Device for examining material samples by means of electromagnetic radiation with selectable detector

Abstract

The invention relates to a device (10) for examining material samples (40) by means of electromagnetic radiation. The device (10) comprises a lighting unit (20) for generating the electromagnetic radiation with at least two radiation sources (21, 21*), the radiation (22, 22') of which can be selectively directed onto the material sample (40). The device further comprises a detection unit having at least two detectors (71, 71') for capturing electromagnetic radiation emanating from the material sample (40). A deflection element (73) is arranged in the detection unit (70), by means of which the electromagnetic radiation emanating from the material sample (40) can be selectively deflected onto one of the detectors (71, 71'). This deflection element (73) comprises a mirror (74), by means of which the radiation (78) emanating from the material sample (40) can be selectively deflected onto one of the detectors (60, 71, 71'). The mirror (74) is rotated about an axis (76) extending perpendicular to the optical axes of the detectors (71, 71').

Description

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

[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 understood below to refer to a measurement method using electromagnetic radiation, particularly electromagnetic radiation in a 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] In such measurements, it is often desired to examine the sample using electromagnetic radiation of different wavelengths. For example, for 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. In this way, biochemical properties can be measured.

[0005] DE 699 29 086 T2 discloses a measuring device comprising a radiation source and a detector module. The radiation source emits a combined beam of UV and IR radiation, and the detector module comprises a plurality of individual detectors. A rotating mirror arranged inside the detector module allows the radiation received by the detector module to be directed sequentially to the individual detectors without being split.

[0006] The object of the present invention is to further develop the measuring device known from the prior art in such a way that a precise assignment of the radiation measured in a given spectral range to a spectral range of the excitation radiation is ensured. Furthermore, the device should allow for quick and easy switching between different spectral measurement ranges.

[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 an illumination device for generating electromagnetic radiation and a detection device with at least two detectors for detecting electromagnetic radiation emanating from the fabric sample. The illumination device comprises at least two radiation sources, so that the radiation from one radiation source or the radiation from the other radiation source can be directed onto the fabric sample. The detection device comprises a deflection element by means of which the radiation emanating from the fabric sample can be selectively directed onto one of the detectors. According to the invention, this deflection element of the illumination device comprises a rotatable mirror, with which the radiation can be selectively directed onto one of the detectors.

[0009] The inventive design of the device has the advantage that multiple radiation sources can be provided, whose radiation can be used to illuminate the material sample. The inventive device is particularly suitable for fluorescence analysis, in which the material sample is excited by polychromatic radiation or radiation within a limited spectral range, and the fluorescent radiation emitted by the material sample in a predetermined direction is evaluated using the detection device.

[0010] In a first embodiment of the invention, at least two of the radiation sources are of the same design. This enables redundant lighting, 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.

[0011] In an alternative embodiment of the invention, at least two of the radiation sources are designed differently, for example, they radiate in different spectral ranges, with different intensities, etc. This allows the selection of a radiation source optimally suited for the respective measurement task. Furthermore, it enables rapid switching of the radiation source if radiation of different wavelengths is to be directed successively onto the material sample for a given measurement task.

[0012] LED diodes, which emit light in specific spectral ranges, can be used as radiation sources. Alternatively, halogen lamps, for example, can be used, whose radiation can be limited to a specific spectral range using a filter.

[0013] The illumination device advantageously comprises a deflection element, with the aid of which the radiation from one or another radiation source can be selectively directed onto the fabric sample. This deflection element is designed in such a way that it allows the different radiation sources to be switched on and off quickly, without the need for complex adjustments when changing the radiation source.

[0014] The deflecting element of the illumination device advantageously has beam-shaping properties. For example, the deflecting element can be designed in such a way that it focuses the radiation emitted by the respective radiation source onto the fabric sample; such a design is particularly advantageous when small objects are to be examined. Alternatively, the deflecting 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.

[0015] The deflection element of the illumination device can, in particular, comprise a mirror with which one or the other radiation source can be selectively directed onto the material sample. For example, a concave mirror, in particular a parabolic mirror, can be used, which has a collimating effect advantageous for spectroscopic measurements.

[0016] The deflecting element of the illumination device is advantageously mounted for rotation, in such a way that the axis of rotation is aligned parallel to the direction of propagation of the deflected radiation. In this case, the two or more radiation sources can be arranged in a circular arc around the deflecting element, and by rotating the deflecting element, the radiation from one or the other radiation source can be selectively directed onto the fabric sample without the need for further adjustments.

[0017] The deflecting element of the illumination device 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, in the course of determining the intensity or functional testing in transmission measurements. Furthermore, it is advantageous to provide an optical fiber, in particular a fiber optic rod, in the region of this passage opening, which guides the radiation reflected by the material sample in the direction of incidence through the deflecting element of the illumination device with low loss.

[0018] To allow rapid fluorescence measurements in different spectral ranges, it is advantageous to synchronize the switching on and off of the various radiation sources of the illumination device with the switching on and off of the various detectors of the detection device. In this way, a large number of measurements in different spectral ranges can be performed on the material sample in rapid succession.

[0019] If the illumination device, as described above, is provided with a deflection element with which radiation from a specific radiation source can be selectively directed onto the material sample, then it is advantageous to synchronize the movements of this deflection element with the movements of the deflection element of the detection device, so that the radiation source active at a given time corresponds to the associated detector.

[0020] Analogous to the design of the deflection element of the illumination device, the deflection element of the detection device can also have beam-shaping properties, for example by focusing the radiation emanating from the material sample onto the detectors.

[0021] In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings.

[0022] Figure 1 is a schematic sectional view of a device for examining material samples with multiple light sources and multiple detectors;

[0023] Figure 2 is a schematic sectional view of another device for examining material samples with multiple light sources and multiple detectors;

[0024] Figure 3 is a schematic sectional view of an alternative device for examining material samples with multiple light sources and multiple detectors.

[0025] Figure 1 shows a schematic sectional view of a device 10 for examining a fabric sample 40 using fluorescence spectroscopy. The device 10 comprises an illumination device 20 for generating the electromagnetic radiation and a detection device 70 for detecting the electromagnetic radiation emanating from the fabric sample 40. The illumination device 20 is tilted at an angle of incidence 80, for example 45°, relative to the fabric sample 40, so that the radiation 28 emanating from the illumination device 20 strikes the fabric sample 40 at the angle of incidence 80. The detection device 70 is also tilted relative to the fabric sample 40, so that the intensity of the radiation 78 emitted by the fabric sample 40 is measured at an angle 80'.

[0026] The illumination device 20 comprises two radiation sources 21, 21' in the form of halogen lamps, which are provided with different wavelength-selective filters 32, 32', whereby the outgoing radiation 22, 22' has different spectral properties. The two radiation sources 21, 21' are arranged diametrically opposite one another so that their respective optical axes are aligned with one another. A deflection element 23 arranged in the beam path between the two radiation sources 22, 22' 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. The deflection 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 beams 22, 22'.

[0027] In Figure 1, the mirror 24 is in a position 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 from the first radiation source 21 is reflected in a propagation direction 27 that runs parallel - and in the present embodiment collinear - to the axis of rotation 26 of the deflecting element 23. With the help of a drive unit 35, the mirror 24 can be rotated by 180° from the position shown in Figure 1, 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 deflecting element 23. As an alternative to the halogen lamps shown in Figure 1, LEDs with a narrow spectral emission range can be used as radiation sources 21, 21'.In addition to the two halogen lamps, further radiation sources can be provided, which are preferably arranged on a great circle around the axis of rotation 26 of the deflection element 23.

[0028] The detection device 70 comprises two detectors 71, 71', which in the embodiment of Figure 1 are arranged diametrically opposite one another so that their respective optical axes are aligned with one another. The two detectors 71, 71' serve to measure the intensity of radiation 78 incident on the detection device 70 in the direction of incidence 78 in different spectral ranges. For this purpose, detectors 71, 71' can be used which inherently measure in different spectral ranges. Alternatively, detectors 71, 71' of identical design and a broad spectral sensitivity range can be used, which are provided with different wavelength-selective filters 79, 79' so that the radiation 78 is filtered wavelength-specifically before it reaches the detectors 71, 71'.

[0029] A deflecting element 73 is arranged between the two detectors 71, 71', with the aid of which radiation 78 incident on the detection device 70 can be selectively directed onto one of the two detectors 71, 71'. The deflecting element 73 comprises a mirror 74, in this exemplary embodiment a concave mirror 74', which can be rotated about an axis of rotation 76 parallel to the incident radiation 78. A drive unit 75 is provided for rotating and positioning the mirror 74. In Figure 1, the mirror 74 is in a position in which the radiation 78 emitted by the material sample 40 is focused via the mirror 74 onto the detector 71 (beam 72), while the second detector 71' is shielded from the radiation 78 by the deflecting element 73. A rotation of the mirror 74 by 180° directs the radiation 78 onto the second detector 71' (beam 72'), while the first detector 71 is now shielded.In this way, by rotating the mirror 74, the intensity of the radiation 78 can be measured in different wavelength ranges using the detectors 71, 71'. In addition to the detectors 71, 71' shown in Figure 1, further detectors (not shown in the figures) may be present, arranged in a great circle in a plane perpendicular to the rotation axis 76 of the mirror 74. A drive unit 75 is provided for the precise rotation of the mirror.

[0030] The illumination device 20 and the detection device 70 are sealed from the environment by observation windows 31, for example sapphire windows, in order to prevent the penetration of dust and other contaminants into the interior.

[0031] Advantageously, the wavelength-selective filters 32, 32' of the illumination device 20 and the wavelength-selective filters 79, 79' of the detection device are matched to one another in pairs, so that the material sample 40 can be examined in two different spectral ranges without any equipment effort, simply by rotating the mirrors 24, 74. Furthermore, by synchronously rotating the two mirrors 24, 74, it is possible to switch back and forth between the two different spectral measurement ranges in rapid succession. The rotation of the mirrors 24, 74 can occur continuously or stepwise. Thus, by continuously rotating the mirrors 24, 74, radiation from one or the other radiation source 21, 21' can be directed onto the material sample 40 at regular intervals and synchronously detected in a wavelength-selective manner by the detectors 71, 71'. Alternatively, the mirrors 24, 74 can be rotated for positioning.

[0032] Figure 2 shows a further 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 in alignment and perpendicular to the fabric sample 40. The deflection element 23 of the illumination device 20 is provided with an opening 25 for receiving a light guide rod 36, through which radiation reflected by the fabric sample 40 in the direction of incidence 27 can be transmitted through the deflection element 23 in the direction of the detection device 70. By means of the illumination device 20, the fabric sample 40 is illuminated selectively or in temporal alternation with radiation from the radiation source 21 or the radiation source 21'.The radiation 78 reflected by the material sample 40 in the direction of incidence 27 is guided by a light guide rod 36 through the deflection element 23 of the illumination device 20' and impinges on the detection device 70, in which the radiation 78 is directed selectively or in temporal alternation onto the detector 71 or the detector 71'. If measurements are to be performed in different spectral ranges in rapid succession, the movements of the deflection elements 23, 73 in the illumination device 20' and the detection device 70 are advantageously synchronized in such a way that, for a given radiation 22, 22' in the detection device, the detector 71, 71' corresponding to the spectral range of this radiation 22, 22' is enabled. Figure 3 shows an embodiment of a device 100 according to the invention, in which the detection device 70 essentially corresponds to the detection device shown in Figures 1 and 2.The illumination device 120 comprises a plurality of LEDs 121, 121' with different spectral properties, which are arranged in a great circle around the fabric sample 40 in such a way that their radiation 122, 122' is directed onto the fabric sample 40. By alternately switching these LEDs 121, 121* on and off, the fabric sample 40 is exposed to radiation of different wavelengths. The detection device 70 comprises detectors 71, 71', whose spectral properties are matched to the spectra of the LEDs 121, 121'.

[0033] The alternating switching of the LEDs 121, 121* can be achieved in particular with the aid of a rotatable disk 130. The disk 130 has a central recess 131 for the radiation 78 emanating from the fabric sample 40. Furthermore, a lateral recess 132 is provided on the disk 130, through which radiation from one of the LEDs (in this case, the LED 121) can fall onto the fabric sample 40. The angular position of the disk 130 is synchronized with the angular position of the mirror 74 in the interior of the detection device 70. In this way, the fabric sample 40 can be irradiated successively by different LEDs, and simultaneously, via the mirror 74, a measurement of the radiation emitted by the fabric sample 40 can be carried out by the detector 71 assigned to this LED. The disk 130 can be connected electrically or mechanically to the drive unit 75 of the mirror 74.

[0034] List of reference symbols

[0035] 10, 10', 100 device

[0036] 20, 120 lighting equipment

[0037] 21, 21' radiation source

[0038] 22, 22' Rays of radiation sources

[0039] 23 Deflection element

[0040] 24 mirrors, 24' concave mirror

[0041] 25 Opening in the deflection element

[0042] 26 Rotation axis deflection element

[0043] 27 Direction of radiation of the lighting device

[0044] 28 Radiation of the lighting device

[0045] 31 observation windows

[0046] 32, 32' wavelength selective filter

[0047] 35 Mirror drive unit

[0048] 36 light guide rod

[0049] 40 fabric samples

[0050] 70 Detection device

[0051] 71.71' detector

[0052] 72.72' radiation deflected by mirror 74

[0053] 73 Deflection element

[0054] 74 mirrors, 74' concave mirrors

[0055] 75 Mirror drive unit

[0056] 76 Rotation axis deflection element

[0057] 77 Direction of propagation of the reflected radiation

[0058] 78 Radiation emitted / reflected by fabric sample

[0059] 79, 79' wavelength-selective filter

[0060] 80, 80' angle of incidence, angle of exit

[0061] 100 device

[0062] 120 lighting equipment

[0063] 121, 121' LEDs 122,122' beams

[0064] 130 slice

[0065] 131 , 132 Recesses in the disc

Claims

Patent claims 1. Device (10, 10', 100) for examining material samples (40) by means of electromagnetic radiation, comprising - a lighting device (20, 120) for generating the electromagnetic radiation, wherein the lighting device (20, 120) comprises at least two radiation sources (21, 21', 121, 121'), the radiation (22, 22', 122, 122') of which can be selectively directed onto the fabric sample (40), - a detection device (70) with at least two detectors (71, 71') for detecting electromagnetic radiation (78) emanating from the material sample (40), wherein the detection device (70) comprises a deflection element (73) by means of which the radiation (78) emanating from the material sample (40) can be selectively directed onto one of the detectors (71, 71'), characterized in that - the deflection element (73) of the detection device (70) comprises a mirror (74) by means of which the radiation (78) emanating from the material sample (40) can be selectively directed onto one of the detectors (60, 71, 71'), - wherein the mirror (74) is designed to be rotatable about an axis (76) running perpendicular to the optical axes of the detectors (71, 71').

2. Device according to claim 1, characterized in that at least two of the radiation sources (21, 21', 121, 121') are of the same design.

3. Device according to claim 1 or 2, characterized in that at least two of the radiation sources (21, 21', 121, 121') are designed differently.

4. Device according to one of the preceding claims, characterized in that the at least two radiation sources (21, 21', 121, 121') are LED diodes.

5. Device according to one of the preceding claims, characterized in that the illumination device (120) comprises a rotatable disc (130) provided with recesses (131, 132), by means of which radiation from one of the radiation sources (21, 21') can be selectively directed onto the fabric sample (40).

6. Device according to claim 5, characterized in that the respective angular position of the disc (130) of the lighting device (120) can be synchronized with a respective position of the deflection element (73) of the detection unit (70).

7. Device according to one of claims 1 to 4, characterized in that the illumination device (20) comprises a deflection element (23) by means of which radiation from one of the radiation sources (21, 21') can be selectively directed onto the fabric sample (40).

8. Device according to claim 7, characterized in that the deflection element (23) of the lighting device (20, 120) has beam-forming properties.

9. Device according to claim 7 or 8, characterized in that the deflection element (23) of the illumination device (20, 120) comprises a mirror (24), by means of which radiation from one of the radiation sources (21, 21') can be selectively directed onto the fabric sample (40).

10. Device according to one of claims 7 to 9, 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.

11. Device according to one of claims 7 to 10, characterized in that the deflecting element (23) has an opening (25) for the passage of electromagnetic radiation.

12. Device according to claim 11, characterized in that a light guide rod (36) is arranged in the region of the opening (25).

13. Device according to one of claims 7 to 12, characterized in that the respective settings of the deflection element (23) of the lighting device (20) and the deflection element (73) of the detection unit (70) can be synchronized.

14. Device according to one of the preceding claims, characterized in that the deflection element (73) of the detection device (70) has beam-forming properties.

15. Device according to one of the preceding claims, characterized in that the mirror (74) is designed as a concave mirror (74').

Images