DE102017200356A1 - Method for analyzing a measuring range and miniature spectrometer - Google Patents

Abstract

The invention relates to a method (10) for analyzing a measuring region (5) taking into account a spectral evaluation (14) of at least one individual measurement, comprising the steps of: irradiating an object of the measuring region (5) with electromagnetic radiation, spectrometric measurement of one of At least two individual measurements are carried out for the analysis of the measuring area (5), wherein the irradiation (110 ') of the object with electromagnetic radiation for a first individual measurement (11') takes place with a first radiation distribution and by the spectrometric measurement ( 111) is provided, the irradiation (110 ") of the object with electromagnetic radiation for a second individual measurement (11") with a second radiation distribution deviating from the first radiation distribution, and by the spectrometric measurement ( 111) a second spectrometric detector by comparing (12) the first and second spectrometric detector signals (111 ', 111 ") a comparison value (12') is determined, which is an indicator for the presence of a direct reflection and Spectral evaluation (14) a selection (13) of the detector signals (111 ', 111 ") for analyzing the measuring range (5) in dependence of the comparison value (12') takes place.

Description

The invention relates to a method for analyzing a measuring range and a miniature spectrometer.

State of the art

In DE 102007007040 A1 is a measuring device for the optical and spectroscopic examination of a sample described. In this case, a falsification of the measurement results by direct reflection is avoided in that the camera and the spectrometer are arranged outside the specular angle.

In DE 102011076677 A1 a spectroscopic measuring device and a spectroscopic measuring method are described. The spectroscopic measuring device comprises a lighting device, a spectrometer for detecting a spectrum of a sample, a camera for detecting an image of the sample and an evaluation unit for evaluating the spectrum as a function of the image. It is described that with the help of a lighting device and a camera, a shine, that is, a direct reflection can be detected. The camera must be installed in the same optical path to detect the gloss with the help of the camera.

Core and advantages of the invention

The invention relates to a method for analyzing a measuring range and a miniature spectrometer.

Spectrometers can be used to determine spectral information, such as a chemical composition of an object or the presence of a particular substance mixture in an object. The object to be examined is not always directly accessible. The object may for example be welded into a foil or be at least partially encased by a material other than the object. Depending on the illumination angle and the detection angle of the spectrometer, radiation which is reflected on the film or the cladding can strike a detector of the spectrometer. This effect is referred to as direct reflection, as the radiation is reflected before impacting the object and thus contains no information about the object to be examined. The direct reflection can superimpose the radiation, which contains information about the object, for example, the object diffuse reflected radiation. In direct reflection, radiation is reflected with a high intensity and can thus superimpose or cover the material spectrum of the object to be detected, since this usually has a lower intensity than the directly reflected radiation. If the material spectra of the film or of the material surface differ from the material of the object to be examined, and if both the directly reflected radiation and the radiation coming from the object, which contains information about the object, strike the detector of the spectrometer, a superimposed one results Spectrum of directly reflected radiation and radiation containing information about the object.

An advantage of the invention with the features of the independent claims is that direct reflection can be detected in a simple manner and thus the reliability of measurement results for the analysis of a measuring range can be increased. In particular, it is advantageously possible to separately evaluate the spectra of different elements of the measuring range, that is, for example, of the object and a material arrangement at least partially surrounding the object, such as a foil or packaging, or to evaluate only the spectra of selected elements of the measuring range. Thus, for example, a spectral information of the packaging can be determined and, separately, the object arranged in the packaging. Thus, also packaged or not directly accessible objects can be checked for their composition. The direct reflection can be determined by existing means, so that no additional devices for determining the direct reflection are needed.

Further advantages are that a detection of an angle-dependent direct reflection, that is the dependence of the direct reflection of a tilting of a measuring surface surface to the optical axis of a miniature spectrometer, can take place, if no or superimposed object information is present in the spectrum of direct reflection. Subsequent compensation or suppression of the direct reflection can lead to an increase in the metrological robustness in manual measurement situations, e.g. in smartphones or handheld spectrometer systems. Furthermore, the direct reflection can thus also be measured and used as a useful signal, e.g. be used for special surface information, packaging identification or the like.

This is achieved with a method for analyzing a measuring range according to claim 1 taking into account a spectral evaluation of at least one individual measurement, wherein the individual measurement comprises the steps of irradiating an object of the measuring range with electromagnetic radiation and spectrometric measurement of a radiation coming from the measuring range. The method is characterized in that at least two individual measurements are carried out for the analysis of the measuring range, the irradiation of the object with electromagnetic radiation being carried out for a first individual measurement with a first radiation distribution and the spectrometric measurement of a first radiation coming from the measuring range being followed by a first spectrometric detector signal is provided, the irradiation of the object with electromagnetic radiation for a second individual measurement with a second radiation distribution, which is different from the first radiation distribution, and by the spectrometric measurement of a coming of the measuring range second radiation, a second spectrometric detector signal is provided by comparing the first a comparison value is determined spectrometric detector signal and the second spectrometric detector signal, wherein the comparison value is an indicator of a direct R eflexion and for the spectral evaluation, a selection of the spectrometric detector signals for the analysis of the measuring range as a function of the comparison value takes place. One advantage is that the position of the object relative to the miniature spectrometer can be chosen within a wide tolerance range so that reliable measurement results can be obtained even if the exact position of the object relative to the miniature spectrometer or the angle under which the measurement is performed is not known. Furthermore, a distinction can be reliably made between the radiation coming from the object and the directly reflected radiation. This can thus be taken into account in the spectral evaluation of the detector signals. In particular, an influence of the direct reflection on the spectral information of the object can be reduced or prevented.

According to one embodiment, the first spectrometric detector signal and the second spectrometric detector signal each comprise photon intensities. If one of the detector signals has a significantly higher photon intensity, this is an indication that the radiation coming from the measuring range comprises directly reflected radiation. When considering a time-varying photon intensity distribution of the first spectrometric detector signal with respect to the second spectrometric detector signal, a solid angle with direct reflection can advantageously be determined and this information can be taken into account in the spectral evaluation in order to increase the reliability of the measurement results.

In an embodiment, the first spectrometric detector signal and the second spectrometric detector signal may be received by a measuring unit with a time offset. One advantage is that an interaction between the individual measurements can be reduced or avoided and thus the reliability of the measurement results can be increased.

In one embodiment, the comparison value may be a normalized relative difference signal of the first spectrometric detector signal and the second spectrometric detector signal. One advantage is that there is thus a dimensionless indicator which makes it possible to compare different measurement series and the indicator can be valid for different measurement series in which different physical quantities, such as a photocurrent of wavelength-dependent radiation intensity, can be used in each case as spectrometric detector signals.

In one embodiment, in a comparison value indicative of the presence of direct reflection, the spectrometric detector signal having a first value that is a measure of the detected electromagnetic radiation, the first value being greater than a second value of another detector signal, for determining a spectral information of a medium, in which the direct reflection takes place, are evaluated and the further spectrometric detector signal with a second value, which is smaller than the first value, are evaluated for determining a spectral information of the object. One advantage is that even with ignorance of the exact position of the object relative to the miniature spectrometer or the angle at which the measurement is performed, spectral information about the medium at least partially surrounding the object and spectral information about the object itself can be determined.

If an ambiguous comparison value results, then in one embodiment a radiation intensity detected by the detection unit can be a further indicator for the presence of a direct reflection and the spectral evaluation can be carried out as a function of the further indicator. One advantage is that thus spectral information about the object and / or the medium surrounding the object at least partially can be reliably determined even in the case of an ambiguous comparison value.

In an embodiment, in the case of an ambiguous comparison value, both spectrometric detector signals may be suitable for determining a spectral information of the object if the radiation intensity has a low value, in particular a value of 0.2% or 5% or a value between 0.2% and 5%. the intensity of the electromagnetic radiation irradiated on the measuring range, or both spectrometric detector signals are discarded when the radiation intensity assumes a high value, in particular a value of 10% or 100% or a value between 10% and 100% of the intensity of the measuring range radiated electromagnetic radiation. One advantage is that thus a reliable selection of the spectrometric detector signals can take place and thus a spectral evaluation can take place even in the case of an ambiguous comparison value. This results in a very robust method for analyzing the measuring range.

In one embodiment, an evaluation of the spectrometric detector signal, in which there is no direct reflection, for determining a spectral information of the object and discarding the spectrometric detector signal, in which there is direct reflection, take place. Advantageously, even if the exact position of the object relative to the miniature spectrometer or the angle at which the measurement is carried out can therefore be reliably determined, a spectral information of the object can be reliably determined.

In one embodiment, an evaluation of the spectrometric detector signal, in which there is direct reflection, for determining a spectral information of a medium on which the direct reflection takes place, and an evaluation of the spectrometric detector signal, in which there is no direct reflection, to determine a spectral Information of the object take place. One advantage is that, thus, spectral information about the object as well as spectral information about the medium at least partially surrounding the object are determined from the spectrometric detector signals without changing the position of the object relative to the miniature spectrometer or the angle at which the measurement is carried out can be.

In one embodiment, an evaluation of the spectrometric detector signal, in which there is direct reflection, for determining a spectral information of a medium at least partially surrounding the object, on which the direct reflection takes place and discarding the spectrometric detector signal, in which there is no direct reflection, take place , Advantageously, a range for analysis can thus be selected from the measuring range.

Alternatively or additionally, a main angle of incidence of the electromagnetic radiation on the measuring range can be determined from the individual measurements. One advantage is that thus a correction of a spectral offset can be made. Such spectral offsets occur, for example, when using Fabry-Pérot interferometers as a spectral element for spectrometric measurements. In Fabry-Pérot interferometers, varying the angle of incidence of the electromagnetic radiation on the Fabry-Pérot interferometer causes a shift in the wavelength to be measured by the interferometer. The distribution of the angles of incidence may be centered at an angle which deviates from the normal to the Fabry-Pérot interferometer. This angle, around which the angles of incidence are centered, is called the main angle of incidence. If the main angle of incidence deviates from the normal, the entire spectrum is shifted, a so-called spectral offset. If the main angle of incidence is known, this spectral offset can be determined and the spectrum corrected accordingly. As a result, the spectral information of the measuring range can be reliably determined, even if the main angle of incidence deviates from the normal. As a result, user-friendliness can be increased because the user does not have to pay attention to the main incident angle when performing the analysis of the measurement area and still obtain measurement results with high accuracy.

A miniature spectrometer for carrying out the analysis of the measuring range comprises a lighting unit, comprising at least two lighting elements for illuminating a measuring range with electromagnetic radiation from different illumination angles, a detection unit, a spectral element which is arranged in the beam path between the measuring range and the detection unit and an evaluation unit, which is designed to control the lighting elements of the lighting unit temporally independent of each other. The miniature spectrometer is characterized in that the evaluation unit comprises a comparison unit, a signal selection unit and a calculation unit, wherein the comparison unit is set up to determine the comparison value from the results of the individual measurements, the signal selection unit selects the detector signals for analysis of the measurement area as a function of Reference value is set up and the arithmetic unit is arranged to determine a spectral information from the at least one selected spectrometric detector signal. One advantage is that it simplifies the analysis of the measuring range, as well as measurements in which direct Reflection is available to analyze the measuring range can be used while high reliability of the measurement is achieved. Furthermore, both information about the object and information about a surface of the object or the medium surrounding the object, such as a packaging material, can be obtained. Furthermore, the robustness of the measurements can be increased since the spectrometric detector signals, which comprise spectral information of the directly reflected radiation, can be detected, compensated, hidden and / or evaluated separately. Thus, the miniature spectrometer has a high fault tolerance with respect to the position of the object relative to the miniature spectrometer or the angle at which the measurement is carried out.

In one embodiment, the spectral element may comprise at least one Fabry-Perot interferometer, with which advantageously a small size for a "handheld device" can be achieved.

list of figures

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Like reference numerals in the figures indicate the same or equivalent elements.

• 1 ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs,
• 2 zeigt einen Querschnitt eines Messbereichs, umfassend ein Objekt und ein das Objekt teilweise umgebendes Medium,
• 3 zeigt einen Querschnitt eines Messbereichs, umfassend ein Objekt und ein das Objekt umgebendes Medium,
• 4 zeigt einen Querschnitt eines Messbereichs, umfassend ein Objekt und ein das Objekt umgebendes Medium, wobei zwischen dem Objekt und dem Medium ein Hohlraum ausgebildet ist,
• 5 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei eine spektrale Information eines Objekts und eines das Objekt zumindest teilweise umgebenden Mediums ermittelt wird,
• 6 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei eine spektrale Information eines Objekts ermittelt wird,
• 7 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei die Durchführung neuer Einzelmessungen angesteuert wird,
• 8 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei eine spektrale Information eines Objekts ermittelt wird und ein spektrometrisches Detektorsignal, welches spektrale Informationen des das Objekt zumindest teilweise umgebenden Mediums umfasst, verworfen wird,
• 9 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei eine spektrale Information eines das Objekt umgebenden Mediums ermittelt wird und ein spektrometrisches Detektorsignal, welches spektrale Informationen des Objekts umfasst, verworfen wird,
• 10 zeigt ein Ablaufdiagramm eines Verfahrens zur Analyse eines Messbereichs, wobei ein Haupteinfallswinkel zur Korrektur eines spektrometrischen Detektorsignals ermittelt wird,
• 11 zeigt einen Querschnitt eines Miniaturspektrometers zur Analyse eines Messbereichs, wobei keine direkt reflektierte Strahlung von einer Detektionseinheit des Miniaturspektrometers aufgenommen wird und
• 12 zeigt einen Querschnitt eines Miniaturspektrometers zur Analyse eines Messbereichs, wobei direkt reflektierte Strahlung und vom Objekt kommende Strahlung auf von einer Detektionseinheit des Miniaturspektrometers aufgenommen wird.

Show it

• 1 a flowchart of a method for analyzing a measuring range,
• 2 shows a cross-section of a measuring area comprising an object and a medium partially surrounding the object,
• 3 shows a cross section of a measuring area comprising an object and a medium surrounding the object,
• 4 shows a cross section of a measuring area, comprising an object and a medium surrounding the object, wherein a cavity is formed between the object and the medium,
• 5 shows a flow chart of a method for analyzing a measuring range, wherein a spectral information of an object and of the object at least partially surrounding medium is determined,
• 6 shows a flowchart of a method for analyzing a measuring range, wherein a spectral information of an object is determined,
• 7 1 shows a flow diagram of a method for analyzing a measuring range, wherein the execution of new individual measurements is controlled,
• 8th shows a flow chart of a method for analyzing a measuring range, wherein a spectral information of an object is determined and a spectrometric detector signal, which spectral information of the object at least partially surrounding the medium, is discarded,
• 9 shows a flowchart of a method for analyzing a measuring range, wherein a spectral information of a medium surrounding the object is determined and a spectrometric detector signal, which comprises spectral information of the object, is discarded,
• 10 1 shows a flow chart of a method for analyzing a measuring range, wherein a main angle of incidence for correcting a spectrometric detector signal is determined,
• 11 shows a cross section of a miniature spectrometer for analyzing a measuring range, wherein no directly reflected radiation is received by a detection unit of the miniature spectrometer and
• 12 shows a cross section of a miniature spectrometer for analyzing a measuring range, wherein directly reflected radiation and radiation coming from the object is recorded by a detection unit of the miniature spectrometer.

Description of the embodiments

Radiation from an object may comprise, for example, radiation reflected, transmitted, scattered and / or emitted by the object.

For example, one may be at least partially between the object and a detection unit, which can detect the radiation coming from the object for a spectral evaluation of the radiation be arranged reflective medium. Such a medium may be, for example, a packaging film, a partially reflecting surface of the object, which may have a different chemical composition than the object, and / or a liquid, such as water drops, which may be disposed on a surface of the object. The object can form a measuring range together with the medium. The measuring range covers the object and the medium. Electromagnetic radiation, which is reflected from the medium before hitting the object, does not contain any information about the object. However, the radiation reflected by the medium contains information about the medium. The radiation reflected by the medium is electromagnetic radiation that is reflected at a high intensity before it strikes the object. This effect is called direct reflection.

Radiation coming from the measuring area may comprise the radiation coming from the object and / or the electromagnetic radiation directly reflected by the medium as described above.

A radiation distribution describes an electromagnetic radiation emitted by a light source. The radiation distribution can be characterized, for example, by an angular distribution of the electromagnetic radiation, a main angle of incidence, a spectral composition and / or by a periodicity of a light output, for example in the case of temporally pulsed illumination elements or a combination of the beam distribution specified above. An angle by which the angles of incidence of the electromagnetic radiation coming from a lighting element are centered with respect to the surface of the measuring area is referred to as the main angle of incidence. For example, if all the light rays of the light source run parallel to one another when hitting the surface, then all the light rays strike the surface at an angle of incidence which corresponds to the main angle of incidence.

A miniature spectrometer is a centimeter scale spectrometer, including smaller dimensions below the centimeter range.

Spectral information may include, for example, a chemical composition, that is, a spectrum or the occurrence of a particular substance mixture in an object.

1 shows a flowchart of a method 10 for the analysis of a measuring range. The procedure 10 for the analysis of the measuring range can be implemented for example in software or hardware or in a mixed form of software and hardware in a control unit. In 1 become a first single measurement 11 ' and a second single measurement 11 " carried out. The individual measurements 11 ' . 11 " be in a measuring unit 7 carried out. The measuring unit 7 For example, it may comprise a lighting unit, an optical imaging system, a spectral element, and a detection unit. The first single measurement 11 ' includes the steps irradiation 110 ' an object of the measuring range with electromagnetic radiation having a first radiation distribution and spectrometric measurement 111 a first radiation coming from the measuring range. By the spectrometric measurement 111 the first radiation coming from the measuring area can be a first spectrometric detector signal 111 ' to be provided. The second single measurement 11 " includes the steps irradiation 110 ' of the object with electromagnetic radiation having a second radiation distribution, which is different from the first radiation distribution, and spectrometric measurement 111 a second radiation coming from the measuring range. By the spectrometric measurement of the second radiation coming from the measuring range, a second spectrometric detector signal 111 ' to be provided. The first spectrometric detector signal 111 ' and the second spectrometric detector signal 111 ' For example, they can be recorded by a detection unit with a time delay. In a further exemplary embodiment not shown here, more than two individual measurements can also be used 11 ' . 11 " to be performed at and taken into account in the analysis of the measuring range. The first and the second radiation distribution may differ, for example, in the main angle of incidence. The first radiation distribution may, for example, have a larger main angle of incidence than the second radiation distribution. The spectrometric detector signals 111 ' . 111 ' are a measure of the radiation coming from the measuring area and may, for example, photon intensities, interferograms, etc. include. As spectrometric detector signals 111 ' . 111 ' detector signals are suitable, the spectral information 14 ' over the measuring range. The method steps described below can, for example, in an evaluation 6 respectively. The measuring unit 7 may comprise a communication interface which transmits the spectrometric detector signals 111 ' . 111 ' to the evaluation unit 6 and receiving data or signals from the evaluation unit 6 allows. The evaluation unit 6 may comprise a communication interface which is suitable for data or signals, in particular the spectrometric detector signals 111 ' . 111 ' , from the measurement unit 7 to receive and signals, such as control signals 16 ' or data to the measuring unit 7 transferred to. The spectrometric detector signals 111 ' . 111 ' be in 1 from the measurement unit 7 to the evaluation unit 6 transfer. By comparing 12 of the first spectrometric detector signal 111 ' and the second spectrometric detector signal 111 ' can be a comparison value 12 ' be determined. The comparison 12 can, for example, in a comparison unit 61 carried out, which may or may not be adapted to the comparison value 12 ' from the results of the individual measurements 11 ' . 11 " , For example, by forming a difference of the detector signals 111 ' . 111 ' to determine. The comparison value 12 ' is an indicator of the existence of direct reflection. That is, based on the comparison value 12 ' For example, it may be determined whether one or more of the spectrometric detector signals 111 ' . 111 ' on a spectrometric measurement 111 based directly reflected radiation. Depending on the comparative value 12 ' can a selection 13 the spectrometric detector signals 111 ' . 111 ' done and a spectral evaluation 14 the selected detector signals / the selected spectrometric detector signals 13 ' to analyze the measuring range. The selection 13 can in a signal selection unit 62 can be done, which may be suitable or set up a selection 13 of the spectrometric detector signals 111 ' . 111 ' for analysis of the measuring range 5 depending on the comparative value 12 ' make. Depending on the comparative value 12 ' in particular, no spectrometric detector signal 111 ' . 111 ' to be selected. Include the spectrometric detector signals 111 ' . 111 ' For example, photon intensities, it may happen that when comparing 12 shows that in each case the photon intensities of the spectrometric detector signals 111 ' . 111 ' too low values for a spectral evaluation 14 exhibit. In this case, it is not possible to use a spectrometric detector signal 111 ', 111 "for the spectral evaluation 14 select. It may also be just one of the spectrometric detector signals 111 ' . 111 ' be evaluated and other spectrometric detector signals 111 ' . 111 ' Both spectrometric detector signals can be discarded 111 ' . 111 ' be evaluated or it may all spectrometric detector signals 111 ' . 111 ' discarded 16 "and again individual measurements 11 ' . 11 " be carried out, a comparative value 12 ' be determined and again a selection 13 respectively. The spectral evaluation 14 may have one or more spectral information as the case may be 14 ' or determine spectra of the object and / or the medium. The spectral evaluation 14 can, for example, in a computing unit 63 which may be suitable or arranged for one or more spectral information 14 ' from the at least one selected spectrometric detector signal 13 ' to investigate. By way of example, spectrometric detector signals could be rejected if certain wavelength ranges behave differently, for example other reference wavelength ranges.

If at least one of the spectrometric detector signals 111 ' . 111 ' in selecting 13 is selected, the at least one selected spectrometric detector signal 13 ' spectrally evaluated 14. The spectral evaluation 14 can be used to analyze the measuring range depending on the comparison value 12 ' be furnished. It can, for example, a spectral information 14 ' or a spectrum of the object and / or the medium surrounding the object at least partially in the spectral evaluation 14 be determined. It can be an issue 15 the spectral information 14 ' or the spectral information 14 ' respectively. This edition 15 can be done, for example, optically, haptically or acoustically. For example, the spectral information 14 ' via an output unit 15 For example, a display, a touch screen or a speaker can be output.

If none of the spectrometric detector signals 111 ' . 111 ' when selecting 13 is selected 16 ", so can a control signal 16 ' to the measuring unit 7 be transmitted to perform further individual measurements 11 ''',11'''', as for example, in 7 is shown. In this case, at least one of the further individual measurements 11 ''',11''''with respect to the individual measurements 11 ' . 11 " the previous run of the process 10 a modified radiation distribution and / or a different measuring distance between the measuring unit 7 and measuring range. Alternatively, both further individual measurements 11 ''',11''''with the same radiation distribution as in the previous run and a deviating from previous run measurement distance between the measuring unit 7 and measuring range. The control signal 16 ' can be designed to, for example, the main angle of incidence of at least one lighting element depending on the selection 13 the spectrometric detector signals 111 ' . 111 ' to adjust. In one embodiment, the lighting elements may be connected to an actuator, which by means of the control signal 16 ' can be controlled, for example, to tilt the lighting elements, so that the main angle of incidence of the lighting elements adjusted. Alternatively or additionally, the actuator can be designed to measure the measurement between the measuring unit 7 and the measuring range. The aim of these possible settings is that a sufficiently robust measurement result can be generated without using additional sensors for the optimization.

Alternatively or additionally, for example, an optical, haptic or acoustic output via an output unit 64 which indicates that no spectrometric detector signal 111 ' . 111 ' has been selected and further individual measurements can be carried out for an analysis of the measuring range. In particular, instructions may be issued which, for example, allows a user to measuring unit 7 relative to the measuring range in a position for further individual measurements 11 ''',11''''to bring, so a spectral evaluation 14 as described above can be made possible.

2 . 3 and 4 show cross sections of embodiments of measuring ranges 5 where, for example, direct reflection can occur. The measuring ranges 5 For example, each one object 5 ' and a medium at least partially surrounding the object 5 " 5 ' include. The measuring range 5 may in an embodiment not shown, only one object 5 ' or part of an object 5 ' include. The object 5 ' In the exemplary embodiments shown, for example, has a rectangular cross section, the object 5 ' however, is not limited to a rectangular cross section. For example, the object may include a food such as fruit, meat, vegetables, a drink, etc. The object 5 ' For example, it can be gaseous, liquid or solid. The medium at least partially surrounding the object 5 ' For example, a packaging film or a surface of the object 5 ' which is a different chemical composition than the object 5 ' having. In 2 is only a first surface 51 " of the object 5 ' from the medium 5 ' covered. Meets electromagnetic radiation from one of the object 5 ' opposite side of the medium 5 ' on the measuring range, so at least a first portion of the electromagnetic radiation directly on the medium 5 ' be reflected and a second portion of the electromagnetic radiation from the medium 5 ' be transmitted. The second portion may be at the first surface 51 " be reflected, or in the object 5 ' penetrate and from there towards the medium 5 ' be scattered back. Consequently, the first part contains spectral information about the medium 5 ' but no spectral information about the object 5 ' , contain. The second part comprises spectral information about the object 5 ' , In 3 is the first surface 51 " , a second surface 52 " and a third surface 53 " from the medium 5 ' covered. In 4 is between the medium 5 ' and the object 5 ' a cavity 50 educated. For example, between the medium 5 ' and the object 5 ' be enclosed by a vacuum or a gas.

In one embodiment, the comparison value 12 ' a normalized relative difference signal of the first spectrometric detector signal 111 ' and the second spectrometric detector signal 111 ' be. This relative difference signal can be used as a measure to determine the direct reflection and thus as a comparison value 12 ' be used. In one exemplary embodiment for determining the comparison value 12 ', the first individual measurement may first be performed in a first time interval 11 ' be performed, in a second time interval, which is temporally after the first time interval, a second individual measurement 11 " be carried out and in a third time interval, which is temporally after the second time interval, a dark measurement be performed. Alternatively or additionally, a first dark measurement for the first individual measurement 11 ' and a second dark measurement for the second individual measurement 11 " be performed. The difference of the first spectrometric detector signal 111 ' and the detector signal of the first dark measurement forms a first difference value. The difference of the second detector signal 111 ' and the detector signal of the second dark measurement forms a second difference value. The first and second difference values are each greater than or equal to zero. The comparison value 12 ' can for example be calculated as follows: $$\text{comparison value}=\frac{\left|\text{first difference value}-\text{second difference value}\right|}{\text{first difference value}+\text{second difference value}}$$

The comparison value 12 ' may assume values between zero and one in this embodiment. If only a single dark measurement is carried out, the value for the first dark measurement and the second dark measurement can be used to determine the comparison value 12 ' in each case the value of the single dark measurement can be used. If no dark measurement is performed, the value of the first and the second dark measurement can be set to zero. In the embodiment described below, it is assumed that for the radiation coming from the object according to Lambert's law on the object 5 ' was reflected, that is, that the radiation was diffusely reflected. The limit values of the comparison value described below 12 ' Among other things, they depend on an angular offset of the illumination elements to the optical axis, the emission characteristic of the illumination elements and the absorption behavior of the measurement area 5 and thus can vary depending on these sizes. In the present embodiment results in the comparison 12 a comparative value 12 ' with a value of 0.15, this indicates that there is direct reflection and one of the spectrometric detector signals 111 ' . 111 ' Shares directly reflected radiation has. In this case, the spectral evaluation 14 For example, as in the flowchart in 5 . 8th or 9 shown, done.

In 5 becomes the spectrometric detector signal 131 ' with a first value, wherein the value is a measure of the detected electromagnetic radiation, and wherein the first value is greater than a second value another detector signal 132 ' is for determination 141 a spectral information 141 ' of the medium 5 ' In particular, with good spectral correlation (that is, the same spectral behavior at different wavelengths), the further spectrometric detector signal 132 ' with a second value smaller than the first value for determination 142 a spectral information 142 ' of the object 5 "can be evaluated 14. It can output 15 the spectral information 141 ' of the medium 5 ' and the spectral information 142 ' of the object 5 ' respectively.

A comparative value 12 ' for example, if only very few photons were detected, that is, both spectrometric detector signals 111 ' . 111 ' Accept values that approximately correspond to the dark measurement / dark measurements. Furthermore, a comparison value 12 ' of about zero when the spectrometric detector signals 111 ' . 111 ' are about the same size. Equal-sized spectrometric detector signals 111 ' . 111 ' may arise if not with any single measurement 11 ' . 11 " or in both single measurements 11 ' . 11 " directly reflected radiation was detected. Because from the comparison value 12 ' With a value of approximately zero, no statement can be made about the existence of a direct reflection, the comparison value applies 12 ' as ambiguous. In the case of an ambiguous comparison value 121 ' For example, a radiation intensity of an electromagnetic radiation irradiated on the measuring range before striking the measuring range may be another indicator 122 ' be for the presence of direct reflection and the selection 13 the spectrometric detector signals 111 ' . 111 ' depending on the further indicator 122 ' respectively.

If there is an ambiguous reference value 121 ' Both spectrometric detector signals 111 ' . 111 ' for determining a spectral information 142 ' of the object 5 ' be used when the radiation intensities of the spectrometric detector signals 111 ' . 111 ' assume a low value, with a low value, for example, a value of 0.2% or 5% or a value between 0.2% and 5% of the radiation intensity of the measuring range 5 radiated electromagnetic radiation before hitting the measuring range 5 includes. Such a case is exemplary in the in 6 shown flowchart shown. In 6 is a measurement 11 '''of the measuring range 5 irradiated electromagnetic radiation made. The detected here detector signal 111 ''', which is a measure of the radiation intensity of the irradiated on the measuring range electromagnetic radiation is in 6 to the evaluation unit 6 , in particular the comparison unit 61 , transmitted. The measurement 11 '''of the radiation irradiated onto the measuring region can, for example, be applied to the illumination elements which are to be irradiated 110 ' . 110 ' of the measuring range are set up with electromagnetic radiation. Alternatively or additionally, the measurement 11 '''for each lighting element can be made once and the resulting values stored in a memory as a reference value (not shown) to which the comparison unit 61 , in particular in the case of an ambiguous reference value 121 ' can access the other indicator 122 ' to determine and to the selection unit 62 to convey. In this embodiment, not shown here, the detector signal 111 ''', which is a measure of the on the measuring range 5 irradiated radiation is retrieved from the memory. The step measuring 11 '''of the measuring range 5 irradiated radiation can be omitted here. The further indicator 122 ' is a measure of how much radiation from the measuring area 5 in relation to the on the measuring range 5 irradiated radiation is detected in the detection unit. For example, the further indicator 122 ' assume a value between 0% and 100%, with the interval margins included.

If there is an ambiguous reference value 121 ' Both spectrometric detector signals 111 ' . 111 ' 16. Such a case is in the flowchart in FIG 7 shown. The process can be up to the selection unit 62 for example, with the in 6 match shown process. The further indicator 122 ' is a measure of how much radiation from the measuring range 5 in relation to that on the measuring range 5 irradiated radiation is detected in the detection unit. Both spectrometric detector signals 111 ' . 111 ' be in the in 7 shown embodiment, when the radiation intensity assumes a high value, in particular a value of 10% or 100% or a value between 10% and 100% of the intensity of the irradiated on the measuring range electromagnetic radiation. The further indicator 122 ' indicates that direct reflection may be present. Alternatively, the spectral evaluation could 14 at least one of the detector signals 111 ' . 111 ' for determination 141 the spectral information 141 ' of the medium. When the radiation intensity at an ambiguous comparison value 121 ' assumes a low value, in particular a value of less than 0.1% of the intensity of the electromagnetic radiation radiated onto the measuring area, this can be an indication that the measuring distance to the measuring area 5 under which the individual measurements 11 ' . 11 " were inappropriate. As in 7 shown, discarded 16 the spectrometric detector signals 111 ' , 111 "due to the low value of the other indicator 122 ' , The control signal 16 ' can be generated as described above, for example, to change the measuring distance.

It can thus on the basis of the further indicator 122 ' be controlled, whether a provision 141 . 142 a spectral information 14 ' . 141 ' . 142 ' or a discard 16 the detector signals 111 ' . 111 ' and a control of the measuring unit 7 for performing new individual measurements 11 ''',11''''and transmit the spectrometric detector signals to the evaluation unit 6 he follows. When discarding 16 may as described above a control signal 16 ' be generated, which is the measuring unit 7 controls.

In 8th is shown a flowchart, which is from the comparison 12 of the first spectrometric detector signal 111 ' and the second spectrometric detector signal 111 ' a clear comparison value 12 ' results. The comparison value 12 ' indicates in this embodiment that one of the spectrometric detector signals 111 ' . 111 ' directly reflected radiation and one of the spectrometric detector signals 111 ' . 111 ' does not include directly reflected radiation. The procedure of the procedure 10 is up to the spectral evaluation 14 for example, analogous to that in 5 described procedure. In 8th is shown, for example, the spectral evaluation 14 the spectrometric detector signal 132 ' in which there is no direct reflection, for determination 142 the spectral information of the object 5 ' done and discarding 16 the spectrometric detector signal 131 ', in which there is direct reflection occurs. It can be the output 15 the spectral information of the object 5 ' respectively.

A difference of the procedure in 8th and in 9 The flowchart shown is seen in that in 9 after the selection 13 the spectrometric detector signals for analysis, the spectral evaluation 14 the spectrometric detector signal 131 ' in which there is direct reflection, for detection 141 the spectral information 141 ' of the object at least partially surrounding medium 5 ' done and discarding 16 the spectrometric detector signal 132 ' , in which there is no direct reflection occurs.

5 . 8th and 9 show embodiments in which one of the spectrometric detector signals 111 ' . 111 ' directly reflected radiation and one of the spectrometric detector signals 111 ' . 111 ' does not include directly reflected radiation. Depending on the specification, which can be specified for example by a user, spectral information 14 ' of the object 5 ' and / or the medium 5 ' to be determined 141, 142.

In 10 is a flowchart for an embodiment of the spectral evaluation 14 shown in which the provision 141 the spectral information 141 ' of the medium 5 ' at which the direct reflection takes place and / or the determination 142 the spectral information 142 ' of the object 5 ' he follows. It also takes place in 10 a provision 143 the main incident angle 143 'of the electromagnetic radiation on the measuring range 5 for at least one of the individual measurements 11 ' . 11 " , The main incident angle information 143 'and the spectral information / spectral information 141 ' . 142 ' be in a correction unit 144 processed. For example, a Fabry-Perot interferometer in the spectrometric measurement 111 for the individual measurements 11 ' . 11 " used, so can change the main angle of incidence 143 ' lead to a shift in the spectrum. In Fabry-Pérot interferometers, varying the angle of incidence of the electromagnetic radiation on the Fabry-Pérot interferometer causes a shift in the wavelength to be measured by the interferometer. If the main angle of incidence deviates from the normal, the entire spectrum is shifted, a so-called spectral offset. Is the main angle of incidence 143 ' As is known, this spectral offset can be determined and the spectrum (s) 141 ' . 142 ' be corrected accordingly. This correction takes place in the in 10 shown embodiment in the correction unit 144 , The corrected spectrum or the corrected spectra 1410 ' . 1420 ' can be spent 15.

11 shows a cross section of a miniature spectrometer 1000 to carry out the analysis of the measuring range 5 for example, according to one of the methods described above. The miniature spectrometer 1000 For example, it can be arranged in a housing (not shown). The miniature spectrometer 1000 includes a lighting unit 1 comprising at least a first lighting element 1' and a second lighting element 1" for illuminating the measuring range 5 with electromagnetic radiation from different illumination angles 1010 ' . 1010 " , a detection unit 2 , a spectral element 3, which in the beam path between the measuring range 5 and the detection unit 2 is arranged and an evaluation unit 6 , which is adapted to the lighting elements 1' . 11 " the lighting unit 1 to control independently of each other. A first control signal 161 ' the evaluation unit 6 may be the first lighting element 1' to control, that is, for example, the first lighting element 1' on and off, the first radiation distribution of the first lighting element 1' set a first illumination angle 1010 ' adjust and / or the distance between lighting element 1' and set measuring range 5. Analogously, a second control signal of the evaluation unit 6 the second lighting element 1" to drive, that is, for example, the second lighting element 1" on and off, the second radiation distribution of the second illumination element 1" adjust, a second illumination angle 1010 " adjust and / or the distance between the second lighting element 1" and measuring range 5 to adjust. The first control signal 161 ' and the second control signal 162 'can be generated independently of each other. In this embodiment, the lighting elements 1' . 1" each from an optical axis 1001 spaced from the miniature spectrometer, so that an eccentric illumination of the measuring range 5 can be realized. In the beam path between the spectral element 3 and the measuring range 5 is an imaging system 4 arranged, which the coming of the measuring range radiation 501 to the spectral element 3 leads. The radiation 501 coming from the measuring area is in 11 sketched as an area between two rays. The imaging system 4 may include, for example, a positive lens and / or a light guide. The spectral element 3 For example, it may comprise at least one micromechanical Fabry-Pérot interferometer comprising two mirror elements spaced apart by a gap. The first lighting element 1' and the second lighting element 1" may be implemented as separate emitters, such as light-emitting diodes (LED), LED + phosphors or bulb + shutter, which are arranged at different locations. Alternatively or additionally, the lighting elements 1' . 1" different light paths from a common emitter, such as a light emitting diode (LED), LED + phosphors, bulb + shutter denote. These different light paths can be separately switched on and off or modulated by modulators, for example, so that, for example, a time-independent control of the light paths can be made possible. The time-independent control can be done for example by lock-in with different frequencies or different phase. For example, the first lighting element 1' be switched in a phase angle of 0 ° to 120 ° to the measuring range 5 to irradiate with the first radiation distribution 110 'and the spectrometric measurement 111 perform the second lighting element 1" be turned on in a phase position of 120 ° to 240 °, wherein the first lighting element 1' is off to the measuring range 5 to irradiate with the second radiation distribution 110 "and the spectrometric measurement 111 and perform a spectrometric measurement in a phase position of 240 ° to 360 °, while no lighting element 1' . 1" is turned on to with the detection unit 2 To record a detector signal 111 '''for the dark measurement. Ambient light, which is not from the lighting unit 1 can be suppressed, for example, by a lock-in method is performed with different frequencies or a fixed phase relationship for the lighting elements 1' . 1" is used. Thus, also interactions between the lighting elements 1' . 1" be reduced or avoided. The first illumination angle 1010 ' denotes the main angle of incidence 143 ' of the first lighting element 1' , the second illumination angle 1010 " denotes the main incident angle of the second lighting element 1" , As in 10 shown, the main angle of incidence 143 ' to every single measurement 11 ' . 11 " 143 are determined to the spectrum 141 ' . 142 ' to correct. The detection unit 2 , the spectral element 3 and the imaging system 4 form in 11 together the measuring unit 7 , The evaluation unit 6 includes the comparison unit 61 , the signal selection unit 62 and the arithmetic unit 63 , As described above, the comparison unit 61 for determining the comparative value 12 ' from the results of the individual measurements 11 ' , 11 ", the signal selection unit 62 is to a selection 13 the spectrometric detector signals 111 ' . 111 ' for analysis of the measuring range 5 depending on the comparative value 12 ' set up and the arithmetic unit 63 is for investigation 141 . 142 a spectral information 14 ' . 141 ' . 142 ' from the at least one selected spectrometric detector signal 13 ' . 131 ' . 132 ' set up. In 11 are the first directly reflected radiation 1002 ' , that is the first single measurement 1' occurring on the medium 5 ' directly reflected radiation, the second directly reflected radiation 1002 ' , that is the second single measurement 1" occurring on the medium 5 ' directly reflected radiation and the radiation coming from the object 1003 outlined. Be the lighting elements 1' . 1" timed offset, so enter the directly reflected radiation 1002 ' . 1002 " offset in time. For simplicity, in 11 and 12 all for the individual measurements 11 ' . 11 " relevant occurring radiation 1002 ' . 1002 " . 1003 each in 11 and 12 outlined. The radiation 501 coming from the measuring area, which is incident on the detection unit 2 is guided comprises in this embodiment, only a part of the radiation coming from the object 1003 , The directly reflected radiation 1002 is in this embodiment in the direction of the other lighting element 1' . 1" is reflected and thus will not affect the detection unit 2 guided. That is, that of the detection unit 2 recorded spectrometric detector signals 111 ' . 111 ' The individual measurements 11 ', 11 "do not contain any direct reflection, for example they can be determined according to the methods described above 10 be evaluated to a spectral information 142 ' of the object 5 ' to obtain.

In 12 is the measuring range 5 relative to the miniature spectrometer 1000 opposite to the 11 shown embodiment tilted by an angle. This changes the first illumination angle 1010 ' and the second illumination angle 1010 "versus the illumination angles in 11 each at the tilt angle. As with the sketched beam path of the direct, reflected radiation 1002 . the radiation coming from the object 1003 and the radiation coming from the measuring area 501 pointing to the detection unit 2 is clear, comprises the first spectrometric detector signal 111 ' which by irradiation 110 ' of the measuring range 5 with the first radiation distribution is measured spectrometrically 111, shares of directly reflected radiation 1002 and parts of the object 5 ' coming radiation, which is shown here as diffuse reflected radiation. The second detector signal 111 ' includes only portions of the object 5 ' coming radiation 1003 , Thus, for example, with one of the methods described above 10 from the first detector signal 111 ' the spectral information 141 ' of the medium 5 ' be determined 141 and / or from the second detector signal 111 ' the spectral information 141 "of the object 5 ' be determined.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 102007007040 A1 [0002]
• DE 102011076677 A1 [0003]

Claims (13)

Method (10) for analyzing a measuring range (5) taking into account a spectral evaluation (14) of at least one individual measurement (11 ', 11 ", 11''', 11 ''''), wherein the individual measurement (11 ', 11" , 11 ''',11'''') comprises the following steps: irradiating (110', 110 ") an object (5") of the measuring area (5) with electromagnetic radiation, • spectrometric measurement (111) of one of Measuring range coming radiation (501), characterized in that for the analysis of the measuring range (5) at least two individual measurements (11 ', 11 ", 11''', 11 '''') are performed, wherein • the irradiation (110 ') of the object (5 ") with electromagnetic radiation for a first individual measurement (11 ') with a first radiation distribution, and a first spectrometric detector signal (111') is provided by the spectrometric measurement (111) of a first radiation coming from the measurement area, the irradiation (110 ") of the object (5") with electromagnetic radiation for e In a second individual measurement (11 ") takes place with a second radiation distribution, which is different from the first radiation distribution, and a second spectrometric detector signal (111") is provided by the spectrometric measurement (111) of a second radiation coming from the measurement area, 12) of the first spectrometric detector signal (111 ') and the second spectrometric detector signal (111 "), a comparison value (12', 121 ') is determined, wherein the comparison value (12', 121 ') is an indicator for the presence of a direct reflection and • a selection (13) of the spectrometric detector signals (111 ', 111 ") for the analysis of the measuring range (5) as a function of the comparison value (12', 121 ') takes place for the spectral evaluation (14). Method (10) according to Claim 1 , characterized in that the first spectrometric detector signal (111 ') and the second spectrometric detector signal (111 ") each comprise photon intensities. Method (10) according to one of the preceding claims, characterized in that the first spectrometric detector signal (111 ') and the second spectrometric detector signal (111 ") are recorded with a time offset by a measuring unit (7). Method (10) according to one of the preceding claims, characterized in that the comparison value (12 ', 121') is a standardized, relative difference signal of the first spectrometric detector signal (111 ') and the second spectrometric detector signal (111 "). Method (10) according to one of the preceding claims, characterized in that, in the comparison value (12 ') indicating the presence of direct reflection, • the spectrometric detector signal (131') having a first value, the value being a measure of the detected electromagnetic radiation and wherein the first value is greater than a second value of a further detector signal (132 '), for determining (141) a spectral information (141') of a medium (5 ') at which the direct reflection takes place evaluated and • the further spectrometric detector signal (132 ') having a second value, which is smaller than the first value, is evaluated for determining (142) spectral information (142') of the object (5 "). Method (10) according to one of the preceding claims, characterized in that, in the case of an ambiguous comparison value (12 ', 121'), a radiation intensity detected by the measuring unit (7) is a further indicator (122 ') for the presence of a direct reflection and the spectral evaluation (14) as a function of the further indicator (122 ') takes place. Method (10) according to Claim 6 characterized in that, in the case of an ambiguous comparison value (12 ', 121'), both spectrometric detector signals (111 ', 111 ") are suitable for determining (142) spectral information (142') of the object (5") if the Radiation intensity assumes a low value, in particular a value of 0.2% or 5% or a value between 0.2% and 5% of the intensity of the irradiated on the measuring range electromagnetic radiation or • both spectrometric detector signals (111 ', 111 ") discarded when the radiation intensity becomes high, in particular a value of 10% or 100% or a value between 10% and 100% of the intensity of the electromagnetic radiation radiated onto the measuring area. Method (10) according to one of the preceding claims, characterized in that • the spectral evaluation (14) of the spectrometric detector signal (132 '), in which there is no direct reflection, for determining (142) a spectral information (142') of the object (5 ") takes place and • discarding (16) the spectrometric detector signal (131 ') in which there is direct reflection. Method according to one of Claims 1 to 7 , characterized in that • the spectral evaluation (14) of the spectrometric detector signal (131 ') takes place, in which there is direct reflection, for determining (141) a spectral information of the medium (5') at which direct reflection takes place, and • the spectral evaluation (14) of the spectrometric detector signal (132 '), in which there is no direct reflection, for determining (142) a spectral information (142') of the object (5 ") takes place. Method (10) according to one of Claims 1 to 7 , characterized in that • the spectral evaluation (14) of the spectrometric detector signal (131 '), in which there is direct reflection, for determining (141) a spectral information (141') of a medium surrounding the object (5 ") at least ( 5 '), at which the direct reflection takes place and • discarding (16) of the spectrometric detector signal (132'), in which there is no direct reflection occurs. Method (10) according to one of the preceding claims, characterized in that from the individual measurements (11 ', 11 ", 11''', 11 '''') a main angle of incidence (143 ') of the electromagnetic radiation on the measuring range (5) is determined. Miniature spectrometer (1000) for carrying out the analysis of the measuring area (5) according to a method (10) according to one of the preceding claims, comprising • a lighting unit (1) comprising at least two lighting elements (1 ', 1'') for illumination (110') of the measuring area (5) with electromagnetic radiation from different illumination angles (1010 ', 1010 "), • a detection unit (2), • a spectral element (3) which is arranged in the beam path between the measuring area (5) and the detection unit (2) and • an evaluation unit (6) which is designed to control the lighting elements (1 ', 1 ") of the lighting unit (1) independently of each other, characterized in that the evaluation unit (6) has a comparison unit (61), a signal selection unit ( 62) and a computing unit (63), wherein • the comparison unit (61) determines the comparison value (12 ', 121') from the results of the individual measurements (1 1 ', 11 ", 11''', 11 ''''), the signal selection unit (62) for selecting (13) the spectrometric detector signals (111 ', 111") for analyzing the measuring area (5) as a function of the arithmetic unit (63) for determining (141, 142) spectral information (14 ', 141', 142 ') from the at least one selected spectrometric detector signal (13', 131 ', 132') is set up. Miniature spectrometer (1000) after Claim 12 , characterized in that the spectral element (3) comprises at least one Fabry-Pérot interferometer.

Images