Optical sensor device, method for providing an optical sensor device and method for using an optical sensor device

Abstract

The present invention relates to an optical sensor device (10) comprising a light source (1); an input optical unit (2), which is irradiatable and by means of which a light beam is steerable to a sample (p), wherein the input optical unit (2) comprises a linear optical polarizer (LP) and a lens (L), wherein the lens is disposed downstream or placed upstream of the linear polarizer in an incoming light direction, and a light beam that was linearly polarized by the linear polarizer is steerable to the sample; an output optical unit (3) and a filter device (FE), wherein a light beam emitted by the sample (p) is steerable to the output optical unit (3) and is steerable by the latter to the filter device (FE); a detector device (D), by means of which the filtered light beam is detectable; and an evaluation device (AE), by means of which the filtered light beam is evaluable, wherein the input optical unit (2) also comprises a beam splitter (ST) which is arranged between the linear polarizer (LP) and the sample and by means of which a reference beam (RS) is steerable to the detector device (D).

Description

[0001] Description

[0002] title

[0003] Optical sensor device, method for providing an optical sensor device and method for using an optical sensor device

[0004] The present invention relates to an optical sensor device, a method for providing an optical sensor device and a method for using an optical sensor device.

[0005] State of the art

[0006] In common applications, a negatively charged NV center (nitrogen vacancy) in a diamond can be used for highly sensitive measurements of magnetic fields, electric fields, mechanical stresses, and / or temperature. Such measurements utilize quantum effects, and such quantum technologies can offer decisive advantages over classical sensor principles. The use of NV centers can offer the following advantages: high sensitivity (< 1 pT / VHz), applicable vector magnetometry (determination of the direction of the magnetic field), a large dynamic measurement range (pT to greater than 1 Tesla), linearity of the change in re-emitted radiation from the applied magnetic field (Zeeman effect), and little or no degradation of the transducer mechanism, since the measurement is based on quantum mechanical states.

[0007] To read out such a sensor based on NV centers, the magnetic resonance of a ground-state triplet can be optically detected (ODMR, optically detected magnetic resonance). An NV center can be excited, for example, with green light. The resulting red-shifted fluorescent light exhibits a characteristic shape at the energy level of the electron spin resonance. This level can be linearly dependent on the magnetic field due to the Zeeman effect. These concepts can be used to construct a highly sensitive magnetic field sensor.

[0008] US2013265042 describes a device for measuring a magnetic field. Disclosure of the invention

[0009] The present invention provides an optical sensor device according to claim 1, a method for providing an optical sensor device according to claim 11 and a method for using an optical sensor device according to claim 12.

[0010] Preferred further training is the subject of the subclaims.

[0011] Advantages of the invention

[0012] The idea underlying the present invention is to provide an optical sensor device, a method for providing an optical sensor device and a method for using an optical sensor device, wherein a signal-to-noise ratio (SNR) can be improved.

[0013] To excite a quantum sensor, it may be necessary to excite it with optical radiation. Quantum sensors are typically read optically, whereby either the excitation radiation is directly detected after transmission through the sensor medium or, in the case of NV centers, the wavelength-shifted (e.g., red-shifted) fluorescence generated by the NV centers can be detected. The sensor's sensitivity scales with the SNR of this optical detection.

[0014] In order to improve the SNR, it is advantageous to pass an additional polarizer through the excitation light before this light excites the sensor medium (e.g. diamond with NV centers).

[0015] According to the invention, the optical sensor device comprises a light source with which a light beam can be generated; an input optics system which can be irradiated by the light beam and through which the light beam can be directed onto the sample, wherein the input optics system comprises a linear optical polarizer and a lens, wherein the lens is arranged downstream of or upstream of the linear polarizer in a light incidence direction and a light beam linearly polarized by the linear polarizer can be directed onto the sample; an output optics system and a filter device, wherein a light beam emitted by the sample, advantageously a fluorescent light beam, can be directed onto the output optics system and through this onto the filter device, or vice versa, and a filtered light beam can be generated with the filter device, in which excitation radiation from the light source can be filtered out; a detector device with which the filtered light beam can be detected.and an evaluation device with which the filtered light beam, advantageously the fluorescent light, can be evaluated. The input optics further comprise a beam splitter arranged between the linear polarizer and the sample, with which a reference beam can be directed onto the detector device. The beam splitter can also direct the light from the light source onto the sample.

[0016] The optical sensor device can be used in the field of magnetic field sensing and quantum technology. An optical change in the properties of the light passing through the sensor device, in particular through the sample, can be measured and evaluated by the evaluation device, for example whether the sample is located in a magnetic field and what influence the magnetic field has on the absorption and emission of light by the sample (for example, through the Zeeman effect). This means that the optical sensor device can also serve as a magnetic field sensor. The fluorescent light that is emitted by the sample after it has been excited is advantageously evaluated. The excitation light is absorbed by the sample and emitted as fluorescent light (in the case of NV centers in diamond), whereby the applied magnetic field can influence the fluorescent light.The fluorescent light can have a different wavelength than the excitation light.

[0017] The light source can be one or more thermal light sources and / or LEDs and / or lasers.

[0018] Such a sensor can, for example, be used to determine the compass direction for navigation in vehicles or with a smartphone by measuring the Earth's magnetic field. By inferring the influence of a magnetic field on the sample and a measurable modification of the emitted light beam due to the magnetic field, the optical sensor device can also serve as a magnetic field sensor. For example, the optical sensor device can be used to locate metallic or magnetic objects.

[0019] According to a preferred embodiment of the optical sensor device, the input optics further comprises a beam splitter which is arranged between the linear polarizer and the sample and with which a reference beam can be directed onto the detector device.

[0020] The reference beam can extend between the beam splitter and the detector device with a beam path of similar or equal length, whereby the reference beam is neither irradiated onto the sample nor passes through it. A difference between the filtered beam through the sample and the reference beam can then be determined at the detector device, and the difference can be evaluated. Variations in light intensity and other properties of the reference beam can then be attributed to the at least one light source. After filtering, there is little or no excitation light in the filtered beam, but there is in the reference beam because the reference beam does not pass through the filter device.According to a preferred embodiment of the optical sensor device, the input optics comprises a deflection mirror which can be irradiated with the reference beam by the beam splitter and the reference beam can be directed onto the detector device by means of the deflection mirror.

[0021] With the deflecting mirror, the reference beam can be advantageously guided through the sample parallel to the light path of the filtered light beam. Instead of a deflecting mirror, a prism can also be used, which has a similar deflecting effect by exploiting total internal reflection.

[0022] According to a preferred embodiment of the optical sensor device, the detector device comprises a first input channel and a reference channel, wherein the filtered light beam can be directed onto the first input channel and the reference beam can be directed onto the reference channel.

[0023] The detector device can advantageously comprise two photodiodes in one housing or in separate housings, and their signals can be transmitted to the evaluation device. The filtered light beam is advantageously the beam path that passes through the sample.

[0024] According to a preferred embodiment of the optical sensor device, the excitation light of the light source can be received by the evaluation device through the reference beam at the detector device and can be evaluated by the evaluation device and compared with the filtered light beam at the input channel.

[0025] For this purpose, the respective photodiode on the reference channel and / or the first input channel can be designed to receive a specific wavelength or a specific wavelength range.

[0026] Polarization can detect fluctuations in the light output in the (first) input channel and the reference channel, and the fluctuations in the light source can be detected and subtracted from the input channel (taken into account). The excitation light can, for example, have wavelengths in the green visible range, and the fluorescence can, for example, have wavelengths in the red visible range. The filter device can then filter out the green excitation light for the input channel (which the sample could transmit). It is possible to evaluate the frequency at which a resonance of the radiation from the sample occurs during excitation of the sample by microwaves, and how this resonance may depend on the applied magnetic field. From this (Zemann effect), conclusions can be drawn about the strength of the magnetic field. According to a preferred embodiment of the optical sensor device, the beam splitter comprises a polarizing beam splitter.

[0027] By using a polarized beam splitter and generating a reference beam, an improvement in the sensitivity of an NV-based magnetic field sensor can be achieved by reducing the influence of intensity or polarization fluctuations of the exciting light source, especially in the case of a laser.

[0028] Quantum sensors, such as NV-based magnetic field sensors, are optically excited and read out. During readout, fluctuations in the detected optical signal (fluorescence) can occur, which can be attributed to polarization fluctuations of the light source. These fluctuations can impair the sensor's sensitivity. The reference channel allows these light source influences to be taken into account when evaluating the signal from the sample.

[0029] According to a preferred embodiment of the optical sensor device, the sample comprises a diamond with NV centers.

[0030] The sensitivity of optically excited sensors (e.g. magnetometry with NV centers in diamond) can be improved by stabilizing the optical polarization.

[0031] A magnetic field sensor based on NV centers—in other words, an optical sensor device with a diamond and NV centers within the diamond—can provide the sensitivity required for locating magnetic objects or current-carrying conductors. Another application is a so-called human-machine interface, where NV center-based magnetic field sensors can, for example, detect the magnetic fields on the human head that can be generated by brain activity and the associated currents.

[0032] Such sensors can be used, for example, to detect cables and magnetic objects in walls and floors, or to monitor the battery current of electric vehicles. Diamond-based sensors can, for example, offer a galvanically isolated sensor solution with a high dynamic range and high sensitivity. Another application could be localization in robotics, where precise and absolute positioning can be achieved with the help of highly sensitive magnetometers.

[0033] An NV center in the diamond lattice can be aligned along one of four possible bond directions in the diamond crystal. A ground state can exist with a spin triplet with total spin S=1. The states with a magnetic spin quantum number ms = ±1 are energetically shifted from the state with ms = 0.

[0034] According to a preferred embodiment of the optical sensor device, it comprises a microwave source for exciting the sample. According to a preferred embodiment of the optical sensor device, the filter device comprises a long-pass filter.

[0035] According to a preferred embodiment of the optical sensor device, the detector device comprises a common-mode suppression balanced photodetector.

[0036] A common-mode rejection balanced photodetector, for example, comprises two photodiodes. One photodiode (E1) is illuminated by the signal to be detected (input channel). The second photodiode (reference channel) is used to detect a reference beam derived from the excitation light. The power levels of the two photodiodes are selected to produce comparable photocurrents in both photodiodes. Typically, the photocurrent of the reference photodiode is the same or a factor of 2 to 10 higher than the photocurrent of the signal photodiode (E1). The photocurrents are subtracted from each other in an electronic circuit and then amplified. This results in only the difference between the photocurrents being amplified. Fluctuations in the intensity of the re-emitted light, which are caused by fluctuations in the excitation light and are present in the same frequency across both photocurrents, can thus be suppressed (common-mode rejection).

[0037] According to a preferred embodiment of the optical sensor device, the evaluation device can use the filtered light beam to infer a magnetic field applied to the sample.

[0038] With a sequence of a polarizer and a beam splitter, which can split the excitation light beam into a laser (signal beam), especially the filtered light beam (= fluorescent light) (for exciting the sensor medium, e.g., NV centers in diamond), and a reference beam, polarization fluctuations of the light source / laser can be converted into intensity fluctuations. These intensity fluctuations can be detected by a balanced photodetector. Balanced detection ensures that both polarization fluctuations and intensity fluctuations can be corrected within the framework of the photodetector's common-mode rejection.

[0039] For an optical readout of the sensor device according to the invention, a linear relationship can usually exist between the achievable sensitivity and an inverse signal-to-noise ratio (SNR) of the optical measurement. In this case, a sensitivity can be 1 / SNR (i.e., inversely proportional to the noise signal).

[0040] Regarding a physical limit of photon shot noise, the noise can scale proportionally to the square root of the signal P (of the sensor) or the applied excitation power. In this context, a direct proportionality results:

[0041] Sensitivity « NoiseSignal=VP / P=l / P.

[0042] The "" indicates a direct proportionality. It should also be noted that a signal corresponds to the optical power incident on the photodiode(s) (in the input channel and / or the reference channel).

[0043] Consequently, the sensitivity can be improved by increasing the optical excitation power.

[0044] It may also be possible that the light source(s) used to excite the sensor, or there may be several of them, represent typical technical noise sources, whereby for such technical noise sources the noise may be proportional to their power.

[0045] The technical noise can advantageously be compensated, at least partially, by means of a balanced photodetection and a measurement can be made possible that is limited by the physical limit of the photon shot noise.

[0046] In a balanced photodetector, both photocurrents, particularly those of the first input channel (the signal photodiode) from the filtered light beam and those of the reference channel (reference photodiode), can be subtracted from each other. This difference can then be output as an amplified voltage signal, particularly to the evaluation device. This makes it possible to detect technical noise and perform an evaluation limited by photon shot noise.

[0047] However, one prerequisite for this may be that the intensities of the signal beam and the reference beam are subject to the same fluctuations. This may be the case when using an ideal beam splitter. In reality, however, the beam splitting at the beam splitter depends on the polarization of the incident beam. If the polarization of the incident beam changes (due to polarization fluctuations of the light source), the splitting ratio can also change. Accordingly, a polarization fluctuation can lead to an intensity difference on the two detectors of the balanced photodetector, thus generating a difference signal, which can significantly increase the noise in the detected signal.

[0048] The absorption behavior of the sensor medium (e.g., NV centers in diamond) can depend on the polarization of the incident light. A fluctuation in polarization can translate into a fluctuation in the optical excitation of the sensor medium. To prevent or at least reduce such signal degradation caused by polarization fluctuations, an additional linear polarizer can be placed in front of the beam splitter, which projects the polarization in a desired direction. A polarization fluctuation can then lead to an intensity fluctuation or power fluctuation behind the linear polarizer, but the polarization is now fixed by the linear polarizer. Thus, the splitting of the incident light at the beam splitter occurs at a fixed ratio.The common-mode rejection of the balanced photodetector allows intensity fluctuations that can occur equally in both paths of the photodetector to be compensated.

[0049] If the polarization of the beam incident at the beam splitter changes, for example due to polarization fluctuations in the light source, the splitting ratio (between the reference beam and the beam) on the sample and / or the detector also changes. Accordingly, a polarization fluctuation can lead to an intensity difference on the two detectors of the balanced photodetector, thus generating a differential signal that significantly increases noise in the detected signal. The polarization-dependent reflection or transmission behavior at dielectric surfaces can be relevant for all further refractive transitions that may occur in the beam path downstream of the beam splitter. This can, for example, affect the lens that focuses the signal beam onto the diamond. As a result, the absorption behavior of the sensor medium (e.g., NV centers in diamond) can depend on the polarization of the incident light.In this case, a polarization fluctuation can also be translated into a fluctuation in the optical excitation of the sensor medium. The unwanted polarization fluctuations of the light source / laser can be converted into intensity fluctuations that can be detected by the balanced photodetector. A polarizing element such as a linear polarizer is used for this purpose.

[0050] The polarizing beam splitter advantageously transmits p-polarized light and reflects s-polarized light. However, with sufficiently precise adjustment, a non-polarizing beam splitter may be sufficient, since the desired polarization setting can already be achieved with the linear polarizer.

[0051] The polarizing beam splitter advantageously allows the polarization of the light source to be fixed to a specific angle by the linear polarizer. This angle indicates the ratio between p-polarization and s-polarization.

[0052] Furthermore, the excitation light can be converted into fluorescence by the NV centers and detected by the signal photodiode (at the first input channel). The reflection (at the beam splitter) is detected by the reference photodiode.

[0053] For the balanced photodetector to operate properly, it may be necessary for the two photocurrents to be approximately equal. To achieve this and to adjust the optical power on the photodiode accordingly, the linear polarizer can be rotated, changing the angle and thus the ratio between s- and p-polarization.

[0054] One or more polarizing elements can be used to stabilize the polarization used for the sample.

[0055] According to the invention, the method for providing an optical sensor device comprises providing a light source with which a light beam can be generated; providing an input optics which can be irradiated by the light beam and through which the light beam can be directed onto the sample, wherein the input optics comprise a linear optical polarizer and a lens, wherein the lens is arranged downstream of or upstream of the linear polarizer in a light incidence direction and a light beam linearly polarized by the linear polarizer can be directed onto the sample;Providing an output optic and a filter device, wherein a light beam emitted by the sample, such as the fluorescent light of the sample, can be directed onto the output optic and directed thereby onto the filter device, or vice versa, and a filtered light beam can be generated with the filter device, in which excitation radiation from the light source can be filtered out; providing a detector device with which the filtered light beam can be detected; and providing an evaluation device with which the filtered light beam can be evaluated, wherein the input optics further comprise a beam splitter which is arranged between the linear polarizer and the sample and with which a reference beam can be directed onto the detector device.

[0056] According to the invention, an optical sensor device according to the invention is used.

[0057] The optical sensor device may also be characterized by the features and advantages mentioned in connection with the methods and vice versa.

[0058] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings. Brief description of the drawings

[0059] The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing.

[0060] They show:

[0061] Fig. 1 is a schematic representation of a structure of an optical sensor device according to an embodiment of the present invention;

[0062] Fig. 2 is a schematic diagram showing a structure of an optical sensor device according to a comparative example of the present invention;

[0063] Fig. 3 is a block diagram of method steps of the method for providing an optical sensor device according to an embodiment of the present invention.

[0064] In the figures, the same reference symbols denote the same or functionally identical elements.

[0065] Fig. 1 shows a schematic representation of a structure of an optical sensor device according to an embodiment of the present invention.

[0066] Fig. 1 shows a general arrangement of an optical sensor device 10. The sample p can be arranged between an input optics 2 and an output optics 3 and a light source 1, for example one or more lasers or one or more LEDs, can generate one or more light beams or a bundle of light beams and shine onto the sample p and through it or put it into an excited state, after which a re-emission can occur and the sample can emit a light signal for sensing, which light signal can be modified by the sample due to external influences, such as a magnetic field, compared to the input light or the light signal without a magnetic field.

[0067] The output optics can comprise a converging lens LI, which can irradiate a filter, and then a converging lens L2 can irradiate a detector device D, or also irradiate another filter element FE. The evaluation device (AE) can carry out several steps and for this purpose comprise several program or control modules. The first block AE1 can relate to signal processing. The second block AE2 can be a further processing of the processed and determined signal, for example an evaluation of the signal, for example with regard to reference data or reference measurements of the light from the light source (as shown in Fig. 2), for example inference about a temperature and / or a magnetic field and / or a pressure and / or further parameters on the sample p.In case the sample comprises a diamond with NV centers, the optical sensor device may comprise a microwave source MV for exciting the sample and the filter device may comprise a long-pass filter with which the excitation light can be filtered out.

[0068] Fig. 2 shows a schematic diagram of a structure of an optical sensor device according to a comparative example of the present invention.

[0069] The optical sensor device 10 of Fig. 2 can also be equipped with the evaluation blocks AE1 and AE2 of Fig. 1, as well as with the microwave source, although this is not shown in Fig. 2 for reasons of clarity. The optical sensor device 10 comprises a light source 1 with which a light beam can be generated; an input optics 2, which can be irradiated by the light beam and through which the light beam can be directed onto a sample p, wherein the input optics 2 comprises a linear optical polarizer LP and a lens, wherein the lens is arranged downstream or upstream of the linear polarizer in a light incidence direction, and a light beam linearly polarized by the linear polarizer can be directed onto the sample; an output optics 3 and a filter device FE, wherein a (fluorescence) light beam emitted by the sample p can be directed onto the output optics 3 and through this onto the filter device FE, or vice versa.and with the filter device FE, a filtered light beam can be generated, in which excitation radiation from the light source can be filtered out; a detector device D, with which the filtered light beam can be detected; an evaluation device AE, with which the signal detected by the balanced photodetector can be evaluated. The input optics 2 further comprises a beam splitter ST, which is arranged between the linear polarizer LP and the lens and with which a reference beam RS can be directed onto the detector device D. The beam splitter ST can transmit the excitation light to the sample p. The input optics 2 can comprise a deflection mirror US, which can be irradiated by the beam splitter ST with the reference beam RS, and with the deflection mirror US, the reference beam RS can be directed onto the detector device D. The detector device D can comprise a first input channel E1 and a reference channel RK,The filtered light beam can be directed to the first input channel E1, and the reference beam RS can be directed to the reference channel RK. The excitation light from the light source 1 can be received by the evaluation device AE through the reference beam RS at the detector device D, and can be evaluated by the evaluation device AE and be comparable to the filtered light beam at the input channel. In the embodiment of Fig. 2, or alternatively in other embodiments of the invention, the beam splitter ST can comprise a polarizing beam splitter, and the sample can comprise a diamond with NV centers. In order to prevent or reduce signal degradation caused by polarization fluctuations, a linear polarizer is additionally placed in front of the beam splitter, which projects the polarization in a desired direction.Where a polarization fluctuation can only lead to an intensity fluctuation behind the linear polarizer, the polarization can be fixed by the linear polarizer now present. As a result, the splitting of the incident light at the beam splitter can occur at a fixed ratio.

[0070] Fig. 3 shows a block diagram of method steps of the method for providing an optical sensor device according to an embodiment of the present invention.

[0071] In the method for providing an optical sensor device, a light source is provided S1 with which a light beam can be generated; an input optical system is provided S2 which can be irradiated by the light beam and through which the light beam can be directed onto the sample, wherein the input optical system comprises a linear optical polarizer and a lens, wherein the lens is arranged downstream of or upstream of the linear polarizer in a light incidence direction and a light beam linearly polarized by the linear polarizer can be directed onto the sample; an output optical system and a filter device are provided S3, wherein a light beam emitted by the sample can be directed onto the output optical system and can be directed by the output optical system onto the filter device, and a filtered light beam can be generated with the filter device, in which excitation radiation from the light source can be filtered out;providing S4 a detector device with which the filtered light beam can be detected; and providing S5 an evaluation device with which the filtered light beam can be evaluated, wherein the input optics further comprise a beam splitter arranged between the linear polarizer and the sample, and with which a reference beam can be directed onto the detector device.

[0072] Although the present invention has been fully described above using the preferred embodiment, it is not limited thereto but can be modified in many ways.

Claims

Claims Optical sensor device (10), comprising - a light source (1) with which a light ray can be produced; - an input optic (2) which can be irradiated by the light beam and through which the light beam can be directed onto a sample (p), wherein the input optic (2) comprises a linear optical polarizer (LP) and a lens (L), wherein the lens is arranged downstream or upstream of the linear polarizer in a direction of incidence of light and a light beam linearly polarized by the linear polarizer can be directed onto the sample; - an output optics (3) and a filter device (FE), wherein a light beam emitted from the sample (p) can be directed to the output optics (3) and by it to the filter device (FE) or vice versa, and with the filter device (FE) a filtered light beam can be generated in which an excitation radiation from the light source (1) can be filtered out; - a detector device (D) with which the filtered light beam can be detected, - an evaluation device (AE) with which the filtered light beam can be evaluated, wherein the input optics (2) further comprises a beam splitter (ST) which is arranged between the linear polarizer (LP) and the sample, and with which a reference beam (RS) can be directed onto the detector device (D). Optical sensor device (10) according to claim 1, in which the input optics (2) comprises a deflecting mirror (US) which can be irradiated by the beam splitter (ST) with the reference beam (RS) and with which the reference beam (RS) can be directed onto the detector device (D). Optical sensor device (10) according to claim 2, in which the detector device (D) comprises a first input channel (El) and a reference channel (RK), wherein the filtered light beam can be directed onto the first input channel (El) and the reference beam (RS) can be directed onto the reference channel (RK).Optical sensor device (10) according to claim 3, in which the excitation light of the light source (1) is received by the evaluation device (AE) via the reference beam (RS) at the detector device (D) and can be evaluated by the evaluation device (AE) and is comparable to the filtered light beam at the input channel (El). Optical sensor device (10) according to any one of claims 1 to 4, in which the beam splitter (ST) comprises a polarizing beam splitter. Optical sensor device (10) according to any one of claims 1 to 5, wherein the sample comprises a diamond with NV centers. Optical sensor device (10) according to claim 6, wherein a microwave source for excitation of the sample. Optical sensor device (10) according to any one of claims 1 to 7, wherein the filter device comprises a long-pass filter. Optical sensor device (10) according to any one of claims 1 to 8, wherein the detector device (D) comprises a common-mode suppressing balanced photodetector. Optical sensor device (10) according to any one of claims 1 to 9, wherein the evaluation device (AE) allows conclusions to be drawn about a magnetic field applied to the sample (p) from the filtered light beam. [The following appears to be unrelated and possibly a separate document:] Experiences for providing an optical sensor device (10), comprising the steps: - Providing (Sl) a light source (1) with which a light beam can be produced; - Providing (S2) an input optic (2) which can be irradiated by the light beam and through which the light beam can be directed onto the sample (p), wherein the input optic (2) comprises a linear optical polarizer (LP) and a lens (L), wherein the lens is arranged downstream or upstream of the linear polarizer in a direction of incidence of light and a light beam linearly polarized by the linear polarizer can be directed onto the sample; - Providing (S3) an output optics (3) and a filter device (FE), wherein a light beam emitted from the sample (p) can be directed to the output optics (3) and by it to the filter device (FE) or vice versa, and a filtered light beam can be generated with the filter device (FE), in which an excitation radiation from the light source (1) can be filtered out; - Providing (S4) a detector device (D) with which the filtered light beam can be detected and - Providing (S5) an evaluation device (AE) with which the filtered light beam can be evaluated, wherein the input optics (2) further comprises a beam splitter (ST) which is arranged between the linear polarizer (LP) and the sample, and with which a reference beam (RS) can be directed onto the detector device (D). Method for using an optical sensor device (10) according to any one of claims 1 to 10.

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