阅读说明：本技术 用于时间解析地测量测量信号的测量设备和方法 (Measuring device and method for the time-resolved measurement of a measurement signal ) 是由 J.特布吕格 J.费尔斯特 T.弗里奇 于 2019-06-19 设计创作，主要内容包括：本发明描述并示出时间解析地测量测量信号并时间分离测量信号的至少一个第一分量的测量设备,其具有发出脉冲状激励信号的光源、至少一个接收测量信号的探测器、至少一个产生第一比较信号的第一变换单元和至少一个分析单元,其中探测器由测量信号产生探测器信号。测量设备的特征在于,第一比较信号与激励信号关联,存在至少一个第一逻辑功能,其中第一逻辑功能运行时至少将第一比较信号与依赖于探测器信号的信号相互连接,使得逻辑功能的输出提供测量信号或探测器信号的第一分量的强度的度量,其中测量信号的分量的强度通过在测量信号的待分离的分量的持续时间期间落到探测器上的光子的数量得出,并且第一逻辑功能的输出端与至少一个分析单元连接。(The invention describes and shows a measuring device for the time-resolved measurement of a measurement signal and for the time separation of at least one first component of the measurement signal, comprising a light source which emits a pulse-like excitation signal, at least one detector which receives the measurement signal, at least one first transformation unit which generates a first comparison signal, and at least one evaluation unit, wherein the detector generates a detector signal from the measurement signal. The measuring device is characterized in that the first comparison signal is associated with the excitation signal, at least one first logic function is present, wherein the first logic function is operative to connect at least the first comparison signal to a signal dependent on the detector signal such that an output of the logic function provides a measure of the intensity of the measurement signal or of a first component of the detector signal, wherein the intensity of the component of the measurement signal is derived from the number of photons falling onto the detector during the duration of the component of the measurement signal to be separated, and an output of the first logic function is connected to the at least one evaluation unit.)

1. Measuring device (1) for the time-resolved measurement of a measurement signal (3) and for the time separation of at least one first component (4) of the measurement signal (3), having a light source (5) for emitting a pulse-like excitation signal (6), at least one detector (9) for receiving the measurement signal (3), at least one first transformation unit (12 a) for generating a first comparison signal (13), and at least one evaluation unit (14), wherein the detector (9) generates a detector signal (11) as a function of the measurement signal (3), characterized in that,

the first comparison signal (13) is associated with the excitation signal (6), at least one first logic function (15 a) is present, wherein the first logic function (15 a) connects at least the first comparison signal (13) to a signal (11, 18) that is dependent on the detector signal (11) when in operation, such that the output of the logic function (15 a) provides a measure of the intensity of the measurement signal (3) or of a first component (4) of the detector signal (11), wherein the intensity of the component of the measurement signal is derived from the number of photons that fall onto the detector during the duration of the component of the measurement signal that is to be separated, and the output of the first logic function (15 a) is connected to the at least one evaluation unit (14).

2. Measuring device (1) according to claim 1, characterized in that the first comparison signal (13) is correlated with the excitation signal (6) in that the first comparison signal (13) is derived from the excitation signal (6).

3. Measuring device (1) according to claim 1 or 2, characterized in that the light source (5) has a trigger (7), wherein the trigger (7) triggers a pulse-like excitation signal (6) by means of a trigger signal (8) and wherein the first comparison signal (13) is correlated with the excitation signal (6) in that the first comparison signal (13) is derived from the trigger signal (8).

4. Measuring device (1) according to one of claims 1 to 3, characterized in that the transformation unit (12 a) has at least one delay unit (16), wherein the delay unit (16) is designed such that, in operation, a pulse-like excitation signal (6) or trigger signal (8) is synchronized in time by the delay unit (16) with a signal (11, 18) that depends on the detector signal (11).

5. Measuring device (1) according to one of claims 1 to 4, characterized in that the transformation unit (12 a) has at least one means (17) for generating at least one time duration t₂With the excitation signal (6) or the trigger signal (8)Has a time interval of t₁≥0。

6. Measuring device (1) according to one of claims 1 to 5, characterized in that the transformation unit (12 a) has at least one means for temporally expanding and/or temporally compressing the excitation signal (6) or the trigger signal (8).

7. Measuring device (1) according to one of claims 1 to 6, characterized in that at least one further transformation unit (12 b) is connected to the output of the detector (9), wherein the further transformation unit (12 b) preferably has a delay unit (16), wherein the delay unit (16) preferably synchronizes the first component (4) of the detector signal (11) in time with the excitation signal (6) or the trigger signal (8).

8. Measuring device (1) according to one of the claims 1 to 7, characterized in that the logic function (15 a, 15 b) comprises at least one AND operation, OR operation, XOR operation, NAND operation, NOR operation or XOR operation.

9. Measuring device (1) according to one of claims 1 to 8, characterized in that a time-to-digital converter (TDC) (19) is present for determining the time offset, in particular between the excitation signal (6) or the trigger signal (8) and the first component (4) of the detector signal (11).

10. Measuring device (1) according to one of claims 1 to 9, characterized in that at least one of the logic functions (15 a, 15 b) and/or at least one of the transformation units (12 a, 12b, 12 c) is implemented in a microcontroller (20).

11. Measuring device (1) according to one of claims 1 to 10, characterized in that at least one of the logic functions (15 a, 15 b) is designed as a logic gate.

12. Measuring device (1) according to one of the claims 1 to 11, characterized in that the analysis unit (14) comprises at least one counter.

13. Measuring device (1) according to one of the claims 1 to 12, characterized in that at least one further transformation unit (12 c) for generating a second comparison signal (21) is present, wherein the second comparison signal (21) is associated with the excitation signal (6), wherein at least one second logic function (15 b) is present, wherein the second logic function (15 b) connects the second comparison signal (21) and the signal (11, 18) dependent on the detector signal to each other such that the output of the logic function (15 b) provides a measure of the strength of the second component (22) of the measurement signal (3) and the output of the second logic function (15 b) is connected with at least the analysis unit (14).

14. Method for the time-resolved measurement of a measurement signal (3) with a measurement device (1) and for the time separation of at least one first component (4) of the measurement signal (3), wherein the measurement device (1) has a light source (5) for emitting a pulse-like excitation signal (6), wherein the measurement device (1) has at least one detector (9) for receiving the measurement signal (3), wherein the detector (9) generates a detector signal (11) as a function of the measurement signal (3), wherein the measurement device (1) has at least one first transformation unit (12 a) for generating a first comparison signal (13), and wherein the measurement device (1) has at least one evaluation unit (14), characterized in that,

the first comparison signal (13) is correlated with the excitation signal (6), at least one first logic function (15 a) is present, wherein the first logic function (15 a) connects the first comparison signal (13) to a signal (11, 18) that depends on the detector signal, and the output of the first logic function (15 a) is connected to the at least one evaluation unit (14), wherein the method (2) has the following steps in one measuring cycle:

-emitting (24) a pulse-like excitation signal (6) by the light source (5),

-the excitation signal (6) interacts with the sample (10),

-detecting a measurement signal (3) by means of the detector (9) and converting (25) it into a detector signal (11),

-generating a comparison signal (13) in the transformation unit (12 a),

-connecting (28) the comparison signal (13) with a signal (11, 18) dependent on the detector signal (11) in a logic function (15 a) for separating the first component (4) of the measurement signal (3), and

-forwarding and analyzing (29) the output of the logic function 15a by the analysis unit (14), wherein the analyzing comprises determining the number of photons falling onto the detector during the duration of the component of the measurement signal to be separated.

15. Method according to claim 14, characterized in that it comprises a measuring device (1) according to one of claims 1 to 13.

Technical Field

The invention proceeds from a measuring device for the time-resolved measurement of a measuring signal and for the time separation of at least one first component of the measuring signal, having a light source for emitting a pulse-like excitation signal, at least one detector for receiving the measuring signal, at least one first transformation unit for generating a first comparison signal, and at least one evaluation unit, wherein the detector generates a detector signal as a function of the measuring signal.

The excitation signal for exciting the sample to be investigated is within the scope of the invention an electromagnetic signal. For example, the wavelength of the excitation signal may be in the visible spectral range or in the UV or IR range. Particularly preferably, the light source is designed as a laser.

During operation of the measuring device, a measuring signal is generated by interaction of the excitation signal with the sample to be investigated.

The invention further relates to a method for the time-resolved measurement of a measurement signal by means of a measurement device and for the time separation of at least one first component of the measurement signal, wherein the measurement device has a light source for emitting a pulse-like excitation signal, wherein the measurement device has at least one detector for receiving the measurement signal, wherein the detector generates a detector signal as a function of the measurement signal, wherein the measurement device has at least one conversion unit for generating a comparison signal, and wherein the measurement device has at least one evaluation unit.

The measuring device according to the invention relates in particular to a raman or fluorescence spectrometer.

Background

Raman spectroscopy is particularly an established technique for the qualitative and quantitative determination of the concentration of substances in complex mixtures spectroscopically. Usually, especially in biological media (fermentation, brewing, milk) or in the presence of pigments (for example in soft drinks), the raman emission is superimposed strongly by fluorescence emission.

In addition to the analysis of raman scattering, the fluorescence intensity of the sample and its time course can also be used for qualitative and quantitative analysis of, for example, mixtures.

A technique to separate the fluorescent emission and the raman emission from each other is time-gated raman spectroscopy. It is fully utilized in this case that after excitation of the sample raman emission occurs almost immediately, whereas the fluorescence emission is emitted time-staggered. This can be achieved by different measures: the measurement signal may fall onto the detector only within a short time window or the detector may be switched on only during a short time window. The time window is set such that mainly raman signals are detected and fluorescence signals are suppressed. However, such a connection of the detector is technically very complex.

From printed document EP 2761276B 1, a microscope having an evaluation circuit for evaluating an electrical signal of a photodetector, in particular for recording fluorescence events, and a method for recording fluorescence events are known. The analysis circuit comprises an analog-to-digital converter (a/D converter) connected to the detector. The evaluation circuit further comprises a shift register, wherein the light intensities recorded at different points in time are stored in the levels of the shift register independently of one another in the form of digital values emitted by means of the analog-to-digital converter. The delay unit generates a marker value which is temporally assigned to the fluorescence event and is likewise stored in the shift register. By correlating the marker values with the recorded measurement events, raman and fluorescence events can finally be distinguished in time.

It is known from printed document US 2001/0015411 a1 that, for the temporal separation of the measurement signals, the excitation signal, in particular the laser pulse, is converted by a conversion unit and delayed in time and an a/D converter arranged downstream of the detector is connected by means of the time-delayed signal, so that the a/D converter digitizes only the fluorescence signal to be separated.

Furthermore, it is known from documents GB 723240a and GB 1077501a to separate signals of temporally successive events into different channels by logical operations.

Disclosure of Invention

The object of the present invention is to provide a measuring device for the time-resolved measurement of a measurement signal, which makes it possible to achieve a time separation of at least one component of the measurement signal in a particularly simple manner. Furthermore, the object of the invention is to specify a corresponding method for the time-resolved measurement of a measurement signal.

According to a first teaching of the invention, the above object is achieved by the measuring device described at the outset in that a first comparison signal is associated with the excitation signal, at least one first logic function is present, wherein the first logic function connects at least the first comparison signal and a signal dependent on the detector signal to one another during operation, such that the output of the logic function provides a measure of the intensity of the measurement signal or of a first component of the detector signal, and the output of the first logic function is connected to at least one evaluation unit, wherein the intensity of the component of the measurement signal is determined by the number of photons falling onto the detector during the duration of the component of the measurement signal to be separated.

According to the invention, the detector signal has a sequence of at least two preferably pulse-like components. The pulse-like signal component is generated in the detector by absorption of photons. For example, the first signal component corresponds to a raman signal and the second signal component corresponds to a fluorescence signal. The first component of the measurement signal to be separated is also the first signal component in time, according to one embodiment. According to a further embodiment, the first component to be separated can also fall onto the detector after the other signal component in time.

It is recognized that at least one component of the measurement signal can be separated particularly simply by synchronizing the signal dependent on the detector signal with another signal (comparison signal) and by performing an operation by a logic function dependent on the logic device, such that the output of the logic function provides a measure of the strength of the signal component to be separated. In this way, complex wiring of the detector can be advantageously avoided.

Within the scope of the invention, the intensity of the component of the measurement signal is derived from the number of photons falling onto the detector during the duration of the component of the measurement signal to be separated. Since each photon occurring in the detector generates a pulse-like signal, the number of pulse-like signals of the first component of the detector signal and, for that matter, the number of photons falling onto the detector during this duration can be determined on the basis of the output of the logic function.

The measuring device according to the invention is particularly suitable for measuring the raman activity of a sample. In particular, the measurement device measures the number of raman photons falling onto the detector within a defined time window when in operation. The defined time window particularly preferably covers a time range in which one or more raman photons and the fluorescence photons emitted later in time do not fall onto the detector at the same time. Within the scope of the invention, a measurement cycle comprises the emission of excitation pulses and the measurement of the strength of the first component of the measurement signal. If the intensity, i.e. the measured number of photons, is summed per measurement cycle during a measurement time and the sum of the measured photons is averaged over a plurality of measurement times, the analysis unit is used to draw conclusions about the raman activity of the sample, the measurement times having a predeterminable number of measurement cycles.

In determining the measurement time, it is preferred to proceed without changing the type and/or the properties of the sample during one or more measurement times that are considered for determining the raman activity of the sample.

In measuring raman activity, the number of raman photons directly emitted by the sample depends inter alia on the energy of the pulse-like excitation signal.

According to a preferred embodiment, the excitation signal or the comparison signal is designed during operation such that an intensity of 0 or 1 is measured within a measurement period. According to this embodiment, typically at most one photon falls on the detector within the relevant time window.

According to a further embodiment, the excitation signal or the comparison signal is designed in operation such that an intensity of more than 1 can be measured within one measurement cycle. According to this embodiment, typically more than one photon can fall onto the detector within the relevant time window. This embodiment has the advantage that the measuring time can be shortened and the measuring accuracy can be increased.

According to one embodiment, the signal dependent on the detector signal corresponds to the detector signal. In a further embodiment, it is derived from the detector signal, for example by means of a time delay element and/or by means for transforming the detector signal, in particular for temporally expanding or compressing the detector signal.

The detector is preferably designed such that it continuously detects and forwards the measurement signal. By continuously recording the measurement signal, not only can the component to be separated be filtered out of the detector signal, but there is also the possibility of: the remaining components of the measurement signal or the detector signal are filtered out and analyzed in order to obtain further information from these remaining components. Alternatively, the detector can also be designed such that it is only activated at times.

For example, the detector is designed as a multi-pixel photon counter (MPPC). According to the next embodiment, the detector is designed as a photomultiplier, an enhanced charge-coupled device (ICCD) or a single-photon avalanche diode (SPAD).

According to one embodiment, the first comparison signal and the excitation signal are correlated in that the comparison signal is derived from the excitation signal during operation. Preferably, then, there is at least one second detector which is designed and arranged such that the second detector detects the excitation signal emanating from the light source directly, i.e. without prior interaction with the sample to be investigated, and forwards it to the transformation unit.

According to a further embodiment, the light source has a trigger, wherein the trigger triggers a pulse-like excitation signal by means of a trigger signal, and wherein the first comparison signal and the excitation signal are correlated in that the comparison signal is derived from the trigger signal. According to this embodiment, the trigger signal is forwarded to the conversion unit.

According to a particularly preferred embodiment, the comparison signal has at least one positive signal component whose amplitude lies in a voltage range which is interpreted by the logic function as 1.

According to a particularly preferred embodiment, the conversion unit has at least one preferably programmable delay unit, wherein the delay unit is designed such that, in operation, the pulse-like excitation signal and/or trigger signal is synchronized in time with the signal dependent on the detector signal by the delay unit. In this case, the excitation signal and/or the trigger signal is delayed by a time interval Δ t.

Within the scope of the present application, the synchronization of the comparison signal with the signal dependent on the detector signal is understood, for example, to mean that the positive part of the comparison signal is applied to the logic function in the same time as the first component of the detector signal. In this case, the pulsed excitation signal and/or the trigger signal is delayed by a delay element by a time interval Δ t, wherein the time interval Δ t corresponds to the time interval between the pulsed excitation signal or the trigger signal and the first component of the measurement signal. This time interval Δ t lies, for example, in the ps range.

Furthermore, however, the synchronization of the comparison signal with the signal dependent on the detector signal also means that, according to the next embodiment, there can be a fixedly defined time interval between the excitation signal or trigger signal and the first component of the detector signal.

For example, the positive part of the comparison signal can also be applied to the logic function in the same way as the at least one second component of the detector signal. This design of the synchronization depends in particular on the type of logic operation.

If the conversion unit has a programmable delay unit, for example a programmable delay line, the delay time Δ t is predefined. Preferably, the delay time Δ t is based on an estimate or on a previously determined time difference according to the design.

According to a further embodiment, the conversion unit has at least one means for generating at least one time duration t₂With a time interval t from the excitation signal or trigger signal₁Is more than or equal to 0. Particularly preferably, the positive signal is designed as a simple rectangular signal. Other suitable signal shapes are also contemplated.

By having a duration t₂Generates a time window for separating the first component of the detector signal.

Preferably, duration t₂Substantially corresponding to the duration of the first component of the detector signal or the duration of the second component of the detector signal.

According to a particularly preferred embodiment, the time period t is₂Substantially corresponding to the duration of the pulse-like excitation signal. This ensures that the duration t is sufficiently short for the measurement of the Raman activity of the sample₂Only raman photons are measured and not fluorescence photons.

If the positive signal is at time interval t₁=0 is generated, the process corresponds to a deformation of the initial excitation signal or the initial trigger signal. If the positive signal is at time interval t₁>0 is generated, then t₁Preferably corresponding to the time interval between the excitation signal or trigger signal and the first signal component of the detector signal.

According to a further embodiment, a plurality of temporally successive positive signal components are generated in the conversion unit. The individual signal components can have the same duration t in this case₂But they may also have different durations. If this sequence of positive signal components is applied to the logic function, for example, in the same time as the first signal component to be separated, and the logic function is designed, for example, as an and operation, the evaluation of the temporal course of the intensity of the first component of the detector signal can be continued.

According to a further preferred embodiment, the conversion unit has at least one means for temporally expanding and/or compressing the excitation signal or the trigger signal.

According to a further embodiment, at least one further conversion unit is present, wherein the further conversion unit is connected to the output of the detector, wherein the further conversion unit preferably has a delay unit, wherein the delay unit synchronizes the detector signal with the comparison signal. For this, the detector signal is delayed by a time interval Δ t.

According to one embodiment, the detector signal is delayed such that a first component of the detector signal coincides in time with the next following excitation signal or trigger signal.

According to one embodiment, two delay cells are present, wherein the delay cells are preferably designed as programmable delay cells. According to this embodiment, the conversion unit for generating the comparison signal has a delay unit and, in addition, a further conversion unit between the detector output and the logic function has a delay unit. The presence of two delay units generally makes it possible to set the synchronization of the signals particularly accurately.

According to a further embodiment, a two-channel delay line is present, wherein the trigger signal or the excitation signal is supplied to the first input and wherein the detector signal is supplied to the second input. According to this embodiment, two transformation units are combined to form a device.

According to another design, the logic function includes at least one and operation, or operation, exclusive or operation, nand operation, nor operation, or exclusive nor operation.

If the first comparison signal and the signal dependent on the detector signal are connected by means of an and operation, the comparison signal is preferably synchronized with the first component of the measurement signal, so that at least one positive component of the comparison signal is applied to the logical and operation in time the same as the first component of the detector signal.

According to a further embodiment, at least two identical and/or different logic operations can also be implemented in at least one logic function.

According to a further embodiment, a time-to-digital converter (TDC) is provided for determining the time offset Δ t, in particular between the excitation signal or trigger signal and the first component of the detector signal. Advantageously, the time offset Δ t may be determined empirically, whereby estimations with inaccuracies may be avoided.

According to one embodiment, the TDC measures the time offset between the excitation signal or trigger signal and the second component of the detector signal during operation.

According to a further embodiment, at least one logic function and/or at least one conversion unit is implemented in the microcontroller.

It is furthermore advantageous if at least one logic function is designed as a logic gate.

According to another embodiment, the logic function is implemented as a multiplier.

According to a further embodiment of the measuring device, the evaluation unit comprises at least one counter. According to a further embodiment, at least two counters are present. In operation, the counter counts the number of photons falling on the detector during a relevant time period defined by comparing the synchronization of the signal with a signal dependent on the detector signal.

Preferably, the evaluation unit is designed such that the at least one counter sums up the number of photons falling onto the detector within the measuring time, i.e. during successive measuring cycles. Particularly preferably, the analysis unit is furthermore designed such that it carries out a statistical analysis with respect to the number of raman photons measured during different successive measuring times in order to determine the raman activity of the sample.

According to a further embodiment, the evaluation unit is designed such that further parameters of the pulsed detector signal are evaluated for determining the number of photons falling onto the detector. The respective parameter is in particular the pulse height and/or the pulse area and/or the pulse shape. According to this embodiment, the logic function is preferably implemented as a multiplier, so that the pulse-like detector signal or the part of the detector signal to be extracted is passed to the evaluation unit.

According to a further embodiment, at least one further conversion unit is present for generating a second comparison signal, wherein the second comparison signal is associated with the excitation signal, wherein at least one second logic function is present, wherein the second logic function connects the second comparison signal and the signal dependent on the detector signal to one another, such that the output of the logic function provides a measure of the strength of the second component of the measurement signal and the output of the second logic function is connected to the at least one evaluation unit. According to this embodiment, the second component of the measurement signal can likewise be separated in addition to the first component of the measurement signal, thereby providing more information about the sample to be measured.

According to a second teaching of the present invention, the object initially stated is achieved by the method initially described in that the first comparison signal is correlated with the excitation signal, at least one first logic function is present, the first logic function connects the first comparison signal and the signal dependent on the detector signal to one another, and the output of the first logic function is connected to at least one evaluation unit, the method having the following steps in one measuring cycle:

a pulse-like excitation signal is emitted by the light source,

the excitation signal interacts with the sample and,

the measurement signal is detected by a detector and converted into a detector signal,

a comparison signal is generated in the transformation unit,

connecting the comparison signal with a signal dependent on the detector signal in a logic function for separating a first component of the measurement signal, an

The output of the logic function is forwarded and analyzed by an analysis unit, wherein the analysis comprises determining the number of photons falling onto the detector during the duration of the component of the measurement signal to be separated.

Here, the output of the logic function corresponds to a measure of the strength of the first component of the measurement signal.

According to a particularly preferred embodiment, the method comprises a plurality of measurement cycles which are carried out over a measurement time, wherein the evaluation unit sums the intensity measured in each measurement cycle with respect to the total number of photons which have fallen onto the detector during the measurement time.

Preferably, the method further comprises a plurality of measurement times for determining the raman activity, wherein a statistical analysis of the total number measured per measurement time is carried out by the analysis unit according to one design variant, wherein in particular an average of the total number measured per measurement time is determined.

Particularly preferably, the method according to the invention has the previously described measuring device. The individual embodiments of the method and their advantages are described with reference to the corresponding embodiments of the measuring device.

Drawings

In detail, there are now a number of possibilities for designing and extending the measuring device according to the invention and the method according to the invention. Reference is hereby made not only to the patent claims following the independent patent claims but also to the subsequent description of the preferred embodiments in connection with the accompanying drawings. In the drawings:

figure 1 shows a first embodiment of a measuring device according to the invention,

figure 2 shows a second embodiment of the measuring device according to the invention,

figure 3 shows a third embodiment of the measuring device according to the invention,

figure 4 shows a fourth embodiment of the measuring device according to the invention,

figure 5 shows a fifth embodiment of the measuring device according to the invention,

figure 6 shows in a schematic diagram the temporal course of the excitation signal, the comparison signal and the different detector signals,

figure 7 shows a second example of a time course of a comparison signal and a detector signal,

figure 8 shows a third example of a time course of a comparison signal and a detector signal,

figure 9 shows a fourth example of a time course of a comparison signal and a detector signal,

figure 10 shows a sixth example of a measuring device according to the invention,

FIG. 11 shows a schematic representation of the temporal course of the comparison signal and the detector signal of the exemplary embodiment shown in FIG. 10, an

Fig. 12 shows a first embodiment of the method according to the invention.

Detailed Description

Fig. 1 shows a measuring device 1 for the time-resolved measurement of a measurement signal 3 and for the time separation of at least one first component 4 of the measurement signal 3, having a light source 5 for emitting a pulse-like excitation signal 6, having at least one detector 9 for receiving the measurement signal 3, wherein the light source 5 has a trigger 7 which triggers the pulse-like excitation signal 6 by means of a trigger signal 8, wherein the measurement signal 3 is formed by interaction with a sample 10 to be characterized, wherein the detector 9 operates continuously in time, and wherein the detector 9 generates a detector signal 11 as a function of the measurement signal 3. In particular, the measurement device 11 is designed for determining the raman activity of the sample 10.

The measuring device 1 also has a transformation unit 12a for generating a first comparison signal 13 and an evaluation unit 14. The first comparison signal 13 is designed such that it is correlated with the excitation signal 6. In particular, the comparison signal 13 is derived from the trigger signal 8. The conversion unit 12 is designed such that it delays the trigger signal 8 in time and furthermore converts the trigger signal 8 such that it lasts for the time t₂Is designed as a positive signal. As a result, the comparison signal 13 is designed such that the positive component of the comparison signal 13 is synchronized with the first component 4 of the detector signal 11 to be separated. Furthermore, a logic function 15a in the form of an and gate is present, wherein the logic function 15a interconnects the comparison signal 13 with the detector signal 11. Since the positive component of the comparison signal 13 is synchronized with the first component 4 of the detector signal 11 to be separated, a signal is forwarded to the analysis unit 14, which provides a measure of the strength of the first component 4 of the detector signal 11. In the embodiment shown, the evaluation unit 14 has a counter which sums up a measure of the intensity of the first component 4 of the measurement signal, in particular the number of raman photons falling onto the detector during a measurement time having a plurality of measurement periods. Advantageously, the measuring device shown can be used to particularly easily separate and analyze the detector signal 11 or the first component 4 of the measurement signal 3. In particular, only the emission of raman photons can thus be determined, wherein a superposition with fluorescence photons can be avoided.

In the exemplary embodiment of the measuring device 1 shown in fig. 2, a second conversion unit 12b is additionally present, which is connected to the detector 9, wherein the second conversion unit 12b likewise has a delay element 16, wherein the delay element 16 delays the detector signal 11 in time such that the detector signal is correlated in time with the converted trigger signal 8. According to this embodiment, the time synchronization of the comparison signal 13 with the signal 18 derived from the detector signal 11 can be set particularly accurately.

In a third embodiment, shown in fig. 3, the logic function 15a and the transformation unit 12a are implemented in a microcontroller 20. In order to determine the time offset between the trigger signal 8 and the first portion 4 of the detector signal 11, a time-to-digital converter (TDC) 19 is present.

In the embodiment shown in fig. 4, the trigger signal 8 is converted in a first conversion unit 12a into a first comparison signal 13, wherein the first comparison signal 13 is synchronized with the first component 4 of the detector signal 11, so that a first logic function 15a, which is designed to operate with, forwards a measure of the strength of the first signal component 4 of the detector signal 11 to the analysis unit 14.

At the same time, the trigger signal 8 is converted in the second conversion unit 12c into a second comparison signal 21, wherein the second comparison signal 21 is synchronized with the detector signal 11 or the second component 22 of the measurement signal 3, so that the second logic function 15b, which is likewise designed here as an and operation, forwards the measure of the strength of the second signal component 22 of the detector signal 11 to the evaluation unit 14. According to this embodiment, the signal components of the measurement signal 3 or of the detector signal 11 can advantageously be separated from one another and, for this purpose, be analyzed separately.

In principle, the different logic functions 15a, 15b can be realized by separate transistor circuits, instead of which these functions can likewise be realized by an integrated circuit 23 as shown in fig. 5.

Fig. 6 shows the signal profile of the excitation signal 6, the comparison signal 13 and the six successive detector signals 11, the comparison signal 13 being designed and adjusted such that the positive component of the comparison signal 13 is synchronized with the first component 4 of the detector signals 11 to be separated. In cases 1, 3 and 6, raman photons are detected, respectively, and in the remaining detector signals 2, 4 and 5 no raman photons are detected within the observed time period. In the embodiment shown, the duration t of the comparison signal 13₂Corresponding substantially to the excitation signal 6Duration, it can be ensured that the duration t is set to be sufficiently short₂Only raman photons are detected and no fluorescence photons are detected.

In fig. 7, the comparison signal 13 has a sequence of positive signal components, wherein the sequence of positive signal components is generally synchronized with the first component 4 of the detector signal 11 to be separated. If the detector signal 11 is scanned, for example, by connecting the signals via an and gate, and the number of measured photons of each positive component of the comparison signal 13 is evaluated separately in an evaluation unit, conclusions can be drawn about the course of the intensity of the first component 4 of the detector signal.

In the exemplary embodiment shown in fig. 8, the excitation signal 6 is designed such that a plurality of raman photons is emitted directly, such that the component 4 of the measurement signal 3 to be divided has a plurality of raman photons, wherein the duration t of the positive component of the comparison signal 13 is compared₂Corresponding to the duration of the raman photon to be demonstrated.

In contrast, the comparison signal 13 is designed in fig. 9 such that the time interval t after the trigger signal 8 is₁After which the duration t is realized₂Of a positive signal of, wherein t₂Which substantially corresponds to the duration of the signal component 4 to be separated of the detector signal 11.

In fig. 10, a further exemplary embodiment of the measuring device 1 is shown, wherein, in contrast to the previously described exemplary embodiments, a second detector 9 is present, which detects the excitation signal 6 directly, i.e. without prior interaction with the sample, and forwards it to the conversion unit 12 a. In this respect, the comparison signal 13 is derived from the excitation signal 6 instead of the trigger signal 8 according to this embodiment.

Fig. 11 shows the time profile of the comparison signal 13 derived from the excitation signal 6 and the detector signal 11. According to the embodiment shown, the excitation signal 6 is delayed in time and transformed by the transformation unit 12a such that the excitation signal 6 is temporally correlated with the first component 4 of the detector signal 11.

Fig. 12 shows a first exemplary embodiment of a method 2 according to the invention, in which a measuring device 1 is designed according to fig. 1. The method 2 according to the invention comprises the following steps in each measurement cycle:

-emitting 24 a pulse-like excitation signal 6 by means of a light source 5,

the excitation signal 6 interacts with the sample 10,

the measurement signal 3 is detected by the detector 9 and converted 25 into a detector signal 11,

-transforming 26 and delaying 27 the trigger signal 8 and generating a comparison signal 13 in a transformation unit 12,

connecting 28 the comparison signal 13 to the detector signal 11 in the logic function 15a for separating the first component 4 of the measurement signal 3, and

the output of the logic function 15a is forwarded and analyzed 29 by the analysis unit 14, wherein the analysis comprises determining the number of photons falling onto the detector 9 during the duration of the component to be separated of the measurement signal 3.

Here, steps 25 to 27 shown in this embodiment occur substantially identically in time.

According to the illustrated embodiment, the method is subjected to a plurality of measurement cycles having steps 24 to 30 during the measurement time. During the measurement time, the analysis unit sums 30 the number of photons measured in each measurement period to a total number. According to the illustrated embodiment, the method includes a plurality of measurement times. Subsequently, the analysis unit determines 31 the raman activity of the sample based on a statistical analysis, for example comprising an averaging of the total number determined during the different measurement times.

Reference numerals

1 measuring device

2 method

3 measuring signals

4 first component of measurement signal

5 light source

6 excitation signal

7 trigger

8 trigger signal

9 Detector

10 samples

11 detector signal

12a-c conversion unit

13 first comparison signal

14 analysis unit

15a, b logic function

16 delay element

17 apparatus for conversion

18 signal dependent on the detector signal

19 TDC

20 microcontroller

21 second comparison signal

22 second component of the detector signal

23 Integrated Circuit

24 emission of an excitation signal

25 detecting and converting the measurement signal

26 transforming the excitation signal or trigger signal

Delaying the activation or trigger signal 27

28 connecting the comparison signal with a signal dependent on the detector signal

29 forwarding and analyzing

30 total of

31 statistical analysis