DE102012016345A1 - Spectrometer and method for operating a spectrometer - Google Patents

Abstract

Known spectrometers (1) comprise an entry opening (3) for the light to be analyzed (P), a dispersive element (5) for the spatial-spectral splitting of light entering through the entry opening, a spatially resolving detector (6) for the wavelength-dependent conversion of light split in this way (S) into electrical signals (Ui) and a control unit (7) for processing the electrical signals (Ui). A value of a sample property at the measuring location is determined from the measured values in the course of further processing using predetermined parameters, for example reference variables, and is visually displayed and / or stored for later evaluation. The storage typically takes place in real time, i.e. immediately after the determination of the value of the sample property has ended. This known procedure has the disadvantage that the evaluation results depend on the parameters specified in the further processing of the electrical variable. An improved spectrometer should enable evaluations with different further processing parameters. For this purpose, the control unit (7) is set up to determine values of the electrical signals (Ui) and to digitally store them together with a time value in an electronic database structure (8). As a result, further processing of the raw data for a sample property can be postponed and, if necessary, carried out with different parameters. The evaluation of the sample property can also be carried out with different parameters.

Description

The invention relates to an optical spectrometer with a housing, an inlet opening for the light to be analyzed, a dispersive element for spatial-spectral splitting of light entering through the inlet opening, a spatially resolving detector for wavelength-dependent conversion of such split light into electrical signals and a control unit for processing the electrical signals and a method for operating such a spectrometer.

The spectrometer may include other optical elements. In particular, the dispersive element can be designed to be imaging. In addition, a spectrometer expediently comprises inside or outside the housing a light source for (defined) illumination of a sample to be examined. The inlet opening is typically formed as a gap, but instead of a rectangular opening can also have any other outline shape.

For the purposes of the invention, the term "light" encompasses any electromagnetic radiation which can be manipulated by optical means, in particular infrared (IR) and ultraviolet (UV) light.

The dispersive element spatially splits the light to be analyzed such that different wavelength ranges reach different detector elements. The detector elements convert the respective light energy into an electrical quantity such as charge, voltage or current and output the value of the magnitude at a respective output (digital or analog) for further processing to the control unit.

A measurement procedure on a sample comprises a) illuminating the sample, b) recording light to be analyzed from a location of the sample (measurement location) into the spectrometer through the inlet opening during illumination, c) dispersively splitting the sample light and d) spatially resolved conversion of the split Light into electrical signals ("readings") with a respective value per detector element. In the course of a further processing - typically by means of the electronic control unit - from the measured values, a value of a sample property at the measuring location is determined on the basis of given parameters, for example reference values, and visually displayed and / or stored for later evaluation. The representation / storage typically takes place in (quasi) real-time, ie immediately after the end of the determination of the value of the sample property.

In the prior art, such measures are for example US 2001/050339 A1 known. As a sample property, the sugar content at the measuring location is determined from the electrical parameters of the detector. The samples are fruits, especially sugar beet. In addition, the GPS coordinates of the measuring location are determined and stored together with the sugar content determined for the measuring location in a database structure, for example a table or a relational database (RDBMS), and displayed visually.

The (quasi) real-time representation of the determined sample property can be done in the prior art in the form of distribution, trend, spectral and / or table charts. Later, static subsets of the stored sample property values can be determined and evaluated from the database structure based on query criteria such as the measurement time, the measurement location, or (for individually labeled samples) the sample identification code, such as a serial number, if such criteria are included in the database structure. The evaluation may include, for example, a statistical analysis of the sample property values.

This known approach has the disadvantage that the evaluation results depend on the parameters specified in the further processing of the electrical variable.

The invention has for its object to improve a spectrometer of the type mentioned and specify an operating method for a spectrometer, so that evaluation results can be determined with different processing parameters.

The object is achieved by a spectrometer having the features specified in claim 1, and by a method having the features specified in claim 5.

Advantageous embodiments of the invention are specified in the subclaims.

According to the invention, it is provided that the control unit (in terms of circuitry and / or programming technology) is set up to determine values of the electrical signals and store them digitally together with a (current) time value in an electronic database structure. The time value preferably indicates a time between the conversion and the storage, in particular a time of conversion or storage. The time value may indicate the relevant time relatively, for example as a difference to a predetermined time, in particular an initial value at the beginning of a measurement, or quasi-absolute, for example in a local time of the measurement. The Storage can be carried out in particular in a relational database and / or in a common data record. For the purposes of the invention, the time of conversion is a time between the incidence of light on the detector and the output of the analog or digital signals to the control unit. A time value according to the invention is such that a period or an equivalent of a period can be determined by forming a difference between two values. The value of the respective time point is expediently determined for each data record in the same way, for example via a query of a time-of-day function of the database structure when creating a new data record comprising the values of the signals.

The storage of the raw data output by the detector together with a respective time value ("time stamp") makes it possible to postpone the further processing of the raw data to a sample property and, if necessary, to execute it with different parameters (ie several times). As a result, the evaluation of the sample property with different parameters (multiple) can be performed, which is particularly advantageous for experimental purposes.

Embodiments in which the control unit is set up to read a sequence of stored values of the electrical signals and associated time values for successive time values from the database structure and to display the values in an (ascending or descending) order of the time values via an interface are particularly preferred. The corresponding method steps are reading a sequence of stored values of the electrical signals and respective associated times for successive time values from a database structure and reproducing the stored values in an (ascending or descending) order of the time values via an interface. In this way, a virtual measurement can be performed with real measured values. In particular, all subsequent evaluation and / or presentation steps can be the same as in a measurement with evaluation / representation in (quasi) real time. For this purpose, the values of the electrical signals for the evaluation are preferably transmitted via the interface and received by the evaluation unit. The steps according to the invention can then be performed transparently between the real measurement and the evaluation. On a special adjustment of the evaluation / presentation can be advantageously dispensed with.

The method expediently comprises the step of determining a derived quantity from the displayed values on the basis of predefined parameters. It is preferably carried out by the control unit. This step is called evaluation.

Advantageously, the control unit can be set up to reproduce the stored values at intervals over the interface, the time intervals corresponding to a predetermined or specifiable multiple of the time intervals between the relevant stored time values. The corresponding method step is the reproduction of the stored values via the interface at time intervals, the time intervals corresponding to a predetermined or predefinable (positive or negative) multiple of the time intervals between the respective stored time values. The amount of the multiple may in particular be less than one, equal to one or greater than one. In this way, the virtual measurement can take place in slow motion, in real time or in time. The reproduction of the stored values of the signals output by the detector with the original time intervals (multiples equal to one) makes it possible to emulate a measurement, which may be advantageous in particular for test purposes and further developments. The spectrometer is set back to the time of the real measurement. With various further processing parameters it is possible to play through different measurement scenarios, for example a measurement in the field on the one hand and a measurement in the laboratory on the other hand. If the multiple is negative, the playback is performed in the reverse order as in the storage, wherein the speed is scalable as in the regular order on the basis of the amount of multiples.

Preferably, the spectrometer is equipped with an operating element for triggering the storage in the database structure and an operating element for triggering the reproduction via the interface. Particularly advantageous are an operating element for stopping the playback and / or controls for specifying the multiple of the time intervals and / or a control element for specifying either an ascending and a descending order of playback. Such controls allow virtual measurement with real metrics even without technical knowledge of the user.

• – Ermitteln von Werten der elektrischen Signale des Detektors und eines (aktuellen) Zeitwerts,
• – Speichern des Zeitwerts zusammen mit den Signalwerten digital in einer elektronischen Datenbankstruktur, insbesondere in einer relationalen Datenbank, insbesondere in einem gemeinsamen Datensatz,
• – Empfangen eines Befehls zum Wiedergeben der gespeicherten Werte,
• – Lesen einer Folge von gespeicherten Werten der elektrischen Signale und jeweiligen zugehörigem Zeitpunkten für aufeinanderfolgende Zeitpunkte aus der Datenbankstruktur und
• – Wiedergeben der gespeicherten Werte in einer Reihenfolge der Zeitpunkte über eine Schnittstelle

umfassen. Es kann sich dabei um verschiedene Softwaremodule handeln. Es ist aber auch möglich, dass ein Softwaremodul mehrere oder alle der obigen Aufgaben ausführt.In particular, the invention comprises a computer program and a control unit, in each case (in terms of circuitry and / or programming technology) set up to carry out the method according to the invention. The computer program or the control unit can, for example, software modules for

• Determining values of the electrical signals of the detector and a (current) time value,
• Storing the time value together with the signal values digitally in an electronic database structure, in particular in a relational database, in particular in a common data record,
• Receiving a command to play the stored values,
• Reading a sequence of stored values of the electrical signals and respective associated times for successive times from the database structure and
• - Playback of the stored values in a sequence of times via an interface

include. These can be different software modules. But it is also possible that a software module performs several or all of the above tasks.

The invention will be explained in more detail by means of exemplary embodiments.

In the drawings show:

1 a spectrometer,

2 a flowchart describing the storage and later reproduction of raw data, and

3 a virtually usable spectrometer.

In all drawings, like parts bear like reference numerals.

1 shows a spectrometer 1 that is a case 2 with an entrance opening 3 for light P to be analyzed from a location of a sample 4 , a dispersive element 5 for the spatial-spectral splitting of the incoming light P, a spatially resolving detector 6 for the wavelength-dependent conversion of the split light S into n electrical signals U _{i = 1... n} (for example one per detector element 6.i ) and a control unit 7 for processing the electrical signals U has. The detector 6 For example, n = 32 detector elements 6.1 ... 6:32 and due to the spatial splitting of the light S can detect the light intensities in as many different wavelength ranges λ _i . For example, the detector comprises 6 for each element an A / D converter such that the measured electrical signals U _i in digital form to the control unit 7 be transmitted, for example, in parallel on 16 parallel data lines per signal U _i or sequentially on a data bus.

The control unit 7 includes, for example, a relational database 8th , a control panel 9 and an interface 10 to which an evaluation unit 11 is connectable. The controls of the control panel 9 are, for example, buttons whose operation is a respective event within the operating software of the control unit 7 triggers. A button 9A Used to start and stop a measurement with the detector 6 , From the start of a measurement, the measured data set of signals U _i measured and converted in each time integration interval (given length) are respectively stored in the database with a respective time stamp 8th saved. In addition, for example, (optionally) the measured signals U _i at the interface 10 issued, this may be omitted in particular embodiments. By means of the button 9B the storage can be switched on and off. When storage is switched off, only one output is output via the interface 10 , In alternative embodiments, the button 9B omitted, so that during a measurement is always stored. The button 9C starts and stops playing in the database 8th stored measured values via the interface 10 , The button 9D pauses playback until it is pressed again. The button 9E continues playback with a timed earlier record, repeating the output of at least one record. The button is set against that 9F the playback continues with a delayed later record, so leaves at least one record during playback. The control unit 8th can have one or more other controls 9G For example, have a knob to adjust the playback speed and / or the playback order.

In the exemplary evaluation unit 11 a software M for the evaluation of spectral measurement data U _i for determining a sample property Q is executed. The software M takes the raw spectral measurement data in the form of the digitized signals U _i via the interface 10 from the spectrometer 1 and evaluates them by determining from the digital values of the signals U _i a property Q of the sample, for example a moisture content and / or a layer thickness. For example, it displays the evaluation results graphically and numerically on a screen (not shown).

Instead of the explicit storage of time stamps by instructions of the control unit 7 to the database 8th can the database 8th be formed so that when creating a new record automatically the current time is stored to the record so that it can be used when reading the database as a query and / or sorting criterion.

In other embodiments (not shown), the control unit may 7 outside the case 2 be arranged. The housing 2 then has, for example, only electrical input terminals for the power supply of the detector 6 and electrical output terminals for the (analog or digitized) signals U _i .

The spectrometer 1 may in particular be part of a spectrometric measuring head (not shown) comprising a light source for illuminating the sample. In this case, for example, the illumination and the recording of the sample light P through the same window can be an additional housing surrounding the light source and the spectrometer.

In 2 an exemplary process flow is shown in the form of a flowchart. The procedure in Sections R and V in this case is by the control unit 7 carried out in section A of the evaluation unit 11 , The section R represents a real measurement, whereas the section V represents a virtual measurement. The measured values U _i can be included in the evaluation in section A from both sections R, V.

During the interval recording of sample light P and optoelectronic conversion of the spectrally split light S in the n elements of the detector 6 , which represent n spectral detection channels with a respective spectral range λ _i , takes the control unit 7 after each temporal integration interval, the electrical signals U _{i of} the detector 6 opposite. The signals U _i represent, for example by means of voltages digitized by means of an A / D converter, the number of photons (light intensity) detected in the relevant spectral range λ _i in the integration interval. For voltage alternative electrical quantities are, for example, the photoelectrically absorbed charge or the resulting current during reading. The control unit 7 stores the digitized values U _i (here: numbers), for example in an RDBMS. In this case, all values U _i ("raw data") of an integration interval are stored together with a current time stamp in a common data record. For each integration interval, a separate record is stored.

By means of the control element 9C the reproduction of the stored values U _{i can be} triggered. Each reproduced value U _i is then over the interface 10 output, so for example to the evaluation 11 transmitted as if it had been measured immediately before, the control unit 8th waits between the output of successive records a pause duration, which corresponds to the time difference between the time stamps of the two records concerned. By specifying a multiple other than one as a scaling factor for the time intervals between the output of the individual data sets, for example by means of the operating element, which are determined as the distances of the stored time stamps 9G , the playback speed and thus the simulated measuring time can be gathered (multiples less than one) or stretched (multiples greater than one).

The virtual measurement in section V has the advantage that it (and thus also the evaluation in section A) can be repeated as often as desired with identical accuracy (in particular with different evaluation parameters).

In a special, in 3 schematically illustrated embodiment, the spectrometer according to the invention operates 1 exclusively virtual. It is then a device 1 in the form of a control unit 7 on the one hand to an output interface 10 ' a real spectrometer 1' and on the other hand to an evaluation unit 11 , which is a commercial PC, for example, is connectable. The real spectrometer 1' here includes by way of example also a light source 14 taken from the spectrometer control unit 7 which also carries out the digitization of the measured values U _i and them via their interface 10 ' outputs.

The two compounds A and B may be sequential or simultaneous. For example, they are sequential when the device 1 first with the spectrometer 1' (Compound A) to get real readings from the spectrometer 1' record and in the database 8th and only after separation of the compound A with the real spectrometer 1 the connection B with the evaluation unit 11 will be produced.

Such a device 1 includes, for example, a central processing unit 13 , an input interface 12 for connection to the spectrometer 1' and an output interface 10 for connection to an evaluation unit 11 , wherein the control unit 7 is set up via the input interface 12 Values of signals U _{i of} an optoelectronic conversion and an associated time (for example, the conversion) to determine and the value of the time together with the values of the signals digitally in an electronic database structure 8th in particular in a relational database, in particular in a common data record, and the stored values in an order of the times via the output interface 10 play.

Is the device 1 at the spectrometer 1' connected (connection A), it stores all of the spectrometer 1' output measured values U _i in the database structure 8th , Is she at the evaluation unit 11 connected (connection B), the stored measured values U _i as often as desired to the evaluation unit 11 be issued with selectable time scale multiple, selectable order or selectable break. From the point of view of the evaluation unit 11 the device acts 1 then as a spectrometer. That it is a virtual spectrometer 1 is for the evaluation unit 11 for example, completely transparent. The spectrometer 1 can at any time either at the input interface 12 with the spectrometer 1' or at the output interface 10 with the evaluation unit 11 or be connected to both simultaneously. In the latter case, those of the real spectrometer 1' output measured values in addition to the storage in the database 8th for example, in real time via the output interface 10 be issued.

It is also possible that the device 1 an identifier to the evaluation unit 11 sends the output measured values U _i as real (passing the measured values from the real spectrometer 1' in real time) or as virtual (playback).

LIST OF REFERENCE NUMBERS

1

spectrometer

2

casing

3

inlet opening

4

sample

5

Dispersive element

6

detector

7

control unit

8th

Database

9

controls

10

(Output) interface

11

evaluation

12

Input interface

13

central processing unit

14

light source

P

Sample light to be analyzed

S

Split light

U _i

Electrical signals

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

• US 2001/050339 A1 [0006]

Claims (8)

Spectrometer ( 1 ) with an inlet opening ( 3 ) for light (P) to be analyzed, a dispersive element ( 5 ) for the spatial-spectral splitting of light entering through the inlet opening, a spatially resolving detector ( 6 ) for the wavelength-dependent conversion of such split light (S) into electrical signals (U _i ) and a control unit ( 7 ) for processing the electrical signals (U _i ), characterized in that the control unit ( 7 ) is arranged to determine values of the electrical signals (U _i ) and together with a time value digital in an electronic database structure ( 8th ), in particular in a relational database, in particular in a common data record. Spectrometer ( 1 ) according to claim 1, wherein the control unit ( 7 ), a sequence of stored values of the electrical signals (U _i ) and associated times for successive times from the database structure ( 8th ) and read the values in an order of times over an interface ( 10 ) play. Spectrometer ( 1 ) according to claim 2, wherein the control unit ( 7 ), the stored values at intervals over the interface ( 10 ), wherein the time intervals correspond to a predetermined or predefinable multiple of the time intervals between the respective stored time points, in particular with a multiple smaller than one, equal to one or greater than one. Spectrometer ( 1 ) according to one of the preceding claims, with an operating element ( 9A ) for triggering the storage in the database structure and a control element ( 9B ) for triggering the reproduction via the interface, in particular with an operating element for stopping the reproduction, more particularly with operating elements ( 9G ) for specifying the multiple of the time intervals, further in particular with a control element for specifying either an ascending or a descending order of playback. Method for operating a spectrometer ( 1 ) with an inlet opening ( 3 ) for light (P) to be analyzed, a dispersive element ( 5 ) for the spatial-spectral splitting of the incoming light, a spatially resolving detector ( 6 ) for the wavelength-dependent conversion of the split light (S) into electrical signals (U _i ) and a control unit ( 7 ) for processing the electrical signals (U _i ), characterized by the following steps: reading a sequence of stored values of the electrical signals (U _i ) and respective associated times for successive times from a database structure ( 8th ), - reproducing the stored values (U _i ) in an order of the times via an interface ( 10 ). The method of claim 5, further comprising the following step: - Determine a derived size from the rendered values using given parameters. Method according to claim 5 or 6, wherein the reproduction of the stored values (U _i ) via the interface ( 10 ) takes place at time intervals, wherein the time intervals correspond to a predetermined or predefinable multiple of the time intervals between the respective stored time points, in particular with a multiple smaller than one, equal to one or greater than one. Computer program or control unit ( 7 ) arranged for carrying out a method according to one of the preceding method claims.

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