DE102022116884A1 - Optical measuring device for spectral analysis of a sample - Google Patents

Abstract

The disclosure relates to an optical measuring device for the spectral analysis of a sample and includes an illumination unit that is set up to irradiate the sample with light, as well as a spectral sensor unit that is set up to detect light transmitted by the sample via a first observation path and a to provide a corresponding first sensor signal, and to detect the light emitted by the illumination unit independently of the sample via a second observation path and to provide a corresponding second sensor signal. The illumination unit and the spectral sensor unit are located on the same side of the sample.

Description

The present disclosure relates to an optical measuring device for the spectral analysis of a sample, to a corresponding method, to the use of the optical measuring device in an agricultural or food technology device, whereby the spectral analysis is carried out as far as possible without disturbing intervention in the ongoing process.

In exemplary embodiments, the present disclosure relates to measuring devices and measuring methods that are designed to spectrometrically record and evaluate the (diffuse) transmission of light through the sample in an uninterrupted or uninterrupted manner in order to be able to draw precise conclusions about the properties of the sample .

A spectrometer is an arrangement that is designed to record the intensity of incident light depending on the wavelength and to output a corresponding signal. This can be done, for example, on the basis of dispersion (for example through a grating or prism), filter-based, with selective sensitivity or interferometrically.

Designs of spectrometers as such are known. A spectrometer usually comprises three functionally distinct elements, although these can certainly be structurally combined. A first element serves to “collect” incident light (or electromagnetic radiation in the visible range and in areas adjacent to the visible range). A second element is used to “split up” the incident light to separate different wavelengths in the light. The first element and the second element can be combined together in an optical assembly. A third element is used to detect the incident light that has passed through the first element and the second element. For example, individual sensors or pixel-based sensor arrays are used. A control unit is also usually provided for control and evaluation.

Measuring systems for the spectral evaluation of samples are generally known in various designs from the prior art. This includes arrangements for absorption spectroscopy. These are often systems for use in laboratory environments. Measuring systems are known which are based on the observation of the transmission of light through the sample. On the other hand, there are measuring systems that make use of the reflection of light on the sample.

In both types of measurement systems, so-called standards (also referred to as standards) are used to separate the influences of the measurement setup during a measurement from the properties of the sample. In absorption spectroscopy, which is based on the transmission of light, for example, so-called “black” and “white” standards are used to record sensor signals that are representative of signals from very bright or very dark samples. Basically, detected sensor signals have characteristics that result both from the sample or the interaction with the sample and from the measuring device or its environment. However, since the (sample) properties of the standards are known, the device properties can be determined alone (i.e. independent of the sample) and compensated or numerically corrected accordingly when measuring unknown samples. The device properties that can influence the measurement signal include, for example, a wavelength-dependent emission of the illumination by the device, a wavelength-dependent sensitivity of the detectors, as well as interference and extraneous light that is not adequately shielded by the device. If this process is carried out before a measurement, an initial calibration of the measuring device can take place.

The measurement results in relation to the samples to be measured are usually between the two measurement values for the standard “black” and “white”. However, standards or auxiliary standards are also conceivable, which are not necessarily assigned to an edge (extremum) of the dynamic range of the measurement, but are arranged within this range.

For the most precise measurement results possible, changes in the measurement conditions during operation of the measuring device should ideally be taken into account. Such changes can result, for example, from deposits or contamination on the light source or from changes in the intensity or color temperature of the light source over the course of operating time. Furthermore, thermal influences on the measuring system are also relevant with regard to any fluctuations in sensitivity or falsification of measurement results. The properties of optical components or detector components within the spectrometer used in the measuring device can change in such a way that measurement inaccuracies can arise. Along the chain between the light source, sample and sensor unit, various factors can have an influence on the spectral measurement. Especially when the measuring device is in continuous operation (not just individual measurements or intermittent measurements), a certain amount of drift in the measurement result is to be expected. This is even more true more the further the specific measurement task is from ideal laboratory environments.

In order to continue to ensure correct measurement results, recalibrations with the auxiliary standards mentioned are required at regular intervals. This increases the effort and may require an interruption of the observed process. Therefore, regular recalibration is not necessary. As a rule, for recalibration, the sample is removed from the sample plane and replaced by the standards or calibration standards. After measuring the standards, the sample is then brought back into the sample plane and measured in relation to the recently determined standards.

However, this process is not only disruptive and time-consuming, but may not be possible at all. This applies in particular to at least partially continuous processes in agricultural, food technology or a comparable industrial environment. Such processes should ideally run without interruption.

The DE 10 2004 021 448 A1 discloses a spectrometric reflection measuring head with internal recalibration. The measuring head has at least two standards (normals), preferably a black and a white standard, in the housing of the measuring head for internal recalibration, which can optionally be pivoted into the beam path of the reflection measuring head. After the measurement data from the standards have been recorded by the spectrometer, the reflection measuring head is recalibrated by a control and evaluation unit. In addition, at least two external standards can be used to calibrate the reflection measuring head before commissioning the measuring arrangement or at certain intervals. Recalibration therefore requires an interruption in observation of the sample.

The DE 10 2004 048 102 A1 also relates to an arrangement for measuring the diffuse reflection of corresponding samples and a method for internal recalibration of the measuring head. The disclosed spectrometric measuring head with recalibration consists of a housing provided with a window, in which an illumination source, a spectrometer arrangement and at least two standards (normals) for internal recalibration are present, whereby these standards can optionally be pivoted into the beam path of the measuring head in such a way that all measuring light emitted from the illumination source is used for recalibration. The internal recalibration occurs intermittently; the sample cannot be observed during the recalibration. The proposed arrangement can be used in the visible light range and in the near-infrared range.

The use of transmitted light to examine a sample is, for example, from DE 10 2017 108 552 A1 known, which discloses a spectrometric measuring head with a measuring surface that can be positioned on an examination surface of a sample. The measuring head comprises a light source, at least one illumination window in the measuring surface, through which light provided by the light source is emitted towards the examination surface of the sample, at least two transmission light entry windows, which are also positioned in the measuring surface and allow light remitted by the sample to enter , which has traveled an optical path through the sample, with each transmission light entry window being spaced from the illumination window by a predetermined, mutually different amount, and a spectral sensor unit with a plurality of spectral sensors or sensor channels, with each transmission light entry window being assigned at least one of these spectral sensors or sensor channels in order to detect the light that has entered there and to send a corresponding sensor signal to a downstream signal processing unit.

In particular, in the DE 10 2017 108 552 A1 disclosed measuring head optically shields the transmission light entrance windows to shield scattered light that exits directly from the illumination window or light reflected from the sample that has not passed through an optical path in the sample. The measuring head thus allows the spectrometric evaluation of the diffuse transmission of light that has passed through a sample, for example to determine properties of the sample using chemometric models.

Challenging in the in the DE 10 2017 108 552 A1 The approach disclosed is that a practical implementation in continuous operation can possibly only deliver reliable results under idealized conditions (“laboratory conditions”). For example, in an implementation in the agricultural sector, this is due to the unavoidable vibration influences caused by machines and the like, which do not allow light path lengths to remain constant. The chosen approach, namely the derivation of a stable model for tracking the white standard over different lengths through the sample, is highly challenging in terms of practical implementation. In addition, the disclosed method cannot replace the calibration of an initial white standard.

The above-described and other known approaches and devices for determining Measurement of sample properties using transmission measurements must also face the challenge of use in practical operations, for example in the field or in an agricultural or food technology company.

Due to the harsh operating conditions, it is desirable to re-reference or re-calibrate the detector using an auxiliary standard. While, as described above, pivoting in an auxiliary standard enables recalibration in reflection measurements, it is generally not possible to pivot in an auxiliary standard in transmission measurements because the sample is simply “in the way” when it is positioned as usual between the light source and detector and, if necessary, Is part of a material stream. If this material flow is to be recorded and evaluated as directly as possible - in the sense of an in-process measurement - this conversely means that the measuring device with the illumination window and transmission light entry window must be brought as close as possible to a path/channel of the material flow. An auxiliary standard cannot simply be placed there.

When measuring samples in the agricultural or food technology sector, it has been found that measurements using transmission generally offer the advantage over measurements using reflection in that the signal strength is higher. This is due to the substances and materials used in these areas, which often have a granular structure with many cavities and thus enable multiple reflections with diffuse transmission. Furthermore, samples can be at least partially fluid, in particular at least partially liquefied. If necessary, inexpensive detectors can be used for transmission measurements, while more sensitive detectors, such as indium-gallium-arsenide detectors, may be required for reflection measurements.

A general objective for the development and design of optical measuring devices for the property analysis of samples, especially for industrial and agricultural use, is to increase the accuracy and improve the robustness or suitability for use under harsh conditions, such as when used in agricultural devices , food technology systems and the like. Furthermore, an optical measuring device should enable continuous use in such applications, with as little or no interruption as possible. In addition, the improved properties should be able to be achieved as far as possible without additional costs, preferably at lower costs.

Against this background, the present disclosure is based on the object of providing an optical measuring device for the spectral analysis of a sample, which can be used as uninterrupted as possible and with which long-term high measurement accuracy can be achieved. The measuring device should be suitable for agricultural and related food technology applications, especially with regard to the robustness of the device. The measuring device should be suitable for applications in the agricultural or food technology environment. The measuring device should, if possible, enable in-process measurement of a material stream without influencing the material stream as such.

At least in exemplary embodiments, the present disclosure aims to provide an optical measuring device for spectral analysis, which enables high accuracy and reliability with an ideally simple and inexpensive structure. In general, the measuring device should be suitable for use in the agri-food environment and in related areas (agricultural energy sector, food technology and similar).

• - eine Beleuchtungseinheit, die dazu eingerichtet ist, die Probe mit Licht zu bestrahlen, und
• - eine Spektralsensoreinheit, die dazu eingerichtet ist,
• - über einen ersten Beobachtungspfad von der Probe transmittiertes Licht zu erfassen und ein entsprechendes erstes Sensorsignal bereitzustellen, und
• - über einen zweiten Beobachtungspfad das von der Beleuchtungseinheit abgestrahlte Licht unabhängig von der Probe zu erfassen und ein entsprechendes zweites Sensorsignal bereitzustellen,

wobei sich die Beleuchtungseinheit und die Spektralsensoreinheit auf derselben Seite der Probe befinden.This task is solved by an optical measuring device for the spectral analysis of a sample, the measuring device having the following:

• - an illumination unit that is designed to irradiate the sample with light, and
• - a spectral sensor unit that is set up to
• - to detect light transmitted by the sample via a first observation path and to provide a corresponding first sensor signal, and
• - to detect the light emitted by the lighting unit independently of the sample via a second observation path and to provide a corresponding second sensor signal,

wherein the illumination unit and the spectral sensor unit are on the same side of the sample.

In this way the object of the invention is completely solved.

According to the disclosure, the sample is analyzed using light transmitted by the sample. In comparison to a signal that is primarily based on reflection, the first sensor signal is ideally stronger, which can enable more precise spectral analysis of the sample's properties. The sample is analyzed, for example, with a structure in which the illumination unit and the spectral sensor unit are located on the same side of the sample, i.e. are not separated from each other by the sample. This means that the device can also withstand adverse circumstances, for example in agricultural machinery. Even if the sample includes, for example, cereal grains, chopped material, silage or manure, the arrangement enables precise and robust transmission measurement.

In the context of the present disclosure, an arrangement of the illumination unit and the spectral sensor unit on the same side of the sample is to be understood as meaning a positioning in which the sample is not spatially arranged between the illumination unit and the spectral sensor unit. In this way, an arrangement is dispensed with in which the observation beam path of the first observation path and the associated illumination beam path are arranged essentially coaxially, at least in the vicinity of the sample. In other words, a transmitted light arrangement, as used in microscopes or other image processing applications, is deliberately avoided. In this way, the measuring device is suitable for observing material flows, with no need to take any diameter of a flow channel into account, since the measuring device can be flanged laterally to such a flow channel.

In an exemplary embodiment, the arrangement of the illumination unit and the spectral sensor unit on the same side of the sample accordingly relates to an adjacent arrangement of the illumination unit and the spectral sensor unit in a peripheral section of the flow channel. With respect to such a flow channel and its imaginary center, the lighting unit and the spectral sensor unit are not offset from one another by 180° with respect to the center. Instead, the lighting unit and the spectral sensor unit are arranged in a circumferential section with an extension of less than 180°, preferably less than 90°, more preferably less than 45°. In an exemplary embodiment, the first observation path and the associated illumination path lie geometrically in the same hemisphere with respect to an (imaginary) center of the flow channel, with an axis of symmetry of the hemisphere being oriented perpendicular to the (imaginary) flow direction.

This exemplary division can also be transferred to flow channels with a non-round cross section. In the case of a flow channel with a rectangular cross section, this means, for example, that the lighting unit and the spectral sensor unit are arranged together on one of the four sides of the rectangle. The arrangement of the illumination unit and the spectral sensor unit can also include an offset along the flow direction between the illumination unit and the spectral sensor unit, especially when taking into account a flowing sample. The spectroscopic detection is therefore not based on the transmitted light principle. Instead, the intention is to capture light that was otherwise transmitted by the sample.

At least in exemplary embodiments, the measuring device allows in-process measurement or in-process monitoring. This can also be done in adverse conditions. The measuring device is suitable for monitoring a material flow, for example for monitoring crops or comparable goods.

The design of the measuring device allows the constant provision of a reference signal. Ideally, a reference signal is permanently available that is not or only minimally influenced by the sample. In exemplary embodiments, the detection takes place via the first observation path and the second observation path in parallel time (simultaneously). In other words, first sensor signals via the first observation path and second sensor signals via the second observation path are available at least temporarily (preferably permanently) during operation of the measuring device. Ideally, a reference signal is available at all times that allows the consideration/elimination of external influences that do not originate from the sample.

For example, this design can also be used if a normal (black normal or white normal) is also used. It can also be advantageous if, in addition to the normal (for example moved into the first observation path), a reference is available via the second observation path. Any influences that do not relate to the respective standard can then be recorded and taken into account.

At least in exemplary embodiments, however, there is no need to use additional (for example mechanically retractable/pivotable) auxiliary standards (for example black standards or white standards), since the light emitted by the light source is also detected independently of the sample. According to these configurations, complicated mechanical components are eliminated, which fundamentally simplifies the structure of the measuring device. On the other hand, it increases the robustness of the device, as there are no moving parts in particular, which are often damaged by vibrations or shocks and can therefore be the cause of falsified measurement results.

In principle, the sample-independent observation of the light source in the measuring device according to the disclosure can take place permanently and without interrupting the measuring process, while the measurement of an auxiliary standard requires a dedicated measurement in which the actual measurement of the sample must be interrupted because, for example, the auxiliary standard falls into the light path between the light source and detector must be swiveled in. A temporally parallel referencing can therefore be carried out instead of a temporally serial referencing. This means that the referencing can take place at the same time as the measurement of the sample, so that there is no time lag between the sample measurement and the measurement of the deviation from a standard. This means that the respective deviations can be recorded much more precisely, so that the accuracy of the measurement of the sample properties can be significantly increased.

The fact that the light emitted by the illumination unit via the second observation path can be detected independently of the sample means that the second observation path goes past the sample, i.e. does not pass through it. In other words, there is no interaction between the light emitted on this observation path and the sample, so that the light on this path remains unaffected by the sample, and thus in particular by its light-changing properties. The observation of the lighting unit via the spectral sensor unit or, more precisely, the detection of light via the second observation path preferably takes place simultaneously with the detection of light via the first observation path. However, it is also conceivable that the detection of light via the second observation path and the detection of light via the first observation path take place at a time offset (i.e. asynchronously), with the time offset assuming, for example, a predetermined value. A partial temporal overlap is also conceivable. Furthermore, the detection of light via both paths (each) can take place at discrete, but preferably as short as possible, time intervals. The time intervals preferably correspond to the integration time of the assigned detector (or the respective assigned detectors) in the spectral sensor unit. In principle, it is also conceivable to capture the light via the first path and the second path in a continuous manner.

The first observation path includes an observation beam path that is directed directly or indirectly at the sample. Typically, an illumination beam path is also provided, via which the sample is illuminated by the illumination unit, with transmitted light that has interacted with the sample entering the observation beam path of the first observation path. The second observation path includes an observation beam path that is directed directly or indirectly at the lighting unit. In other words, in the second observation path, the observation beam path coincides at least in sections with the illumination beam path, since the light from the illumination unit enters the observation beam path of the second observation path without interaction with the sample.

According to an exemplary embodiment, a spectral sensor unit according to the disclosure comprises common optics for both (albeit sufficiently separated) observation paths, which can be used to guide, collect the light and separate the light into different wavelength ranges. According to a first variant, this design can be combined with a (single) spectral detector that is capable of receiving light via both observation paths. According to a second variant, this design can be combined with two spectral detectors, each of which is assigned to one of the two paths. These designs may further include placement of the components on a common circuit board. Overall, a spectral sensor unit designed in this way can be referred to as an integrated spectral sensor unit.

According to a further exemplary embodiment, a spectral sensor unit according to the disclosure comprises two spectral sensors, each of which includes its own optics and its own spectral detector. Each of the two spectral sensors is assigned to one of the two spectral observation paths. The two spectral sensors can be combined with one another in a suitable manner. This may include an adjacent or spaced arrangement. Overall, such a spectral sensor unit can be referred to as a distributed spectral sensor unit.

Regardless of whether there is an integrated spectral sensor unit or a distributed spectral sensor unit, a joint evaluation of the detected sensor signals from the two observation paths is provided. In this way, the reference signal provided via the second observation path can be taken into account when evaluating the sensor signal provided via the first observation path. Regardless of whether the spectral detectors are structured are actually coupled with each other, a functional coupling is achieved in this way.

In an exemplary embodiment, the optical measuring device has a separating element that is designed to block a reflection path that delivers light reflected (directly) from the sample to the spectral sensor unit. The light that is recorded in the first observation path mostly includes light that was transmitted through the sample. Although parts of directly reflected light are generally not harmful to the measurement, they contain less information about the sample properties. It is therefore desirable to capture the highest possible proportion of transmitted light and a low proportion of reflected light through the geometric-optical arrangement of lighting, sample, separating element and first observation path. However, a low proportion of reflected light cannot usually be ruled out. The separating element can be adjusted or optimized depending on the nature of the sample. In this way, for example, the ratio of directly reflected light to transmitted light can be optimized depending on the granularity of bulk materials and the like.

According to an exemplary embodiment, a reflection observation path is further provided, via which light reflected directly from the sample is detected, in particular with spatial resolution, by a light-sensitive sensor unit. Accordingly, the measuring device is deliberately set up to detect light directly reflected from the sample via a further, third observation path (also: reflection path) and to provide a corresponding further sensor signal (reflection signal). A suitable sensor unit for this purpose is, for example, a spatially resolving light-sensitive sensor, for example a camera with an image sensor array, which is provided in addition to the at least one spectral sensor of the spectral sensor unit. According to this embodiment, the spatially resolving sensor does not detect any spectrometric signals divided into wavelength ranges. In this embodiment, the detection takes place without spectral decomposition, although in principle spectrometric detection via the reflection observation path is also conceivable. In this way, additional reference data can be obtained that can be used in the evaluation.

In a further exemplary embodiment, the spectral sensor unit is set up to directly detect the light emitted by the lighting unit. Direct detection of the emitted light by the spectral sensor unit means, at least in exemplary embodiments, that the light reaches the spectral sensor unit on the second observation path in the form of free light propagation (without deflection). The aim is generally to have as little interaction as possible with the sample, preferably no interaction at all with the sample. Furthermore, according to this embodiment, the light is ideally not influenced by an optical unit. In this respect, according to this embodiment, the second observation path runs along a path that extends directly and without being influenced by optical elements between the lighting unit and the spectral sensor unit.

In a further exemplary embodiment, the spectral sensor unit is set up to detect the light emitted by the lighting unit via an optical unit (also: optically effective unit). This refers by way of example to the first and/or the second observation path. Examples of optical units are mirrors, diffuse surfaces (in particular auxiliary standards), light guides, lenses, beam splitters, homogenizers, filters and beam transformers. Ideally, it is known in which way the optical units influence the light emitted by the lighting unit so that their influence can be taken into account when evaluating the corresponding sensor signal.

In another exemplary embodiment, the spectral sensor unit of the optical measuring device has a first beam path and a second beam path, the first beam path being set up to record the light transmitted by the sample via the first observation path, and the second beam path being set up to do so to record light emitted by the lighting unit independently of the sample via the second observation path. For example, the first observation path and the second observation path are sufficiently spatially or structurally separated from one another so that interactions are avoided as far as possible. The spectral sensor unit can thus detect the light of the first observation path via the first beam path independently of the light of the second observation path via the second beam path (and vice versa).

In an exemplary embodiment, the first observation path and the second observation path have a common spectroscopic optical unit through which the light transmitted by the sample runs along the first observation path and the light emitted by the illumination unit independently of the sample runs along the second observation path.

In an exemplary embodiment, the spectral sensor unit has monolithic optics unit (also: optics) into which at least the first observation path or the second observation path are integrated at least in sections. In an exemplary embodiment, the first observation path and the second observation path are integrated - at least in sections - into the monolithic optical unit. This design can further include one or more spectral sensors that are adjacent to the optical unit, so that overall a compact module is created that includes at least a beam guide (optical unit) and a detector for the first observation path and the second observation path. In principle, it is also conceivable to provide separate monolithic optics for the first observation path and the second observation path.

An exemplary embodiment of a monolithic optics for a spectrometer is in WO 2014/001074 A1 shown. Monolithic refers in particular to the relevant design of the optics. In the case of a spectrometer, for example, this can include at least the collecting optics and the dispersive element. In an exemplary embodiment, the monolithic optic is made in one piece from a material (plastic) that can be processed by injection molding. This simplifies series production. Furthermore, there are cost advantages, particularly in series production. Monolithic optics increase the robustness of the spectral sensor unit.

In an exemplary embodiment, the two observation paths lead to a common detector, the detector being, for example, a spatially resolving detector. For example, the spectra of the incident light from the two observation paths are imaged in two different detector dimensions. This can be done simultaneously. The respective orientation is, for example, adapted to a dispersion element that is assigned to the respective observation path. For example, two different detector rows each represent a measurement channel. Such spectral sensors use, for example, a sensor matrix or a sensor array, whereby the observation paths can be assigned to different sections of it.

In an exemplary embodiment, the spectral sensor unit has two spectral sensors, one of which is assigned to the first observation path and another to the second observation path. In an exemplary embodiment, the two spectral sensors are arranged adjacent to one another or spaced apart from one another. For example, the spectral sensors are so-called line detectors, each of which is assigned to one of the observation paths.

For the purposes of the present disclosure, the terms first observation path and second observation path refer to the subdivision of the light that is supplied to the spectral sensor unit. The first observation path relates to light that has interacted with the sample, usually transmitting. The second observation path refers to light that is supplied to the spectral sensor unit independently of the sample (ideally without interaction with the sample).

In one embodiment of the optical measuring device, the first observation path and the second observation path have a common spectroscopic optics through which the light transmitted by the sample and the light emitted by the illumination unit independently of the sample pass. This means that the light from the first observation path and the light from the second observation path pass through the same spectroscopic optics. The spectroscopic optics can include, as optical elements, one or more of mirrors, light guides, lenses, beam splitters, homogenizers, filters, beam transformers, diffraction gratings, prisms and apertures (for example an optical slit).

The use of common spectrometric optics for the light of both observation paths has the advantage that any influences on the first observation path (measuring channel for observing the sample) also influence the second observation path (reference path). In this way, such influences can be partially or completely compensated for.

If the first observation path and the second observation path are each aligned in a straight line, an orientation inclined to one another is conceivable. In this way, the fact is taken into account that the second observation path is directed directly at the illumination unit and the first observation path is directed directly at the sample illuminated by the illumination unit, but not directly at the illumination unit. This applies at least to exemplary embodiments. An angle of inclination between the first observation path and the second observation path is, for example, in a range between 10° and 170°, in particular in a range between 75° and 105°. It is understood that the observation paths (comprising beam paths) in other embodiments can also have optically effective elements that deflect or otherwise influence beams.

According to a further exemplary embodiment, the spectral sensor unit has at least one spectral sensor with at least one photoelectric detector, which is set up to detect light in the visible range and in the near-infrared range. This includes, for example, the range between 550 nm and 1100 nm (nanometers). The spectrum that can be detected usually depends on the detector material. Visible light, for example, includes wavelengths between 380 nm and 750 nm, although only partial ranges may be used for spectral recording and evaluation. The near-infrared range, for example, includes wavelengths between 690 nm and 3000 nm, although only partial ranges may be used for spectral recording and evaluation. The person skilled in the art can influence the detectable spectrum by choosing a suitable detector material, with frequency ranges other than visible light and near-infrared also being conceivable, for example UV radiation.

The detectable area usually depends on the detector material used. For example, the photoelectric detector is a photodiode sensor. It is conceivable to use silicon-based, germanium-based and indium-gallium-arsenide-based detectors. The use of detectors based on lead sulfide or lead selenide is also fundamentally conceivable. In principle, the photoelectric detector can comprise a detector array with several sensors.

By way of example, the lighting unit of the optical measuring device has one or more light sources. Various types of light sources are conceivable, for example semiconductor light sources, thermal light sources, gas discharge lamps. Luminescence light sources that use phosphorescence or fluorescence, for example, are also conceivable. In an exemplary embodiment, the at least one light source can comprise a light-emitting diode (LED), an incandescent lamp (in particular a tungsten incandescent lamp) or a halogen lamp (in particular a quartz halogen lamp). Combinations are fundamentally conceivable. It is understood that the emission spectrum of the at least one light source of the lighting unit is suitably adapted to the detectable spectrum of the at least one detector. The at least one light source can be operated pulsed or continuously.

According to a further exemplary embodiment, the optical measuring device has an evaluation unit which is set up to determine at least one property of the sample based on the first sensor signal and the second sensor signal. The at least one property of the sample relates, for example, to moisture, composition, components, surface quality, size, shape or temperature of the sample. It goes without saying that the evaluation can also aim at another variable that can be derived from this. The at least one property of the sample can affect the sample as a whole or a component thereof.

Since the second sensor signal (reference signal) only reflects properties of the lighting unit or in particular has no properties that can be traced back to the sample, while the first sensor signal is based on both properties of the lighting unit and properties of the sample, it is possible to include the first sensor signal To clean up with the help of the second sensor signal and thus to generate a sensor signal or measurement result that has little or no distortions due to changes in the lighting unit (such as fluctuating intensity) or other influences that are not due to the sample.

By way of example, the evaluation unit is set up to determine the (current) properties of the lighting unit from the second sensor signal and to determine the properties of the sample from the first sensor signal, taking into account the evaluation of the second sensor signal (or the determination of the properties of the lighting unit). This can refer, for example, to fluctuations in the intensity of the lighting unit. This enables the evaluation unit to determine the properties of the sample in such a way that influences due to changes in the lighting unit are taken into account and compensated for.

In principle, with the measuring device according to the disclosure there is also the possibility of taking into account other effects and influencing factors that are not necessarily due to the lighting unit. In principle, effects can be recorded and compensated for that can be detected both in the first observation path and in the second observation path.

For example, the evaluation unit is set up to determine the moisture or size of crops, such as grains. However, the protein content, starch content or oil content of harvested crops can also be determined. It is also conceivable that the evaluation unit is set up to monitor the properties of seeds or fertilizer or to determine the cutting length, the fiber condition or the like of cuttings. It is also conceivable that ingredients in manure or other agricultural waste products could be determined. Another conceivable application is, for example, the analysis of silage or comparable products.

According to another exemplary embodiment of the optical measuring device, the spectral sensor unit is further set up to detect incoming light via the first and/or second observation path when the lighting unit is switched off or the light from the lighting unit is shielded, and to provide a corresponding normal signal. The normal signal can be obtained for the first observation path and/or the second observation path.

In addition to the “white calibration” via the light source, this also enables a “black calibration”. While, for example, a lighting unit with a semiconductor light source can be switched on and off with little or no delay (for example for pulsed operation), other light sources react much more slowly, for example thermal light sources. Such light sources are usually operated continuously. With such light sources, it is conceivable to leave the light source in its state for the black or dark calibration and to block the emitted light beams with a blocking element so that they do not reach the detector.

The blocking element is designed, for example, such that it blocks both the light on the first observation path and the light on the second observation path. It goes without saying that two or more blocking elements are also conceivable. In an exemplary embodiment, the blocking element also shields any stray light from the spectral sensor unit or blocks all light emanating from the lighting unit. The blocking element can be, for example, a mechanical shutter. It goes without saying that arrangements with comparatively “dynamic” light sources can also be combined with at least one blocking element.

In a further exemplary embodiment of the optical measuring device, the evaluation unit is further set up to determine the property of the sample taking into account the at least one normal signal. By way of example, this includes determining a sample property both taking into account the white calibration (or white referencing based on the light source) and taking into account the black calibration.

In an exemplary embodiment, the sample that is to be analyzed by the optical measuring device is part of an agricultural or food technology material stream. The material stream can be a mixture. The material stream can contain solid or liquid components. The material stream can contain a mixture of solid and liquid components. The material stream can be a granular, granular or lumpy mixture that can be poured. The material stream may contain suspended matter. Gaseous components are also conceivable. The material stream may contain plant and/or animal based components. The material stream can also contain components of synthetic origin, for example synthetic fertilizer and/or synthetic pesticides. By way of example, the material flow includes plants or plant parts, plant waste or animal waste, agricultural products, food technology products, and the like. For example, the material flow includes agricultural auxiliary materials such as organic or synthetic-based fertilizers or pesticides. For example, the material stream contains crops, manure or the like.

Accordingly, the optical measuring device preferably has a protective device which is located between the sample and the illumination unit or spectral sensor unit and thus protects the illumination unit and the spectral sensor unit from the sample. The protective device is usually transparent to the light emitted by the illumination unit and to the light transmitted by the sample. The protective device can be, for example, a protective glass that is both robust and scratch-resistant, such as sapphire glass. The protective device can be one piece or comprise several parts. For example, the protective device can have a first protective glass between the lighting unit and the sample and a second protective glass between the spectral sensor unit and the sample. In an exemplary embodiment, the protective device is selected such that there is no or, if possible, only little interaction with the light that is transmitted by the sample.

In a preferred exemplary embodiment, the optical measuring device is designed to be installed in an agricultural or food technology machine. Agricultural or food technology machines include tractors, equipment for soil cultivation, equipment for sowing, fertilization and plant care, harvesting technology, transport technology and logistics, forestry technology, machines and systems for indoor farming (e.g. milking technology), irrigation systems and equipment for the garden - and landscape conservation in question. In exemplary embodiments it is a mobile (mobile) machine. Machines for harvesting technology include, for example, combine harvesters, forage harvesters and the like.

Furthermore, a measuring device according to the disclosure can also be used in machines from the agri-food sector, which are also assigned to agricultural machines in the context of the present disclosure.

Preferably, the optical measuring device is mounted in the agricultural or food technology machine in such a way that it is arranged in the vicinity of a material stream applied or taken in by the machine, so that the first observation path and/or the second observation path are as short as possible. In this way, in-process measurement and/or in-process monitoring is possible directly on the machine. The material flow can be continuously monitored if necessary.

According to a further aspect, the present disclosure relates to the use of an optical measuring device according to at least one of the embodiments described herein in an agricultural or food technology device for analyzing a sample, in particular for analyzing a material stream.

According to a further aspect, the present disclosure also relates to an agricultural or food technology device with an optical measuring device according to the disclosure. The agricultural or food technology device is therefore designed, for example, as a harvesting machine, soil cultivation machine, sowing machine and machine for applying fertilizer or plant protection products.

• - Anordnen einer Beleuchtungseinheit und einer Spektralsensoreinheit auf derselben Seite der Probe,
• - Bestrahlen der Probe mit Licht der Beleuchtungseinheit,
• - Erfassen von von der Probe transmittiertem Licht mit der Spektralsensoreinheit über einen ersten Beobachtungspfad und Bereitstellen eines entsprechenden ersten Sensorsignals, und
• - Erfassen von von der Beleuchtungseinheit unabhängig von der Probe abgestrahltem Licht mit der Spektralsensoreinheit über einen zweiten Beobachtungspfad und Bereitstellen eines entsprechenden zweiten Sensorsignals.

According to a further aspect, the present disclosure also relates to an optical measurement method for spectral analysis of a sample, the method comprising the following steps:

• - Arranging an illumination unit and a spectral sensor unit on the same side of the sample,
• - irradiating the sample with light from the lighting unit,
• - Detecting light transmitted by the sample with the spectral sensor unit via a first observation path and providing a corresponding first sensor signal, and
• - Detecting light emitted by the lighting unit independently of the sample with the spectral sensor unit via a second observation path and providing a corresponding second sensor signal.

A measuring device according to the disclosure and the measuring method according to the disclosure are particularly suitable for use in the agricultural and food industry. This does not exclude other applications, for example in the pharmaceutical industry. Material flows are also processed in this area and in related areas and it is desirable to monitor them closely.

In the context of the present disclosure, the term “reflection” includes the reflection of light as it impinges on an interface of the sample. To put it more precisely, this means the one-time reflection of the light away from the sample, for example towards a detector or a spectral sensor unit.

The term “transmission” includes the passage of light through the sample. The transmission of light is subject to various mechanisms, which can also include reflection within the sample.

Both reflection and transmission can be accompanied by diffusion (also called scattering). The light beam entering the sample is deflected in different directions. Diffuse reflection is also called “remission”. Diffuse transmission can also be understood as a series of light reflections within the sample. If no diffusion occurs, in both reflection and transmission, according to the laws of geometric optics, a light beam with a specific direction of propagation is deflected into a light beam with a (different) specific direction. Whether reflection or transmission occurs in a directed or diffuse manner depends largely on the type of sample. With translucent samples such as manure, direct transmission can predominate in transmission measurements, while with a stream of grains as a sample, diffuse transmission can predominate due to the many cavities between the grains.

The term “calibration” is to be understood as a process in which the deviation of the measurement result of a measuring device from a measured value determined elsewhere, which is referred to as normal (or standard), is recorded and documented. As a further step, calibration can include taking the determined deviation into account during the subsequent use of the measuring device to correct the measured values. Calibration usually takes place before an actual measurement process and is therefore often referred to as “initial calibration”. A “recalibration” is to be understood as the repetition of a calibration.

A “referencing” in the sense of a reference measurement can be part of a “calibration”. In the context of the present disclosure, the term “referencing” is to be understood as meaning the provision of a reference (obtained via the second observation path) to which the signal of primary interest (obtained via the first observation path) is referenced. This allows the continuous or quasi-continuous consideration and compensation of influencing factors that are present both in the second observation path and in the first observation path and are therefore not due to the interaction of the light with the sample.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present disclosure.

• 1 eine Ausgestaltung einer agrartechnischen Maschine;
• 2 eine schematische, vereinfachte Darstellung einer optischen Messvorrichtung;
• 3 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung;
• 4 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung;
• 5 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung;
• 6 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung;
• 7 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung;
• 8 eine weitere schematische Darstellung einer Ausführungsform einer optischen Messvorrichtung; und
• 9 ein Blockdiagramm zur Veranschaulichung einer beispielhaften Signalverarbeitung in einer Steuereinheit einer optischen Messvorrichtung.

Further features and advantages of the invention result from the following description and explanation of various exemplary embodiments with reference to the drawings. Show it:

• 1 an embodiment of an agricultural machine;
• 2 a schematic, simplified representation of an optical measuring device;
• 3 a further schematic representation of an embodiment of an optical measuring device;
• 4 a further schematic representation of an embodiment of an optical measuring device;
• 5 a further schematic representation of an embodiment of an optical measuring device;
• 6 a further schematic representation of an embodiment of an optical measuring device;
• 7 a further schematic representation of an embodiment of an optical measuring device;
• 8th a further schematic representation of an embodiment of an optical measuring device; and
• 9 a block diagram to illustrate exemplary signal processing in a control unit of an optical measuring device.

1 shows, based on a schematically simplified representation, an exemplary embodiment of an agricultural machine 10, which in the exemplary embodiment is designed as a mobile harvester 12, in particular as a so-called forage harvester.

The machine 10 has a chassis 14 which carries a structure 16. Furthermore, a drive 18 is provided, which is designed as a travel drive and as a process drive for other units. The structure 16 carries a cabin 20. The machine 10 can be used in a field 22, for example to harvest plants 24. In this way, the machine 10 can pick up crop 26 with a stem 30. In the exemplary embodiment as a forage harvester, the machine 10 has a process chamber 32 for treating the crop 26. In the exemplary embodiment, this includes a chopper 34, which shreds the crop 26. In the exemplary embodiment, shredded/chopped crop 40 is conveyed as a material stream 42 via a channel/shaft surrounded by a wall 44 in the direction of an ejection 46 for transfer to other machines or storage. It goes without saying that the machine 10 can also have an internal memory for crop 26 or chopped crop 40.

The material stream 42 can be monitored spectroscopically using an optical measuring device 50. In this way, various properties of the material stream 42 can be determined. This can be done in particular during operation of the machine 10, whereby this requires a certain robustness of the measuring device 50. Preferably, the measuring device 50 is positioned close to the material stream 42. The measuring device 50 is preferably suitable for continuous measurement and monitoring of the material stream 42 flowing past, which acts here as a sample.

The machine 10 also has a (global) control device 52, which communicates with the measuring device 50 in a suitable manner. This can include data exchange with a control unit integrated into the measuring device 50. This can also include receiving and processing sensor data provided by at least one spectral sensor of a spectral sensor unit of the measuring device 50. The control device 52 is designed, for example, to change parameters of the process taking place in the process chamber 32 (for example comminution of the crop 26) depending on the data provided by the measuring device 50.

Based on the in 1 Machine 10 shown is an exemplary application of a disclosed one Approximate optical measuring device 50 illustrated. It goes without saying that various other applications are conceivable, especially those with a material flow that needs to be monitored.

2 illustrates an exemplary embodiment of an optical measuring device 50 according to the disclosure using a schematic block diagram. The measuring device 50 is used to observe a sample 54, which in the exemplary embodiment is a material stream 42, for example from chopped crop 40. The material stream 42 runs through one of one Wall 44 surrounded channel. The measuring device 50 is docked to the wall 44 in the exemplary embodiment.

Essential components of the measuring device 50 in the exemplary embodiment are a lighting unit 56 with at least one light source 58 and a spectral sensor unit 62. In the exemplary embodiment, the spectral sensor unit 62 comprises a first spectral sensor 64 and a second spectral sensor 66. These can be functionally and/or structurally coupled to one another. The spectral sensor unit 62 observes a first observation path 70 and a second observation path 80. In the exemplary embodiment according to 2 the first spectral sensor 64 observes the first observation path 70. The second spectral sensor 66 observes the second observation path 80.

An observation beam path 72 extends along the first observation path 70. Light (electromagnetic radiation in the visible range and possibly in neighboring areas) that was transmitted by the sample 54 is detected via the first observation path 70, compare a radiation path through the sample indicated by 74. The light transmitted through the sample 54 goes back to the lighting unit 56. The illumination unit 56 sends light along an illumination path 76 towards the sample 54, which is then transmitted by the sample 54. The illumination path 76 includes an illumination beam path 78.

The spectral sensor unit 62 thus detects light emanating from the lighting unit 56 that has interacted with the sample 54. In the exemplary embodiment, this is done via the first spectral sensor 64. However, detection also takes place along the second observation path 80. The second observation path 80 extends between the lighting unit 56 and the spectral sensor unit 62 in such a way that the detected light via the second observation path 80 does not coincide with the Sample interacted. By way of example, this includes a direct detection of the light emitted by the lighting unit 56 via the second spectral sensor 66. In the exemplary embodiment, the second observation path 80 includes a beam path 82, which is both an illumination beam path and an observation beam path. The beam paths 72, 78, 82 are in 2 indicated schematically by imaginary optical axes.

The spectral sensor unit 62 includes an optical unit 88, which, for example, provides the function of collecting incident light and separating it into different wavelengths. In the exemplary embodiment, the optical unit 88 comprises a first optics 90, which is assigned to the first spectral sensor 64, and a second optics 94, which is assigned to the second spectral sensor 66. The optics 90, 94 are designed, for example, as monolithic optics. It is also conceivable to design the optical unit 88 with the optics 90, 94 overall as a monolithic optical unit.

The spectral sensor unit 62 further comprises at least one detector, wherein in the exemplary embodiment a first detector 92, which is assigned to the first spectral sensor 64, and a second detector 96, which is assigned to the second spectral sensor 66, are provided. The spectral sensor unit 62 can in principle also be designed in such a way that images are imaged on one and the same detector via both observation paths 70, 80. This can, for example, include the use of individual rows of a pixel matrix.

In the exemplary embodiment according to 2 A control unit designated 100 is also indicated, which is designed to process signals detected by the spectral sensor unit 62 via the first observation path 70 and the second observation path 80.

Signals detected via the second observation path 80 are used for referencing; in the design of the optical measuring device 50 shown, any influences on the second observation path 80 are not due to the interaction of the light emitted by the lighting unit 56 with the sample 54. Therefore, such influences can be compensated for in the signals detected via the first observation path 70, whereby the spectrometric analysis of the sample 54 can be carried out more precisely.

2 further illustrates that the illumination unit 56 and the spectral sensor unit 62 are arranged adjacent to one another near the sample 54. This includes, for example, an arrangement on one and the same side of the sample 54, for example with respect to the wall 44 that surrounds the flow channel of the sample 54. In the exemplary embodiment shown, the sample 54 does not travel via the first observation path 70 observed using a transmitted light method. Instead, the observation via the first observation path 70 focuses on light that was transmitted by the sample. The light enters and exits via windows 102, 104 in the wall 44. The windows 102, 104 are designed to be sufficiently optically transparent and sufficiently wear-resistant. The light emitted by the illumination unit 56 via the illumination path 76 enters the sample 54 via the window 104. At least part of this light is transmitted by the sample in such a way that exit from the sample 54 can occur via the window 102 along the first observation path 70 of the spectral sensor unit 62.

Based on the 2 illustrated embodiment of an optical observation device 50 are described below with reference to 3-7 further designs and aspects of such observation devices 50 are explained. It goes without saying that individual aspects and individual features of the various embodiments can be combined with one another.

3 illustrates an embodiment of an optical measuring device designated overall by 50 using a simplified schematic representation. The optical measuring device 50 includes an illumination unit 56 and a spectral sensor unit 62, the illumination unit 56 being set up to irradiate a sample 54 with light (visible light and adjacent wavelength ranges). The spectral sensor unit 62 is set up to detect both the light of the illumination unit 56 transmitted by the sample 54 and the light emitted by the illumination unit 56 independently of the sample 54. Furthermore, the optical measuring device 50 comprises a separating element 110, which is only indicated schematically, which ensures that light reflected from the sample (simple reflection) does not reach the spectral sensor unit 50.

The optical measuring device 50 is separated from the sample 54 by a protective device with windows 102, 104. The illumination unit 56 emits light (for example visible light and neighboring wavelength ranges) and thus illuminates the sample 54 behind the protective windows 102, 104. The windows are transparent to light in the wavelength range used. The light is at least partially transmitted within the sample 54, with reference number 74 illustrating an exemplary radiation profile, and then emerges from the sample 54 again. The emerging transmitted light is then detected by the spectral sensor unit 62. The spectral sensor unit 62 observes the light that has interacted with the sample 54 via the first observation path 70. The path of the light to the sample 54 takes place via an illumination path 76.

At the same time as detecting the light via the first observation path 70, the spectral sensor unit 62 detects the light from the lighting unit 56 directly via the second observation path 80. In the exemplary embodiment, the second observation path 80 runs in a straight line (directly) from the lighting unit 56 to the spectral sensor unit 62 and is therefore unaffected by sample 54. The control unit 100 is used to evaluate the signals obtained with the spectral sensor unit 62.

4 illustrates a modified embodiment of the optical measuring device 50 based on the in 3 design shown. According to the order 4 is further designed to detect light reflected directly from the sample 54 via a sensor unit 120 with a spatially resolving image sensor 122. By way of example, the sensor unit 120 is designed as a camera with a pixel matrix. In this way, a reflection observation path 124 can also be used. The signals captured with the spatially resolving image sensor 122 can be further processed while maintaining the spatial resolution. However, agglomeration over a plurality of pixels is also conceivable. Data and signals recorded via the sensor unit 120 can be used as an additional reference when evaluating the signals recorded with the spectral sensor unit 62. Light reflected directly from the sample 54 was not or not significantly transmitted through the sample 54. In the exemplary embodiment, the detection via the reflection observation path 124 is not carried out spectroscopically. In principle, spectroscopic detection is also conceivable. According to the design 4 the reflection observation path 124 is adjacent to the first observation path 70.

In a further exemplary embodiment, the reflection observation path 124 is provided with a light source 126 (in 4 only shown in dashed lines), which illuminates the image captured by the image sensor 122, possibly in addition to the illumination via the illumination unit 56. In order to avoid disruptive influences of the light source 126 on the acquisition with the spectral sensor unit 62 via the first observation path 70, a clocked or pulsed operation of the Light source 126 can be imagined for the reflection observation path 124, which is synchronized with the spectral acquisition. In other words, the illumination via the light source 126 and the detection via the image sensor 122 can take place in a timing gap in the recording via the spectral sensor unit 62 in the first observation path 70. The timing or synchronization can be done via the control unit 100 take place. A reflection observation path 124 may also be provided in other embodiments shown herein.

4 further illustrates a design in which the two windows 102, 104 for the first observation path 70 and the illumination path 76 are designed integrally (in one piece). This can simplify the production of the protective device and further increase the quality of detection due to the identical properties of the windows 102, 104 when designed integrally. Preferably, the separating element 110, which separates the first observation path 70 and the illumination path 76 from one another, is then in the vicinity of the windows 102, 104 in such a way that the thickness of the protective device (which provides the windows 102, 104) and expected angles of incidence across the illumination path 76 adapted so that an internal reflection within the protective device in the direction of the first observation path 70 is avoided. In this way it is ensured that the majority of the light that can be detected via the first observation path 70 has been transmitted through the sample 54. The continuous design of the windows 102, 104 can be combined with other embodiments shown herein.

5 illustrates a further modified embodiment of the optical measuring device 50 based on the in 3 design shown. In this embodiment, the measuring device 50 is supplemented by at least one blocking element 130, 134 for the first observation path 70 and/or the second observation path 80. In the exemplary embodiment according to 5 the blocking element 130 is assigned to the first observation path 70 and the blocking element 134 to the second observation path 80. The blocking element 130 can, if necessary, be pivoted or retracted into the beam path of the first observation path 70, compare the double arrow 132. The blocking element 134 can, if necessary, be pivoted or retracted into the beam path of the second observation path 80, compare the double arrow 136. With the observation path 70, 80 blocked (Black normal) a signal can be obtained for calibration, regardless of the switching state of the lighting unit 56.

6 illustrates a further modified embodiment of the optical measuring device 50 based on the in 3 design shown. In this embodiment, the measuring device 50 has a spectral sensor unit 62 with two separate spectral sensors 64, 66, which are not designed integrally but are functionally combined in the spectral sensor unit 62. The spectral sensor 64 is used to detect radiation along the first observation path 70. The spectral sensor 66 is used to detect radiation along the second observation path 80. The control unit 100 can process signals provided by the two spectral sensors 64, 66 and combine them in a suitable manner.

7 illustrates a further modified embodiment of the optical measuring device 50 based on the in 3 shown design. The embodiment according to 7 illustrates that the respective paths 70, 76, 80 do not have to be designed in such a way that the beam guidance is as direct as possible. For example, at least one optically effective element 140 is assigned to the first observation path 70, for example a series of optics for collecting and concentrating the incident light. The illumination path 76 and the second observation path 80 are assigned optically effective elements 142, 144, which in the exemplary embodiment each serve to deflect the beam. In other words, the spectral sensor unit 62 in the exemplary embodiment has no direct view of the light incident via the second observation path 80, which goes back directly to the illumination unit 56 (without interaction with the sample 54). In a similar manner, the beam guidance in the direction of the sample 54 in the illumination path 76 can also include at least one deflection. The optically effective elements 140 (balancing optics), 142 (mirrors or plane mirrors), 144 (mirrors or plane mirrors) are shown as representatives of a wide variety of optically effective elements that are installed in the observation paths in addition to the optics of the spectral sensor unit 62.

8th illustrates a further modified embodiment of the optical measuring device 50 based on the in 3 shown design. The embodiment according to 8th shows an arrangement with several illumination paths 76. In the exemplary embodiment, the illumination unit 56 has two light sources 58, with the sample being illuminated accordingly via two windows 104. The first observation path 70 is arranged between the two illumination paths 76 shown. In the exemplary embodiment, an optically effective element 150 is used to guide the beam for the second observation path 80, which is designed, for example, as a concavely curved mirror. In this way, the light from two or more light sources 58 of the lighting unit 56 can be concentrated via the second observation path 80 and fed to the spectral sensor unit 62 in a combined manner. It goes without saying that other optically effective elements can also be used to guide the beam and combine the light sources. It is further understood that the exemplary embodiment according to 8th may have further light sources 58 outside the plane of the drawing, for example in total including four or six light sources oriented in a circle around the first observation path.

9 illustrates an exemplary signal processing of the signals obtained using the observation device 50 using a block diagram. The signal processing takes place, for example, in the control unit 100 (see 2 ). It is also conceivable to outsource parts of the signal processing, for example to a higher-level control device that is part of the agricultural machine 10 (see 1 ). It is understood that the signal processing is carried out at least partially by an external server to which the signals and the data embodying them are transmitted by the control unit 100.

In the exemplary embodiment according to 9 Essentially mandatory steps are illustrated by blocks with solid lines and essentially optional steps are illustrated by blocks with dashed lines. It goes without saying that signal processing can in principle also be carried out according to other schemes and specifications.

A block labeled 200 refers to first signals that were obtained via the first observation path by observing the sample with the spectral sensor unit. A block labeled 202 refers to second signals obtained via the second observation path by observing the light source with the spectral sensor unit. The designation first signals and second signals primarily serves to differentiate and is not to be understood as restrictive. The signals 200, 202 are offset against one another in a block designated 210. The second signals 202 relate to information that does not relate to the sample. Therefore, the first signals 200 can be adjusted/compensated for this contribution. This increases the overall significance and accuracy of the spectrometric observation.

In this way, a cleaned sample signal 212 is obtained, which is evaluated in a block 218 with the addition of an evaluation model 214 that contains a database. The database relates, for example, to the spectroscopic properties of certain ingredients in the sample. The data obtained can be output as measurement results in a block 220. An exemplary measurement result relates to the indication of a proportion of a specific ingredient in the observed sample. This is not to be understood as limiting.

To further increase the accuracy, the second signals 202, which are obtained by observing the lighting unit, can be combined with a calibration model 230. The calculation takes place in a block 232. The calibration model 230 can, for example, refer to a so-called white standard. A correspondingly adjusted signal 234 can be used as the basis for the calculation at 210. Deviations from the white standard can be attributed to influences that may also be present in the observed sample. To increase the significance of the second signals 202, which are obtained via the second observation path, signals 238 in the second observation path can also be used, which are obtained when the lighting unit is switched off or the beam path is blocked along the second observation path. The signals 238 correspond, for example, to a black standard in the second observation path. In this way, calibration for the second observation path can take place at least periodically.

In a similar way, calibration can also be taken into account for the first observation path. By way of example, a calibration model 240 is provided for a so-called black standard in the first observation path. If the lighting unit is deactivated or the beam path along the first observation path is otherwise blocked, signals 242 for the black standard can be determined. These signals 242 are compared with the calibration model 240 in a block 244. The signals 242 can be determined at least periodically, in which case no observation of the sample is possible in the first observation path. Correspondingly adjusted signals 246 for the black standard can be included in the calculation of the signals of interest 200, 202 along the first observation path and the second observation path at 210.

List of reference symbols:

10

agricultural machine

12

Harvester

14

landing gear

16

Construction

18

drive

20

cabin

22

Field

24

Plant

26

crop

30

Stem

32

Trial Chamber

34

shredder

40

chopped crops

42

Material flow

44

Wall

46

sputum

50

optical measuring device

52

global control facility

54

sample

56

Lighting unit

58

light source

62

Spectral sensor unit

64

Spectral sensor

66

Spectral sensor

70

first observation path

72

beam path

74

Radiation course

76

lighting path

78

beam path

80

second observation path

82

beam path

88

Optical unit

90

optics

92

detector

94

optics

96

detector

100

Control unit

102

Window

104

Window

110

Separator

120

Sensor unit

122

spatially resolving sensor

124

Reflection observation path

126

light source

130

Blocking element

132

Movement

134

Blocking element

136

Movement

140

visually effective element

142

visually effective element

144

visually effective element

150

visually effective element

200

first signals

202

second signals

210

billing

212

cleaned sample signal

214

Evaluation model

218

billing

220

output

230

Calibration model

232

billing

234

balanced signal

238

Signal at black normal

240

Calibration model

242

Signal at black normal

244

billing

246

balanced signal

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004021448 A1 [0011]
• DE 102004048102 A1 [0012]
• DE 102017108552 A1 [0013, 0014, 0015]
• WO 2014/001074 A1 [0045]

Claims (18)

Optical measuring device (50) for spectral analysis of a sample (54), which has the following: - an illumination unit (56) which is designed to irradiate the sample (54) with light, and - a spectral sensor unit (62) which is set up to - to detect light transmitted by the sample (54) via a first observation path (70) and to provide a corresponding first sensor signal, and - to detect the light emitted by the illumination unit (56) independently of the sample (54) via a second observation path (80) and to provide a corresponding second sensor signal, the illumination unit (56) and the spectral sensor unit (62) being on the same side of the Sample (54) is located. Optical measuring device (50). Claim 1 , further comprising a separating element (110) which is designed to block a reflection path which delivers light reflected from the sample (54) to the spectral sensor unit (62). Optical measuring device (50). Claim 1 or 2 , wherein the spectral sensor unit (62) is set up to detect the light emitted by the lighting unit (56) via the second observation path (80) directly or via an optical unit (144, 150). Optical measuring device (50) according to one of the Claims 1 - 3 , wherein the spectral sensor unit (62) has a first beam path (72) and a second beam path (82), the first beam path (72) being set up to record the light transmitted by the sample (54) via the first observation path (70). , and wherein the second beam path (82) is set up to record the light emitted by the illumination unit (56) independently of the sample (54) via the second observation path (80). Optical measuring device (50) according to one of the Claims 1 - 4 , wherein the first observation path (70) and the second observation path (80) have a common spectroscopic optical unit through which the light transmitted by the sample (54) along the first observation path (70) and that from the illumination unit (56) independently of the Light emitted from the sample (54) runs along the second observation path (80). Optical measuring device (50) according to one of the Claims 1 - 5 , wherein the spectral sensor unit has a monolithic optical unit into which at least the first observation path (70) or the second observation path (80) are integrated at least in sections. Optical measuring device (50) according to one of the Claims 1 - 6 , wherein the spectral sensor unit (62) has at least one spectral sensor with at least one photoelectric detector, which is set up to detect light in the visible range and in the near-infrared range, in particular in the range between 550 nm and 1100 nm. Optical measuring device (50) according to one of the Claims 1 - 7 , wherein the lighting unit (56) has one or more light sources, and wherein the one or more light sources are selected from the group consisting of semiconductor light sources, thermal light sources, gas discharge lamps and luminescent light sources. Optical measuring device (50) according to one of the Claims 1 - 8th , wherein the spectral sensor unit (62) has at least two spectral sensors, one of which is assigned to the first observation path (70) and another to the second observation path (80). Optical measuring device (50) according to one of the Claims 1 - 9 , further comprising an evaluation unit which is set up to determine at least one property of the sample based on the first sensor signal and the second sensor signal. Optical measuring device (50) according to one of the Claims 1 - 10 , wherein the spectral sensor unit (62) is further set up to detect incoming light via the first observation path (70) and/or via the second observation path (80) when the lighting unit (56) is switched off or the light from the lighting unit (56) is shielded and to provide a corresponding normal signal. Optical measuring device (50). Claim 11 , further comprising at least one blocking element (130, 134), which, if necessary, blocks light over the first observation path (70) and / or over the second observation path (80). Optical measuring device (50). Claim 11 or 12 , if on Claim 10 referred back, the evaluation unit also being set up to determine the property of the sample (54) taking into account the at least one normal signal. Optical measuring device (50) according to one of the Claims 1 - 13 , wherein a reflection observation path (124) is also provided, via which a light-sensitive sensor unit (120) Light reflected directly from the sample (54), in particular with spatial resolution, is detected. Optical measuring device (50) according to one of the Claims 1 - 14 , wherein the sample (54) is part of an agricultural or food technology material stream. Use of the optical measuring device (50) according to one of the Claims 1 - 15 in an agricultural or food technology device for analyzing a sample, in particular for analyzing a material stream. Agricultural or food technology device with an optical measuring device (50) according to one of Claims 1 - 15 . Optical measurement method for the spectral analysis of a sample (54) with the following steps: - Arranging an illumination unit (56) and a spectral sensor unit (62) on the same side of the sample (54), - irradiating the sample (54) with light from the lighting unit (56), - Detecting light transmitted by the sample (54) with the spectral sensor unit (62) via a first observation path (70) and providing a corresponding first sensor signal, and - Detecting light emitted by the lighting unit (56) independently of the sample (54) with the spectral sensor unit (62) via a second observation path (80) and providing a corresponding second sensor signal.

Images