Device for analysing material samples by means of electromagnetic radiation with selectable light source

Abstract

The invention relates to a device (10, 10', 10'') for analysing material samples (40) by means of electromagnetic radiation. The device (10) comprises an illumination device (20) with at least two radiation sources (21, 21*) for generating the electromagnetic radiation, and a deflection element (23) for deflecting the electromagnetic radiation onto the material sample (40). Furthermore, at least one detector (60) is provided for detecting the electromagnetic radiation emitted by the material sample. The deflection element (23) is designed to be rotatable about an axis (26) parallel to the direction of propagation (27) of the deflected radiation and is movable in such a way that the material sample (40) can be selectively exposed to radiation from one of the radiation sources (21, 21'). Advantageously, the deflection element is designed as a mirror (24), for example as a concave mirror (24').

Description

[0001] Device for examining material samples using electromagnetic radiation with selectable light source

[0002] The invention relates to a device for examining material samples by means of electromagnetic radiation according to the preamble of claim 1.

[0003] In many areas of the manufacturing and processing industries, such as medical technology, the food industry, etc., optical measurement methods are used to evaluate the condition or quality of a product or intermediate product. The term "optical measurement method" is used below to refer to a measurement method using electromagnetic radiation, particularly electromagnetic radiation in the spectral range between infrared and ultraviolet. "Optical measurement" therefore includes, in particular, measurements in the far infrared (FIR), mid-infrared (MIR), near infrared (NIR), visible spectral range, and UV range.

[0004] Often, such measurements require the examination of the sample using electromagnetic radiation of different wavelengths. For example, to conduct fluorescence measurements, biochemical samples can be labeled with two or more fluorescent carriers so that they glow differently when excited by different wavelengths of light. This allows biochemical properties to be measured.

[0005] DE 100 38 185 C2 discloses a measuring device with two light sources and a detector. A rotatable mirror with transparent areas selectively directs the light from either the first or the second light source onto a sample carrier. The light emitted by the sample carrier is then directed onto a detector.

[0006] The object of the present invention is to propose a device for examining material samples using electromagnetic radiation, which can comprise a plurality of radiation sources that can be selectively directed onto the material sample. The device should allow for quick and easy switching between the different radiation sources.

[0007] This object is achieved by a device having the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention.

[0008] A device according to the invention comprises at least two radiation sources for generating electromagnetic radiation, a deflecting element for deflecting this radiation onto a material sample located in an observation area, and at least one detector for detecting the electromagnetic radiation emanating from the material sample. The deflecting element is movable such that the radiation from one radiation source or the radiation from the other radiation source is selectively directed onto the material sample.

[0009] "Steering" or "deflection" refers to a change in the direction of the radiation emitted by the radiation source. This type of device design has the advantage that multiple radiation sources can be provided, which can be used to illuminate the material sample by simply moving the deflection element.

[0010] According to the invention, the deflection element is mounted for rotation, specifically in such a way that the axis of rotation is aligned parallel to the propagation direction of the deflected radiation. In this case, the two or more radiation sources can be arranged on a circular arc around the deflection element, and by rotating the deflection element, the radiation from one or the other radiation source can be selectively directed onto the fabric sample without the need for further adjustments.

[0011] In a first embodiment of the invention, at least two of the radiation sources are of identical design. This enables redundant illumination, particularly in problematic environments where, for example, the filaments of halogen lamps or the anodes of mercury vapor lamps can crack or break due to mechanical stress, vibrations, etc. In an alternative embodiment of the invention, at least two of the radiation sources are of different design, radiating, for example, in different spectral ranges, with different intensities, etc. This allows the selection of a radiation source optimally suited to the respective measurement task. Furthermore, it enables rapid switching of the radiation source if, for a given measurement task, radiation of different wavelengths needs to be directed successively onto the material sample.

[0012] The deflection element advantageously has beam-shaping properties. For example, the deflection element can be designed to focus the radiation emitted by the radiation source onto the fabric sample; such a design is particularly advantageous when small objects are to be examined. Alternatively, the deflection element can expand (defocus) the beam emitted by the radiation source, which can be advantageous, for example, in applications of reflection spectroscopy in the visible or infrared spectral range when the fabric sample is to be illuminated over a large area.

[0013] The deflection element can, in particular, comprise a mirror. For example, a parabolic mirror can be used, which has a collimating effect that is advantageous for spectroscopic measurements.

[0014] The deflecting element can have an opening for the passage of electromagnetic radiation. This is particularly useful when the spectrum or intensity of the radiation reflected by the material sample in the direction of incidence is to be measured, for example when determining the intensity or functional testing in transmission measurements. Furthermore, it is advantageous to connect an optical fiber in the region of this passage opening, by means of which the radiation incident into the opening can be transmitted to the detector. It is particularly advantageous to provide an optical fiber rod in the region of the opening, which guides the radiation reflected by the material sample in the direction of incidence through the deflecting element with low loss. In addition to detecting the radiation reflected by the material sample, it may be desirable to detect the radiation transmitted by the material sample.For this purpose, an optical element can be arranged on the side of the observation area facing away from the deflection element, which focuses the electromagnetic radiation emanating from the material sample. This optical element serves to couple the radiation into a fiber connected to a detector or to focus it directly onto a detector surface. Accordingly, a detector or the end face of an optical fiber can be arranged at the focus of this optical element, which then transmits the radiation to a detector.

[0015] To validate measurements or calibrate the device, a validation element can be provided in the beam path between the deflection element and the fabric sample. This validation element can, for example, be a white reference or a filter or filter wheel, which is advantageously provided with recesses for transmission measurements.

[0016] In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings.

[0017] Figure 1 is a schematic perspective view of a device according to the invention for examining material samples;

[0018] Figure 2 is a schematic sectional view of a lighting device of Figure 1 along the section line II-II in Figure 1;

[0019] Figure 3 shows a further schematic sectional view of the lighting device of Figure 2 with rotated deflection element;

[0020] Figure 4 is a schematic perspective view of a device with multiple radiation sources and multiple detectors;

[0021] Figure 5 shows a schematic perspective view of an alternative device with multiple radiation sources and multiple detectors. Figure 1 shows a first embodiment of a device 10 for examining material samples using electromagnetic radiation. The device 10 comprises a housing 12 in which an illumination device 20 for generating the electromagnetic radiation and a detector 60 for detecting the electromagnetic radiation emanating from the material sample are arranged. Located below a base plate 13 of the housing 12 is an observation area 42 in which the material sample 40 to be examined (not shown in Figure 1) is arranged.

[0022] Figure 2 shows a schematic sectional view of the illumination device 20. In the present embodiment, the illumination device 20 comprises two radiation sources 21, 21', whose beams 22, 22' are directed onto a deflecting element 23. In the present embodiment, halogen lamps are used as radiation sources 21, 21', which are provided with different wavelength-selective filters 32, 32', as a result of which the emerging radiation has different spectral properties. Alternatively, LEDs with a narrow emission range in different spectral ranges, for example, can be used as radiation sources. The two radiation sources 21, 21' are arranged diametrically opposite one another, so that their respective optical axes are aligned with one another.The deflecting element 23 serves to selectively direct the rays 22 of the first radiation source 21 or the rays 22' of the second radiation sources 21' onto the fabric sample 40, which is arranged in the observation area 42 below the illumination device 20 on an observation table 42'. The deflecting element 23 comprises a mirror 24, in this embodiment a concave mirror 24', which can be rotated about an axis of rotation 26 perpendicular to the propagation direction of the rays 22, 22'. In Figure 2, the mirror 24 is in a central position in which neither light from the radiation source 21 nor light from the radiation source 21' is directed onto the fabric sample 40.By rotating the deflecting element 23 about the rotation axis 26, the mirror 24 can be brought into the position shown in Figure 3, in which the radiation 22 from the first radiation source 21 is deflected by the mirror 24 and focused onto the fabric sample 40, while the radiation 22' from the second radiation source 21' is blocked by the deflecting element 23. With the help of the mirror 24, the radiation 21 is reflected in a propagation direction 27 that runs parallel—and in the present embodiment, collinear—to the rotation axis 26 of the deflecting element 23. A drive unit 35 is provided for rotating the mirror 24. With the aid of this drive unit 35, the mirror 24 can be rotated by 180° from the position shown in Figure 3, so that radiation 22' from the second radiation source 21' reaches the fabric sample 40, while the radiation 22 from the first radiation source 21 is blocked by the deflection element 23. In addition to the radiation sources 21, 21.1 Further radiation sources (not shown in the figures) may be present, arranged in a great circle in a plane perpendicular to the axis of rotation 26 of the mirror 24. By rotating the mirror 24, the light from one of these radiation sources can be directed onto the fabric sample 40, as described above.

[0023] The rotation of the mirror 24 can occur continuously or stepwise. Thus, by continuously rotating the mirror 24, radiation from one or the other radiation source 21, 21' can be directed onto the fabric sample 40 at regular time intervals. Alternatively, the mirror 24 can be rotated for positioning purposes. In particular, the rotation of the mirror 24 can occur only when necessary, e.g., in the event that the radiation source 21 fails due to a defect and therefore an (identical) radiation source 21' is to be used to measure the fabric sample 40.

[0024] The deflection element 23 is provided with an opening 25 through which radiation reflected by the fabric sample 40 in the direction of incidence 27 can be guided outward. In order to be able to guide this reflected radiation to the detector 60, a light wave rod 36 can be provided in the region of the opening 25. The radiation guided through the deflection element 23 by the light wave rod 36 is forwarded to the detector 60 using an optical fiber 29, for example, a fiber 29', and analyzed there. This reflected radiation can be used, for example, to determine the intensity in transmission measurements or to determine a spectrum reflected by the fabric sample 40.

[0025] On a side of the observation area 42 facing away from the illumination device 20, an optical element 45 is provided, by means of which the radiation 44 emanating from or transmitted by the fabric sample 40 is focused. An end face 50 of a further optical waveguide 49 can be arranged in the region of the focus of this optical element 45, with which the radiation 44 is guided into the detector 60. Alternatively, a further detector can be arranged in the focus of the optical element 45.

[0026] The illumination device 20 is sealed from the environment by an observation window 31, in particular a sapphire window, to prevent dust and other contaminants from penetrating the interior of the illumination device. A validation element 30 for calibrating the device 10 and / or for validating measurements can be present in the radiation path 28 after the mirror 24. This validation element 30 can, in particular, be a white reference or a filter or filter wheel (with a recess for transmission measurements).

[0027] In addition to the two radiation sources 21, 2T shown in Figure 2, further radiation sources can be provided which are arranged together with the radiation sources 21, 2T in a plane perpendicular to the axis of rotation 26 of the deflection element 23, so that their rays can be directed onto the fabric sample 40 by rotating the mirror 24.

[0028] Figure 4 shows a further device 10' for examining a fabric sample 40 with the aid of an illumination device 20' and a detection device 70'. The illumination device 20' essentially corresponds to the illumination device shown in Figures 2 and 3 with two radiation sources 21, 2T and is tilted at an angle of incidence 80, for example 45°, relative to the fabric sample 40. The detection device 70' comprises two detectors 71, 7T and is located in an angular position tilted at an angle of reflection 80' relative to the fabric sample 40. The radiation 78 emitted by the fabric sample 40 in the radiation direction 77 can be directed selectively onto one of the two detectors 71, 7T by a deflection unit 73 integrated in the detection device 70'. The deflection unit 73 comprises a mirror 74, in the present case a concave mirror 74'.To direct the beam 78 onto one or the other detector 71, 7T, the mirror 74 can be rotated about a rotation axis 76 by means of a drive unit 35'. In Figure 4, the mirror 24 is in a position in which the radiation 78 reflected by the fabric sample 40 in the direction 80' is focused onto the detector 71 via the mirror 74, while the second detector 71' is shielded from the radiation 78 by the deflection element 73. Rotating the mirror 74' by 180° directs the radiation 78 onto the second detector 71', while the first detector 71 is shielded. By selecting suitable wavelength-selective filters 79, 79', which are arranged in front of the detectors 71, 71', the intensity of the radiation 78 in different wavelength ranges can be measured by means of the detectors 71, 71'.

[0029] Figure 5 shows a device 10" for examining a fabric sample 40 with the aid of the illumination device 20' and the detection device 70', which in this exemplary embodiment are both arranged perpendicular to the fabric sample 40. The fabric sample 40 can be illuminated by means of the illumination device 20' optionally with radiation from the radiation source 21 or the radiation source 21'. The radiation 78 reflected by the fabric sample 40 in the direction of incidence 27 is guided by means of a light guide rod 36 through the deflection element 23 of the illumination device 20' and strikes the detection device 70', in which the radiation 78 can be directed optionally onto the detector 71 or the detector 72.

[0030] List of reference symbols

[0031] 10, 10", 10" device

[0032] 12 housings

[0033] 13 Base plate

[0034] 20.20" lighting device

[0035] 21 ,21“ radiation source

[0036] 22.22" beams

[0037] 23 Deflection element

[0038] 24 mirrors, 24" concave mirror

[0039] 25 Opening in the deflection element

[0040] 26 Rotation axis deflection element

[0041] 27 Direction of propagation of the deflected radiation

[0042] 28 Radiation path after deflection element

[0043] 29 optical fibers; 29" fiber; 29" end face optical fiber

[0044] 30 Validation element

[0045] 31 observation windows

[0046] 32 wavelength-selective filters

[0047] 35.35" drive unit mirror

[0048] 36 light guide rod

[0049] 40 fabric samples

[0050] 42 observation area; 42" observation table

[0051] 44 Radiation emanating from the sample

[0052] 45 Focusing element

[0053] 49 optical fibers

[0054] 50 end face optical fiber

[0055] 60 Detector = Spectrometer

[0056] 70" detection device

[0057] 71 .71" detector

[0058] 72.72" radiation deflected by the mirror 74

[0059] 73 Deflecting element mirror, 74' Concave mirror axis of rotation deflecting element propagation direction of the reflected radiation emitted / reflected radiation from the sample, 79' wavelength-selective filter, 80' angle of incidence

[0060] - IQ -

Claims

Patent claims 1. Device (10, 10', 10") for examining material samples (40) by means of electromagnetic radiation, comprising at least two radiation sources (21, 21') for generating the electromagnetic radiation, a deflecting element (23) for deflecting the electromagnetic radiation onto the material sample (40), wherein radiation from one of the radiation sources (21, 21') can be selectively deflected onto the material sample (40) by means of the deflecting element (23), at least one detector (60, 71, 71') for detecting the electromagnetic radiation emanating from the material sample (40), characterized in that the deflecting element (23) is designed to be rotatable about an axis (26) parallel to the propagation direction (27) of the deflected radiation. . Device according to claim 1, characterized in that at least two of the radiation sources (21, 21') are designed to be identical. .Device according to one of the preceding claims, characterized in that at least two of the radiation sources (21, 21') are designed differently. Device according to one of the preceding claims, characterized in that the deflection element (23) has beam-shaping properties. Device according to claim 4, characterized in that the deflecting element (23) exerts a focusing effect on the radiation. Device according to claim 4, characterized in that the deflecting element (23) exerts a defocusing effect on the radiation. Device according to one of the preceding claims, characterized in that the deflecting element (23) comprises a mirror (24), by means of which radiation from one of the radiation sources (21, 21') can be selectively directed onto the material sample (40). Device according to claim 7, characterized in that the mirror (24) is designed as a concave mirror (24'). Device according to one of the preceding claims, characterized in that the deflecting element (23) has an opening (25) for the passage of electromagnetic radiation. Device according to claim 9, characterized in that an end face of an optical waveguide (29), in particular a fiber (29'), is arranged in the region of the opening (25).Device according to claim 9, characterized in that a light guide rod (36) is arranged in the region of the opening (25). Device according to one of the preceding claims, characterized in that an optical element (45) for focusing the electromagnetic radiation emanating from the material sample (40) is arranged on the side of the observation area (42) provided for the material sample (40) facing away from the deflection element (23). Device according to claim 12, characterized in that a detector is arranged in the region of a focus (46) of the optical element (45). Device according to claim 12, characterized in that an end face (50) of an optical waveguide (49) is arranged in the region of the focus (46) of the optical element (45). Device according to one of the preceding claims, characterized in that a validation element (30) for calibrating the device (10) and / or for validating measurements is present in the radiation path (28) downstream of the deflection element (23).

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