Measuring device with sensor system for detecting at least one property of water

Abstract

Measuring device (11) with at least one sensor (1) arranged below the water surface for detecting a measured value that varies depending on at least one water property and which has at least one measuring cell (2) or a measuring window through which a measuring signal is emitted into the water and / or received from the water, characterized in that at least one irradiation unit (3) is provided and is arranged such that at least a part of the measuring cell (2) or the measuring window is irradiated at least temporarily with UV radiation, wherein the irradiation unit (3) has at least one means (4) by which the beam guidance and / or beam shaping of the UV radiation can be changed.

Description

[0001] The invention relates to a measuring device with a sensor system for detecting at least one property of water. The described measuring device is designed to ensure that a sensor, which is arranged below the water surface for measuring at least one property of the water and has at least one measuring window or measuring cell through which the measurement signals are exchanged with the water, is reliably protected from fouling by organisms.

[0002] Both measuring instruments and technical systems installed in or near water often record or utilize measurements obtained from sensors located below the water's surface. Due to the submerged location of these sensors, the installation and maintenance of such sensor systems can be quite complex. Therefore, it is crucial that these sensors, even when exposed to harsh environmental conditions, particularly in marine environments, can operate reliably over extended periods without damage and deliver the most accurate measurements possible.

[0003] A significant problem in the operation of such sensor systems is so-called biofouling. Biofouling, or simply fouling, refers to the unwanted growth of organisms on technical surfaces such as ship hulls, hydraulic structures, and, of course, sensors. Besides affecting the specifications of the measuring instruments, biofouling repeatedly and considerably limits the measurement quality and the service life of submerged measuring devices. The growth of organisms on sensor surfaces where signals are exchanged with the surrounding water is particularly problematic, as such growth can quickly impair the measurement accuracy. In some cases, the growth of organisms even leads to massive damage to the sensors, for example, when barnacles grow on a wiper blade and scratch the measuring window during a wiper operation.

[0004] From the publication "A. Lakretz, EZ Ron and H. Mamane, 'Biofouling control in water by various UVC wavelengths and doses,' Biofouling, pp. 257-267, 04 2010" it is known that ultraviolet radiation, especially in the wavelength range of 280-200 nm, i.e., so-called UV-C radiation, is suitable for hindering or even preventing the formation of biofilms and the associated deposition of organic material on technical surfaces underwater. From "C. Bueley and B. Bocking, 'The (in)fluence of light,'" The Journal of Ocean Technology, Vol. 9, No. 4, pp. 49-67, 2014" describes a currently commercially available system for preventing the adhesion of organisms to technical surfaces, particularly sensors. The device comprises a UV radiation source that irradiates the sensor's measuring window, through which radiation is exchanged with the surrounding water, with UV light.

[0005] The problem with the known system is that the energy requirement of the irradiation unit used is comparatively large, so that when operating the irradiation unit together with sensor systems that are to remain for a longer period of time, for example at a measuring station on the open sea, a corresponding power supply or energy storage system must be provided.

[0006] Furthermore, US Patent 5,322,569 discloses a device that uses a UV irradiation unit to prevent the unwanted colonization of organisms on the surface of underwater technical installations. A key technical feature of the described device is that the irradiation intensity varies, particularly in specific cycles. This technical solution is primarily intended for large underwater technical surfaces, where irradiation of the surface is not continuous but occurs at predetermined intervals. Specifically, irradiation units are described that move along the surface to be irradiated, such that the irradiation intensity varies depending on the selected irradiation cycles or the length of the period during which no irradiation takes place.The described irradiation technique does not appear to be useful for relatively small sensor surfaces.

[0007] Furthermore, WO 2016 / 001227A1 describes an irradiation unit used to treat surfaces that are at least temporarily submerged or exposed to spray water with UV radiation to prevent biofouling. The described irradiation unit is suitable for treating the underwater areas of ships, other structures that come into contact with water (such as pipelines), or in canals, lakes, or aquariums, and features

[0008] Essentially, the system uses an LED or multiple LEDs and a control unit to vary the radiation intensity as needed, particularly in response to a signal specific to the risk of biofouling on or around the irradiated surface. In addition to varying the radiation intensity, the system aims to enable on-demand, intermittent irradiation of a surface, for example, with pulsed radiation. Furthermore, the combined use of UVA radiation in a wavelength range of 315 to 400 nm and UVC radiation in a wavelength range of 100 to 280 nm is also disclosed. To achieve the desired beam shaping, it is proposed to use an optical medium with fluid-filled channels or spaces.

[0009] Starting from the problem of the unwanted colonization of organisms on the sensor surfaces of underwater sensors, and considering known devices that use UV radiation to prevent or at least delay the long-term accumulation of organic material, the invention aims to provide a corresponding system that can inhibit or even prevent fouling on measuring instruments of various designs in a particularly energy-efficient manner. The proposed technical solution should therefore enable the use of irradiation units that are optimized with regard to light output and the electrical energy required for effective irradiation.In particular, it should be possible to operate a sensor system even under comparatively harsh conditions at remote measuring locations, especially at sea, while ensuring that reliable and accurate measurements are generated over a comparatively long period. To achieve this, the energy consumption of an antifouling device should be designed to be so energy-efficient that it allows for the operation of a decentralized measuring station powered solely by battery units, rather than by a power grid.

[0010] The aforementioned problem is solved by a measuring device according to claim 1. Advantageous embodiments of the invention are the subject of the dependent claims and are explained in the following description with partial reference to the figures.

[0011] The invention relates to a measuring device with at least one sensor arranged below a water surface for measuring at least one property of the water. The sensor has at least one measuring window or measuring cell through which a measurement signal is emitted into and / or received from the water, wherein at least one irradiation unit is provided and configured such that at least a portion of the measuring window or measuring cell is irradiated with UV radiation, at least temporarily. According to the invention, the device is further developed such that the irradiation unit has at least one means by which the beam guidance and / or shaping of the UV radiation can be changed. Preferably, such a means is designed such that the focusing of the irradiation unit can be changed and, in particular, adapted to the shape and size of the sensor, especially the measuring window or measuring cell.Advantageously, an irradiation unit can be operated in at least two different operating modes with regard to beam guidance and / or shaping.

[0012] In general, it is conceivable that a measuring window or measuring cell is irradiated with UV radiation continuously or at specific intervals. In this context, it is advantageous to carry out the irradiation depending on the measurement periods. Irradiation preferably takes place outside of the measurement cycles to largely eliminate any influence on the measurement. It is also conceivable to perform pulsed irradiation or to define irradiation periods at time intervals.

[0013] In a particular embodiment of the invention, the means of the irradiation unit has at least one fastening element to which a light source and / or an optical element for beam guidance and / or beam shaping is detachably and non-destructively attached. According to the invention, it is thus initially provided that an irradiation unit, which irradiates sensors below the water surface with UV radiation, preferably with UV-C radiation in the wavelength range of 200 to 280 nm, can be configured as required depending on the respective measurement purpose. According to a further development of the invention, it is provided in this context that the irradiation unit is designed as a surface or point source, depending on the selected light source and / or optical element configuration.Advantageously, the irradiation source may include at least one light source, for example an LED, whose radiation is optionally focused onto the area to be irradiated by an additional optical element, preferably a lens. Such an irradiation unit can be used either as a surface emitter without an additional element or, once an additional optical element has been mounted, as a point emitter. The irradiation of the sensor surface, in particular the measuring window, is thus carried out as needed and therefore particularly effectively.

[0014] In known systems, quartz glass tubes are typically used, encased in a POM housing. These tubes are rotatably and slidably mounted and connected to the power supply of a power station via a Subconn underwater connector and corresponding cable. The known irradiation units are compact modules whose irradiation, particularly their beam power and beam geometry, cannot be adapted to the design of the sensor being irradiated. In contrast, the invention demonstrates that significant energy savings can be achieved if an irradiation unit, designed for irradiating at least one measuring window or measuring cell of a sensor, can be adapted to the sensor with regard to beam generation and beam guidance.

[0015] It is therefore highly advantageous if an irradiation unit designed for underwater operation has a mounting element, allowing a light source and / or an optical element for beam guidance to be selected and attached to the irradiation unit as needed. This is particularly beneficial for relatively small measuring windows or cylindrical measuring cells if the irradiation unit is designed as a point source, with the generated UV radiation being focused onto the measuring window by means of an optical element, especially a convex lens. If necessary, the optical element can be removed or replaced to either adjust the focus or to use the irradiation unit as an area source.

[0016] Due to such a measure, the light output during the irradiation of a sensor is adapted to the geometry and size of the respective sensor, especially its measuring window, which enables particularly energy-efficient operation with regard to the individual sensor and the irradiation unit.

[0017] In a specialized training program, a constant current source is provided to supply the irradiation unit with electrical energy. Such a constant current source can be located in the immediate vicinity of the irradiation unit, integrated into the unit itself, or positioned at a central location. In this context, it is conceivable that the constant current source could, for example, be located on a platform anchored in the sea or on a semi-submersible.

[0018] In a particular embodiment, at least two sensors are provided, wherein a first of the at least two sensors is irradiated by an irradiation unit designed as a surface emitter, while a second of the at least two sensors is irradiated by an irradiation unit designed as a point or line emitter. According to this embodiment, at least two sensors and two irradiation units, each assigned to one of these sensors, are thus provided, which are adapted as required to the geometry and size of the sensors, in particular the measuring windows through which corresponding measurement signals are exchanged with the water.

[0019] Furthermore, it is advantageous if the irradiation unit includes an LED and an optical element for beam guidance. These components are preferably designed such that the LED and / or the optical element for beam guidance are attached to a mounting element of the irradiation unit in a non-destructively removable manner. For example, the LED could be attached to a mounting element designed as a slot, and / or the optical element to a snap-in or clamping element of the mounting element. It is also generally conceivable that the mounting elements could be designed in the form of threads.

[0020] In a specialized development, the optical element features a focusing optic with a variable focal length. This technical solution allows the focal length of the focusing optic to be adapted relatively easily to the distance and size of the measurement window of the sensor being irradiated. A corresponding optical element can thus be advantageously used with different light sources and / or for various sensors and always adjusted to the required focal length. Furthermore, with such a beam-guiding optical element, it is possible to change the focal length so that either a point or an area on the sensor surface is selectively irradiated with UV radiation, particularly UV-C radiation in a wavelength range of 200 to 280 nm.A suitably designed irradiation unit with a focusing optic whose focal length can be changed as required can thus be used as a point source or as a surface source within the limits defined by the adjustability of the focal point.

[0021] If at least two irradiation units are used, then, with regard to the supply of electrical energy to the irradiation units, it is preferably provided that at least two irradiation units are supplied with electrical energy from parallel-arranged current supply lines. According to this further development, two irradiation units are thus advantageously supplied with electrical energy from a constant current source, wherein the two irradiation units are preferably electrically connected in series. If several irradiation units are used, it is generally advantageous if they are electrically connected in series. If the connection voltages of the individual irradiation units, in particular the forward voltages of the LEDs of the irradiation units, exceed the available supply voltage, at least two electrically parallel supply lines are preferably provided.

[0022] In general, it is conceivable that, if more than two irradiation units are used, at least two electrically parallel power supply lines are provided, with at least two irradiation units connected in series within each power supply line. Naturally, in this context, it is advantageous if both an irradiation unit and the sensor associated with that irradiation unit, and / or the measuring device to which the sensor belongs, are supplied with electrical energy from the same power supply line or via the same path.

[0023] In a further embodiment, a central control unit is provided that monitors the supply of electrical energy to the irradiation units and controls it appropriately, or preferably even implements a regulation system. It is advantageous if the current within a supply line can be varied when at least a defined voltage and / or current limit is exceeded or fallen below. Generally, it is conceivable that the control unit monitors the power supply to at least one irradiation unit, preferably a plurality of irradiation units, in such a way that, on the one hand, all irradiation units are adequately supplied with electrical energy, and, on the other hand, damage due to overvoltages or excessive currents is reliably prevented.Furthermore, it is conceivable that, if necessary, individual irradiation units and / or measuring devices could be selectively disconnected from the power supply network to reliably prevent damage to the individual supply lines and / or to the remaining irradiation units and / or measuring devices. Such a control unit, in turn, contributes to increasing the energy efficiency of a device for fouling protection of underwater sensors using at least one irradiation unit and ensures the long-lasting, reliable, and proper operation of the energized irradiation units and / or measuring devices.

[0024] Furthermore, the invention relates to a measuring device with at least one sensor arranged below the water surface for detecting a measured value that varies depending on at least one water property, wherein the sensor is irradiated at least partially with UV radiation, in particular with UV-C radiation in the wavelength range of 200 to 280 nm, by means of a device having at least one of the properties described above. Such a measuring device has at least one interface via which the at least one detected measured value is transmitted wirelessly or via a wired connection to a central data storage device and / or a central evaluation unit for data processing. According to a particular embodiment, the measuring device has at least one data logger with which the detected measuring values ​​are stored at least temporarily before being read out.The measuring device(s) are arranged below the water surface and serve to record the physical and / or chemical properties of the water surrounding them. Typically, a connection exists between the at least one measuring device and a central data storage and / or evaluation unit for data processing, which is arranged on a platform anchored in the water or on a semi-submersible, for unidirectional or bidirectional data exchange and power supply. Preferably, a plurality of measuring devices are connected to a platform and / or a semi-submersible arranged at different water depths.

[0025] Furthermore, the invention also relates to a sensor system with a device configured according to at least one of the previously described embodiments. Preferably, at least two sensors are provided, arranged underwater at different distances from the water surface. Moreover, according to a specific embodiment, the at least one sensor is configured to perform an optical method for measuring turbidity and / or chlorophyll fluorescence in the water. It is also conceivable that at least one of the sensors is configured to detect a conductivity value, a temperature value, and / or a pressure value in the water.

[0026] Essential to the solution according to the invention is the use of UV radiation, in particular UV-C radiation in the wavelength range of 200 to 280 nm, as an active measure to prevent or at least significantly inhibit fouling on the sensors, especially in the area of ​​the surfaces intended for measurement, the so-called measuring windows. The irradiation units are attached to the measuring devices containing the sensors to be irradiated and / or to ropes, cables, and / or guides located in the water in such a way that the UV radiation emitted by the irradiation unit strikes at least the sensor area essential for measurement, in particular a measuring window or a measuring cell through which the measurement signals are exchanged with the water, in order to keep this surface as free of fouling as possible.

[0027] According to specialized training, additional passive measures are planned to prevent or at least hinder the accumulation of organic matter on measuring devices and the sensors used. In this context, it is conceivable that passive sensor surfaces, in particular those not performing a direct measurement function, could incorporate copper to prevent the accumulation of organic material on these surfaces.

[0028] The invention achieves a particularly high ratio of emitted light power to electrical power required to generate the radiation compared to commercially available systems. Preferably, a plurality of sensors with associated irradiation units are electrically connected in series in a power supply line, whereby the inclusion of at least one series connection again results in an energy-efficient configuration. Alternatively, it is conceivable to connect at least two power supply lines, at least one of which contains at least two series-connected sensors with their associated irradiation units, in parallel and to supply them with the required electrical energy from a constant current source.

[0029] The invention will now be explained in more detail with reference to specific embodiments and the figures, without limiting the general concept of the invention. The figures show: Fig. 1: Electrical circuitry of a measuring setup with ten sensors, each irradiated with UV radiation by an irradiation unit; Fig. 2: Fluorometer with a sensor for optical measurement of turbidity and chlorophyll fluorescence and with an irradiation unit; Fig. 3: Probe with sensor for conductivity measurement and with an irradiation unit; Fig. 4: Irradiation unit with an SMD LED and a plano-convex lens; Fig. 5: Irradiation unit with an SMD LED and a biconvex lens as well as Fig. 6: Irradiation unit with an SMD LED and a plano-convex lens in a fiber optic cable.

[0030] Fig. Figure 1 shows the electrical circuitry of a sensor system comprising ten measuring devices 11 arranged below the water surface, each equipped with sensors 1 for detecting different properties of the water. Such a sensor system can be preferably used for marine research, for example, in the Baltic Sea.

[0031] Each individual sensor 1 is assigned an irradiation unit 3, from which it is irradiated with UV-C radiation, which has a wavelength of approximately 280 nm, particularly in the area of ​​a measuring cell or a measuring window 2 through which measurement signals are exchanged with the water. This irradiation prevents or at least inhibits the growth of organic material in this area.

[0032] According to the embodiment shown here, a total of ten sensors 1 are provided, which are arranged at least partially at different water depths in order to detect certain parameters of the water, preferably seawater.

[0033] The measuring devices 11 with sensors 1 are attached to an insulated support cable 16 and each has an irradiation unit 3, wherein all irradiation units 3 have an SMD LED as a light source 6 and some irradiation units 3 additionally have an optical element 7, in particular a plano-convex or a biconvex lens, as a means 4 for beam guidance. The irradiation units 3 with LED as light source 6 and partially with LED as light source 6 and additional optical element 7 are each arranged in a glass body made of quartz glass, the interior of which is sealed watertight against the surrounding seawater at its interface with the measuring device 11 by means of a gasket.

[0034] Depending on the design of the sensor 1 to be irradiated, the irradiation units 3 are configured as point emitters or as area emitters, wherein the irradiation units 3 configured as point emitters have an additional optical element 7, in particular a lens, as a means 4 for beam guidance. According to the Fig. In the embodiment shown in Figure 1, the ten measuring devices 11 with corresponding sensors 1 and irradiation unit 3 are supplied with the required electrical energy via three parallel supply lines 9 from a constant current source 8, which is arranged on a base station, e.g. on a platform anchored in the sea or a semi-submersible.

[0035] According to the in Fig. The electrically powered measuring devices 11 (M1, M2, M3, M4, M5, M6, M7, M8, M9, M10) shown in the circuit shown, each with sensor 1 and irradiation unit 3, are attached to an insulated support cable 16 and arranged at a water depth of 2 m (M1, M4), 5 m (M2, M5), 7 m (M3), 16 m (M6), 25 m (M7), 33 m (M8), 40 m (M9) and 42 m (M10). The measuring instruments 11 are supplied with electrical energy via three parallel-connected supply lines 9 (S1, S2, S3), whereby measuring instruments M1, M2 and M3 are supplied via the first supply line S1, measuring instruments M4, M5 and M6 via the second supply line S2, and measuring instruments M6, M7, M8, M9 and M10 via the third supply line S3. The current in the first line S1 is 40 mA, and the current in the second and third lines S2 and S3 is 20 mA each.

[0036] At water depths of 2 m, 5 m, 7 m, 16 m, 25 m, 33 m, 40 m, and 42 m, measuring instruments M1, M2, M3, M6, M7, M8, M9, and M10 record the temperature, pressure, and conductivity of the water. A central evaluation unit 14 uses these values ​​to determine, in particular, the salinity of the water at the respective depth. At water depths of 7 m and 40 m, measuring instruments M3 and M9 also measure the oxygen content of the water. Measuring instruments M1, M2, M6, M7, M8, and M10 are all Sea-Bird Scientific SBE 37-IMP MicroCAT probes. Measuring instruments M3 and M9 are all Sea-Bird Scientific SBE 37-IMP-ODO MicroCAT probes. Furthermore, fluorometers M4 and M5 are provided at water depths of 2 m and 5 m respectively, with which turbidity and chlorophyll fluorescence measurements are carried out.These are 2-channel fluorometers of the type ECO FLNTU from the company Sea-Bird Scientific.

[0037] Four of the ten measuring instruments 11, namely the fluorometers M4, M5 and the measuring probes M3, M9 for determining the temperature, conductivity, pressure and additionally the oxygen content, are irradiated with an irradiation unit 3 designed as a surface emitter, which has an SMD element of type VPC164, while six of the ten measuring instruments 11, namely the measuring instruments M1, M2, M6, M7, M8 and M10 for determining the temperature, conductivity and pressure, are irradiated with an irradiation unit 3 designed as a point emitter, which has a THT element of type VPT761 with integrated lens. The SMD LEDs of type VPC164, which are used as area emitters, have a beam angle of 120°, emit UV-C radiation with a wavelength of 280 nm and have a luminous flux of 40 mW at 350 mA and a forward voltage of 5.8 V.The LED as light source 6 is located on a substrate with a metal core and connections for electrical contact.

[0038] The VPT761 type spotlights have an LED as a light source 6, a lens as an optical element 7 and a Zener diode, have a beam angle of 7°, also emit UV-C radiation with a wavelength of 280 nm and have a luminous flux of 1.6 mW at 20 mA and a forward voltage of 5.0V.

[0039] Essential feature of the embodiment according to Fig. The principle is that each measuring device 11 with sensor 1 is assigned an irradiation unit 3, which is adapted to the design of the sensor 1 as required. The irradiation of the sensors 1 is carried out, in particular depending on the shape and size of the measuring window or measuring cell 2 to be irradiated, through which measurement signals, either optical or electrical signals, are exchanged with the surrounding seawater, either with a point or a surface emitter.

[0040] Compared to known technical solutions for fouling protection using UV-C irradiation, the illustrated embodiment achieves approximately seven times better efficiency in terms of light output. In particular, the ratio between light output and required electrical power is correspondingly high compared to known commercial solutions. Furthermore, since different optics 7 are used as needed to irradiate the individual sensors 1 and the measuring devices 11 located at different depths, and since some of these are also designed as point sources, especially with LEDs as the light source 6 and with a focusing lens as the optical element 7, energy efficiency is significantly increased. By providing a centrally located constant current source 8, series circuits can be implemented, as shown, to further increase the efficiency of the overall system.Advantageously, the constant current source 8 is stationed on a base station arranged above water, on a platform anchored in the sea, or on a semi-submersible.

[0041] Furthermore, it shows Fig. 2 A measuring device 11, designed as a fluorometer. Using the illustrated measuring device 11 and the integrated sensor 1, measured values ​​representing the turbidity and chlorophyll fluorescence of the water are recorded. Optical beams are emitted from the sensor 1 through a measuring window 2 into the seawater surrounding the sensor 1, and radiation reflected from particles located along a measuring path is also recorded. Using a suitable evaluation unit 14, the turbidity of the water and / or the concentration of certain substances in the water is determined based on the received radiation.

[0042] The measuring window(s) 2 of the sensor 1 are irradiated with UV-C radiation having a wavelength of 280 nm by means of an SMD LED as a light source 6, which forms a surface emitter. The irradiation unit 3 with the LED 6, which is arranged in a quartz glass bulb, is supplied with the required electrical energy by a constant current source 8. Due to the irradiation of the measuring window(s) 2 of the sensor 1 with the UV-C radiation, the accumulation of organic material in the area of ​​the measuring window(s) 2 is reliably prevented.

[0043] The effectiveness of the device in promoting or preventing fouling can be verified through visual inspection during routine maintenance runs. It is also possible to assess the functionality of the measuring devices and their integrated sensors based on the measurement data obtained.

[0044] Fig. Figure 3 shows a measuring device 11 for recording the conductivity of the seawater surrounding the sensor 1 of the measuring device 11. Since the conductivity of the water cannot be measured directly, an indirect measurement is carried out, for example by measuring the voltage after applying a current of known strength.

[0045] Sensor 1 of the in Fig. The measuring device 11 shown in Figure 3 has a measuring cell 2 that encloses a defined volume of seawater. By applying a current of known intensity, the conductivity of the seawater in the measuring cell can be determined from the voltage applied to the measuring cell 2. The measuring cell 2 of the sensor 1 is irradiated by an irradiation unit 3, which in this case is a through-hole technology (THT) element with an integrated lens, forming a point source. Surface areas of the measuring cell 2 are irradiated with UV-C radiation with a wavelength of 280 nm. This irradiation prevents or at least hinders the growth of organic material on the measuring cell 2.

[0046] Even those in Fig. The irradiation unit 3 shown is supplied with the energy required for the generation of UV-C radiation by a constant current source 8 arranged on a platform or a semi-submersible.

[0047] Preferably, a measuring station comprises a measuring arrangement with a plurality of measuring devices 11 or sensors 1 for recording various parameters of the seawater and / or individual water parameters at different water depths. A central unit is provided at the measuring station, comprising a central evaluation unit 14 for processing measurement data and a constant current source 8. The constant current source 8 supplies the various measuring devices 11 with their integrated sensors 1 with the electrical energy required for each measurement. A central control unit 10 monitors the power supply to the various sensors 1 and checks whether permissible voltage and / or current limits are exceeded or fallen below, for example, in parallel-connected supply lines 9 or at individual measuring devices 11 with sensors 1 and irradiation units 3 connected in series in the supply lines 9.The power supply is adjusted in such a way that reliable voltage and current values ​​are always maintained in each existing supply line 9 for supplying the measuring instruments 11 and in particular the irradiation units 3 with the required electrical energy.

[0048] Likewise, individual supply lines 9 with the sensors 1 and irradiation units 3 connected in series therein can be selectively switched off as soon as impermissible overvoltages or excessive currents occur in a supply line 9. In principle, however, it is also conceivable to implement a control unit 10 in such a way that individual irradiation units 3 can be selectively and as required controlled, in particular switched on or off, or their light output varied.

[0049] In the Fig. 4, Fig. 5 and Fig. Figure 6 shows side views of special irradiation units 3 with means for beam guidance 4. Fig. Figure 4 shows an irradiation unit 3 comprising an SMD LED mounted on a substrate 17 as a light source 6 and an optical element 7 designed as a plano-convex lens for beam guidance. The plano-convex lens 7 focuses the radiation emitted by the LED 6, which has a wavelength of 280 nm, thus providing a surface emitter. By changing the distance h between the LED 6 and the plano-convex lens 7, the size of the irradiated area can be varied as required.

[0050] Fig. Figure 5 shows an irradiation unit 3 comprising an SMD LED mounted on a substrate 17 as a light source 6 and an optical element 7 designed as a biconvex lens for beam guidance. The biconvex lens 7 focuses the radiation emitted by the LED 6, which has a wavelength of 280 nm, at the focal point of the outer lens, thus providing a point source. By changing the distance h between the LED 6 and the biconvex lens 7, the focal point, and in particular its distance from the focusing lens, can be varied as required.

[0051] Both lenses, i.e., both the plano-convex lens according to Fig. 4 as well as the biconvex lens according to Fig. 5 are advantageously made of quartz glass.

[0052] Fig.Figure 6 shows a schematic representation of another irradiation unit 3 according to the invention. The irradiation unit 3 has an SMD LED as a light source 6 and a plano-convex lens as an optical element 7, through which the radiation emitted by the LED 6 is focused. The LED 6 and the plano-convex lens 7 are arranged within a fiber optic cable 15, so that the emitted light is directed as required to the sensor surface to be irradiated, in particular a measuring window or a measuring cell 2.

[0053] The irradiation of the measuring window or measuring cell 2 can be carried out with an irradiation unit 3 or a plurality of irradiation units 3, which are arranged, for example, in a ring shape. Reference symbol list 1 sensor 2 measuring cells or measuring windows 3 irradiation units 4. Means for beam guidance and / or beam shaping 5 Fastening element 6 light bulbs 7 Optical element 8 Constant current source 9 Power supply line 10 central control unit 11 Measuring device 12 Interface 13 Data storage 14 evaluation units 15 optical fibers 16 Support cable 17 Substrat

Claims

[1] Measuring device (11) with at least one sensor (1) arranged below the water surface for detecting a measured value which varies depending on at least one water property and which has at least one measuring cell (2) or a measuring window through which a measuring signal is emitted into the water and / or received from the water, characterized by , that at least one irradiation unit (3) is provided and arranged in such a way that at least a part of the measuring cell (2) or the measuring window is irradiated at least temporarily with UV radiation, wherein the irradiation unit (3) has at least one means (4) by which the beam guidance and / or beam shaping of the UV radiation can be changed. [2] Measuring device (11) according to claim 1, characterized by , that the means (4) are designed in such a way that the focusing of the irradiation unit (3) can be changed at least temporarily. [3] Measuring device (11) according to claim 1 or 2, characterized by, that the means (4) for changing the beam guidance and / or beam shaping has a fastening element (5) to which a light source (6) and / or an optical element (7) for beam guidance and / or beam shaping is detachably attached without damage. [4] Measuring device (11) according to any one of the preceding claims, characterized by , that the means (4) of the irradiation unit (3) for beam guidance and / or beam shaping is designed such that the irradiation unit (3) is designed as a surface or point emitter depending on a selected lamp and / or optical element configuration. [5] Measuring device (11) according to any one of the preceding claims, characterized by , that a constant current source (8) is provided which supplies the irradiation unit (3) with electrical energy. [6] Measuring device (11) according to any one of the preceding claims, characterized by, that at least two sensors (1) are provided, wherein a first of the at least two sensors (1) is irradiated by an irradiation unit (3) designed as a surface emitter, while a second of the at least two sensors (1) is irradiated by an irradiation unit (3) designed as a point or line emitter. [7] Measuring device (11) according to any one of the preceding claims, characterized by , that the irradiation unit (3) has an LED as a light source (6) and an optical element (7) for beam guidance and / or beam shaping. [8] Measuring device (11) according to claim 7, characterized by is that the optical element (7) has a focusing optic whose focal length is variable. [9] Measuring device (11) according to any one of the preceding claims, characterized by, that at least two irradiation units (3) are provided for irradiating each of a sensor (1), which are supplied with electrical energy by parallel connected power supply strands (9). [10] Measuring device (11) according to any one of the preceding claims, characterized by , that a central control unit (10) is provided which monitors the supply of electrical energy to the irradiation unit (3) and changes the voltage and / or current of the supply current if at least a specified voltage and / or current limit value of a supply current is exceeded or fallen below. [11] Measuring device (11) according to one of the preceding claims, characterized by, that a central control unit (10) is provided which monitors the supply of electrical energy to the irradiation unit (3) and, in the event of an exceedance or fall below at least a specified voltage and / or current limit, interrupts the power supply to at least one sensor (1), at least temporarily. [12] Measuring device (11) according to any one of the preceding claims, characterized by , that an interface (12) is provided via which the at least one recorded measurement value is transmitted wirelessly or via a wired connection to a central data storage device (13) and / or a central evaluation unit for data processing (14). [13] Measuring device (11) according to claim 12, comprising a data logger as a data storage device (13) which stores the at least one recorded measurement value at least temporarily. [14] Measuring device (11) according to any of the preceding claims, characterized by, that at least two sensors (1) are provided which are arranged at different distances from the water surface. [15] Measuring device (11) according to any one of the preceding claims, characterized by , that at least one sensor (1) is set up to carry out an optical method for measuring turbidity and / or chlorophyll fluorescence in water. [16] Measuring device (11) according to any one of the preceding claims, characterized by , that at least one sensor (1) is set up to detect a conductivity value, a temperature value and / or a pressure value in the water.

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