Radiation measuring meter

Abstract

The present disclosure relates to a pyranometer for measuring solar irradiance. In particular, the pyranometer comprises a dome (1), a thermopile-based sensor (2) comprising a receiving surface (22), a diffuser (3) configured to diffuse radiation passing through the dome (1) from outside the pyranometer towards the receiving surface (22) of the thermopile-based sensor (2), and at least one optical filter (4) arranged in the optical path of the radiation in front of the receiving surface (22) of the thermopile-based sensor (2) so as to modify the spectral composition of the radiation measured by the thermopile-based sensor (2).

Description

Technical Field

[0001] The present invention relates to an irradiance meter for measuring irradiance (e.g., solar irradiance). Background Technology

[0002] An irradiance meter is an instrument that measures the amount of irradiance (such as solar irradiance) incident on a surface.

[0003] Based on the working principle of irradiation measurement, irradiation meters can be divided into two different categories: thermopile-based sensor irradiation meters and silicon semiconductor-based irradiation meters.

[0004] Regarding the thermopile-based sensor irradiance meter, irradiance is measured by a sensor that is based on a thermopile and designed to measure a substantially broadband radiative flux density from a field of view of approximately 180°. The thermopile-based sensor is positioned beneath a transparent dome (particularly a glass dome) that confines the spectral response from approximately 190 nm to approximately 4000 nm, particularly from approximately 300 nm to approximately 2800 nm, while maintaining a substantially 180° field of view. Simultaneously, the glass dome protects the thermopile-based sensor from external environmental influences.

[0005] Irradiance meters can be used in conjunction with other systems, such as other solar simulators, photovoltaic systems, and weather stations. In these systems, the solar radiation measured by the irradiance meter is used to determine other system parameters and / or performance, such as the effective power of photovoltaic modules. Therefore, the measurement accuracy of an irradiance meter is one of the most prominent aspects of this instrument. In particular, the measurement accuracy of an irradiance meter is even more crucial in climate applications where percentage variations of multiple components over the years are recorded.

[0006] The characteristics of an irradiance meter can be found in its spectral sensitivity (spectral response), that is, the ability of an irradiance meter to sense radiation within a certain range of the radiation spectrum. The radiation spectrum measured by an irradiance meter can be affected by (and may be changed by) many factors, including the angle of incidence (solar angle) of the radiation (e.g., solar radiation) and atmospheric conditions (i.e., the presence of clouds and aerosols).

[0007] To achieve high measurement accuracy, the spectral response (photosensitivity) of the radiometer should preferably be as constant as possible for different ranges of radiation spectra. The ISO 9060:2018 standard provides a specific classification of the spectral responses of radiometers for different spectra.

[0008] Specifically, to achieve a substantially constant spectral response for irradiance measurement, known thermopile-based irradiance meters employ a black-coated thermopile sensor and a glass dome. The black-coated thermopile sensor absorbs virtually all radiation (e.g., solar radiation), thus obtaining a substantially flat spectrum ranging from approximately 300 nm to approximately 50,000 nm. The glass dome confines the spectral response to approximately 300 nm to approximately 2800 nm, truncating the portion above approximately 2800 nm, while maintaining a substantially 180° field of view.

[0009] However, in irradiance meters that include sensors based on miniature thermopiles arranged in combination with diffusers, a substantially constant irradiance meter spectral response has not been achieved.

[0010] Thermopile-based sensors are characterized by faster response times and more stable thermal behavior. However, to achieve the desired field of view, the thermopile-based sensor is combined with a light diffuser. A diffuser is an optical element (light diffuser) configured to diffuse and transmit incident light toward the receiving surface of the radiation sensor. The light diffuser is positioned on top of the thermopile-based sensor so as to be approximately opposite the receiving surface of the sensor. As a result, light incident on the diffuser from outside the irradiance meter can be diffused onto the receiving surface of the thermopile-based sensor.

[0011] However, when a micro-thermopile-based sensor is combined with a light diffuser, the spectral response varies considerably with wavelength. In other words, the combined spectral response (the combination of the thermopile-based sensor's spectral response and the diffuser's spectral response) varies substantially with the wavelength of the relevant spectrum.

[0012] As a result, the measurement accuracy of the irradiance meter equipped with a light diffuser was negatively affected.

[0013] Therefore, it is necessary to improve the measurement accuracy of irradiance meters equipped with light diffusers. Summary of the Invention

[0014] The purpose of this invention is to improve the measurement accuracy of irradiation meters.

[0015] The above objectives are achieved through the features of the independent claims, wherein the specific embodiments are the subject of the dependent claims.

[0016] According to one aspect, an irradiance meter is provided, the irradiance meter comprising: a dome; a thermopile-based sensor including a receiving surface; a diffuser configured to diffuse radiation from outside the irradiance meter through the dome toward the receiving surface of the thermopile-based sensor; and at least one filter disposed in the optical path of the radiation in front of the receiving surface of the thermopile-based sensor to modify the spectral composition of the radiation measured by the thermopile-based sensor.

[0017] Specifically, filters arranged in the optical path of the radiation (particularly in front of the receiving surface of the thermopile-based sensor) allow modification of the spectral composition of the radiation passing through the dome and / or diffuser and measured by the thermopile-based sensor. In particular, the radiation incident on the dome and / or diffuser can be solar radiation. As a result, a substantially flat spectral response can be obtained. In other words, the irradiance meter has a substantially constant spectral response. Specifically, the spectral response of the irradiance meter is unaffected by variations caused by the optical diffuser included in the optical path and / or the spectral selectivity of the thermopile-based sensor. More specifically, the filters also provide (at least partially) compensation for the Fresnel loss of the dome.

[0018] Furthermore, without the filters arranged as disclosed above, the output measured by the irradiance meter will depend on the irradiance level and the variations in the irradiance spectrum caused by changes in the solar zenith angle (solar angle) and atmospheric conditions (e.g., the presence of clouds). Specifically, the filters described above allow the response of the irradiance meter to remain substantially constant under different specific spectral conditions (particularly atmospheric conditions such as wind, temperature, rain, etc.). In other words, this disclosure provides a thermopile-based irradiance meter with a constant spectral response. In particular, the spectral response can be constant under different solar and / or atmospheric conditions affecting the spectrum of solar irradiance (time of day, solar angle, clear or cloudy skies, pollution levels on the dome of the irradiance meter, etc.). More specifically, this improves the measurement accuracy of the irradiance meter.

[0019] In particular, at least one filter at least partially compensates for the spectral selectivity of thermopile-based sensors and / or diffusers and / or domes (i.e., thermopile-based sensors, diffusers, or domes; or a combination of thermopile-based sensors and diffusers, and / or domes).

[0020] Specifically, filters that at least partially compensate for the spectral selectivity of thermopile-based sensors and / or diffusers allow the radiometer to remain substantially invariant to varying atmospheric conditions, which cause changes in the spectral composition of incident radiation, particularly incident solar radiation. This, in turn, improves the measurement accuracy of the radiometer.

[0021] Specifically, the at least one filter modifies the spectral composition of the radiation (solar radiation) measured by the thermopile-based sensor such that the spectral selectivity based on the spectral absorptivity and spectral transmittance of the thermopile-based sensor, and / or the diffuser, and / or the dome has a maximum percentage deviation of about ±3% relative to the average value in the wavelength range of the radiation (solar radiation) spectrum from about 350 nm to about 1500 nm.

[0022] Specifically, the filter with the above configuration makes the response of the irradiance meter flat across the spectrum (especially within the maximum percentage deviation relative to the average value). Therefore, the measurement accuracy of the irradiance meter is improved.

[0023] More specifically, the at least one filter can be configured such that the at least one filter has a greater transmittance for spectral wavelengths below about 400 nm than the at least one filter has a greater transmittance for spectral wavelengths above about 700 nm.

[0024] Specifically, the filter with the above configuration makes the response of the irradiance meter substantially flat (or at least relatively flat) spectrally, particularly by compensating for the spectral characteristics of the diffuser and / or the thermopile-based sensor. Therefore, the measurement accuracy of the irradiance meter is improved.

[0025] More specifically, the at least one filter comprises one or more layers, each configured to have different refractive, transmission, absorption, and / or reflection properties for a given specific radiation (solar radiation) wavelength value or range.

[0026] Specifically, the filter with the above configuration makes the response of the irradiance meter substantially flat spectrally, particularly by compensating for the spectral characteristics of the diffuser and / or the thermopile-based sensor. Therefore, the measurement accuracy of the irradiance meter is improved.

[0027] In particular, the at least one filter can be arranged in the optical path between the diffuser and the receiving surface of the thermopile-based sensor.

[0028] More specifically, the at least one filter may be arranged substantially facing the receiving surface of the thermopile-based sensor, particularly wherein the at least one filter may be arranged substantially facing the active black-coated surface of the thermopile-based sensor.

[0029] More specifically, the at least one filter is embedded in the active black coating material of the thermopile-based sensor.

[0030] More specifically, the thermopile-based sensor may be located at least partially within the housing, and wherein the at least one filter may be arranged to substantially cover a window of the housing.

[0031] More specifically, the at least one filter may be arranged to at least partially cover the outer surface of the diffuser.

[0032] More specifically, the at least one filter may be arranged on the inner portion of the diffuser.

[0033] More specifically, the at least one filter may be arranged to at least partially cover the inner and / or outer surfaces of the dome.

[0034] More specifically, the at least one filter may comprise one or more vacuum-deposited dielectric metal layers.

[0035] More specifically, the at least one filter may be a transmission interference filter.

[0036] More specifically, the at least one filter may be a reflective filter.

[0037] More specifically, the at least one filter may be an absorptive filter.

[0038] More specifically, the irradiance meter may also include at least one collimator configured to collimate the radiation (solar radiation) irradiating the receiving surface of the thermopile-based sensor.

[0039] Specifically, a collimator configured to collimate radiation (solar radiation) incident on the receiving surface of a thermopile-based sensor allows modification of the optical path followed by the radiation (solar radiation) in the irradiance meter. Specifically, the transmission of the radiation (solar radiation) is optimized.

[0040] More specifically, the distance between the optical path between the diffuser and the thermopile-based sensor can be set such that the radiation (solar radiation) diffused by the diffuser onto the receiving surface of the thermopile-based sensor has a generally conical shape. Attached Figure Description

[0041] These and other objects, features, and advantages of the invention will become more apparent upon reading the following detailed description and accompanying drawings. It should be understood that, even though embodiments are described separately, individual features of these embodiments can be combined into additional embodiments.

[0042] Figure 1 This is an isometric view of an irradiation meter according to one aspect of the present invention;

[0043] Figure 2 yes Figure 1 An exploded isometric view of a portion of the irradiance meter shown.

[0044] Figure 3 This is a plan view of the irradiation measuring instrument according to the present invention;

[0045] Figure 4 yes Figure 3 A cross-sectional view of the radiation meter shown;

[0046] Figures 5 to 8 This is a sectional side view of different arrangements of filters according to the present invention;

[0047] Figure 9 This is a graph showing the spectral selectivity of the light diffuser; and

[0048] Figure 10 This is a graph showing the spectral selectivity of the filter. Detailed Implementation

[0049] Referring to the above figures, the radiation measuring instrument according to the present invention is generally indicated by reference numeral 100.

[0050] refer to Figure 1 and Figures 5 to 8 The irradiance meter 100, generally designated by reference numeral 100, is a device for measuring radiation according to this disclosure. The irradiance meter 100 includes a dome 1. The dome 1 may be the outer dome of the irradiance meter 100. In other words, when mounted on the irradiance meter 100, the dome 1 may form the outermost dome 1 of the irradiance meter 100. If the dome 1 is the outer transparent dome 1 of the irradiance meter 100, then the outer surface 11 of the dome 1 substantially faces the environment 13 outside the irradiance meter 100. Conversely, the inner surface 12 of the dome 1 substantially surrounds a cavity 10. In particular, the cavity 10 is an air cavity beneath the dome 1. Therefore, the inner surface 12 of the dome 1 substantially faces the cavity 10. The cavity 10 substantially corresponds to the space surrounding the cavity 10. Preferably, the cavity 10 may have a substantially hemispherical shape and include a bottom opening 14 having a substantially circular shape.

[0051] The dome 1 may include an edge 15. The edge 15 may be a peripheral edge that substantially forms the edge of the dome 1. The edge 15 may preferably have a substantially annular surface. In particular, the difference between the outer radius (i.e., the radius of the outer surface 11) and the inner radius (i.e., the radius of the inner surface 12) substantially corresponds to the thickness of the dome 1.

[0052] The dome 1 is at least partially transparent to radiation (e.g., sunlight). Specifically, the radiation may be solar radiation. Specifically, the dome 1 is configured to limit the spectral response to about 190 nanometers to about 4000 nanometers (nm), preferably from about 300 nanometers to about 2800 nanometers (nm), while maintaining a substantially 180° field of view. The transparency of the dome 1 is such that at least about 60% (more particularly at least about 70%) of the incident radiation (e.g., solar radiation or light) in the relevant spectral range can pass through. In other words, the dome 1 is configured to allow at least a portion of the radiation spectrum to be transmitted from the external environment 13 through the outer surface 11, through the material forming the dome 1, and through the inner surface 12 into the cavity 10. Within the cavity 10, this radiation can be measured, as will be described in more detail below.

[0053] Dome 1 can be made of any suitable, at least partially transparent material that allows radiation (particularly solar radiation or light) to pass through. Specifically, dome 1 can be made of any material having physical / chemical properties that physically protect the measuring surface of the irradiance meter 100 while being transparent to (most) light (e.g., at least partially transparent to the spectrum of the radiation (e.g., solar radiation) that the irradiance meter 100 intends to detect). For example, dome 1 can be made of glass, quartz, or sapphire. Alternatively, dome 1 can be made of a transparent thermoplastic polymer (i.e., polymethyl methacrylate (PMMA), also known as acrylic, acrylic glass, or plexiglass).

[0054] refer to Figures 1 to 8 The irradiance meter 100 includes an irradiance meter housing 6. The irradiance meter housing 6 may be, or may include, a container configured to house components of the irradiance meter 100, such as a thermopile-based sensor 2, a diffuser 3, a filter 4, and / or a control unit 5. These components and their functions will be described in more detail below. The irradiance meter housing 6 may be provided with one or more leveling feet 61 for supporting the irradiance meter housing 6 on a support surface S. The leveling feet (one or more) 61 also allow the irradiance meter housing 6 to be leveled on the support surface S.

[0055] like Figures 1 to 4 As shown, the irradiance meter housing 6 may include a first (outer) portion 62 and a second (inner) portion 63. The first portion 62 may be an outer cover portion arranged to cover and thus protect the second portion 63 from the environment 13 outside the irradiance meter 100. In particular, the first portion 62 may be configured to at least partially surround the second portion 63. The first portion 62 may be a light shield removably attached to the second portion 63 by one or more clips.

[0056] like Figure 2 As shown, the second part 63 can be configured to support the thermopile-based sensor 2, the diffuser 3, and / or the filter 4. In particular, the second part 63 may include a support plate 64 configured to support the thermopile-based sensor 2.

[0057] The thermopile-based sensor 2 can be directly or indirectly connected to the support plate 64. Furthermore, the support plate 64 can be directly or indirectly, removably connected to the second part 63, to enclose the thermopile-based sensor 2 between them. Specifically, the thermopile-based sensor 2 can be located within a cavity surrounded by the second part 63 of the housing 6 and the support plate 64.

[0058] The top surface of the first part 62 can also be directly or indirectly, removably attached to the edge 15 of the dome 1, so that the dome 1 can be connected to the shell 6, such as Figure 1 and Figures 5 to 8 As shown.

[0059] like Figure 2 , Figure 4 , Figures 5 to 8 As shown, the irradiance meter 100 includes a thermopile-based sensor 2. The thermopile-based sensor 2 is a measuring sensor configured to measure the radiation irradiating the irradiance meter 100. Specifically, the radiation irradiating the irradiance meter 100 can be solar radiation. The thermopile-based sensor 2 can be based on a broadband thermopile particularly suitable for specifically measuring radiative flux density from a substantially 180° field of view. The thermopile is specifically an electronic device that converts thermal energy into electrical energy and includes several thermocouples connected in series or parallel. When the different metals of the thermopile or the thermocouples are exposed to a temperature difference, the thermopile operates according to the principle of the thermoelectric effect that generates voltage. Thermocouples operate by measuring the temperature difference from their junctions to the point where the thermocouple output voltage is measured. Once a closed loop is formed by more than one type of metal and a temperature difference exists between the junctions and the transition point from one metal to another, a current is generated, just as a current is generated by the potential difference between the junctions at different temperatures. In other words, the irradiation meter 100 of this disclosure is particularly a thermopile irradiation meter (also known as a thermoelectric irradiation meter).

[0060] Specifically, the thermopile irradiance meter 100 specifically detects light from approximately 300 nm to approximately 2800 nm with a substantially flat spectral sensitivity. Specifically, the thermopile-based sensor 2 includes a black coating that absorbs (particularly all) radiation irradiated upon it (e.g., solar radiation or modified solar radiation, the spectral composition of which is modified, for example, by optical elements (such as dome 1 and / or diffuser 3) in front of it). The active (hot) junction of the thermocouple is located below (or corresponding to or adjacent to) the surface of the black coating and is heated by the radiation absorbed from the black coating. The passive (cold) junction of the thermocouple is (particularly completely) protected from radiation and is in thermal contact with the irradiance meter housing 6, which specifically functions as a heat sink. Specifically, the passive (cold) junction of the thermocouple is in contact with the thermopile housing 23, which can be in thermal contact with the irradiance meter housing 6 to substantially dissipate heat to or through the irradiance meter housing 6. This specifically reduces or prevents any changes caused by yellowing or attenuation when measuring temperatures in the shade, and thus impairs the irradiance measurement of the 100 solar irradiance.

[0061] Specifically, the thermopile-based sensor 2 can be a sensor based on a micro thermopile. Specifically, the thermopile can be located in a TO (transistor profile) housing with a diameter ranging from about 1 mm to about 20 mm or less than about 10 mm. Specifically, the TO housing and / or (one or more) active components of the thermopile-based sensor 2 can be micromachined.

[0062] like Figure 2 and Figure 7 As shown, the thermopile-based sensor 2 includes a receiving surface 22 and an opposite second (bottom) surface 21. The receiving surface 22 of the thermopile-based sensor 2 may include a black-coated surface, or may correspond to the black-coated surface. The second surface 21 is substantially facing the support plate 64. In particular, the second surface 21 may directly or indirectly contact the support plate 64, such that the thermopile-based sensor 2 is directly or indirectly supported by the support plate 64.

[0063] The receiving surface 22 is configured to substantially receive radiation irradiating the irradiance meter 100. Specifically, the radiation irradiating the irradiance meter 100 can be solar radiation. Specifically, the solar radiation irradiating the irradiance meter 100 is at least partially transmitted through the dome 1 and diffused onto the receiving surface 22 of the thermopile-based sensor 2 by the diffuser 3. Therefore, the diffuser 3 is specifically arranged to diffuse the radiation through the dome 1 onto the receiving surface 22 of the thermopile-based sensor 2. Specifically, the thermopile-based sensor 2 and the diffuser 3 can be stacked on top of each other.

[0064] like Figure 2As shown, the thermopile-based sensor 2 can be located within a housing 23 having a window 22a. The housing 23 may have or define a cavity configured to integrally or at least partially accommodate the thermopile-based sensor 2. The window 22a of the housing 23 can be arranged substantially facing the bottom side of the receiving surface 22 of the thermopile-based sensor 2. Specifically, a gap may exist between the receiving surface 22 and the window 22a to specifically prevent heat leakage that could degrade sensor performance. The window 22a of the housing 23 can be arranged substantially facing the upper side of the second (bottom) surface 32 of the diffuser 3. Specifically, a gap may exist between the second (bottom) surface 32 of the diffuser 3 and the window 22a. In other words, the window 22a of the housing 23 can be substantially arranged between the second (bottom) surface 32 of the diffuser 3 and the receiving surface 22 of the thermopile-based sensor 2, but not in contact with either the second (bottom) surface 32 of the diffuser 3 or the receiving surface 22 of the thermopile-based sensor 2. The window 22a of the housing 23 is at least partially transparent to radiation (light). In particular, the window 22a of the housing 23 may be transparent such that at least about 60% (more particularly at least about 70%) of the incident radiation (light) in the relevant spectral range can pass through the window 2a. Therefore, the window 22a of the housing 23 may also be part of the light path of the radiation, which will be described in detail below.

[0065] like Figures 1 to 8 As shown, the radiation meter 100 includes a diffuser 3. The diffuser 3 is configured to diffuse radiation (e.g., solar radiation or light) passing through the dome 1 from outside the radiation meter 100 toward the receiving surface 22 of the thermopile-based sensor 2. Therefore, the radiation illuminating the receiving surface 22 of the thermopile-based sensor 2 can be measured by the thermopile-based sensor 2.

[0066] The diffuser 3 is an optical element having an incident first or top surface 31 that substantially faces the cavity 10 of the dome 1, particularly when the diffuser 3 is mounted on the irradiance meter 100. In other words, the diffuser 3 is arranged such that the incident surface 31 substantially faces the inner surface 12 of the dome 1 within the cavity 10. Specifically, the diffuser 3 may be located in a through opening 65 provided in the second part 63 of the irradiance meter housing 6, such that the incident surface 31 of the diffuser 3 substantially faces the inner surface 12 of the dome 1. The diffuser 3 includes a second (bottom) surface 32 substantially opposite to the incident first or top surface 31 and at least one side surface 33. When the diffuser 3 is mounted on the irradiance meter 100, the second surface 32 is substantially opposite to the incident surface 31 and substantially faces the receiving surface 22 of the thermopile-based sensor 2. In other words, the diffuser 3 is arranged such that the second bottom surface 32 substantially faces the receiving surface 22 of the thermopile-based sensor 2. The incident surface 31 can be a flat circular surface, a conical surface, a convex surface, a concave surface, or an inverted conical surface. In particular, the diffuser 3 can be axisymmetric, that is, symmetric about the longitudinal axis X3 of the diffuser 3. In other words, the diffuser 3 can be a rotationally symmetric body with the longitudinal axis X3. For example, the diffuser 3 can have a substantially cylindrical side surface 33 and / or include a conical incident first or top surface 31.

[0067] like Figure 2 , Figures 4 to 8 As shown, the diffuser 3 can be arranged such that the second surface 32 faces substantially the receiving surface 22 of the thermopile-based sensor 2, while the incident surface 31 faces substantially the inner surface 12 of the dome 1.

[0068] Therefore, radiation or light (or solar radiation) from outside the dome 1 enters the cavity 10 through the dome 1. Within the cavity 10, the radiation or light illuminates the incident surface 31 of the diffuser 3 and is transmitted at least partially through the diffuser 3 toward the thermopile-based sensor 2 (specifically, the receiving surface 22 of the thermopile-based sensor 2), such as... Figure 4 As shown. Therefore, radiation or light (e.g., solar radiation) reaching the thermopile-based sensor 2 can be measured by the thermopile-based sensor 2.

[0069] The diffuser 3 may include any material that allows incident light to be diffused and transmitted through the diffuser 3, or be made of any material that allows incident light to be diffused and transmitted through the diffuser 3. For example, the diffuser 3 may include at least partially porous material (such as bubble quartz) or be made of such at least partially porous material (such as bubble quartz).

[0070] like Figure 4As shown, the irradiation meter 100 may include at least one control unit 5. The control unit 5 may be operatively connected to the thermopile-based sensor 2. The control unit 5 may be a controller, preferably a microcontroller. The control unit 5 may be located within the irradiation meter housing 6.

[0071] Specifically, control unit 5 can be configured to modify the radiation output (solar radiation output) measured by thermopile-based sensor 2 based on a correction factor. In other words, control unit 5 can be configured to perform post-processing correction of the radiation measured by thermopile-based sensor 2. Specifically, post-processing correction can be performed by modifying the radiation output measured by thermopile-based sensor 2 based on a correction factor. Therefore, more accurate irradiance measurements can be achieved.

[0072] refer to Figure 2 , Figure 4 , Figures 5 to 8 The irradiance meter 100 also includes at least one filter 4. In particular, the filter 4 may be a solar radiation filter.

[0073] Filter 4 is arranged in the optical path of radiation, specifically in front of the receiving surface 22 of the thermopile-based sensor 2. The optical path is the path followed by radiation (solar radiation) as it passes through the components of the radiation meter and before irradiating the receiving surface 22 of the thermopile-based sensor 2. As a result, the radiation irradiating the receiving surface 22 of the thermopile-based sensor 2 can be filtered by filter 4. Specifically, the spectral composition of the radiation irradiating the thermopile-based sensor 2, or the spectral composition of the radiation measured by the thermopile-based sensor 2, is modified by filter 4.

[0074] The optical path followed by the radiation (solar radiation) may include (starting from the environment 13 outside the radiation meter 100): the outer surface 11 of the dome 1, the internal material of the dome 1, the inner surface 12 of the dome 1, the cavity 10, the incident surface 31 of the diffuser 3, the internal material of the diffuser 3, the second bottom surface 32 of the diffuser 3, the window 22a of the housing 23, and / or the receiving surface 22 of the thermopile-based sensor 2. In other words, radiation (especially solar radiation) irradiating the radiation meter 100 from outside the radiation meter 100 can pass through the aforementioned elements and / or surfaces before reaching the receiving surface 22 of the thermopile-based sensor 2.

[0075] Specifically, the “spectral composition” of radiation refers to the energy composition of solar radiation within one or more frequency ranges (or one or more wavelength ranges) of solar electromagnetic radiation (sunlight). Specifically, modifying the spectral composition of radiation refers to modifying the solar radiation flux density within one or more frequency ranges (or one or more wavelength ranges) of solar radiation before solar radiation irradiates the receiving surface 22 of the thermopile-based sensor 2.

[0076] Filter 4 can be configured to at least partially compensate for the spectral selectivity of the thermopile-based sensor 2 and / or diffuser 3 and / or dome 1. In other words, the thermopile-based sensor 2 and / or diffuser 3 can have the following properties: Figure 9 The spectral selectivity or spectral transmission characteristics shown vary with the wavelength of the (solar) radiation spectrum of diffuser 3. For example, the thermopile-based sensor 2 and / or diffuser 3 may exhibit high transmission characteristics (total transmittance) for solar radiation within a specific wavelength range of the solar radiation spectrum, and different (particularly lower) transmission characteristics (total transmittance) for solar radiation within different wavelength ranges of the solar radiation spectrum. In other words, the transmission characteristics of the thermopile-based sensor 2, the diffuser 3, and / or the dome 1, and / or the combination thereof (the combined spectral selectivity or spectral transmission characteristics of diffuser 3, thermopile-based sensor 2, and / or dome 1) are not substantially constant within the relevant wavelength range of the solar radiation spectrum. Therefore, in order to achieve a more spectrally flat or substantially spectrally flat response, filter 4 may be configured to at least partially compensate for the spectral selectivity of the thermopile-based sensor 2 and / or diffuser 3. In other words, filter 4 can be configured to have spectral selectivity or spectral transmission characteristics that are substantially opposite to or complementary to the spectral selectivity or spectral transmission characteristics of the thermopile-based sensor 2 and / or diffuser 3, particularly within a specified (predetermined or predeterminable) wavelength range (one or more). More specifically, the spectral selectivity or spectral transmission characteristics can be within the wavelength range of the solar radiation spectrum from about 350 nm to about 1500 nm. Specifically, filter 4 at least partially compensates for the spectral selectivity of the combination of both the thermopile-based sensor 2 and diffuser 3.

[0077] Specifically, the filter 4 can be configured to modify (correct) the spectral composition of radiation (e.g., solar radiation) measured by the thermopile-based sensor 2, such that the spectral selectivity based on the spectral absorbance and spectral transmittance of the thermopile-based sensor 2 and / or diffuser 3 has a maximum percentage deviation of about ±3% relative to the average value in the wavelength range of the radiation spectrum from about 350 nm to about 1500 nm, particularly as required by ISO 9060:2018.

[0078] More specifically, the spectral selectivity (or spectral transmittance characteristics) is particularly proportional to the product of the spectral absorbance and spectral transmittance of the thermopile-based sensor 2 and / or diffuser 3, and / or the spectral absorbance and spectral transmittance of the dome 1, specifically proportional to the product of the spectral absorbance and spectral transmittance of the combination of both the thermopile-based sensor 2 and diffuser 3. In other words, the spectral selectivity or characteristics of the combination of the thermopile-based sensor 2 and diffuser 3 should not exceed approximately ±3% of the average value in the wavelength range of the radiation spectrum (solar radiation spectrum) from approximately 350 nm to approximately 1500 nm.

[0079] Therefore, by placing filter 4 in the optical path of radiation (solar radiation) and configuring the filter to modify the spectral composition of the radiation measured by thermopile-based sensor 2 in order to at least partially compensate for the spectral selectivity of thermopile-based sensor 2, the spectral selectivity of diffuser 3, or a combination of the spectral selectivity of thermopile-based sensor 2 and diffuser 3, a maximum percentage deviation of approximately ±3% relative to the average value in the wavelength range of the radiation spectrum from approximately 350 nm to approximately 1500 nm can be achieved as described above.

[0080] More specifically, by placing filter 4 in the optical path of radiation (e.g., solar radiation) and configuring the filter to modify the spectral composition of the radiation measured by thermopile-based sensor 2, a spectral error of less than 0.5% for a standard spectrum can be achieved, and this in particular results in constraints over the entire range between about 280 nm and about 3500 nm.

[0081] In particular, such as Figure 10 As shown, filter 4 can be configured such that its total transmittance for spectral wavelengths below about 400 nm is greater than its total transmittance for spectral wavelengths greater than about 700 nm. In other words, filter 4 can be configured to transmit radiation with spectral wavelengths below about 400 nm (UV light) (e.g., solar radiation) very much, while transmitting radiation with spectral wavelengths greater than about 700 nm (IR light) only slightly. Figure 10 As shown.

[0082] Specifically, such as Figure 10 As shown, filter 4 is configured to primarily suppress or at least reduce the transmission of radiation in the infrared range, while increasing the transmission of radiation in the UV range.

[0083] At least one filter 4 may include one or more layers, each configured to have substantially different transmission and / or reflection characteristics for a specified radiation (solar radiation) wavelength value or range. Specifically, the one or more layers may include one or more layers of metallic and / or non-metallic materials, each layer having different transmission and / or reflection characteristics for a specified radiation wavelength value or range. More specifically, the one or more layers may be selected to achieve desired spectral selectivity or spectral transmission characteristics of the at least one filter 4. In particular, the one or more layers may be selected to compensate for the spectral selectivity of the thermopile-based sensor 2 and / or diffuser 3, and / or the spectral selectivity of the dome 1, and / or the spectral selectivity of combinations thereof.

[0084] Specifically, at least one filter 4 can be a transmission interferometric filter. A transmission interferometric filter includes one or more thin dielectric layers configured to transmit up to a specific amount of incident radiation within a particular frequency (wavelength) range. Specifically, a transmission interferometric filter can be a filter that transmits one or more spectral bands or lines while maintaining an absorption coefficient of nearly zero for all wavelengths of interest. Specifically, a transmission filter can include multiple thin dielectric (metallic) material layers with different transmission characteristics. Specifically, a transmission filter can be wavelength selective.

[0085] Specifically, at least one filter 4 can be a reflective filter. More specifically, a reflective filter can be a filter that reflects one or more spectral bands or lines and transmits other spectral bands or lines while maintaining an absorption coefficient of almost zero for all wavelengths of interest. In particular, a reflective filter can comprise multiple thin dielectric (metallic) material layers with different refractive indices. Specifically, the filter can be wavelength selective due to the interference effect occurring between the incident and reflected waves at the thin film boundaries.

[0086] Specifically, reflective filters can be easily manufactured and provide good filtering performance.

[0087] Specifically, at least one filter 4 can be an absorptive filter. Specifically, an absorptive filter can be a filter that absorbs one or more spectral bands or lines while transmitting and / or reflecting all wavelengths of interest. Specifically, an absorptive filter can comprise multiple thin dielectric (metallic) material layers with different absorption characteristics. Specifically, an absorptive filter can be wavelength selective.

[0088] It should be understood that filter 4 may include one or more filters selected from transmissive filters, reflective filters and / or absorptive filters.

[0089] According to a particular embodiment, at least one filter 4 may include one or more vacuum-deposited dielectric metal layers. In other words, at least one filter 4 may be vacuum-deposited as one or more layers on one or more components of the irradiance meter 100 (e.g., diffuser 3, window 22a of housing 23 of thermopile-based sensor 2, inner surface 12 of dome 1, and / or receiving surface 22 of thermopile-based sensor 2). Figures 5 to 8 As shown, the filter 4 can be located at different positions in the optical path to modify the spectral composition of the radiation (solar radiation) illuminating the receiving surface 22 of the thermopile-based sensor 2. It should be understood that the filter 4 can be simultaneously positioned at different positions in the optical path to achieve the desired modification of the spectral composition of the radiation measured by the thermopile-based sensor 2 (in particular, at least partially compensating for the spectral composition of the radiation measured by the thermopile-based sensor 2).

[0090] In particular, such as Figure 2 and Figure 4 As shown, at least one filter 4 can be arranged in the optical path, particularly between the diffuser 3 and the receiving surface 22 of the thermopile-based sensor 2. In other words, the filter 4 can be arranged at a position in the optical path between the diffuser 3 (particularly the second bottom surface of the diffuser 3) and the receiving surface 22 of the thermopile-based sensor 2.

[0091] More specifically, the filter 4 can be arranged such that one side is substantially facing the second surface 32 of the diffuser 3, and the opposite side is substantially facing the housing 23 of the thermopile-based sensor 2. Specifically, by arranging at least one filter 4 between the diffuser 3 and the thermopile-based sensor 2, the spectral composition of the radiation (solar radiation) illuminating the receiving surface 22 of the thermopile-based sensor 2 can be modified by the filter 4.

[0092] like Figure 2 As shown, the irradiation meter 100 may include a filter support element 7. The filter support element 7 may be configured to substantially at least partially surround the thermopile-based sensor 2.

[0093] If the thermopile-based sensor 2 includes a housing 25, then the filter support element 7 can be configured to substantially at least partially surround the housing 25 of the thermopile-based sensor 2.

[0094] Specifically, the filter support element 7 may include a through opening 70 having a shape that is substantially complementary to the external shape of the thermopile-based sensor 2 (or the housing 25 of the thermopile-based sensor 2). For example, the through opening 70 may be circular.

[0095] The filter support element 7 may include a base portion 71. In particular, the base portion 71 may be shaped as a flange. Specifically, the base portion 71 may be configured to directly or indirectly contact the support plate 64 in order to stably support at least one filter 4 in the irradiance meter housing 6.

[0096] Specifically, the filter 4 can be positioned and / or fixedly supported relative to the thermopile-based sensor 2 by the filter support element 7.

[0097] The filter support element 7 can be configured to properly position the second part 63 (particularly the one on which the diffuser 3 is mounted) of the thermopile-based sensor 2, filter 4 and / or irradiance meter housing 6 relative to each other.

[0098] The filter support element 7 can be removably connected to the support plate 64 and / or the thermopile-based sensor 2. The thermopile-based sensor 2 can fit snugly into the through opening 70 of the filter support element 7.

[0099] The filter support element 7 may include a recess 72. The recess 72 may be configured to removably support the filter 4. In particular, the recess 72 may have a shape corresponding to the outer peripheral edge of the filter 4.

[0100] like Figure 2 As shown, the groove 72 can be located on the peripheral edge of the through opening 70. Therefore, the filter support element 7 can be coupled to the thermopile-based sensor 2, while removably supporting the filter 4 such that the filter 4 is substantially centered relative to the receiving surface 22 of the thermopile-based sensor 2.

[0101] Specifically, the filter support element 7 can be configured to support the filter 4 between the second bottom surface of the diffuser 3 and the thermopile-based sensor 2.

[0102] like Figure 5 As shown, the filter 4 can be arranged to substantially cover the window 22a of the housing 23 of the thermopile-based sensor 2. In other words, if the thermopile-based sensor 2 is located within the housing 23, the filter 4 can be arranged to substantially cover the window 22a of the housing 23. Specifically, by arranging at least one filter 4 to cover the window 22a of the housing 23, the spectral composition of the radiation (e.g., solar radiation) illuminating the receiving surface 22 of the thermopile-based sensor 2 can be modified by the filter 4.

[0103] like Figure 6As shown, the filter 4 can be arranged to at least partially cover the outer surface of the diffuser 3. In particular, the filter 4 can be arranged to at least partially cover the incident surface 31 of the diffuser 3, the second bottom surface 32 and / or the side surface 33 of the diffuser 3, such that the spectral composition of the radiation illuminating the receiving surface 22 of the thermopile-based sensor 2 can be modified by the filter 4.

[0104] More specifically, the filter 4 can also be arranged on the inner portion of the diffuser 3, that is, the filter 4 can be configured as one or more inner layers of the diffuser 3. Specifically, by arranging at least one filter 4 to at least partially cover the diffuser 3, the spectral composition of the radiation illuminating the receiving surface 22 of the thermopile-based sensor 2 can be modified by the filter 4.

[0105] like Figure 7 As shown, the filter 4 can also be arranged to substantially (at least partially) face the receiving surface 22 of the thermopile-based sensor 2, particularly without directly contacting the receiving surface 22 of the thermopile-based sensor 2. More specifically, the filter 4 can be arranged to substantially face the active black coating surface of the thermopile-based sensor 2, particularly without directly contacting the active black coating of the thermopile-based sensor 2. In particular, at least one filter 4 can also be embedded in the material of the active black coating of the thermopile-based sensor 2. Specifically, at least one filter 4 can be embedded in the active black coating as one or more layers of the material forming the active black coating.

[0106] According to one aspect (not shown), at least one filter 4 may be arranged on or in the dome 1 to specifically at least partially cover the inner surface 12 and / or the outer surface 11 of the dome 1. In particular, the filter 4 may comprise one or more dielectric metal layers vacuum deposited on the inner surface 12 and / or the outer surface 11 of the dome 1.

[0107] Specifically, the radiation meter 100 may also include at least one collimator (not shown). Specifically, the collimator may be configured to collimate radiation (solar radiation) irradiating the receiving surface 22 of the thermopile-based sensor 2. More specifically, the collimator may be arranged in the optical path of the radiation (solar radiation), for example, between the diffuser 3 and the thermopile-based sensor 2. Alternatively, the collimator may be arranged below the window 22a of the thermopile housing 23 and / or above the receiving surface 22 of the thermopile-based sensor 2. Further alternatively, the collimator may be arranged between the window 22a and / or below the filter 4; and / or, the collimator may be arranged between the filter 4 and the diffuser 3. Alternatively, the collimator may be configured to collimate radiation (solar radiation) irradiating at least one filter 4. Specifically, a collimator configured to collimate radiation (e.g., solar radiation) irradiating the receiving surface of the thermopile-based sensor 2 allows modification of the optical path of the radiation. Specifically, radiation transmission can be optimized by collimating radiation (especially solar radiation).

[0108] According to one aspect, the distance of the optical path between the diffuser 3 and the thermopile-based sensor 2 (the distance between the second bottom surface 32 of the diffuser 3 and the receiving surface 22 of the thermopile-based sensor 2) can be set to adjust the angular distribution of radiation (e.g., solar radiation or light). Specifically, the minimum distance between the diffuser 3 and the filter 4 can be set to at least about 1 mm. Specifically, the minimum distance between the filter 4 and the thermopile-based sensor 2 can be set to at least about 1 mm. In other words, mechanical contact between the diffuser 3 and / or the filter 4, and / or the thermopile-based sensor 2, is specifically avoided. More specifically, the minimum distance between the diffuser 3 and the thermopile-based sensor 2 can be set to at least about 3 mm. More specifically, the minimum distance between the diffuser 3 and the thermopile-based sensor 2 can be set to at least between about 3 mm and about 10 mm. Specifically, the distance of the optical path between the diffuser 3 and the thermopile-based sensor 2 can be set such that the radiation (e.g., solar radiation) diffused by the diffuser 3 and illuminating the receiving surface 22 of the thermopile-based sensor 2 has a substantially conical shape, i.e., the radiation is configured as a diverging beam. In particular, the radiation can diverge at a half-angle greater than about 10° relative to the central longitudinal axis of the radiation beam. In other words, the radiation beam can have a divergence angle substantially greater than about 20°.

[0109] Specifically, by modifying the optical path (distance) between the diffuser 3 and the thermopile-based sensor 2, the angular distribution of light incident on or detected by the thermopile-based sensor 2 can be adjusted. Therefore, the performance of the filter 4 can be improved by setting a specified (predetermined or predeterminable) distance between the diffuser 3 and the thermopile-based sensor 2. In particular, by setting the distance between the diffuser 3 and the thermopile-based sensor 2 such that the radiation (light) illuminating the thermopile-based sensor is substantially beam-shaped (having a substantially conical shape), there is an effect of a slight shift in the spectral response with changes in wavelength. Specifically, oscillations are typically present in (dielectric) filters with wavelengths having relatively high frequencies (or short periods). Due to the slight shifts caused by different angles, these oscillations can be significantly smoothed or reduced by setting the diffuser 3 and the thermopile-based sensor 2 at a predetermined distance. In other words, the performance of the filter can be improved by adjusting the angular distribution (by specifically setting the diffuser 3 and the thermopile-based sensor 2 at a predetermined distance).

[0110] Further features, aspects, and embodiments are provided below in the following clauses:

[0111] Clause 1. An irradiation meter (100), comprising:

[0112] Dome (1);

[0113] A thermopile-based sensor (2) includes a receiving surface (22);

[0114] A diffuser (3) is configured to diffuse radiation from outside the irradiance meter (100) through the dome (1) toward the receiving surface (22) of the thermopile-based sensor (2); and

[0115] At least one filter (4) is arranged in the optical path of the radiation in front of the receiving surface (22) of the thermopile-based sensor (2) in order to modify the spectral composition of the radiation measured by the thermopile-based sensor (2).

[0116] Clause 2. The irradiance meter (100) according to Clause 1, wherein the at least one filter (4) at least partially compensates for the spectral selectivity of the thermopile-based sensor (2) and / or the diffuser (3), and / or the spectral selectivity of the dome (1).

[0117] Clause 3. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) modifies the spectral composition of the radiation measured by the thermopile-based sensor (2) such that the spectral selectivity of the spectral absorptivity and spectral transmittance of the thermopile-based sensor (2) and / or the diffuser (3), and / or the spectral absorptivity and spectral transmittance of the dome (1) has a maximum percentage deviation of about ±3% relative to the average value in the wavelength range of the radiation spectrum from about 350 nm to about 1500 nm.

[0118] Clause 4. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is configured such that the at least one filter (4) has a greater transmittance for spectral wavelengths below about 400 nm than the at least one filter (4) has a greater transmittance for spectral wavelengths above about 700 nm.

[0119] Clause 5. The radiation meter (100) according to any of the preceding clauses, wherein the at least one filter (4) comprises one or more layers, each layer being configured to have different refractive, transmission, absorption and / or reflection characteristics for a particular radiation wavelength value or range.

[0120] Clause 6. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is arranged in the optical path between the diffuser (3) and the receiving surface (22) of the thermopile-based sensor (2).

[0121] Clause 7. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is arranged substantially facing the receiving surface (22) of the thermopile-based sensor (2), particularly wherein the at least one filter (4) is arranged substantially facing the active black coating surface of the thermopile-based sensor (2); and / or wherein the at least one filter (4) is embedded in the material of the active black coating of the thermopile-based sensor (2).

[0122] Clause 8. The irradiance measuring instrument (100) according to any of the preceding clauses, wherein the thermopile-based sensor (2) is located in the housing (23), wherein the at least one filter (4) is arranged to substantially cover the window (22a) of the housing (23).

[0123] Clause 9. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is arranged to at least partially cover the outer surface of the diffuser (3), and / or wherein the at least one solar filter (4) is arranged on the inner portion of the diffuser (3).

[0124] Clause 10. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is arranged on the dome (1), particularly arranged to at least partially cover the inner surface (12) and / or outer surface (11) of the dome (1).

[0125] Clause 11. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) comprises one or more vacuum-deposited dielectric metal layers.

[0126] Clause 12. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is a transmission interference filter.

[0127] Clause 13. The irradiance meter (100) according to any of the preceding clauses, wherein the at least one filter (4) is a reflective filter; or wherein the at least one filter (4) is an absorptive filter.

[0128] Clause 14. The radiation measuring instrument (100) according to any of the preceding clauses further includes at least one collimator configured to collimate the radiation irradiated onto the receiving surface (22) of the thermopile-based sensor (2).

[0129] Clause 15. The radiation measuring instrument (100) according to any of the preceding clauses, wherein the distance between the diffuser (3) and the thermopile-based sensor (2) is set such that the radiation diffused by the diffuser (3) onto the receiving surface (22) of the thermopile-based sensor (2) has a generally conical shape.

[0130] Figure Labels

[0131] 1. Dome

[0132] 2 Thermopile-based sensors

[0133] 3 Diffuser

[0134] 4. Filters

[0135] 5 Control Unit

[0136] 6. Irradiation measuring instrument housing

[0137] 7. Filter support element

[0138] 10 cavities

[0139] 11. The outer surface of the dome

[0140] 12. The inner surface of the dome

[0141] 13. External environment of the radiation meter

[0142] 14. Opening at the base of the dome

[0143] 15. The edge of the dome

[0144] 21. Second (bottom) surface of a thermopile-based sensor

[0145] 22 Receiving surface of thermopile-based sensors

[0146] 22a Window of the housing

[0147] 23. The casing of a thermopile

[0148] 31 The first incident or top surface of the diffuser

[0149] 32 The second (bottom) surface of the diffuser

[0150] 33. Side surface of the diffuser

[0151] 61. Leveling feet (one or more) of the irradiation meter housing

[0152] 62. First (outer) part of the irradiation meter housing

[0153] 63 The second (internal) part of the irradiation meter housing

[0154] 64 Support Plate

[0155] 65. Through opening in the second part of the irradiation meter housing.

[0156] 70. Through opening in the filter support element

[0157] 71. Base section

[0158] 72 Grooves

[0159] 100 Irradiation Meter

[0160] S Support Surface

[0161] The longitudinal axis of the X3 diffuser.

Claims

1. An irradiation meter (100), comprising: Dome (1); Thermopile-based sensor (2) includes a receiving surface (22); A diffuser (3) is configured to diffuse solar radiation from outside the irradiance meter (100) through the dome (1) toward the receiving surface (22) of the thermopile-based sensor (2), wherein the distance of the optical path between the diffuser (3) and the thermopile-based sensor (2) is set such that the solar radiation diffused by the diffuser (3) onto the receiving surface (22) of the thermopile-based sensor (2) has a generally conical shape. as well as At least one filter (4) is arranged in the optical path of radiation in front of the receiving surface (22) of the thermopile-based sensor (2) in order to modify the spectral composition of the solar radiation measured by the thermopile-based sensor (2).

2. The irradiation meter (100) according to claim 1, wherein, The at least one filter (4) at least partially compensates for the spectral selectivity of the thermopile-based sensor (2).

3. The radiation measuring instrument (100) according to any one of claims 1 to 2, wherein, The at least one filter (4) at least partially compensates for the spectral selectivity of the diffuser (3).

4. The radiation measuring instrument (100) according to any one of claims 1 to 3, wherein, The at least one filter (4) at least partially compensates for the spectral selectivity of the dome (1).

5. The irradiation meter (100) according to any one of the preceding claims, wherein, The at least one filter (4) modifies the spectral composition of the solar radiation measured by the thermopile-based sensor (2) such that the spectral selectivity of the spectral absorptivity and spectral transmittance of the thermopile-based sensor (2), the diffuser (3), and the dome (1) has a maximum percentage deviation of about ±3% relative to the average value in the wavelength range of the solar radiation spectrum from 350 nm to 1500 nm.

6. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) is configured such that the total transmittance of the at least one filter (4) for spectral wavelengths below 400 nm is greater than the total transmittance of the at least one filter (4) for spectral wavelengths greater than 700 nm.

7. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) is arranged in the optical path between the diffuser (3) and the receiving surface (22) of the thermopile-based sensor (2).

8. The irradiation meter (100) according to any one of the preceding claims, wherein, The at least one filter (4) is arranged substantially facing the receiving surface (22) of the thermopile-based sensor (2).

9. The irradiation meter (100) according to claim 8, wherein, The at least one filter (4) is arranged substantially facing the active black coated surface of the thermopile-based sensor (2).

10. The radiation meter (100) according to any one of claims 8 to 9, wherein, The at least one filter (4) is embedded in the active black coating material of the thermopile-based sensor (2).

11. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The thermopile-based sensor (2) is located in a housing (23), wherein at least one filter (4) is arranged to substantially cover a window (22a) of the housing (23).

12. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) is arranged to at least partially cover the outer surface of the diffuser (3).

13. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) is arranged on the inner part of the diffuser (3).

14. The irradiation meter (100) according to any one of the preceding claims, wherein, The at least one filter (4) is arranged on the dome (1).

15. The irradiation meter (100) according to claim 14, wherein, The at least one filter (4) is arranged to at least partially cover the inner surface (12) and / or outer surface (11) of the dome (1).

16. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) includes one or more vacuum-deposited dielectric metal layers.

17. The radiation measuring instrument (100) according to any one of the preceding claims, wherein, The at least one filter (4) is a transmission interference filter.

18. The irradiation meter (100) according to any one of the preceding claims, wherein, The at least one filter (4) is a reflective filter; or wherein the at least one filter (4) is an absorptive filter.

19. The irradiance meter (100) according to any one of the preceding claims further includes at least one collimator configured to collimate solar radiation irradiating the receiving surface (22) of the thermopile-based sensor (2).

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