temperature measurement.

The long-wave infrared cameras used so far are also comparatively cost-intensive.

The optical properties, such as the emissivity of a receiver coating, can also be determined at ambient temperature by placing a sensor head at the respective measuring point. This measuring method is only possible during maintenance on a power plant and is also very complex because the sensor head has to be moved to different locations on the receiver, which is usually located at a great height.

The methods described above represent a general level of knowledge of the applicant, which, however, does not necessarily relate to a specific state of the art.

It is the object of the present invention to provide a device and a method for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation, with which the temperature and a spectral emissivity can be determined in a simplified and more cost-effective manner.

The device according to the invention is defined by the features of claim 1. The method according to the invention is defined by the features of claim 13.

The device according to the invention for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation has an infrared camera and a first bandpass filter and a second bandpass filter, the first bandpass filter being centered on a first wavelength range of atmospheric absorption bands for solar radiation and the second bandpass filter being centered on a second wavelength range of atmospheric absorption bands for solar radiation is centered, wherein the first wavelength range differs from the second wavelength range, wherein the infrared camera has a spectral sensitivity that includes the first and second wavelength ranges of the first bandpass filter and the second bandpass filter, wherein the infrared camera transmits a first measurement signal receives the measurement channel formed with the first bandpass filter and receives a second measurement signal via the measurement channel formed with the second bandpass filter and a calculation device determines the temperature and a spectral emissivity via a ratio of the measurement signals.

The use of bandpass filters basically eliminates radiation that falls outside the wavelength range that is characteristic of the bandpass filter rich, not transmitted through the filter. By using two bandpass filters, each of which is centered on a wavelength range of atmospheric absorption bands for solar radiation, little intensity of solar radiation or intensity of unwanted scattered radiation reaches the infrared camera in a particularly advantageous manner. Due to the bandpass filter, the infrared camera is solar blind. A measurement signal of the emitted radiation of the irradiated surface is thus generated, which is only slightly influenced by the reflecting solar radiation. The radiation reflected from the irradiated surface is only registered to a negligible extent by the infrared camera due to the solar-blind bandpass filters.

• - von einem spektralen Emissionsgrad ε (λ) der mit der Solarstrahlung bestrahlten Fläche,
• - von einem spektralen Transmissionsgrad τ(λ) der Atmosphäre, die natürlicherweise zwischen der Infrarotkamera und bestrahlten Fläche vorhanden ist und
• - von einer spektralen Bestrahlungsstärke E (λ, T) der bestrahlten Fläche bei einer Temperatur T.

The ratio of the measurement signals that the calculation device determines basically depends on three parameters:

• - a spectral emissivity ε (λ) of the surface irradiated with solar radiation,
• - from a spectral transmittance τ(λ) of the atmosphere that is naturally present between the infrared camera and the irradiated surface and
• - from a spectral irradiance E (λ, T) of the irradiated surface at a temperature T.

It can be ideally assumed that the irradiated surface and the atmosphere have the radiation behavior of a gray body. A gray body in the sense of radiation physics is a body in which the emissivity, reflectance or transmittance is independent of the wavelength in a spectral range.

$$\mathrm{\tau }\left({\mathrm{\lambda }}_1\right)=\mathrm{\tau }\left({\mathrm{\lambda }}_2\right).$$

Assuming that the irradiated surface and the atmosphere emit radiation like a gray body, the spectral emissivity ε at a first and a second wavelength (characteristic wavelength ranges of the first and second band filters) of an atmospheric absorption band (λ _x ) is (approximately ) even. The spectral transmittance τ is also (approximately) the same at a first and a second wavelength of an atmospheric absorption band: $$\mathrm{\epsilon }\left({\mathrm{\lambda }}_1\right)=\mathrm{\epsilon }\left({\mathrm{\lambda }}_2\right)$$

$$\mathrm{\tau }\left({\mathrm{\lambda }}_1\right)=\mathrm{\tau }\left({\mathrm{\lambda }}_2\right).$$

aus dem gemessenen Messsignalverhältnis heraus (k=1), sodass zunächst die Temperatur T der bestrahlten Fläche ermittelt werden kann. Für die Ermittlung der Temperatur T wurde die Infrarotkamera zuvor, beispielsweise im Labor, mit einem Schwarzkörper mit bekannter Temperatur für jedes atmosphärische Absorptionsband radiometrisch kalibriert. Dadurch kann Korrelation des Messsignalverhältnis mit der Temperatur T abgeleitet werden.Under this assumption the ratio is reduced $$\frac{\mathrm{\epsilon \tau }\left({\mathrm{\lambda }}_1\right)}{\mathrm{\epsilon \tau }\left({\mathrm{\lambda }}_2\right)}=\frac{\mathrm{\epsilon }\left({\mathrm{\lambda }}_1\right)}{\mathrm{\epsilon }\left({\mathrm{\lambda }}_2\right)}\cdot \frac{\mathrm{\tau }\left({\mathrm{\lambda }}_1\right)}{\mathrm{\tau }\left({\mathrm{\lambda }}_2\right)}=\text{k}$$

from the measured signal ratio (k=1), so that the temperature T of the irradiated surface can first be determined. To determine the temperature T, the infrared camera was previously radiometrically calibrated, for example in the laboratory, with a black body with a known temperature for each atmospheric absorption band. This allows the correlation of the measurement signal ratio with the temperature T to be derived.

sowie $$\mathrm{\epsilon \tau }\left({\mathrm{\lambda }}_2\right)=\frac{{\text{S}}_{\text{meas}}\left({\mathrm{\lambda }}_2\right)\left(\text{T}\right)}{{\text{S}}_{\text{calc}}\left({\mathrm{\lambda }}_2\right)\left(T\right)}$$

With the now known temperature T of the irradiated surface, the spectral emissivity ε of the irradiated surface is determined in a further step. For this purpose, further ratios are formed from the signals S _meas (T) (0 < ε _T <1) measured with the bandpass filters and an expected signal S _calc (T) of a black body (ε _T = 1) at the temperature T. The expected signal S _calc can be derived by calibrating the infrared camera and has the information of the previously determined temperature T as well as the spectral emissivity of a black body ε = 1, so that the following relationships are formed: $$\mathrm{\epsilon \tau }\left({\mathrm{\lambda }}_1\right)=\frac{{\text{S}}_{\text{meas}}\left({\mathrm{\lambda }}_1\right)\left(\text{T}\right)}{{\text{S}}_{\text{calc}}\left({\mathrm{\lambda }}_1\right)\left(T\right)}$$

as well as $$\mathrm{\epsilon \tau }\left({\mathrm{\lambda }}_2\right)=\frac{{\text{S}}_{\text{meas}}\left({\mathrm{\lambda }}_2\right)\left(\text{T}\right)}{{\text{S}}_{\text{calc}}\left({\mathrm{\lambda }}_2\right)\left(T\right)}$$

The product ε _T and thus the spectral emissivity ε for the characteristic wavelength ranges of the first and second band filters are then determined from the respective conditions. Assuming that the irradiated surface and the atmosphere have the radiation behavior of a gray body, the spectral emissivities ε of both wavelengths of atmospheric absorption bands agree.

The measurement signal generated is therefore advantageously suitable for calculating a measurement signal ratio, via which the temperature and the spectral emissivity of the irradiated surface can be determined.

During the measurement or calculation, a compensation factor can be provided in order to be able to correct an inaccuracy of the gray radiator hypothesis for the atmospheric column. This compensation factor k can either be calculated based on humidity data and a spectral model or measured empirically.

An infrared camera designed for the extended short-wave infrared range can be used as an infrared camera, preferably an e-SWIR camera. This is able to advantageously capture a broad short-wave spectrum of wavelengths that extends into the medium-wave range and is comparatively inexpensive.

The first wavelength range and the second wavelength range are centered on a wavelength range of atmospheric absorption bands. The first wavelength range should be centered on a range between 1.3 µm and 1.5 µm and the second wavelength range on a range between 1.8 µm and 2.0 µm. Preferably, the first wavelength range is centered at 1.38 µm and the second wavelength range is centered at 1.87 µm. For example, atmospheric absorption bands due to water molecules that occur naturally in the atmosphere are 1.4 µm and 1.9 µm. In these wavelength ranges, the atmosphere only transmits solar radiation to a very small extent, since the water molecules in the atmosphere absorb the solar radiation in these ranges. Consequently, by using bandpass filters with a first wavelength range centered at 1.4 µm and a second wavelength range centered at 1.9 µm, only a very small intensity portion of the radiation is transmitted to the infrared camera.

The atmospheric transmittance in the first and second wavelength ranges is preferably below 0.1%.

One embodiment of the invention provides that a Fabry-Perot interferometer is arranged on the infrared camera to provide the first bandpass filter and second bandpass filter. The Fabry-Perot interferometer acts as an optical filter and filters out the desired narrow-band spectra from broadband radiation.

The first bandpass filter and the second bandpass filter can also be formed by a dual filter. By using such a dual filter, radiation from two wavelength ranges of atmospheric absorption bands can be detected in a particularly simple manner.

The device according to the invention can have two further optical bandpass filters, each of which is centered on a wavelength range which is signal-independent with respect to an atmosphere, the wavelength ranges of the two further optical bandpass filters differing from one another and from the first and second wavelength ranges, wherein the infrared camera has a spectral sensitivity which includes the wavelength ranges of the two further optical bandpass filters, wherein the infrared camera receives further measurement signals via two further measurement channels formed with the two further optical bandpass filters and the calculation device determines information about an atmospheric transmittance via a ratio of the further measurement signals and The first and second measurement signals are corrected using the atmospheric transmittance. In principle, further ratios of the measurement signals can also be formed, for example also ratios of the further measurement signals with the first and second measurement signals.

To determine the atmospheric transmittance, the device according to the invention can be calibrated beforehand, for example under similar atmospheric conditions using a hot, unirradiated reference surface.

The wavelength ranges of the two further optical bandpass filters can each be centered on a range between 1.5 µm and 2.2 µm, with one wavelength range of the further optical bandpass filters preferably being on the so-called H-band (1.65 µm) and the other wavelength range Another optical bandpass filter is centered on the so-called K-band (2.2 µm). Such bandpass filters have proven to be particularly advantageous for common atmospheres.

The first bandpass filter, the second bandpass filter and/or the further bandpass filters can be formed by a multizone filter. The first bandpass filter, the second bandpass filter and/or the further bandpass filters can also be formed by a filter wheel.

For example, at least the first bandpass filter and the second bandpass filter are arranged on the filter wheel or the multizone filter. The filter wheel or the multi-zone filter allows a change between the first and second bandpass filters to be carried out in a particularly simple and very quick manner. The first measurement signal of the area is thus recorded using the first bandpass filter. Then you switch to the second bandpass filter by turning the filter wheel or actuating the multizone filter. The second measurement signal of the area is recorded using the second bandpass filter. This means that there are only very short time intervals between the individual measurement signal recordings and the measurement signals are recorded quasi-synchronously.

The filter wheel can be motorized to enable the bandpass filters to be changed in a particularly simple and quick manner and automatically.

The infrared camera can also have an infrared lens. This means that, for example, when the device according to the invention is arranged on the ground, measurement signals can also be advantageously recorded from a receiver on a solar tower several hundred meters away. The focal length of the lens can be adapted to the distance between the infrared camera and the surface irradiated with solar radiation.

The calculation device can evaluate the ratio of the first and second measurement signals pixel by pixel and thereby determine the temperature and/or the emissivity in a spatially resolved manner. Accordingly, the transmittance used for a correction can also be determined in a spatially resolved manner.

The infrared camera and first bandpass filter and the second bandpass filter can in particular be arranged on a flying object. Of course, the additional band filters and the lens can also be arranged on the flying object. For example, the infrared camera is comparatively compact as an e-SWIR camera with, for example, a filter wheel or a multi-zone filter and, for example, a lens, and can advantageously be transported by a flying object, for example a drone. Such an embodiment of the invention enables temperature and emissivity measurement of a surface in a particularly advantageous manner. For example, the drone with the infrared camera can circle around a receiver that is mounted on a solar tower and thus capture measurement signals in a particularly simple manner that would otherwise only be possible to capture with great effort.

1. a) Ausrichten einer Infrarotkamera auf die bestrahlte Fläche,
2. b) Aufnehmen eines ersten Messsignals über einen ersten Messkanal , in dem ein erster Bandpassfilter angeordnet ist, der auf einen ersten Wellenlängenbereich atmosphärischer Absorptionsbänder für Solarstrahlung zentriert ist, und eines zweiten Messsignals über einen zweiten Messkanal, in dem ein zweiter Bandpassfilter angeordnet ist, der auf einen zweiten Wellenlängenbereich atmosphärischer Absorptionsbänder für Solarstrahlung zentriert ist,
3. c) Bilden eines Verhältnisses des ersten und zweiten Messsignals und ermitteln der Temperatur und des spektralen Emissionsgrads der mit Solarstrahlung bestrahlten Fläche aus dem Verhältnis.

The invention further relates to a method for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation with the following steps:

1. a) aligning an infrared camera with the irradiated surface,
2. b) recording a first measurement signal via a first measurement channel, in which a first bandpass filter is arranged, which is centered on a first wavelength range of atmospheric absorption bands for solar radiation, and a second measurement signal via a second measurement channel, in which a second bandpass filter is arranged, which is on a second wavelength range of atmospheric absorption bands for solar radiation is centered,
3. c) forming a ratio of the first and second measurement signals and determining the temperature and the spectral emissivity of the surface irradiated with solar radiation from the ratio.

The advantages described with regard to the device according to the invention, which can also be used in the method according to the invention, fundamentally also apply accordingly to the method according to the invention. In the method according to the invention, a measurement signal of the emitted radiation of the irradiated surface can be generated, which is only slightly influenced by the direct, scattered or reflective solar radiation. The radiation reflected from the irradiated surface is only registered to a negligible extent by the infrared camera due to the solar-blind bandpass filters. The measurement signal generated is therefore advantageously suitable for calculating a measurement signal ratio, via which the temperature and the spectral emissivity of the irradiated surface can be determined.

• aa) Aufnehmen von zwei weiteren Messignalen mittels zwei weiterer optischer Bandpassfilter, die jeweils auf einen Wellenlängenbereich zentriert sind, der in Bezug auf eine Atmosphäre signal-unabhängig ist, wobei sich die Wellenlängenbereiche der zwei weiteren optischen Bandpassfilter voneinander und von dem ersten und zweiten Wellenlängenbereich unterscheiden, wobei über ein Verhältnis der weiteren Messignale Informationen über einen atmosphärischen Transmissionsgrad ermittelt werden, und wobei mittels des atmosphärischen Transmissionsgrads das erste und das zweite Messsignal vor dem Bilden des Verhältnisses in Schritt
• c) korrigiert werden.

In a particularly preferred exemplary embodiment of the method, the following step is also provided:

• aa) Recording two further measurement signals using two further optical bandpass filters, each of which is centered on a wavelength range that is signal-independent with respect to an atmosphere, the wavelength ranges of the two further optical bandpass filters differing from one another and from the first and second wavelength ranges , wherein information about an atmospheric transmittance is determined via a ratio of the further measurement signals, and the first and second measurement signals are determined by means of the atmospheric transmittance before forming the ratio in step
• c) be corrected.

The wavelength ranges of the two further optical bandpass filters can each be centered on a range between 1.5 µm and 2.2 µm, with one wavelength range of the further optical bandpass filters preferably at 1.65 µm and the other wavelength range of the further optical bandpass filters at 2.2 µm is centered.

In principle, it can also be provided that an atmospheric transmittance is determined by meteorological data, in particular ambient temperature and/or humidity, and/or by measurement and/or by simulation, using the atmospheric transmittance sion level, the first and second measurement signals are corrected before forming the ratio in step c).

In the method according to the invention, the first wavelength range of the first band filter can be centered on a range between 1.3 µm and 1.5 µm and the second wavelength range of the second band filter can be centered on a range between 1.8 µm and 2.0 µm, the first Wavelength range is preferably centered at 1.38 μm and the second wavelength range is preferably centered at 1.87 μm.

In a preferred embodiment of the method according to the invention, the ratio of the first and second measurement signals can be evaluated pixel by pixel and the temperature and/or the emissivity can be determined in a spatially resolved manner.

It can be provided that the infrared camera is moved by means of a flying object, with the infrared camera being brought to a predetermined maximum distance from the irradiated surface in step (a). By using a flying object, the infrared camera can be brought particularly close to the irradiated area, for example to a receiver specifically designed for a solar power plant, whereby the influence of atmospheric transmittance can be reduced. By means of the flying object, the infrared camera can be moved, for example, along a predetermined route, with at least step b) being carried out repeatedly or at least steps b) and c) being carried out repeatedly. In other words, a type of scanning of the irradiated area can be carried out. In this way, for example, in a receiver that extends over a large angular range, for example 360 ° around a solar tower, the temperature and the spectral emissivity can advantageously be determined in a spatially resolved manner.

• 1 eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zur Ermittlung einer Temperatur und eines spektralen Emissionsgrads einer mit Solarstrahlung bestrahlten Fläche,
• 2 eine schematische Darstellung eines Solarkraftwerks, bei dem erfindungsgemäßen Vorrichtung verwendet wird.

The invention is explained in more detail below with reference to the following figures. Show it:

• 1 a schematic representation of a device according to the invention for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation,
• 2 a schematic representation of a solar power plant in which the device according to the invention is used.

In 1 a device 1 according to the invention for determining a temperature and a spectral emissivity of a surface 100 irradiated with solar radiation is shown schematically. The device 1 has an infrared camera 2 with a lens 3. Radiation is recorded from a surface 100 irradiated with solar radiation using the infrared camera 2.

A first bandpass filter 4 and a second bandpass filter 5 are arranged on the infrared camera 2. The first and second bandpass filters 4, 5 are formed by a dual filter, with the radiation to be received being filtered either through the first bandpass filter 4 or the second bandpass filter 5 by moving the dual filter.

The first bandpass filter 4 is centered on a first wavelength range of atmospheric absorption bands for solar radiation and the second bandpass filter 5 is centered on radiation in a second wavelength range of atmospheric absorption bands for solar radiation, the first wavelength range being different from the second wavelength range. The infrared camera 2, which can be an e-SWIR camera, for example, has a spectral sensitivity that includes the first and second wavelength ranges of the first bandpass filter 4 and the second bandpass filter 5.

The first wavelength range can be centered, for example, at 1.38 μm and the second wavelength range, for example, at 1.87 μm.

The infrared camera 2 receives a first measurement signal via the measurement channel formed with the first bandpass filter 4 and receives a second measurement signal via the measurement channel formed with the second bandpass filter 5. A calculation device, not shown, determines the temperature and the spectral emissivity via a ratio of the measurement signals. A pixel-by-pixel evaluation can be carried out, whereby spatially resolved results can be determined.

The irradiated surface 100 reflects a portion ρ(λ) of the solar radiation radiated onto the surface 100 at the wavelength λ and emits a portion (1-ρ(λ)) of the black body radiation. The proportion 1-ρ(λ) corresponds to the spectral emissivity ε((λ)). For a solar-blind filter, such as the first bandpass filter 4 and the second bandpass filter 5, the reflected component is negligible.

In 2 a solar power plant 200 is shown schematically. The solar power plant 200 has a large number of heliostats 300, which concentrate solar radiation onto a receiver arranged on a solar tower 400. The receiver thus forms the area 100 irradiated with solar radiation.

As in 2 is shown schematically, the device 1 according to the invention can be used to determine Development of a temperature and a spectral emissivity can either be arranged on the ground or have a flying object 6, by means of which the infrared camera, the lens 3 and the first bandpass filter 4 and the second bandpass filter 5 are arranged.

Using the flying object 6, the infrared camera 2 can be flown relatively close to the receiver 500 and thus the irradiated surface 100, so that the influence of the atmospheric transmittance during the measurement can be reduced. The infrared camera 2 can also be aligned to any point on the irradiated surface 100 using the flying object 6, so that, for example, a receiver 500 extending 360° around the solar tower 400 can also be measured.

The device 1 according to the invention, which is arranged on the floor, is comparatively far away from the irradiated surface 100. The received radiation is therefore influenced by the atmosphere and the atmospheric transmittance can therefore be determined in order to correct the received measurement signals. The atmospheric transmittance can be determined using, for example, a model-based estimate based on meteorological data or through simulation. It is also possible for the atmospheric transmittance to be determined by using the infrared camera 2 to record two further measurement signals using two further optical bandpass filters, each of which is centered on a wavelength range that is signal-independent with respect to an atmosphere, the wavelength ranges being each other the two further optical bandpass filters differ from each other and from the first and second wavelength ranges, wherein information about an atmospheric transmittance is determined via a ratio of the further measurement signals, and the first and second measurement signals are corrected by means of the atmospheric transmittance.

Using the device 1 according to the invention, the temperature and the spectral emissivity of the irradiated surface 100 can be determined in a simple manner, the device being of a relatively simple structure and comparatively inexpensive.

Claims (20)

Device (1) for determining a temperature and a spectral emissivity of a surface (100) irradiated with solar radiation, with an infrared camera (2) and with a first bandpass filter (4) and a second bandpass filter (5), characterized in that the first bandpass filter (4) is centered on a first wavelength range of atmospheric absorption bands for solar radiation and the second bandpass filter (5) is centered on a second wavelength range of atmospheric absorption bands for solar radiation, wherein the first wavelength range differs from the second wavelength range, wherein the infrared camera (2) has a spectral sensitivity which comprises the first and the second wavelength range, wherein the infrared camera (2) receives a first measurement signal via the measurement channel formed with the first bandpass filter (4) and receives a second measurement signal via the measurement channel formed with the second bandpass filter (5) and a Calculating device determines the temperature and the spectral emissivity of the irradiated surface (100) via a ratio of the measurement signals. Device according to Claim 1 , characterized in that the first wavelength range is centered on a range between 1.3 µm and 1.5 µm and the second wavelength range is centered on a range between 1.8 µm and 2.0 µm, the first wavelength range preferably being at 1.38 µm and the second wavelength range is preferably centered at 1.87 µm. Device according to Claim 1 or 2 , characterized in that the atmospheric transmittance in the first and second wavelength ranges is below 0.1%. Device according to one of the Claims 1 until 3 that a Fabry-Perot interferometer is arranged on the infrared camera (2) to provide the first bandpass filter (4) and second bandpass filter (5). Measuring device according to one of the Claims 1 until 3 , characterized in that, characterized in that the first bandpass filter (4) and the second bandpass filter (5) are formed by a dual filter. Device according to one of the Claims 1 until 4 , characterized by two further optical bandpass filters, each centered on a wavelength range that is signal-independent with respect to an atmosphere, the wavelength ranges of the two further optical bandpass filters differing from each other and from the first and second wavelength ranges, wherein the infrared camera ( 2) has a spectral sensitivity which includes the wavelength ranges of the two further optical bandpass filters, wherein the infrared camera (2) receives further measurement signals via two further measurement channels formed with the two further optical bandpass filters and the Calculating device determines information about an atmospheric transmittance via a ratio of the further measurement signals and corrects the first and second measurement signals using the atmospheric transmittance. Device according to Claim 6 , characterized in that the wavelength ranges of the two further optical bandpass filters are each centered on a range between 1.5 µm and 2.2 µm, with preferably one wavelength range of the further optical bandpass filters at 1.65 µm and the other wavelength range of the further optical bandpass filters is centered at 2.2 µm. Device according to one of the preceding claims, characterized in that the first bandpass filter, the second bandpass filter and/or the further bandpass filters are formed by a multizone filter. Device according to one of the preceding claims, characterized in that the first bandpass filter (4), the second bandpass filter (5) and/or the further bandpass filters are formed by a filter wheel. Device according to one of the Claims 1 until 9 , characterized in that the infrared camera (2) has an infrared lens (3). Device according to one of the Claims 1 until 10 , characterized in that the calculation device evaluates the ratio of the first and second measurement signals pixel by pixel and determines the temperature and/or the emissivity in a spatially resolved manner. Device according to one of the Claims 1 until 11 , characterized in that the infrared camera (2), first bandpass filter (4) and the second bandpass filter (5) are arranged on a flying object (6). Method for determining a temperature and a spectral emissivity of a surface irradiated with solar radiation with the following steps: a) aligning an infrared camera (2) with the irradiated surface, b) recording a first measurement signal via a first measurement channel, in which a first bandpass filter (4) is arranged, which is centered on a first wavelength range of atmospheric absorption bands for solar radiation, and a second measurement signal via a second measurement channel, in which a second bandpass filter (4 ) is arranged, which is centered on a second wavelength range of atmospheric absorption bands for solar radiation, c) forming a ratio of the first and second measurement signals and determining the temperature and the spectral emissivity of the surface irradiated with solar radiation from the ratio. Procedure according to Claim 13 , characterized by further the step: aa) recording two further measurement signals using two further optical bandpass filters, each of which is centered on a wavelength range that is signal-independent with respect to an atmosphere, the wavelength ranges of the two further optical bandpass filters being different from one another and from the first and the second wavelength range, wherein information about an atmospheric transmittance is determined via a ratio of the further measurement signals, and wherein the first and the second measurement signals are corrected by means of the atmospheric transmittance before forming the ratio in step c). Procedure according to Claim 14 , characterized in that the wavelength ranges of the two further optical bandpass filters are each centered on a range between 1.5 µm and 2.2 µm, with preferably one wavelength range of the further optical bandpass filters at 1.65 µm and the other wavelength range of the further optical bandpass filters is centered at 2.2 µm. Method according to one of the preceding claims, characterized in that an atmospheric transmittance is determined by meteorological data, in particular ambient temperature and/or humidity, and/or by measurement and/or by simulation, the first and second measurement signals being provided by means of the atmospheric transmittance be corrected after forming the ratio in step c). Method according to one of the preceding claims, characterized in that the first wavelength range is centered on a range between 1.3 µm and 1.5 µm and the second wavelength range is centered on a range between 1.8 µm and 2.0 µm, the first Wavelength range is preferably centered at 1.38 μm and the second wavelength range is preferably centered at 1.87 μm. Method according to one of the preceding claims, characterized in that the ratio of the first and second measurement signals is evaluated pixel by pixel and the temperature and/or the emissivity is determined in a spatially resolved manner. Method according to one of the preceding claims, characterized in that the information infrared camera (2) is moved by means of a flying object (6), the infrared camera (2) being brought to a predetermined maximum distance from the irradiated surface in step (a). Procedure according to Claim 19 , characterized in that the infrared camera (2) is moved along a predetermined route by means of the flying object (6), at least step b) being carried out repeatedly or at least steps b) and c) being carried out repeatedly.

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