Device for measuring absorbance of substance, computer-implemented method, computer program and non-volatile data carrier

Abstract

A device 100 for measuring the absorbance of a substance comprises:-through a sample cell 140 of a flow (F) of a solution (S) comprising said substance,-at least two light sources (D1, D2) emitting light in respective wavelength bands,-a reference photodetector 151, 152, 153) registering first signals (sR) representative of respective reference light intensities of the light emitted by the at least two light sources (D1, D2), and-a second photodetector 154, 155, 156) registering second signals (sR) representative of respective reference light intensities of the light emitted by the at least two light sources (D1, D2). And a sample cell photodetector 152 that registers a second signal sD representative of the intensity of a light beam (LB) that has passed through the sample cell 140, said light beam being generated based on light emitted by at least one of the at least two light sources D1, D2. A respective optical fiber bundle (BF1, BF2) receives light from each of the at least two light sources (D1, D2, Dn) via a starting end (BFi) and outputs light via a terminating end. The terminating ends of the fiber bundle are arranged in a common fiber bundle (BFC) forming an output interface (BFo) that feeds light through the sample cell 140 to the light beam (LB) and to the reference photodetector 151.

Description

Technical Field

[0001] The present invention generally relates to detecting the presence of a substance and measuring the concentration of a substance by studying the absorption of light by the substance. In particular, the present invention relates to an apparatus for measuring the absorbance of a substance according to the preamble of claim 1. The present invention also relates to a computer-implemented method, a computer program, and a non-volatile data carrier storing such a computer program for controlling the proposed apparatus. Background Art

[0002] Many substances absorb ultraviolet or visible light due to their chemical composition. For many years, the absorption of light by substances has been used as a basis for detecting the presence of such substances and measuring the concentration of such substances. The concentration of the substance can be determined by using the Beer-Lambert law:

[0003] A = Ebc

[0004] where: A is the absorbance;

[0005] E is the molar absorptivity, where the unit is L mol -1 cm -1 ;

[0006] b is the optical path length of the sample, defined in cm; and

[0007] c is the concentration of the compound in the solution, expressed in mol -1 represented.

[0008] E max represents the maximum absorption of the substance at a given wavelength.

[0009] The UV region can be considered to consist of light in the region of wavelengths from 1 nm to 400 nm, and light with wavelengths from 180 nm to 300 nm is called deep UV.

[0010] Most analytical instruments for detecting substances that absorb in the deep ultraviolet (UV) region use a mercury lamp, a deuterium lamp, or a xenon flash lamp as a light source. An example of such an instrument is a flow cell, in which a solution containing one or more UV-absorbing substances passes between a UV light source (such as a mercury lamp) and a UV detector (such as a photomultiplier tube or a photodiode), and the change in the intensity of the UV light reaching the detector is related to the concentration of the UV-absorbing substances in the solution.

[0011] The detection of proteins, nucleic acids, and peptides is very important in many fields, including environmental, biological, and chemical sciences. Proteins have two main absorption peaks in the deep UV region: a very strong absorption band with a maximum at about 190 nm, where the peptide bonds absorb, and another less intense peak at about 280 nm, which is due to the light absorption of aromatic amino acids such as tyrosine, tryptophan, and phenylalanine.

[0012] Nucleic acids absorb UV light at approximately 260 nm, with some of the subunits of nucleic acids (purines) having absorbance maxima slightly below 260 nm and other subunits (pyrimidines) having maxima slightly above 260 nm.

[0013] Due to the content of light-absorbing aromatic amino acids, almost all proteins have a maximum absorbance at about 280nm. The light source in the detector of the analytical system for detecting and measuring protein concentration has always been a mercury line lamp. Mercury produces light with a wavelength of 254nm, but does not produce light with a wavelength of 280nm, so a fluorescence converter is required to convert the 254nm light produced by the mercury lamp to a longer wavelength, and a bandpass filter is used to cut off the area near 280nm. Mercury lamps have a relatively short life and may prove unstable over time; in addition, the handling of these lamps may cause environmental problems. Other lamps for generating ultraviolet light (such as deuterium and xenon flash lamps) disadvantageously require high voltages, require complex electronic devices, and are often proven to be unstable over time. All of the ultraviolet light sources currently used are relatively large and are therefore not suitable for miniaturization of analytical instruments. In addition, due to the high voltage required for its operation, all lamps in the lamp generate a lot of heat.

[0014] AlGaN / GaN type light emitting diodes (LEDs) have been developed with emission in the range of 250nm to 365nm. Sensor Electronic Technology, Inc. (Columbia, SC, USA) pioneered the development and use of these UV LEDs, particularly for irradiating and disinfecting fluids, such as biologically contaminated water. Other groups have also used UV LEDs in water purification systems, such as Phillips Electronics.

[0015] LEDs emitting in the visible region of the spectrum have been used for indirect photometric detection (Johns C. et al. (2004) Electrophoresis, 25, 3145 - 3152) and fluorescence detection of substances in capillary electrophoresis (Tsai C. et al. (2003) Electrophoresis, 24, 3083 - 3088). King et al. (Analyst (2002) 127, 1564 - 1567) also reported the use of a UV light emitting diode emitting at 379.5 nm for indirect photometric detection of inorganic anions.)

[0016] The use of deep UV light emitting diodes as a light source in a detection system for nucleic acids is disclosed in US2005 / 0133724. A narrow bandwidth (preferably a ratio of 1 to 10) compared to the natural bandwidth of the sample provides good linearity of response and a wide dynamic range (Practical Absorbance Spectrometry, Ed. A. Knowles and C. Burgess, Chapman and Hall, New York).

[0017] WO 2017 / 144719 shows an apparatus for measuring the absorbance of a substance in a solution, the apparatus comprising at least one sample cell arranged to contain the solution that is at least partially transparent to light in a predetermined wavelength spectrum, at least two light channels through the at least one sample cell, each of the light channels having a known path length, an LED light source arrangement comprising at least two LEDs, each LED arranged to emit a light output having a wavelength within the predetermined wavelength spectrum, wherein a plurality of optical fibers (one for each light channel) are arranged at each LED for receiving the light output and guiding it to the light channels.)

[0018] US 9322772 discloses an apparatus for measuring the absorbance of a substance in a solution, the apparatus comprising: a sample cell (b) of known path length for containing the solution, the cell being transparent to light in a predetermined wavelength spectrum; ii) a plurality of LEDs, each of which can be individually operated by means of a controller, each LED for emitting light within the predetermined wavelength spectrum along an optical path; iii) a band - pass filter in the optical path; iv) a beam splitter for splitting the light propagating along the path from the light source into a first part and a second part, the first part being directable by the beam splitter to a reference detector and the second part being directable to the cell; v) a reference detector for detecting the intensity of the first part of the light guided by the beam splitter; and vi) a sample detector for detecting the intensity of the second part propagating from the cell; the apparatus allows the sample in the cell to be inexpensively subjected to light of more than one wavelength for faster or more accurate analysis.)

[0019] Although the above-described devices provide many beneficial features, they have proven to be relatively inefficient with respect to the amount of light entering the sample cell from the LED. SUMMARY OF THE INVENTION

[0020] Accordingly, it is an object of the present invention to provide a solution to the above problems and to provide a solution for more efficient use of the emitted light.

[0021] According to one aspect of the present invention, this object is achieved by a device for measuring the absorbance of a substance. The device includes a sample cell, at least two light sources, a reference photodetector, a sample cell photodetector, and at least two bundles of optical fibers. The sample cell is configured to allow a solution containing the substance to be examined for its absorbance to flow through. Each of the at least two light sources is configured to emit light in a corresponding wavelength band. The reference photodetector is configured to register a first signal representing the respective reference light intensity of the light emitted by the at least two light sources. The sample cell photodetector is configured to register a second signal representing the intensity of the light beam that has passed through the sample cell. Here, the light beam is generated based on the light emitted by at least one of the at least two light sources, however, only one light source generates the light beam at a time. Each of the at least two bundles of optical fibers is configured to receive the light emitted by the respective one of the at least two light sources via a starting end and to output the light via a terminating end. The terminating ends of the at least two bundles of optical fibers are arranged in a common bundle of optical fibers forming an output interface, which is configured to feed the light into the light beam that passes through the sample cell and to the reference photodetector.

[0022] The above device is advantageous because the bundles of optical fibers enable more light to be fed from each light source into the sample cell in a very efficient manner. That is, it is relatively straightforward to arrange multiple optical fibers at the light source such that the amount of light received from that light source increases by a factor equal to the number of optical fibers used. In addition, compared to a single-fiber design, it is easier to position the optical fiber connectors with high precision at the center of the optical path and thereby obtain high efficiency of light transmission. Moreover, a bundle of optical fibers having a combined effective cross-sectional area is more flexible than a single optical fiber having the same effective cross-sectional area, i.e., it can be bent more sharply. Therefore, the overall design of the device can be made relatively compact.

[0023] According to an embodiment of this aspect of the present invention, the output ends of the at least two bundles of optical fibers are fused together in the output interface. This makes the emitted light energy more concentrated, which improves the detection ability of the light beam fed through the sample cell.

[0024] According to another embodiment of this aspect of the invention, each of the at least two fiber bundles comprises at least three, preferably five to seven optical fibers. That is to say, these numbers of cooperating optical fibers have proven to achieve a good balance between energy efficiency, quality and cost.

[0025] According to yet another embodiment of this aspect of the invention, a termination optical filter is arranged at the output interface. The termination optical filter is configured to allow only light in a first specified wavelength band to pass through, the first specified wavelength band including the corresponding wavelength bands of the light emitted from at least two light sources. Thus, it is ensured that only light with the desired characteristics is fed through the sample cell, which in turn guarantees high-quality measurement results.

[0026] Alternatively or in addition thereto, according to an embodiment of this aspect of the invention, a corresponding starting optical filter is arranged at the starting end of each of the at least two fiber bundles. Here, each corresponding starting optical filter is configured to allow only light in a corresponding second specified wavelength band to pass through, the corresponding second specified wavelength band being unique to the corresponding one of the at least two light sources from which the starting end receives the emitted light.

[0027] According to further embodiments of this aspect of the invention, the device comprises a beam splitter or an optical waveguide configured to divert a portion of the output light from the output interface to a reference photodetector. Thus, the reference photodetector can register any intensity variations in the light emitted from the light source in an effective manner.

[0028] According to yet another embodiment of this aspect of the invention, the sample cell comprises a collimating lens configured to receive light from the output interface of the common fiber bundle and generate a light beam that is fed through the sample cell. Thereby, the light rays in the light beam are aligned to travel through the sample cell parallel to each other. This improves the efficiency and accuracy of the measurement.

[0029] According to further embodiments of this aspect of the invention, the device includes a controller configured to obtain a first signal registered by the reference photodetector while each of the at least two light sources emits light, and in response thereto, calibrate the sample cell photodetector with respect to any variations in the intensity of the light emitted from the at least two light sources. Thus, consistent measurements can be ensured.

[0030] Preferably, the controller is further configured to calibrate the sample cell photodetector with respect to the dark current registered by the sample cell photodetector when none of the at least two light sources emits light. Thus, for example, the dynamic range of the measurement can be increased and / or the non-linearity at high absorbances can be reduced.

[0031] According to another embodiment of this aspect of the invention, each optical fiber in the at least two optical fiber bundles is of multimode type. This allows a relatively large amount of light energy emitted from the light source to be transferred to the sample cell. Preferably, each optical fiber in the at least two optical fiber bundles also has a non-circular core, for example, having a hexagonal or octagonal cross-sectional shape. That is, this enables the light-transmitting portions of the optical fibers to be closer to each other at the starting end and the terminating end. This in turn makes the transmission of light effective and further concentrates the light energy fed into the sample cell.

[0032] According to another aspect of the invention, this object is achieved by a computer-implemented method for operating the above-described device, the method being executed in at least one processor, and the method comprising: controlling the light to be emitted from at least two light sources, each of the light sources emitting light in a respective wavelength band; obtaining a first signal via a reference photodetector, the first signal representing the respective reference light intensity of the light emitted by the at least two light sources; and obtaining a second signal via a sample cell photodetector, the second signal representing the intensity of the light beam that has passed through the sample cell, and the light beam being generated based on the light emitted by at least one of the at least two light sources. Specifically, the method involves controlling the at least two light sources such that light is emitted from the at least two light sources according to a repeating sequence, where light is emitted from only one of the at least two light sources at a time, and the repeating sequence has a repetition frequency higher than 5 Hz. Thereby, light of two or more different wavelength bands can pass through the sample cell substantially simultaneously. This in turn allows absorption measurements of very high quality and precision.

[0033] Additional advantages, beneficial features and applications of the invention will be apparent from the following description and the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will now be explained in more detail by means of preferred embodiments disclosed as examples and with reference to the accompanying drawings.

[0035] Figures 1-3 A schematic diagram of a device according to an embodiment of the invention is shown;

[0036] Figures 4-9 It shows how an optical fiber bundle can be arranged at the starting end according to an embodiment of the invention;

[0037] FIGS. 10 - 11 show graphs illustrating how the light sources can be controlled according to an embodiment of the invention;

[0038] Figure 12 A cable and connector arrangement for connecting two light sources to a sample cell according to an embodiment of the invention is depicted;

[0039] Figure 13 A perspective view of the light generation module of the proposed device according to an embodiment of the invention is shown;

[0040] Figures 14-16 Illustrates how a fiber optic bundle can be arranged in a connector according to an embodiment of the present invention; and

[0041] Figure 17 Illustrates a method for operating the proposed device according to an embodiment of the present invention by means of a flow chart. Detailed Description

[0042] Figure 1 Shows a schematic diagram of a device 100 according to a first embodiment of the present invention, the device being arranged for measuring the absorbance of a substance. The device 100 includes: a sample cell 140, a corresponding first light source D1 and second light source D2, a reference photodetector 151, a sample cell photodetector 152, and two corresponding fiber optic bundles BF1 and BF2.

[0043] The sample cell 140 is configured to allow a flow F of a solution S to pass through, the solution S containing the substance whose absorbance is to be measured.

[0044] Each of the light sources D1 and D2, which can be implemented by an LED, is configured to emit light in a corresponding wavelength band. The reference photodetector 151 is configured to register a first signal s representing the reference light intensity of the light emitted by the light sources D1 and D2 R . Figure 10a Shows a graph illustrating how the light intensities I D1 and I D2 emitted by the light sources D1 and D2 respectively can vary as a function of time t.

[0045] Figure 10b Shows a graph illustrating how the wavelength λ of the light registered by the reference photodetector 151 varies between a first wavelength λ1 (e.g., 260 nm) and a second wavelength λ2 (e.g., 280 nm) depending on whether the first light source D1 or the second light source D2 emits light.

[0046] The sample cell photodetector 152 is configured to register a second signal s representing the intensity of a light beam LB of a known length that has passed through the sample cell 140 D . The light beam LB is generated based on the light emitted by the light sources D1 and D2.

[0047] Specifically, the respective bundles of optical fibers BF1 and BF2 are arranged to transfer light from each of the light sources D1 and D2 to the light beam LB and the reference photodetector 151. Here, the first bundle of optical fibers BF1 is configured to receive the light emitted by the first light source D1 via the starting end BFi of the first bundle of optical fibers BF1 and output the light via the terminating end of the first bundle of optical fibers BF1. The second bundle of optical fibers BF2 is configured to receive the light emitted by the second light source D2 via the starting end BFi of the second bundle of optical fibers BF2 and output the light via the terminating end of the second bundle of optical fibers BF2. In addition, the terminating ends of the first optical fiber bundle BF1 and the second optical fiber bundle BF2 are arranged in a common optical fiber bundle BFC forming an output interface BFo, and the output interface BFo is configured to feed the light into the light beam LB through the sample cell 140.

[0048] According to an embodiment of the present invention, the sample cell 140 includes a collimating lens 141, and the collimating lens 141 is configured to receive the light from the output interface BFo and generate the light beam LB that is fed through the sample cell 140. The collimating lens 141 aligns the light rays in the light beam and makes them travel through the sample cell parallel to each other. This improves the efficiency and accuracy of the measurement.

[0049] According to Figure 1 the embodiment of the present invention illustrated in

[0050] To obtain a small mutual distance between the optical transmission cores of the optical fibers in the optical fiber bundles BF1 and BF2, their output ends can be fused together in the output interface BFo. A specific example of how the optical fiber bundles BF1 and BF2 can be organized in the output interface BFo will be described below with reference to Figure 16

[0051] According to an embodiment of the present invention, a terminating optical filter 120 is arranged at the output interface BFo. The terminating optical filter 120 is configured to allow only the light in a first specified wavelength band to pass through. The first specified wavelength band includes the respective wavelength bands λ1 and λ2 of the light emitted from the light sources D1 and D2. However, it preferably includes only the minimum values of other wavelength bands. Therefore, the characteristics of the light passing through the sample cell 140 via the light beam LB can be well controlled. This in turn ensures high-quality measurement.

[0052] Figure 2 A schematic diagram of the device 100 according to a second embodiment of the present invention is shown. In Figure 2 which, all the reference numerals that also appear in Figure 1 designate the same entities and signals as those described above with reference to Figure 1

[0053] ​​Figure 2 The device 100 in the embodiment includes an optical waveguide 132, which is configured to divert a part of the output light from the output interface BFo to the reference photodetector 151. Preferably, the optical waveguide 132 is represented by at least one optical fiber connecting the output interface BFo and the reference photodetector 151.

[0054] In Figure 2 the embodiment, the device 100 includes corresponding starting optical filters 121 and 122, which are respectively arranged at the starting ends BFi of each of at least two optical fiber bundles BF1 and BF2. The starting optical filters 121 and 122 are configured to allow only the light in the corresponding second specified wavelength bands λ1 and λ2 to pass through. Here, the corresponding second specified wavelength bands are unique to the corresponding one of at least two light sources D1 and D2, and the starting ends BFi receive the emitted light from the light sources. Therefore, the characteristics of the light passing through the sample cell 140 via the light beam LB can be well controlled. If the second specified wavelength bands λ1 and λ2 are separated by a relatively large amount from each other, the starting filter design is particularly advantageous. That is, in such a case, the terminating optical filter 120 will need to have a relatively wide bandwidth and thus also allow a considerable amount of unwanted wavelength bands between λ1 and λ2 to pass through.

[0055] Of course, according to an embodiment of the present invention, the terminating optical filter 120 can be combined with one or more starting optical filters, for example as Figure 3 illustrated. In Figure 3 it also appears in Figure 1 and / or Figure 2 All the reference numerals in Figure 1 and / or Figure 2 designate the same entities and signals as those described above with reference to

[0056] Figure 3 shows a schematic diagram of a device 100 according to an embodiment of the present invention, in which the terminating optical filter 120 is arranged at the output interface BFo. In addition, corresponding starting optical filters 121, 122,..., 12n are arranged at the starting ends BFi of each of the corresponding optical fiber bundles BF1, BF2,..., BFn configured to transmit the light from a set of light sources D1, D2,..., Dn to the output interface BFo.

[0057] Similar to the above, each starting optical filter 121, 122,..., 12n is configured to allow only the light in the corresponding second specified wavelength bands λ1, λ2,..., λ n n to pass through. The corresponding second specified wavelength bands are unique to the corresponding light sources D1, D2,..., Dn from which the starting ends BFi receive the emitted light. Therefore, the characteristics of the light passing through the sample cell 140 via the light beam LB can be very well controlled.

[0058] Figure 4 Shows a first example of how a fiber optic bundle according to an embodiment of the present invention can be arranged in the starting end BFi. Here, the end surfaces of the corresponding seven optical fibers 401, 402, 403, 404, 405, 406, and 407 are arranged close together such that the central optical fiber 407 is surrounded by the remaining six optical fibers 401, 402, 403, 404, 405, and 406. Thus, the light receiving portions of the optical fibers substantially form a conjoined light receiving surface that is approximately seven times the size of the light receiving portion of each individual optical fiber.

[0059] Figure 5 Shows a second example of how a fiber optic bundle according to an embodiment of the present invention can be arranged in the starting end BFi. Here, the end surfaces of the corresponding three optical fibers 501, 502, and 503 are arranged close together such that the light receiving portions of the optical fibers substantially form a conjoined light receiving surface that is approximately three times the size of the light receiving portion of each individual optical fiber.

[0060] Figure 6 Shows a third example of how a fiber optic bundle according to an embodiment of the present invention can be arranged in the starting end BFi. Similarly, the end surfaces of the corresponding three optical fibers 601, 602, and 603 are arranged close together such that the light receiving portions of the optical fibers substantially form a conjoined light receiving surface that is approximately three times the size of the light receiving portion of each individual optical fiber. However, in contrast to Figure 4 and Figure 5 each optical fiber in the fiber optic bundle has a non-circular core. More precisely, in Figure 6 the cross-section of the non-circular core has a hexagonal shape. This is beneficial because it allows the light receiving portions of the optical fibers to be arranged at even smaller distances from each other. Thus, the conjoined light receiving surface can receive light from the light source in a more efficient manner.

[0061] Figure 7 Shows a fourth example of how a fiber optic bundle according to an embodiment of the present invention can be arranged in the starting end BFi. Here, the end surfaces of the corresponding five optical fibers 701, 702, 703, 704, and 705 having a hexagonal core cross-section are arranged close together such that the light receiving portions of the optical fibers substantially form a conjoined light receiving surface that is approximately five times the size of the light receiving portion of each individual optical fiber.

[0062] Figure 8 and Figure 9Shows fifth and sixth examples of how a fiber optic bundle according to an embodiment of the present invention can be arranged in the starting end BFi. In both cases, the end surfaces of the respective seven optical fibers 801, 802, 803, 804, 805, 806, and 807 and the respective 901, 902, 903, 904, 905, 906, and 907 are arranged close together such that the central optical fibers 807 and 907 are respectively surrounded by the remaining six optical fibers, and the light receiving portions of all the optical fibers substantially form a combined light receiving surface equivalent to seven times the size of the light receiving portion of each individual optical fiber.

[0063] In Figure 8 each optical fiber has a hexagonal core shape, while in Figure 9 each optical fiber has an octagonal core shape. Similar to the above, in both cases, the light receiving portions of the optical fibers can be positioned closer to each other than when the core has a circular shape.

[0064] Generally, in order to allow a relatively large amount of light from the light source to be transmitted into the sample cell 140, the optical fibers in the fiber optic bundle are preferably of the multimode type, i.e., where the core diameter is relatively large and where multiple light modes can propagate.

[0065] As described above, Figure 10a and Figure 10b show the light intensities I Figure 1 and Figure 2 emitted from two light sources (e.g., D1 and D2 respectively) D1 and I D2 vary as a function of time t.

[0066] Figure 11a Shows a graph illustrating how the light intensities I Figure 3 emitted from n light sources (e.g., D1, D2,..., Dn) D1 、I D2 、…、I Dn vary as a function of time t.

[0067] Figure 11b Shows a graph illustrating how the wavelength λ of the light registered by the reference photodetector 151 depends on whether the first light source D1, the second light source D2,..., the nth light source emits light and varies between the first wavelength λ1, the second wavelength λ2, and up to the nth wavelength λ n Therefore, as long as the repetition frequency at which the light sources are sequentially activated according to it is high enough, the output interface BFo can appear to emit light of all wavelengths λ1, λ2,..., λ n substantially simultaneously. Preferably, the repetition frequency is higher than 5 Hz.

[0068] According to an embodiment of the present invention, to ensure consistent measurements, the device includes a controller 110 configured to obtain a first signal s registered by a reference photodetector 151 while each of the light sources D1 and D2 or D1 to Dn emits light. R In response thereto, the controller 110 is configured to calibrate the sample cell photodetector 152 relative to the intensity I of the light emitted from the light sources D1 and D2 or D1 to Dn, respectively. D1 or I D2 or I D1 to I Dn for any change in.

[0069] Additionally, particularly to increase the dynamic range of the measurement and / or reduce non-linearity at high absorbance, according to an embodiment of the present invention, the controller 110 is configured to calibrate the sample cell photodetector 152 relative to the dark current registered by the sample cell photodetector 152 when none of the light sources D1, D2, …, Dn emits any light.

[0070] Preferably, the controller 110 includes a processing circuit module in the form of at least one processor 113 and a memory unit 115 storing a computer program 117, i.e., a non-volatile data carrier, and the memory unit 115 further contains software for causing the at least one processor 113 to perform the actions mentioned in the present disclosure when the computer program 117 runs on the at least one processor 113.

[0071] Figure 12 Depicted is a first cable 1201 having a first connector 1211 and a second cable 1202 having a second connector 1212 according to an embodiment of the present invention. The first cable 1201 and the second cable 1202 are joined to form a common cable 1203 having a connector 1213 for connecting two light sources D1 and D2 to a sample cell 140. According to the above reference Figure 1 , Figure 2 and Figures 4 to 9 described, each of the first cable 1201 and the second cable 1202 includes a corresponding fiber optic bundle BF1 and BF2, and each of the fiber optic bundles is configured to receive light emitted by a corresponding one of at least two light sources D1 and D2 via a starting end BFi and output light via a terminating end.

[0072] Figure 14 Illustrated is a first connector 1211 having a first contact pin 1221, and the first contact pin 1221 includes a first light input interface 1401 that houses the starting end BFi of the first fiber optic bundle BF1, and the starting end BFi is configured to receive light emitted from the first light source D1.

[0073] Figure 15 Illustrated is a second connector 1212 having a second contact pin 1222, the second contact pin 1222 including a second optical input interface 1502 that houses a starting end BFi of a second optical fiber bundle BF2, the starting end BFi being configured to receive light emitted from a second light source D2.

[0074] Figure 16 Illustrated is a third connector 1213 having a third contact pin 1223, the third contact pin 1223 including an optical output interface 1603 that houses an output interface BFo having terminating ends of a first optical fiber bundle BF1 and a second optical fiber bundle BF2. Preferably, in the output interface BFo, the terminating ends of the first optical fiber bundle BF1 and the second optical fiber bundle BF2 are end - to - end and mixed relative to each other in different rows, e.g., as Figure 16 illustrated.

[0075] Figure 13 A perspective view of an optical generation module of a proposed device 100 according to an embodiment of the present invention is shown. Here, a first compartment 1310 respectively containing a first light source D1 and a second light source D2 is arranged on a PCB (printed circuit board) 1300. The PCB 1300 is in turn assembled into a holder 1330 connected to a second compartment 1320 that houses a reference photodetector 151 (not shown). The second compartment 1330 is also configured to be attached to a sample cell 140 via a connector member 1340, and a light beam LB can pass through the sample cell 140 via the connector member 1340 to reach a sample photodetector 152, as described above. Cables 1201, 1202, and 1203 and connectors 1211, 1212, and 1213 interconnect the first compartment 1310 and the second compartment 1320 such that light emitted by the first light source D1 and the second light source D2 can be fed to the sample cell 140 and the reference photodetector 151.

[0076] Figure 13 Also shown are a first set of connector pins 1301 configured to be connected to a drive circuit module for driving the first light source D1 and a second set of connector pins 1302 configured to be connected to a drive circuit module for driving the second light source D2.

[0077] For a summary, and referring to the flowchart in Figure 17 a computer - implemented method for operating the device 100 will now be described, the method being executed by a controller 110 according to an embodiment of the present invention.

[0078] In a first step 1710, control the first light source D1 to emit light in a first wavelength band λ1. In a step 1720 parallel to step 1710, obtain first and second signals. The first signal sR represents the reference light intensity I of the light emitted by the first light source D1 D1 . The second signal s D represents the intensity of the light beam LB of a known length that has passed through the sample cell 140, and the light beam LB has been generated based on the light emitted by the first light source D1.

[0079] In step 1730 after step 1710, the first light source D1 is deactivated, that is, controlled to stop emitting light.

[0080] Thereafter, in step 1740, the second light source D2 is controlled to emit light in the second wavelength band λ2. In step 1750 parallel to step 1740, the first and second signals are obtained again. Here, the first signal s R represents the reference light intensity I of the light emitted by the second light source D2 D2 , and the second signal s D represents the intensity of the light beam LB of a known length that has passed through the sample cell 140, and the light beam LB has been generated based on the light emitted by the second light source D2.

[0081] In step 1760 after step 1740, the second light source D2 is deactivated, that is, controlled to stop emitting light.

[0082] Thereafter, the procedure loops back to steps 1710 and 1720. The procedure is repeated at a repetition frequency higher than 5 Hz.

[0083] Reference Figure 17All process steps described and any subsequence of steps can be controlled by means of a programmable processor. Additionally, although the embodiments of the invention described above with reference to the accompanying drawings include a processor and a process executed in at least one processor, the invention thus also extends to a computer program suitable for putting the invention into practice, in particular a computer program on or in a carrier. The program can take the form of source code, object code, code intermediate between source code and object code, such as in a partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention. The program can be part of an operating system or a separate application. The carrier can be any entity or device capable of carrying the program. For example, the carrier can include a storage medium, such as a flash memory, ROM (read-only memory), for example a DVD (digital video / videodisc), CD (compact disc) or semiconductor ROM, EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory) or a magnetic recording medium, such as a floppy disk or a hard disk. Additionally, the carrier can be a transmissible carrier, such as an electrical or optical signal that can be transmitted via a cable or an optical fiber or by radio or by other means. When the program is embodied in a signal that can be directly transmitted by a cable or other device or component, the carrier can consist of such a cable or device or component. Alternatively, the carrier can be an integrated circuit in which the program is embedded, the integrated circuit being suitable for executing the relevant process or for use in the execution of the relevant process.

[0084] As used in this specification, the term "comprises / comprising" is used to specify the presence of the stated feature, integer, step or component. The term does not exclude the presence or addition of one or more additional elements, features, integers, steps or components or groups thereof. The indefinite article "a" or "an" does not exclude a plurality. In the claims, the word "or" should not be interpreted as exclusive or (sometimes referred to as "XOR"). Instead, unless otherwise stated, an expression such as "A or B" covers all cases of "A but not B", "B but not A", and "A and B". The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously. Any reference signs in the claims should not be construed as limiting the scope.

[0085] Also note that features from the various embodiments described herein can be freely combined, unless it is explicitly stated that such a combination would be inappropriate.

[0086] The invention is not limited to the embodiments described in the drawings, but can vary freely within the scope of the claims.

Claims

1. An apparatus (100) for measuring the absorbance of a substance, the apparatus (100) comprising: A sample cell (140), the sample cell (140) being configured to allow a flow (F) of a solution (S) containing the substance to pass through, At least two light sources (D1, D2, Dn), the at least two light sources being configured to emit light in respective wavelength bands (λ1, λ2, λ n ) Referring to the reference photodetector (151), the reference photodetector (151) is configured to register a first signal (s D1 , I D2 , I Dn ) representing the respective reference light intensities (I R ) of the light emitted by the at least two light sources (D1, D2, Dn), and Sample cell photodetector (152), the sample cell photodetector (152) being configured to register a second signal (s D ) representing the intensity of a light beam (LB) that has passed through the sample cell (140), the light beam being generated based on light emitted by at least one of the at least two light sources (D1, D2, Dn). Characterized in that the apparatus (100) comprises: At least two optical fiber bundles (BF1, BF2, BFn), each optical fiber bundle being configured to: Receive light emitted by a respective one of the at least two light sources (D1, D2, Dn) via a starting end (BFi), and Output light via a terminating end, Wherein the terminating ends of the at least two optical fiber bundles are arranged in a common optical fiber bundle (BFC) forming an output interface (BFo), the output interface (BFo) being configured to feed light into the light beam (LB) that passes through the sample cell (140) and is fed to the reference photodetector (151).

2. The device (100) according to claim 1, wherein, The output ends of the at least two optical fiber bundles are fused together in the output interface (BFo).

3. The device (100) according to any one of claims 1 or 2, wherein Each of the at least two optical fiber bundles (BF1, BF2, BFn) comprises at least three optical fibers (401, 402, 403, 404, 405, 406, 407; 501, 502, 503; 601, 602, 603; 701, 702, 703, 704, 705; 801, 802, 803, 804, 805, 806, 807; 901, 902, 903, 904, 905, 906, 907).

4. The apparatus (100) according to any one of the preceding claims, comprising a terminating optical filter (120) arranged at the output interface (BFo), the terminating optical filter (120) being configured to allow only light in a first specified band to pass through, the first specified band including the respective bands (λ1, λ2, λ n ) of the light emitted from the at least two light sources (D1, D2, Dn).

5. The device (100) according to any one of the preceding claims, comprising respective starting optical filters (121, 122, 12n) arranged at the starting end (BFi) of each of said at least two optical fiber bundles (BF1, BF2, BFn), said respective starting optical filters (121, 122, 12n) being configured to only allow light in a respective second specified wavelength band (λ1; λ2; λ n ) to pass through, said respective second specified wavelength band being unique to a respective one of said at least two light sources (D1, D2, Dn), said starting end (BFi) receiving the emitted light from said respective one light source.

6. The apparatus (100) according to any one of the preceding claims, comprising a beam splitter (131), the beam splitter being configured to divert a portion of the output light from the output interface (BFo) to the reference photodetector (151).

7. The apparatus (100) according to any one of claims 1 to 5, comprising an optical waveguide (132), the optical waveguide (132) being configured to divert a portion of the output light from the output interface (BFo) to the reference photodetector (151).

8. The device (100) according to any one of the preceding claims, wherein, The sample cell (140) comprises a collimating lens (141), the collimating lens being configured to receive light from the output interface (BFo) and generate the light beam (LB) that is fed through the sample cell (140).

9. The apparatus (100) according to any one of the preceding claims, comprising a controller (110), the controller being configured to: When each of the at least two light sources (D1, D2, Dn) emits light, the first signal (s R ) registered by the reference photodetector (151) is obtained, and in response thereto: Calibrate the sample cell photodetector (152) relative to any change in the intensity (I D1 , I D2 , I Dn ) of the light emitted from the at least two light sources (D1, D2, Dn).

10. The device (100) according to claim 9, wherein, The controller (110) is further configured to calibrate the sample cell photodetector (152) relative to the dark current registered by the sample cell photodetector (152) when none of the at least two light sources (D1, D2, Dn) emits light.

11. The device (100) according to any one of the preceding claims, wherein, Each optical fiber in the at least two optical fiber bundles (BF1, BF2, BFn) is of multimode type.

12. The apparatus (100) according to any one of the preceding claims, wherein, Each optical fiber in the at least two optical fiber bundles (BF1, BF2, BFn) has a non-circular core.

13. The device (100) according to claim 12, wherein, The cross-section of the non-circular core has a hexagonal shape or an octagonal shape.

14. A computer-implemented method for operating a device (100) according to any one of the preceding claims, the method being executed in at least one processor (113), and the method comprising: Control the light to be emitted from the at least two light sources (D1, D2, Dn), each of the at least two light sources emitting light in a respective wavelength band (λ1, λ2, λ n ) A first signal (s R ) is obtained via a reference photodetector (151), and the first signal (s R ) represents the corresponding reference light intensities (I D1 , I D2 , I Dn ) of the light emitted by the at least two light sources (D1, D2, Dn), and A second signal (s D ) is obtained via the sample cell photodetector (152), the second signal (s D ) representing the intensity of the light beam (LB) that has passed through the sample cell (140), and the light beam (LB) being generated based on light emitted by at least one of the at least two light sources (D1, D2, Dn), characterized in that controlling the at least two light sources (D1, D2, Dn) such that light is emitted from the at least two light sources (D1, D2, Dn) according to a repeating sequence, wherein the light is emitted from only one of the at least two light sources (D1, D2, Dn) at a time, and the repeating sequence has a repetition frequency higher than 5 Hz.

15. The method according to claim 14, further comprising: While each of the at least two light sources (D1, D2, Dn) emits light, relative to the first signal (s R ) reflecting the intensity (I D1 , I D2 , I Dn ) of the light emitted from the at least two light sources (D1, D2, Dn), the sample cell photodetector (152) is calibrated for any change.

16. The method according to any one of claims 14 to 15, further comprising: When none of the at least two light sources (D1, D2, Dn) emits light, calibrate the sample cell photodetector (152) relative to the dark current reflected by the second signal (s D ).

17. A computer program (117) loadable into a non-volatile data carrier (115) communicatively connected to a processing unit (113), the computer program (117) comprising software which, when the computer program (117) is run on the processing unit (113), is operative to perform the method according to any one of claims 14 to 16.

18. A non-volatile data carrier (115) containing the computer program (117) according to claim 17.

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