Method and spectral device for probing a spectrum

Abstract

The invention relates to a method for temporally differentially detecting the spectrum of a test object, comprising providing a first conversion pigment which is designed to convert light having a first spectral distribution in the visible range into light having a second spectral distribution in the infrared range. The first conversion pigment is excited by a light pulse in the first spectral distribution range during a first time period and a fraction of the light in the first spectral distribution range which is reflected or transmitted by the test object is detected during a first time interval. During a second time period which follows, a fraction of the converted light which is reflected or transmitted by the test object is detected. According to the invention, the first time interval is selected such that it is substantially within the luminescence lifetime of the first conversion pigment in the first time period.

Description

[0001] This application claims priority to German patent application DE102020205119.4, dated April 22, 2020, the disclosure of which is incorporated herein by reference. Technical Field

[0002] The present invention relates to a method for detecting the spectrum of an object by time difference and a spectroscopic device. Background Technology

[0003] A typical application of optoelectronic components and sensors is the spectroscopic examination of test objects. In short, the test object is illuminated with light of a first wavelength, and the light reflected, transmitted, or propagated by the test object is detected. Conclusions about the object or its parameters can be inferred from the amount of light detected or its spectral distribution.

[0004] Currently, mobile spectral applications on the market typically involve light-emitting diodes (LEDs) with a relatively broad infrared spectrum. These LEDs consist of photoelectric elements with corresponding conversion pigments that convert visible light, such as blue light, from the photoelectric elements into the infrared spectral range. This converted light is then transmitted to the sample to be inspected and either reflected or transmitted by the sample. The light then falls onto a detector unit and can therefore be detected.

[0005] In typical applications, the detector unit comprises a photodetector with a narrow-band spectral filter, thus detecting only a narrowly defined wavelength range. The reflection or transmission, or transmission spectrum, can then be generated and analyzed by relating the signal strengths of the individual detectors.

[0006] However, currently only a few luminescent material mixtures can cover the desired and possible infrared spectrum in the 700-1050 nm range. Furthermore, luminescent materials do not convert all the light emitted by the electronic components; therefore, unconverted light will also be reflected, transmitted, or propagated by the test object. The intensity of the unconverted light in this spectrum may be several times higher than the average intensity in the infrared spectral range. Accordingly, suitable attenuation filters with high operating current are required for these applications. The filter mounted above the detector also reduces the optical power in the desired spectral range, thus worsening the signal-to-noise ratio.

[0007] An alternative solution to the problem is to use multiple different photoelectric elements with different spectral ranges, thereby simulating the spectrum of a broadband detector. However, this requires multiple photoelectric elements, thus increasing the space requirements accordingly. Furthermore, additional elements are needed to generate light within the visible spectral range when measurements are performed in both the visible and infrared ranges. Therefore, the large space requirements make spectroscopic applications for mobile terminal devices difficult. Summary of the Invention

[0008] Therefore, there is a need for a method and module that are equally applicable to mobile terminal devices and, in particular, require less spatial space. Methods for temporally differentially probing the spectrum and corresponding spectroscopic devices take this need into account. It is recognized that, upon the incidence of a light pulse, the conversion pigment does not immediately, but rather temporally staggers the conversion of the incident light. This is because the excited state of the conversion pigment's light conversion has a certain lifetime. This lifetime keeps the charge carriers in the excited state and thus only returns to the ground state after a period of time by emitting infrared or conversion spectral range light. This is utilized in the method and spectroscopic module of the present invention.

[0009] Therefore, a method for time-differentially probing the spectrum of a test object is proposed, wherein a first conversion pigment is provided in a first step. The conversion pigment is designed to convert light having a first spectral distribution in the visible range into light having a second spectral distribution in the infrared range. This conversion can be performed at least, especially, by fluorescence or at most by phosphorescence. Fluorescence refers to the process by which energy input from an external source is absorbed in a physical system, resulting in an excited state of said physical system. This excited state falls back to the ground state by emitting light in the visible or invisible range. Fluorescence is defined as a process in which no additional activation process is required between the absorption of energy and the subsequent emission. The term "phosphorescence," on the other hand, describes a process in which an additional activation process, usually in the form of photon collisions or similar, is required. In other words, for fluorescence, the transition from the excited state to the ground state is achieved through a so-called permitted transition, characterized by a particularly short lifetime. For phosphorescence, light is emitted through a permitted transition, which requires an activation process and therefore has a significantly longer lifetime.

[0010] This lifetime is used in the proposed method when selecting the conversion pigment. In the second step of the method, the first conversion pigment is excited by a light pulse within a first spectral distribution range during a first time period. This light pulse of the first spectral distribution can, for example, be within the visible range. During this first time period, the portion of light within the first spectral distribution range reflected, transmitted, or transmitted by the test object is detected during a first time interval. This first time interval is substantially within at least one lifetime of the first conversion pigment.

[0011] In addition, during a second time period following the first time period, the proportion of the converted light (or the converted light) reflected or transmitted by the test object is measured.

[0012] The proposed method thereby measures the proportion of reflected or transmitted light, or transmitted, within a first spectral distribution range, such as the visible range, and then measures the proportion of light within a second spectral range, i.e., the proportion of converted light in the second range. The proportion of light within the first spectral distribution range is detected during a first time interval because the light has not yet been converted by the conversion pigment during this time interval. This is due to the minimum lifetime required for the first conversion pigment. In other words, the first time interval is chosen to be so small that it is less than the luminescence lifetime required for the first conversion pigment.

[0013] In one aspect, during the second time period immediately following the first time period, only the light fraction of the converted light is detected, while the fraction of the light pulse, i.e., the fraction of light in the first spectral distribution range, is not detected. Thus, the different spectral fractions of light are detected and measured time-differentially by a photodiode using the proposed method. This allows for a particularly simple design of the photodiode, i.e., without complex filters. It also reduces spatial requirements because the light-emitting diode with the conversion pigment emits light in both the first and second spectral distribution ranges, and the photodetector can detect light in both spectral ranges.

[0014] As previously mentioned, the second time period can immediately follow the first time period. This is suitable because only converted light exists after the light pulse is cut off, and this converted light is emitted at high intensity by the conversion pigment. Since the share of converted light decreases exponentially, it is suitable to set the second time period immediately or shortly after the light pulse is cut off.

[0015] On the other hand, a second conversion pigment is provided, designed to convert light having a first or second spectral distribution into light having a third spectral distribution in the infrared range. The second conversion pigment is excited by a first light pulse. After excitation, during a third time period following a second time period, the light reflected, transmitted, or transmitted by the test object with the converted light having the third spectral distribution is detected. This aspect allows for the excitation of different conversion pigments by light pulses. These conversion pigments are characterized by different minimum lifetimes, resulting in the emission of light converted by the pigments at different time points. In one aspect, the emission lifetime of the second conversion pigment is specified to be longer than the sum of the first and second time periods. Thus, the converted light is emitted by the second conversion pigment only after the light pulse and the light pulse converted by the first conversion pigment. In other words, in one aspect, the start time of the third time period is chosen such that the third time period occurs after the decay of the emission of the first conversion pigment. The start time of the third time period thus depends largely on the relaxation time of the first conversion pigment and is particularly chosen such that essentially no emission is generated by the first conversion pigment.

[0016] In this respect, it is possible to detect different spectra of converted light by individual light pulses and by appropriately selecting different conversion pigments and the lifetime of said conversion pigments.

[0017] On the other hand, a second conversion pigment is provided, which converts light having a first or fourth spectral distribution into light having a third spectral distribution in the infrared range. During a fifth time period, the second conversion pigment is excited by a light pulse within the first or fourth spectral distribution range. In one aspect, the fifth time period may follow a third time period. During a second time interval within the fifth time period, the proportion of light within the first or fourth spectral distribution range reflected, transmitted, or transmitted by the test object is detected. Then, during a sixth time period following the fifth time period, the converted light reflected, transmitted, or transmitted by the test object is detected and assessed.

[0018] The proposed aspect thus generates light pulses for the corresponding conversion pigment at different time points, the light pulses causing converted light to be emitted after the pigment's corresponding luminescence lifetime. At the start of the corresponding light pulse, i.e., before the corresponding conversion pigment begins to emit light, the proportion of unconverted light reflected, transmitted, or transmitted by the test object is detected. After the end of the corresponding light pulse, the converted light emitted by the corresponding conversion pigment is then reflected, transmitted, or transmitted by the test object and measured.

[0019] In the proposed method, the first and second conversion pigments are respectively designed such that only a portion of light having a first or fourth spectral distribution is not converted by the pigment. In one aspect, light, preferably in the visible range, is thus emitted onto the conversion pigment via a first or second light pulse. A portion of this light passes through the conversion pigment and is therefore able to be delivered to the test object. This portion of the light is detected by a detector after reflection or partial transmission. In one aspect, light having a first and / or third spectral distribution in the visible range is converted by only 30%-70%, particularly 45%-55%.

[0020] In another aspect, the ambient light share is detected during a fourth time period. This fourth time period follows the second, third, or sixth time period. Detecting the ambient light share allows for the detection of residual light, which is then used for further signal processing. In another aspect, the start time of the fourth time period depends on the relaxation time of the first and / or second conversion pigment. The start time is specifically chosen when there is essentially no emission in the first and / or second conversion pigment. The ambient light share is thus determined after the emission decay of the corresponding conversion pigment, thereby detecting only ambient light and not the remaining emission.

[0021] Another aspect relates to a spectroscopic device in which at least one first photoelectric element is provided. The first photoelectric element is designed to emit light within a first spectral distribution range, particularly the visible range, during operation. A first conversion pigment is arranged in the optical path of the photoelectric element. The first conversion pigment is designed to convert light in the first spectral distribution within the visible range into light in a second spectral distribution within the infrared range. The conversion pigment thus generates infrared light from light in the visible range. Furthermore, the spectroscopic device includes an optical sensor designed to detect light in both the first and second spectral distributions.

[0022] According to the invention, a control circuit is provided, which is coupled to at least one photoelectric element and an optical sensor. Furthermore, the control circuit controls the sensor such that signals generated by the optical emitter are detected during a time interval within a first time period and during a second time period following the first time period. The first time interval is selected such that it falls substantially within the luminescence lifetime of a first conversion pigment during the first time period.

[0023] The control circuit thus uses time-division multiplexing technology to control the photoelectric element and optical sensor, thereby detecting light reflected or transmitted, or transmitted, by the test object. This light includes, on the one hand, unconverted light reflected by at least one photoelectric element during a first time interval, and on the other hand, converted light reflected or transmitted, or transmitted, by the test object during a subsequent second time interval.

[0024] This approach allows for the simple design of optical sensors because light signals with different spectral components are detected at different times. The proposed spectroscopic device can thus examine the test object over a wide frequency range, encompassing both the visible and infrared spectra.

[0025] In another aspect, the spectral device includes a second conversion pigment disposed in the optical path of the photoelectric element. The second conversion pigment is designed to convert light in a first spectral distribution into light in a third spectral distribution in the infrared range. Control circuitry is also designed to detect a signal generated by an optical sensor during a third time period. The third time period follows the second time period. Furthermore, the second conversion pigment exhibits a longer luminescence lifetime than the sum of the first and second time periods.

[0026] In other words, in this respect, the reflected, transmitted, or proximate signal detected by the sensor during the third time period is generated solely by the luminescence of the second conversion pigment. This ensures that the signal detected by the sensor during the third time period is generated solely by the second conversion pigment and not by the still-present luminescence of the first conversion pigment.

[0027] Therefore, in one aspect, it is stipulated that the start time of the third time period depends on the relaxation time of the first conversion pigment. The start time of the third time period can thus be specifically chosen such that the first conversion pigment essentially ceases to emit light.

[0028] Another aspect relates to a supplementary scheme to the proposed spectroscopic device. This supplementary scheme includes a second photoelectric element that emits light within a fourth spectral distribution range in the visible range during operation. A second conversion pigment is arranged in the optical path of the second photoelectric element, converting the light from the fourth spectral distribution range into light within a third spectral distribution range in the infrared range. Based on this principle, the control circuit is also designed to control the second photoelectric element to generate a second light pulse during a fifth time period. A signal generated by an optical sensor during a second time interval in the fifth time period is detected by the control circuit. Furthermore, the sensor also generates a signal during a sixth time period, which contains the emission share of the second conversion pigment. The sixth time period here follows the fifth time period.

[0029] The aforementioned second time interval is chosen in this respect such that the second time interval is substantially within the luminescence lifetime of the second conversion pigment in the fifth time interval.

[0030] This proposed principle enables the implementation of a spectroscopic device in which multiple photoelectric elements, each having a conversion pigment disposed above it, are controlled sequentially. Simultaneously, a control circuit detects light detected by an optical sensor. This detection is also time-matched, thus detecting, on the one hand, the unconverted light fraction of the corresponding photoelectric element, and on the other hand, the fraction of light converted by the corresponding conversion pigment that is reflected, transmitted, or propagated by the test object. The spectroscopic device thus achieves particularly wide-bandwidth detection; that is, it can detect both the visible and infrared spectra.

[0031] In another aspect, the control circuit is designed to detect the signal generated by the optical sensor during a fourth time period. This fourth time period occurs after the second, third, or sixth time period. In this aspect, the optical sensor is controlled by the control circuit such that it receives residual light or ambient light and transmits it to the control circuit for further analysis. Analysis of the residual light or ambient light improves the signal-to-noise ratio of the spectroscopic device.

[0032] In one aspect, the measurement of residual light or ambient light is suitably performed at a time point when the first or second conversion pigment is substantially no longer emitting light. The start time for the measurement of residual light or ambient light thus depends on the relaxation time of the first and second conversion pigments. Attached Figure Description

[0033] The invention will now be described in detail with reference to the accompanying drawings. In the drawings:

[0034] Figure 1 A spectroscopic device based on the proposed principle is shown;

[0035] Figure 2 The time graphs showing different points in time and time periods are presented to illustrate the proposed principles;

[0036] Figure 3 Other views are shown, with corresponding emission change graphs for different time periods;

[0037] Figure 4 A first embodiment of a method for time-differentially probing the spectrum of a test object is shown;

[0038] Figure 5 A timeline is shown, which includes signals for controlling photoelectric elements or photodiodes and corresponding time changes in the conversion pigment;

[0039] Figure 6 Another embodiment of the proposed method is shown, which is similar to... Figure 5 The implementation method shown corresponds to this. Detailed Implementation

[0040] Figure 1 An embodiment of a spectroscopic device incorporating some aspects of the proposed principles is shown. The spectroscopic device 10 includes an array of multiple photoelectric elements 11, 12, 13, and 14 arranged in a matrix. Here, for example, four photoelectric elements are arranged in a 2×2 matrix; however, additional or fewer elements may be arranged depending on the application and requirements. Each photoelectric element is designed to emit light within a predetermined spectral range of visible light during operation. For example, photoelectric element 11 produces blue light, photoelectric element 12 produces green light, element 13 produces orange light, and element 14 produces red light. Through suitable co-control, mixed colors can be achieved in addition to individual distinct colors, thereby enabling coverage of the visible spectrum over a wide bandwidth using the arrangement shown herein.

[0041] Furthermore, each photoelectric element includes a conversion pigment adapted to the corresponding photoelectric element 11 to 14. The conversion pigment is arranged in the optical path of the corresponding photoelectric element. The corresponding conversion pigment is designed to convert at least partially of the light emitted by the photoelectric element into light in the infrared spectrum.

[0042] Similar to optoelectronic elements, the conversion pigment is selected such that it emits its converted light in correspondingly different ranges of the infrared spectrum. This arrangement enables a broadband emitter, in which the optoelectronic element and the conversion pigment together constitute a light-emitting diode (LED), which emits light in both the visible and infrared ranges.

[0043] The spectroscopic device also includes an optical sensor in the form of a photodiode 3. The diode is designed to receive light emitted by photoelectric elements 11 to 14 and convert the light into a corresponding signal based on the received intensity. The photodiode 3 is designed to be particularly simple, i.e., without an additional filter. To correct for different spectral fractions, the diode 3 of the spectroscopic device can be pre-calibrated. It is also possible to obtain the flattest and most uniform frequency characteristics possible through appropriate measures.

[0044] Furthermore, the spectral device 10 includes a control circuit 2. Circuit 2 is coupled to each photoelectric element 11 to 14 on its output side for control. Additionally, the control circuit is connected to the photodiode 3 via input terminal 25.

[0045] During operation of the proposed spectroscopic apparatus, control circuit 2 individually controls the corresponding photoelectric elements via respective signals from outputs 21 to 24. This control is performed at staggered intervals, so that in this embodiment only one photoelectric element is active. During this time period, the photoelectric element emits light in the visible range. The emitted light is partially absorbed by the conversion pigment, which then enters an excited state. The remaining light fraction is simultaneously emitted unconverted and illuminates the object under inspection. This remaining light fraction is reflected from the object toward photodiode 3. Based on the detected light, photodiode 3 generates a signal and returns the signal to the control circuit. After the conversion pigment begins to emit light, this reflected fraction is also detected and reflected back. The individual fractions of unconverted and converted light reflected or transmitted, or transmitted, by the test object can be detected and measured by appropriately selecting the time of the signal emitted by the photodiode and controlling the photodiode.

[0046] exist Figure 2 The illustration shows the temporal variation of the control of the optoelectronic element and subsequent detection in this embodiment.

[0047] Between time points t1 and t3, the photoelectric element is activated by the control circuit. This emits light pulses, which are then guided to the conversion pigment K1 in the optical path of the corresponding element. The time period between t1 and t3 is called time period T2. Figure 2As shown in the lower part, the luminescence of the conversion pigment K1 does not occur simultaneously with the start of the light pulse emitted by the photoelectric element, but rather they are staggered in time. This is because the light pulse emitted by the element is at least partially absorbed by the conversion pigment K1 and thus enters a higher excitation state.

[0048] The converted pigment remains in this excited state for a period of time until it returns to the ground state or a lower state by emitting photons. This period is also known as the lifetime, specifically the emission lifetime. The term "emission lifetime" here refers to the time during which the excited system remains in the excited state before transitioning back to the ground state or a lower state by emitting photons. Depending on the transition, i.e., whether it occurs spontaneously or after activation, such as by shock or momentum transfer, this lifetime can be longer or shorter. Fluorescence is often referred to as emission with a spontaneous transition and a shorter lifetime. Phosphorescence refers to emission produced by a transition after activation, thus generally producing a longer lifetime than fluorescence.

[0049] In the example described, the conversion pigment K1 thus begins to emit light only after time point t2. No conversion light is emitted during the time interval between t1 and t2 because the conversion has not yet occurred. Alternatively, the conversion pigment can be described as being pumped, i.e., entering an excited state, during this time interval. After time point t2, the luminescence of the conversion pigment K1 begins to increase exponentially until a defined maximum value is reached. This maximum value is still reached during the time period T2, i.e., before time point t3. In this respect, an equilibrium state between emitted conversion light and absorbed light is thus established in this embodiment.

[0050] Starting at time point t3, the light pulse is cut off. Light continues to be emitted only by the pigment. The optical sensor thus detects only the converted light fraction during time period T3. Therefore, the amount of light during time period T3 can be detected by the control circuit from signal changes and the known decrease in intensity. After a certain period, the luminescence of the conversion pigment K1 has decreased to a level where the intensity of luminescence produced by the conversion pigment can be ignored. From time point t5 to time point t6, i.e., during time period T4, the optical sensor detects only the ambient light fraction.

[0051] Therefore, in the proposed principle, different light fractions are detected at different times without the need for additional measures such as filters for the photodiode or optical sensor. During the first time period T1, the photodiode thus detects only unconverted light and ambient light. In the time period T3, which follows the light pulse, the photodiode continues to detect ambient light and the light fraction converted by the pigment. During the detection period between time points T5 and T6, only ambient light is detected, so it can be subtracted from the previous measurements.

[0052] Figure 3Other embodiments are shown, in which two conversion pigments K1 and K2 with different luminescence lifetimes are provided. Both conversion pigments K1 and K2 are excited by the same light pulse.

[0053] During time interval T1 within time period T2, the photodiode detects only unconverted light and ambient light. At time t2, the control circuit shuts off the optical sensor, while the photoelectric element continues to emit light. Shortly after time t2, the luminescence of the first conversion pigment K1 increases sharply. At time t3, at least the luminescence of the first conversion pigment K1 is balanced with the excitation generated by the photoelectric element. t3 is also the time when the control circuit shuts off the optoelectronic element, so now only the light converted by the first conversion pigment and ambient light falls on the photodetector.

[0054] During time period T3, the optical sensor detects the intensity of the converted light from the first conversion pigment K1. The luminescence decreases slightly until the end of time period T3 and then decreases further until time point t7. However, simultaneously, the luminescence of the second conversion pigment K2 increases. This is because the second conversion pigment K2 has a significantly longer luminescence lifetime than the first conversion pigment K1. That is, during time period T2 when the photoelectric element is activated, the second conversion pigment K2 also enters an excited state. This activated state has a longer lifetime, so the pigment only exhibits sufficiently high luminescence for measurement from time point T7 onwards. Accordingly, during time period T5, the optical sensor detects the luminescence of the second conversion pigment K2 reflected from the test object. The intensity of the second conversion pigment K2 also decreases over time, so that at time point t5, the luminescence of the first and second conversion pigments K1 and K2 is essentially negligible. This, in turn, means that during time period T4 between time points t5 and t6, only ambient light can be detected by the optical sensor and subtracted from the previous signal.

[0055] By using conversion pigments with different luminescence lifetimes, the spectrum formed by combining the emission spectrum of the optoelectronic device with the spectrum of different conversion pigments can be detected.

[0056] Figure 4 Relatedly, an embodiment of a method for temporally differentially probing the spectrum of a test object according to the proposed principle is shown. In step S1, a first conversion pigment is provided, which is capable of converting light having or being in the visible range into light having a second spectral distribution in the infrared range. In a subsequent second step, the first conversion pigment is excited by a light pulse in the region of the first spectral distribution. This is achieved during a first time period of the light pulse.

[0057] Furthermore, during the first time interval within the first time period, light reflected, transmitted, or transmitted by the test object within the range of the first spectral distribution is detected. Therefore, this step detects light reflected, transmitted, or transmitted by the object that is not converted by the conversion pigment and thus illuminates the object during the first time period. In the subsequent step S4, the proportion of converted light reflected, transmitted, or transmitted by the test object is detected. Detection is performed during a second time period following the first time period. The second time period can be directly following the first time period; however, it is also possible to have a short time interval between the start of detecting the proportion of converted light and the activation of the light pulse during the first time period.

[0058] By detecting at different times in steps S3 and S4, it is possible to detect only unconverted or converted light, but not the mixture of unconverted and converted light. In the subsequent optional step S5, residual light or ambient light is detected in a later time period. In step S6, the proportions of the detected and probed light are jointly analyzed to obtain the spectrum reflected or transmitted by the test object, or transmitted in other words.

[0059] In addition to the individual method steps suggested herein, step S1 additionally includes an optional step S11. In this optional step S11, a second conversion pigment is provided, the second conversion pigment being designed to convert light in the first spectral distribution into light with a third spectral distribution having an infrared range. The second conversion pigment is characterized in particular by a longer luminescence lifetime than that of the first conversion pigment. Therefore, during step S2, not only the first conversion pigment, but both conversion pigments are excited by a light pulse. In a subsequent optional step S41, after the converted light of the first conversion pigment has been detected, the portion of light reflected or transmitted, or transmitted, by the test object and corresponding to the converted light with the third spectral distribution is also detected.

[0060] Figure 5 Another embodiment is shown, in which not just one photoelectric element, but multiple photoelectric elements are activated sequentially, and the corresponding conversion pigments K1, K2, K3 of the photoelectric elements are at least excited. The activation of each photoelectric element and the detection of the signal are thus staggered in time. In this design, the first photoelectric element is turned on during a first time period T2, thus exciting the first conversion pigment K1. In this embodiment, the luminescence lifetime of the conversion pigment K1 is selected such that it begins to emit light only after the second time period. Therefore, the unabsorbed light fraction can be detected throughout the entire second time period T2. Thus, the first time period for detecting reflected or transmitted signals can be selected to be the same as the second time period.

[0061] The converted light emitted by the first conversion pigment K1 is detected between time points t3 and t4. This converted light is within the known range of the infrared spectrum, which differs from the conversion spectra of the other two conversion pigments K2 and K3. At time point t10, the luminescence of the first conversion pigment K1 has sufficiently decayed, thereby generating new light pulses in the second photoelectric element. The light pulses of the second photoelectric element excite the second conversion pigment K2 and "pump" it into an excited state. Due to the luminescence lifetime of pigment K2, no luminescence is generated during this time period. Thus, the unabsorbed portion of the light from the second photoelectric element is detected during this time period T2. In this design, the luminescence of the second conversion pigment K2 also occurs after time point t11, i.e., after the light pulse is cut off in the subsequent time period T3. The portion of the light converted by the conversion pigment K2 is detected between time points t12 and t13. Finally, after the light of the conversion pigment K2 decays, the third photoelectric element is turned on at time point t14 and a light pulse is emitted to the third conversion pigment K3. The luminescence of the third conversion pigment was detected during the time period T3, between time point t16 and t17.

[0062] By activating photoelectric elements in a sequential manner and subsequently detecting the unconverted and converted light fractions, it is possible to detect and analyze the spectrum reflected or transmitted, or transmitted, by the test object in a wide bandwidth.

[0063] Figure 6 The individual steps of this method are illustrated in relation to this. In step S1, different photoelectric elements and corresponding conversion pigments are provided. Then, in the subsequent step S2, the first photoelectric element is activated while simultaneously detecting the portion of light that was not converted but was reflected or transmitted by the test object. After the light pulse, in step S4, the converted light emitted by the conversion pigment and reflected or transmitted by the test object is re-detected. In step S7, these two steps S2 and S4 are repeated until all photoelectric elements have been activated at least once. This allows for the detection of a wide-bandgap spectrum in both the visible and infrared ranges.

[0064] Next, in step S5, other measurements are performed to detect ambient light. The signal intensity of the remaining light or ambient light thus determined is calculated and analyzed with the results of the previous steps in step S6.

[0065] It is self-evident that the disclosure herein is not limited to the specific components of the described apparatus or the steps of the described method, as such apparatus and method can vary. It is also self-evident that the terminology used herein is for describing specific embodiments only and is not intended to be limiting. It should be noted that, for example, definite and indefinite articles used in the specification and appended claims are intended to indicate the presence of one or more elements unless the context clearly specifies otherwise. For example, references to "a unit" or "unit" may include multiple devices, etc. Furthermore, the words "comprising," "including," and similar terms do not exclude other elements or steps.

[0066] List of reference numerals

[0067] 2 Control Circuit

[0068] 3. Optical sensors, photodiodes

[0069] 10 Spectroscopic devices

[0070] Output terminals 21 and 22

[0071] Output terminals 23 and 24

[0072] 25 input terminals

[0073] Time points T1 and t2

[0074] T3 and t4 time points

[0075] T5 and t6 time points

[0076] T7 and t8 time points

[0077] Time points T11 and t12

[0078] Time points T13 and t14

[0079] T15 and T16 time points

[0080] T17 time point

[0081] T1 time period

[0082] T2 and T3 time intervals

[0083] T4 and T5 time intervals

[0084] K1 and K2 conversion pigments

[0085] K3 Conversion Pigment

[0086] S1, S2 Method Steps

[0087] S3, S4 Method Steps

[0088] S5, S6 Method Steps

Claims

1. A method for time-differentially probing the spectrum of a test object, the method comprising the following steps: - Provide (S1) a first conversion pigment (K1) designed to convert light in a first spectral distribution in the visible range into light in a second spectral distribution in the infrared range; - During the first time period (T2), the first conversion pigment (K1) is excited (S2) by a first light pulse in the first spectral distribution range, so that the first conversion pigment enters the excited state and begins the conversion during the first time period (T2); - During a first time interval (T1) within a first time period (T2), detect (S3) the portion of light reflected or transmitted by the test object within the range of the first spectral distribution, wherein the first time interval (T1) is selected such that the first time interval (T1) falls within the luminescence lifetime of the first conversion pigment during the first time period (T2), the luminescence lifetime being the time period during which the first conversion pigment remains in an excited state and has not yet undergone conversion. - At the end of the first time period (T2), the first light pulse is cut off. In the state of the first light pulse cut off, during the second time period (T3) after the first time period (T2), the share of the converted light reflected or transmitted by the test object is detected (S4), without detecting the share of the first light pulse in the first spectral distribution range.

2. The method according to claim 1, wherein, The first time interval is selected such that the light fraction of the converted light is not detected.

3. The method according to claim 1, wherein, The second time period (T3) is directly connected to the first time period (T2).

4. The method according to any one of claims 1 to 3, wherein the method further comprises... - Provide (S11) a second conversion pigment (K2), the second conversion pigment being designed to convert light in a first spectral distribution into light having a third spectral distribution in the infrared range; - The second conversion pigment (K2) is excited by the first light pulse; - During a third time period following the second time period (T3), the proportion of light reflected or transmitted by the test object of the converted light having a third spectral distribution is detected.

5. The method according to claim 4, wherein, The luminescence lifetime of the second conversion pigment (K2) is longer than the sum of the first time period and the second time period (T2, T3).

6. The method according to claim 4, wherein, The third spectral distribution does not completely overlap with the second spectral distribution.

7. The method according to claim 4, wherein, The start time of the third time period depends on the relaxation time of the first conversion pigment and is selected such that the first conversion pigment no longer emits light.

8. The method according to any one of claims 1 to 3, wherein the method further comprises... - Provide a second conversion pigment (K2) designed to convert light in the first or fourth spectral distribution into light having a third spectral distribution in the infrared range; - During the fifth time period, the second conversion pigment (K2) is excited by a second light pulse in either the first or fourth spectral distribution range; - During the second time interval, detect the share of light reflected or transmitted by the test object that is in the first spectral distribution range or the fourth spectral distribution range; - During a sixth time period following the fifth time period, the proportion of the converted light reflected or transmitted by the test object is detected; The second time interval is selected such that it falls within the luminescence lifetime of the second conversion pigment (K2) in the fifth time interval.

9. The method according to claim 8, wherein, The fifth time period is after the second time period.

10. The method according to claim 8, wherein, The first and / or the second conversion pigment (K1, K2) are designed such that a portion of light having a first spectral distribution range or a third spectral distribution range in the visible range is not converted by the pigment.

11. The method according to any one of claims 1 to 3, wherein, The first conversion pigment is designed such that 30% to 70% of light having a first spectral distribution in the visible range is converted.

12. The method according to claim 8, further comprising the following steps: - The ambient light share was detected during the fourth time period, where... The fourth time period (T4) follows either the second time period (T3) or the sixth time period.

13. The method according to claim 12, wherein, The start time of the fourth time period depends on the relaxation time of the first and / or second conversion pigments and is selected such that luminescence no longer occurs in the first and / or second conversion pigments.

14. The method according to any one of claims 1 to 3, wherein the method further comprises: - Analyze the light share detected during the first time interval and the second time interval.

15. A spectroscopic device, comprising: - At least one first optoelectronic element (11, 12, 13, 14), the first optoelectronic element being designed to emit light in a first spectral distribution range within the visible range during operation; - A first conversion pigment (K1), which is arranged in the optical path of the first photoelectric element and is designed to convert light in a first spectral distribution in the visible range into light in a second spectral distribution in the infrared range; - Optical sensor (3), the optical sensor being designed to detect light in a first spectral distribution and a second spectral distribution; - Control circuit (2), the control circuit being coupled to the at least one first photoelectric element and the optical sensor and designed to perform the method according to any one of claims 1 to 14.

16. The spectroscopic device according to claim 15, further comprising: - Second conversion pigment (K2), which is arranged in the optical path of the first photoelectric element (11, 12, 13, 14) and is designed to convert light in the first spectral distribution into light in the third spectral distribution in the infrared range; - in, The control circuit is designed to detect the signal generated by the optical sensor during a third time period following the second time period, wherein the luminescence lifetime of the second conversion pigment is longer than the sum of the first and second time periods.

17. The spectroscopic device according to claim 16, wherein, The start time of the third time period depends on the relaxation time of the first conversion pigment and is selected such that the first conversion pigment no longer emits light.

18. The spectroscopic device according to claim 15, further comprising: The second optoelectronic element is designed to emit light in a fourth spectral distribution range within the visible range during operation; - Second conversion pigment (K2), which is arranged in the optical path of the second photoelectric element and designed to convert light in the fourth spectral distribution into light in the third spectral distribution in the infrared range; - Wherein, the control circuit is designed to control the second photoelectric element to generate a second light pulse during the fifth time period; and the signal generated by the optical sensor (3) exists during the second time interval within the fifth time period and during the sixth time period after the fifth time period. The second time interval is selected such that it falls within the luminescence lifetime of the second conversion pigment (K2) in the fifth time interval.

19. The spectroscopic device according to claim 18, wherein, The control circuit (2) is designed to detect the signal generated by the optical sensor (3) during a fourth time period, which is after one of the second and sixth time periods.

20. The spectroscopic device according to claim 19, wherein, The start time of the fourth time period depends on the relaxation time of the first and / or second conversion pigments (K1, K2) and is selected such that luminescence no longer occurs in the first and / or second conversion pigments.

21. A spectroscopic device, comprising: - At least one first optoelectronic element (11, 12, 13, 14), the first optoelectronic element being designed to emit light in a first spectral distribution range within the visible range during operation; - A first conversion pigment (K1), which is arranged in the optical path of the first photoelectric element and is designed to convert light in a first spectral distribution in the visible range into light in a second spectral distribution in the infrared range; - Optical sensor (3), the optical sensor being designed to detect light in a first spectral distribution and a second spectral distribution; The spectroscopic device is designed to perform the method according to any one of claims 1 to 14.

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