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

Abstract

The device 100 for measuring the absorbance of a substance comprises a sample cell 140 through which a flow (F) of a solution (S) containing the substance can pass, at least two light sources (D1, D2) emitting light in respective wavelength bands, and a first signal (s) representing the reference light intensity of each of the light emitted by the at least two light sources (D1, D2). R ) and a reference photodetector 151 that records a second signal (s D and a sample cell photodetector 152 that records a light beam (D1, D2) generated based on light emitted by at least one of the at least two light sources (D1, D2). Each optical fiber bundle (BF1, BF2) receives light from each of the at least two light sources (D1, D2, Dn) through a leading end (BFi) and outputs light through a trailing end. The ends of these optical fiber bundles are arranged in a common optical fiber bundle (BFC) to form an output interface (BFo) that provides light to the light beam (LB) passing through the sample cell 140 and the reference photodetector 151.

Description

[Technical Field]

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

[0002] Many substances absorb ultraviolet or visible light depending on their chemical composition. The absorption of light by substances has long been used as the basis for detecting the presence of such substances and measuring their concentration. The concentration of a substance can be determined by utilizing the Beer-Lambert law: A=Ebc where: A is the absorbance, E is the molar extinction coefficient, with units of L mol -1 cm -1 and b is the sample path length in cm; c is the concentration of the compound in solution, mol -1 It is expressed as:

[0003] E max represents the maximum absorbance of a substance at a given wavelength.

[0004] The UV (ultraviolet) region can be considered to consist of light with wavelengths in the range of 1 nm to 400 nm, with light with wavelengths of 180 nm to 300 nm being known as deep UV.

[0005] Most analytical instruments for detecting substances that absorb in the deep UV region use mercury lamps, deuterium lamps, or xenon flash lamps as light sources. One example of such an instrument is a flow cell, in which a solution containing one or more UV-absorbing substances is passed between a UV light source (e.g., a mercury lamp) and a UV detector (e.g., a photomultiplier tube or photodiode), and changes in the intensity of the UV light reaching the detector are related to the concentration of the UV-absorbing substance in the solution.

[0006] The detection of proteins, nucleic acids, and peptides is of great importance in many fields, including environmental science, biology, and chemistry. Proteins have two main absorption peaks in the deep UV region: a very strong absorption band with a maximum at approximately 190 nm due to absorption by peptide bonds, and a slightly weaker peak at approximately 280 nm due to light absorption by aromatic amino acids (e.g., tyrosine, tryptophan, and phenylalanine).

[0007] Nucleic acids absorb UV light at about 260 nm, although some of the subunits of nucleic acids (purines) have absorption maxima slightly below 260 nm and other subunits (pyrimidines) have absorption maxima slightly above 260 nm.

[0008] Nearly all proteins contain light-absorbing aromatic amino acids, resulting in an absorption maximum at approximately 280 nm. Historically, the light source in the detectors of analytical systems used to detect and measure protein concentration has been a mercury lamp. Because mercury produces light with a wavelength of 254 nm but not 280 nm, a fluorescence converter is required to convert the 254 nm light produced by the mercury lamp to longer wavelength light, and a bandpass filter is used to filter out the approximately 280 nm region. Mercury lamps have a relatively short lifespan and can become unstable over time; furthermore, disposal of these lamps can pose environmental issues. Other lamps used to generate ultraviolet light, such as deuterium or xenon flash lamps, are disadvantageous because they require high voltage, require complex electronics, and often become unstable over time. All currently used ultraviolet light sources are relatively large, resulting in a lack of suitability for miniaturization of analytical instruments. Furthermore, all of these lamps generate a large amount of heat due to the high voltage required for their operation.

[0009] AlGaN / GaN type light emitting diodes (LEDs) have been developed that emit in the 250 nm to 365 nm range. Sensor Electronic Technology, Inc. (Columbia, SC, USA) has pioneered the development and use of these UV LEDs, particularly for the irradiation and sterilization of fluids, such as biologically contaminated water. Additionally, other groups (e.g., Philips Electronics) have used UV LEDs for water purification systems.

[0010] LEDs emitting in the visible region of the spectrum have been used for indirect photometric detection (Non-Patent Document 1) and for fluorescent detection of substances in capillary electrophoresis (Non-Patent Document 2). Furthermore, Non-Patent Document 3 reports on the use of UV light-emitting diodes emitting at 379.5 nm for the indirect photometric detection of inorganic anions.

[0011] Patent Document 1 discloses the use of deep ultraviolet light-emitting diodes as a light source in a nucleic acid detection system. A narrow bandwidth compared to the native bandwidth of the sample, preferably a ratio of 1:10, results in good linearity of response and a wide dynamic range (Non-Patent Document 4).

[0012] Patent Document 2 shows an apparatus for measuring the absorbance of a substance in a solution. The apparatus comprises at least one sample cell arranged to contain the solution, the sample cell being at least partially transparent to light of a predetermined wavelength spectrum, at least two optical paths passing through the at least one sample cell, each optical path having a known optical path length, and an LED light source device comprising at least two LEDs, each LED arranged to emit an optical output at a wavelength within the predetermined wavelength spectrum. Each LED is provided with a plurality of optical fibers, one for each optical path, arranged to receive and guide the optical output to its corresponding optical path.

[0013] Patent Document 3 discloses an apparatus for measuring the absorbance of a substance in a solution. The apparatus includes: i) a sample cell of known optical path length (b) for containing the solution, the sample cell being transparent to light of a predetermined wavelength spectrum; ii) a plurality of LEDs, each individually operable by a controller to emit light within the predetermined wavelength spectrum along an optical path; iii) a bandpass filter in the optical path; iv) a beam splitter for splitting light from the light source propagating along the optical path into a first portion and a second portion, the first portion being capable of being transmitted by the beam splitter to a reference detector and the second portion being capable of being transmitted into a cell; v) a reference detector for detecting the intensity of the first portion of light transmitted by the beam splitter; and vi) a sample detector for detecting the intensity of the second portion propagating from the cell. This apparatus allows for the low-cost exposure of a sample in a cell to light of two or more wavelengths for faster or more accurate analysis.

[0014] Although the above-described device has many beneficial properties, it has been found to be relatively inefficient with respect to the amount of light from the LED that enters the sample cell. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] US Patent Application Publication No. 2005 / 0133724 [Patent Document 2] International Publication No. 2017 / 144719 [Patent Document 3] U.S. Patent No. 9,322,772 [Non-patent literature]

[0016] [Non-Patent Document 1] Johns C. et al. (2004), Electrophoresis, 25, 3145-3152 [Non-patent document 2] Tsai C. et al. (2003), Electrophoresis, 24, 3083-3088 [Non-patent document 3] King et al., "Analyst", (2002), 127, pp. 1564-1567 [Non-patent document 4] "Practical Absorbance Spectrometry," Eds. A. Knowles and C. Burgess, Chapman and Hall, New York Summary of the Invention [Problem to be solved by the invention]

[0017] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a solution to address the above problems and to enable a more efficient use of emitted light. [Means for solving the problem]

[0018] According to one aspect of the present invention, this object is achieved by an apparatus for measuring the absorbance of a substance. The apparatus includes a sample cell, at least two light sources, a reference light detector, a sample cell light detector, and at least two optical fiber bundles. The sample cell is configured to pass a flow of solution containing a substance to be tested for absorbance. Each of the at least two light sources is configured to emit light in a respective wavelength range. The reference light detector is configured to record a first signal representative of a reference light intensity of each of the light emitted by the at least two light sources. The sample cell light detector is configured to record a second signal representative of the intensity of a light beam passed through the sample cell. The light beam is generated based on light emitted from at least one of the at least two light sources, but the light is emitted from only one light source at a time. Each of the at least two optical fiber bundles is configured to receive light emitted by a respective one of the at least two light sources via a leading end and to output light via a trailing end. The termini of the at least two fiber optic bundles are disposed within a common fiber optic bundle to form an output interface configured to provide light to a light beam passing through the sample cell and a reference light detector.

[0019] The above-described apparatus is advantageous because these optical fiber bundles allow for more light to be delivered from each light source into the sample cell very efficiently. That is, it is relatively simple to arrange multiple optical fibers at the light source so that the amount of light received from the light source increases by a factor equal to the number of optical fibers used. Furthermore, compared to single-fiber designs, it is easier to accurately center the optical fiber connector in the optical path, resulting in higher light transmission efficiency. Furthermore, optical fiber bundles with combined effective areas are more flexible, i.e., can bend at sharper angles, than single optical fibers with the same effective area. This allows for a relatively compact overall design of the apparatus.

[0020] According to one embodiment of this aspect of the invention, the output ends of the at least two optical fiber bundles are fused together at the output interface, which results in a more focused emitted light energy and improves the detectability of the light beam delivered through the sample cell.

[0021] According to another embodiment of this aspect of the invention, each of the at least two optical fiber bundles comprises at least three, and preferably five to seven, optical fibers, as these numbers of optical fibers working together have been found to provide a good balance between energy efficiency, quality, and cost.

[0022] According to yet another embodiment of this aspect of the invention, a terminal optical filter is disposed at the output interface, the terminal optical filter configured to pass only light of a first specific wavelength band, the first specific wavelength band including each of the wavelength bands of light emitted from the at least two light sources, thereby ensuring that only light having desired characteristics is provided through the sample cell, thereby ensuring high-quality measurement results.

[0023] Alternatively or additionally, according to one embodiment of this aspect of the invention, a respective start-side optical filter is disposed at a respective start end of the at least two optical fiber bundles, wherein each start-side optical filter is configured to pass only light of a respective second particular wavelength band, the respective second particular wavelength band being specific to a respective one of the at least two sources of light received by the start end.

[0024] According to a further embodiment of this aspect of the invention, the apparatus comprises a beam splitter or optical waveguide configured to split a portion of the output light from the output interface to a reference light detector so that the reference light detector can efficiently record any intensity variations of the light emitted by the light source.

[0025] According to yet another embodiment of this aspect of the invention, the sample cell includes a collimating lens configured to receive light from the output interface of the common fiber optic bundle and generate a light beam that is delivered through the sample cell such that light rays in the light beam are aligned to travel parallel to one another as they pass through the sample cell, thereby improving measurement efficiency and accuracy.

[0026] According to a further embodiment of this aspect of the invention, the apparatus comprises a controller configured to acquire a first signal recorded by the reference photodetector while each of the at least two light sources emits light, and in response thereto, calibrate the sample cell photodetector for any changes in the intensity of the light emitted from the at least two light sources, thereby ensuring consistency of measurements.

[0027] Preferably, the controller is further configured to calibrate the sample cell photodetector with respect to a dark current recorded by the sample cell photodetector when none of the at least two light sources is emitting light, thus, for example, increasing the dynamic range of the measurement and / or reducing nonlinearities at high absorbances.

[0028] According to another embodiment of this aspect of the invention, each optical fiber in the at least two optical fiber bundles is of a multimode type, which allows a relatively large amount of light energy emitted by the light source to be transmitted to the sample cell. Preferably, each optical fiber in the at least two optical fiber bundles further has a non-circular core, e.g., having a hexagonal or octagonal cross-sectional shape, which allows the light-transmitting portions of the fibers to be closer to each other at their beginning and end. This further provides efficiency in light transmission, resulting in a more focused light energy being delivered into the sample cell.

[0029] According to another aspect of the present invention, the object is achieved by a computer-implemented method for operating the above-described apparatus. The method is implemented on at least one processor and includes the following steps: controlling light emitted from at least two light sources, each light source emitting light in a respective wavelength band; acquiring a first signal via a reference light detector, the first signal representing a reference light intensity of each of the light emitted by the at least two light sources; and acquiring a second signal via a sample cell light detector, the second signal representing the intensity of a light beam passed through the sample cell, the light beam being generated based on light emitted by at least one of the at least two light sources. Specifically, the method includes controlling the at least two light sources to emit light from the at least two light sources according to a repeating sequence, the light being emitted from only one of the at least two light sources at a time, the repeating sequence having a repetition frequency greater than 5 Hz. This allows light of two or more different wavelength bands to pass through the sample cell substantially simultaneously. Furthermore, this allows for very high quality and precision absorbance measurements.

[0030] Further advantages, beneficial features and applications of the present invention will become apparent from the following description and the dependent claims.

[0031] The invention will now be explained in more detail by way of preferred embodiments disclosed as examples and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic diagram of an apparatus according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of an apparatus according to an embodiment of the present invention; [Figure 3] 1 is a schematic diagram of an apparatus according to an embodiment of the present invention; [Figure 4] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 5] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 6] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 7] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 8] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 9] 1A-1C illustrate how an optical fiber bundle may be positioned at a starting end in accordance with an embodiment of the present invention. [Figure 10a] 4 is a graph illustrating how a light source may be controlled according to an embodiment of the present invention. [Figure 10b] 4 is a graph illustrating how a light source may be controlled according to an embodiment of the present invention. [Figure 11a] 4 is a graph illustrating how a light source may be controlled according to an embodiment of the present invention. [Figure 11b] 4 is a graph illustrating how a light source may be controlled according to an embodiment of the present invention. [Figure 12] FIG. 10 shows a cable-connector arrangement for connecting two light sources to a sample cell according to one embodiment of the present invention. [Figure 13] FIG. 1 is a perspective view of a light-generating module of the proposed device according to one embodiment of the present invention. [Figure 14] 1A-1C are exemplary diagrams illustrating how an optical fiber bundle may be positioned within a connector according to one embodiment of the present invention. [Figure 15] 1A-1C are exemplary diagrams illustrating how an optical fiber bundle may be positioned within a connector according to one embodiment of the present invention. [Figure 16] 1A-1C are exemplary diagrams illustrating how an optical fiber bundle may be positioned within a connector according to one embodiment of the present invention. [Figure 17] FIG. 2 is a flow diagram illustrating a method according to an embodiment of the present invention for operating the proposed device. DETAILED DESCRIPTION OF THE INVENTION

[0033] 1 shows a schematic diagram of an apparatus 100 according to a first embodiment of the present invention, arranged to measure the absorbance of a substance. The apparatus 100 comprises a sample cell 140, a first light source D1 and a second light source D2, a reference photodetector 151, a sample cell photodetector 152, and two optical fiber bundles BF1 and BF2.

[0034] The sample cell 140 is configured to allow a flow F of solution S containing a substance whose absorbance is to be measured to be passed therethrough.

[0035] Each of the light sources D1 and D2, which may be implemented by an LED, is configured to emit light in a respective wavelength band. The reference light detector 151 generates a first signal s R FIG. 10a shows the light intensity I of the light emitted by each of the light sources D1 and D2. D1 and I D2 1 is a graph showing how V changes as a function of time t.

[0036] Figure 10b is a graph showing how the wavelength λ of light recorded 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 the light.

[0037] The sample cell photodetector 152 generates a second signal s that represents the intensity of the light beam LB that has passed through the sample cell 140 over a known length. D The light beam LB is generated based on the light emitted by the light sources D1 and D2.

[0038] Specifically, optical fiber bundles BF1 and BF2 are arranged to transmit light from light sources D1 and D2, respectively, to light beam LB and reference photodetector 151. In this case, first optical fiber bundle BF1 is configured to receive light emitted by first light source D1 via a starting end BFi of first optical fiber bundle BF1 and output light via a terminal end of first optical fiber bundle BF1. Second optical fiber bundle BF2 is configured to receive light emitted by second light source D2 via a starting end BFi of second optical fiber bundle BF2 and output light via a terminal end of second optical fiber bundle BF2. Furthermore, the terminal ends of first optical fiber bundle BF1 and second optical fiber bundle BF2 are arranged within a common optical fiber bundle BFC to form an output interface BFo configured to provide light for light beam LB passing through sample cell 140.

[0039] According to this embodiment of the invention, the sample cell 140 includes a collimating lens 141 configured to receive light from the output interface BFo and generate a light beam LB that is fed through the sample cell 140. The collimating lens 141 aligns the light rays in the light beam so that they travel parallel to one another as they pass through the sample cell, thereby improving the efficiency and accuracy of the measurement.

[0040] According to the embodiment of the present invention shown in FIG. 1, the device 100 comprises a beam splitter 131 configured to split a portion of the output light from the output interface BFo to a reference photodetector 151.

[0041] In order to reduce the distance between the light-carrying cores of the optical fibers in the optical fiber bundles BF1 and BF2, the output ends of these optical fiber bundles may be fused together at the output interface BFo. A specific example of how the optical fiber bundles BF1 and BF2 may be configured at the output interface BFo will now be described with reference to Figure 16.

[0042] According to one embodiment of the present invention, a terminal optical filter 120 is disposed at the output interface BFo. This terminal optical filter 120 is configured to pass only light in a first specific wavelength band. This first specific wavelength band includes the wavelength bands λ1 and λ2 of the light emitted from the light sources D1 and D2, respectively, but preferably includes only a minimum of other wavelength bands. Therefore, the characteristics of the light passing through the sample cell 140 via the light beam LB can be maintained in a well-controlled state. This further ensures high-quality measurements.

[0043] Figure 2 shows a schematic diagram of an apparatus 100 according to a second embodiment of the present invention, in which any reference numerals also used in Figure 1 denote the same entities and signals as those described above with reference to Figure 1.

[0044] 2 comprises an optical waveguide 132 configured to split a portion of the output light from the output interface BFo to the reference photodetector 151. Preferably, this optical waveguide 132 is represented by at least one optical fiber connecting the output interface BFo with the reference photodetector 151.

[0045] In the embodiment of FIG. 2, the apparatus 100 includes start-side optical filters 121 and 122 disposed at the start ends BFi of the at least two optical fiber bundles BF1 and BF2, respectively. The start-side optical filters 121 and 122 are configured to pass only light in the respective second specific wavelength bands λ1 and λ2, where each second specific wavelength band is specific to a respective one of the at least two light sources D1 and D2 of the emitted light received by the start ends BFi. Therefore, the characteristics of the light passing through the sample cell 140 via the light beam LB can be maintained in a well-controlled state. This start-side filter design is particularly advantageous when the second specific wavelength bands λ1 and λ2 are relatively far apart. In such a case, the end-side optical filter 120 needs to have a relatively wide bandwidth and therefore may pass a large amount of unwanted wavelength bands between λ1 and λ2.

[0046] Of course, according to embodiments of the present invention, the terminal optical filter 120 may be combined with one or more start-up optical filters, for example as shown in Figure 3. In Figure 3, any reference numerals that are also used in Figures 1 and / or 2 indicate the same entities and signals as those described above with reference to Figures 1 and / or 2.

[0047] 3 shows a schematic diagram of an apparatus 100 according to an embodiment of the present invention, in which a terminal optical filter 120 is arranged at an output interface BFo, and a respective terminal optical filter 121, 122, ..., 12n is arranged at each start BFi of a respective optical fiber bundle BF1, BF2, ..., BFn configured to transmit light from a set of light sources D1, D2, ..., Dn to the output interface BFo.

[0048] Similarly to the above, each of the start-side optical filters 121, 122, ..., 12n is a second specific wavelength band λ1, λ2, ..., λ n, Dn of emitted light received by the starting end BFi. Thus, the characteristics of the light passing through the sample cell 140 via the light beam LB can be maintained in a well-controlled state.

[0049] 4 shows a first example of a possible optical fiber bundle arrangement at the starting end BFi according to an embodiment of the present invention, where the end surfaces of seven optical fibers 401, 402, 403, 404, 405, 406, and 407, respectively, are arranged closely together such that the central optical fiber 407 is surrounded by the remaining six optical fibers 401, 402, 403, 404, 405, and 406. As a result, the light-receiving portions of these optical fibers essentially form a joint light-receiving surface that is seven times the size of the light-receiving portion of each individual optical fiber.

[0050] 5 shows a second example of a possible optical fiber bundle arrangement at the starting end BFi according to an embodiment of the present invention, where the end surfaces of three optical fibers 501, 502, and 503 are respectively placed closely together so that the light-receiving portions of these optical fibers form a joint light-receiving surface that is three times the size of the light-receiving portion of each individual optical fiber.

[0051] FIG. 6 illustrates a third example of a possible optical fiber bundle arrangement at the starting end BFi according to an embodiment of the present invention. Here, too, the end surfaces of three optical fibers 601, 602, and 603 are closely spaced from one another, so that the light-receiving portions of these optical fibers essentially form a joint light-receiving surface that is three times the size of the light-receiving portions of each individual optical fiber. However, in contrast to FIGS. 4 and 5, each optical fiber in the optical fiber bundle has a noncircular core. More precisely, in FIG. 6, the cross section of the noncircular core has a hexagonal shape. This is advantageous because it allows the light-receiving portions of the optical fibers to be arranged with a smaller distance between them. This joint light-receiving surface can therefore more efficiently receive light from the light source.

[0052] 7 shows a fourth example of a possible optical fiber bundle arrangement at the starting end BFi according to an embodiment of the present invention, where the end surfaces of five respective optical fibers 701, 702, 703, 704, and 705 having hexagonal core cross sections are placed closely together so that the light-receiving portions of these optical fibers substantially form a joint light-receiving surface that is five times the size of the light-receiving portion of each individual optical fiber.

[0053] 8 and 9 show fifth and sixth examples of possible optical fiber bundle arrangements at the starting end BFi according to an embodiment of the present invention. In each case, the end surfaces of seven optical fibers 801, 802, 803, 804, 805, 806, and 807, respectively, and the end surfaces of seven optical fibers 901, 902, 903, 904, 905, 906, and 907, respectively, are placed closely together so that the central optical fibers 807 and 907 are surrounded by the respective remaining six optical fibers, and the light-receiving portions of all these optical fibers essentially form a joint light-receiving surface corresponding to seven times the size of the light-receiving portion of each individual optical fiber.

[0054] In Figure 8, the core of each optical fiber has a hexagonal shape, while in Figure 9, the core of each optical fiber has an octagonal shape. As above, in either case, the light-receiving portions of the optical fibers can be positioned closer to each other than if the cores had a circular shape.

[0055] Generally, 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 optical fiber bundle are preferably of the multimode type, i.e., have a substantial core diameter that allows multiple optical modes to propagate.

[0056] As mentioned above, FIGS. 10a and 10b show the light intensity I of light emitted from two light sources, e.g., D1 and D2 in FIGS. 1 and 2, respectively. D1 and I D2Show how can vary as a function of time t.

[0057] FIG. 11a shows the light intensity I of light emitted from n light sources, for example, D1, D2, ..., Dn in FIG. D1 , I D2 , . . . , IDn may vary as a function of time t.

[0058] FIG. 11b shows that the wavelength λ of light recorded by the reference photodetector 151 varies depending on whether the first light source D1, the second light source D2, ..., the n-th light source emits light. n , λ 1 , λ 2 , . . . , λ 3 . Therefore, as long as the repetition rate at which these light sources are sequentially operated is high enough, the output interface BFo will be able to provide a n Preferably, the repetition rate is greater than 5 Hz.

[0059] According to one embodiment of the present invention, to ensure consistency of the measurements, the device measures the first signal s recorded by the reference photodetector 151 while the light sources D1 and D2 or each of the light sources D1 to Dn is emitting light. R In response, the controller 110 determines the intensity I of each of the light emitted from the light sources D1 and D2 or the light sources D1 to Dn. D1 Or I D2 or Intensity I D1 ~I Dn The sample cell photodetector 152 is configured to calibrate for any changes in the sample cell temperature.

[0060] Furthermore, according to one embodiment of the present invention, in order to increase the dynamic range of the measurement and / or reduce nonlinearity at high absorbance, the controller 110 is configured to calibrate the sample cell photodetector 152 with respect to the dark current recorded by the sample cell photodetector 152 when none of the light sources D1, D2, ..., Dn is emitting light.

[0061] Preferably, the controller 110 comprises processing circuitry in the form of at least one processor 113 and a memory unit 115, i.e., a non-volatile data carrier, that stores a computer program 117. Furthermore, the computer program 117 comprises software that, when executed on the at least one processor 113, causes the at least one processor 113 to perform the operations referred to in the present disclosure.

[0062] 12 shows a first cable 1201 having a first connector 1211 and a second cable 1202 having a second connector 1212. According to one embodiment of the present invention, the first cable 1201 and the second cable 1202 are joined to form a common cable 1203, which has a connector 1213 for connecting two light sources D1 and D2 to the sample cell 140. As described above with reference to FIGS. 1, 2, and 4-9, the first cable 1201 and the second cable 1202 each include a corresponding optical fiber bundle BF1 and BF2, each configured to receive light emitted by a respective one of the at least two light sources D1 and D2 through a leading end BFi and output light through a trailing end BFi.

[0063] 14 shows a first connector 1211 having a first contact pin 1221 with a first optical input interface 1401. This first optical input interface 1401 receives a starting end BFi of a first optical fiber bundle BF1, which starting end BFi is configured to receive light emitted from a first light source D1.

[0064] 15 shows a second connector 1212 having a second contact pin 1222 with a second optical input interface 1502. The second optical input interface 1502 receives a leading end BFi of a second optical fiber bundle BF2, which leading end BFi is configured to receive light emitted from a second light source D2.

[0065] 16 shows a third connector 1213 having a third contact pin 1223 with an optical output interface 1603. The optical output interface 1603 accommodates an output interface BFo having terminal ends of a first optical fiber bundle BF1 and a second optical fiber bundle BF2. Preferably, in the output interface BFo, the terminal ends of the first optical fiber bundle BF1 and the second optical fiber bundle BF2 are intermixed in different rows, for example as shown in FIG.

[0066] 13 shows a perspective view of the light-generating module of the proposed apparatus 100 according to one embodiment of the present invention. Here, a first compartment 1310 housing the first and second light sources D1 and D2, respectively, is arranged on a PCB (printed circuit board) 1300. Furthermore, the PCB 1300 is fitted with a holder 1330 connected to a second compartment 1320 housing a reference light detector 151 (not shown). The second compartment 1320 is further configured to be attached to the sample cell 140 by a connector member 1340, through which the light beam LB passes through the sample cell 140 and reaches the sample cell light detector 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, thereby allowing light emitted from the first light source D1 and the second light source D2 to be supplied to the sample cell 140 and the reference light detector 151.

[0067] Furthermore, FIG. 13 shows a first connector tweezers 1301 configured to be connected to a drive circuit for driving the first light source D1, and a second connector tweezers 1302 configured to be connected to a drive circuit for driving the second light source D2.

[0068] For purposes of overview, and with reference to the flow diagram of FIG. 17, a computer-implemented method for operating device 100, as performed by controller 110 according to one embodiment of the present invention, will now be described.

[0069] In a first step 1710, a first light source D1 is controlled to emit light in a first wavelength band λ1. In a step 1720 parallel to step 1710, a first signal and a second signal are acquired. The first signal s R is 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 a light beam LB that has passed through a known length of the sample cell 140, the light beam LB being generated based on light emitted by the first light source D1.

[0070] Step 1710 is followed by step 1730, in which the first light source D1 is deactivated, ie controlled to stop emitting light.

[0071] Then, in step 1740, the second light source D2 is controlled to emit light in the second wavelength band λ2. In step 1750, which is parallel to step 1740, the first signal and the second signal are again acquired. Here, the first signal s R is the reference light intensity I of the light emitted from the second light source D2 D2 and the second signal s D represents the intensity of a light beam LB that has passed through a known length of the sample cell 140, the light beam LB being generated based on light emitted by a second light source D2.

[0072] Step 1740 is followed by step 1760, in which the second light source D2 is deactivated, ie controlled to stop emitting light.

[0073] The procedure then loops back to steps 1710 and 1720. The procedure is repeated at a repetition rate above 5 Hz.

[0074] All process steps and any subsequence of steps described with reference to FIG. 17 may be controlled by a programmed processor. Furthermore, while the embodiments of the invention described above with reference to the figures include processors and processes executed on at least one processor, the invention also extends to computer programs adapted for carrying out the invention, particularly computer programs on or in a carrier. The program may be in the form of source code, object code, a code intermediate between source code and object code, e.g., partially compiled, or any other form suitable for use in implementing the process according to the invention. The program may either be part of an operating system or a separate application. The carrier may be any entity or device capable of carrying a program. For example, the carrier may comprise a storage medium such as a flash memory, a ROM (read-only memory), e.g., a DVD (digital video / versatile disc), a CD (compact disc), or a semiconductor ROM, an EPROM (erasable programmable read-only memory), an EEPROM (electrically erasable programmable read-only memory), or a magnetic recording medium, e.g., a floppy disk or hard disk. Further, the carrier may be a transmissible carrier such as an electrical or optical signal, which may be transmitted via electrical or optical cable or by radio or by other means. When the program is embodied in a signal which may be transmitted directly by a cable or other device or means, the carrier may be constituted by such a cable or device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.

[0075] When used in this specification, the term "comprises / comprising" is interpreted as explicitly indicating the presence of the listed features, integers, steps, or components. This term does not exclude the presence or addition of one or more additional elements, features, integers, steps, or components, or groups thereof. The indefinite articles "a" and "an" do not exclude a plurality. In the claims, the word "or" should not be interpreted as an exclusive or (sometimes also called "XOR"). Conversely, an expression such as "A or B" includes within its scope "A and not B," "B and not A," and "A and B," unless otherwise indicated. If several measures are recited in mutually different dependent claims, this fact alone does not indicate that these measures cannot be used advantageously in combination. Any reference signs in the claims should not be interpreted as limiting the scope.

[0076] It should also be noted that features of the various embodiments described herein may be freely combined unless there is an explicit indication that such a combination is inappropriate.

[0077] The invention is not limited to the embodiments shown in the drawings, but may be varied freely within the scope of the claims. [Explanation of symbols]

[0078] 100 devices 110 Controller 115 Memory Unit 117 Computer Programs 120 End-side optical filter 121 Optical filter at the start 131 Beam Splitter 132 Optical waveguide 140 Sample Cell 141 Collimating Lens 151 Reference Photodetector 152 Sample cell photodetector 407 Optical Fiber 701 Optical Fiber 807 Optical Fiber 1201 First Cable 1202 Second Cable 1203 Common Cable 1211 First Connector 1212 Second Connector 1213 Third Connector 1221 First contact pin 1222 Second contact pin 1223 Third Contact Pin 1300 PCB, printed circuit board 1301 First Connector Pin Set 1302 Second Connector Pin Set 1310 First Compartment 1320 Second Compartment 1330 Holder 1340 Connector parts 1401 first optical input interface 1502 Second Optical Input Interface 1603 Optical Output Interface BF1 First optical fiber bundle BF2 Second optical fiber bundle D1 First light source D2 Second light source I D1 Reference light intensity I D2 Reference light intensity

Claims

1. An apparatus (100) for measuring the absorbance of a substance, comprising: a sample cell (140) configured to allow a flow (F) of a solution (S) containing the substance to pass therethrough; Each wavelength band (λ １ , λ ２ , λ ｎ at least two light sources (D1, D2, Dn) configured to emit light at a reference light intensity (I) of each of the light emitted by the at least two light sources (D1, D2, Dn); Ｄ１ , I Ｄ２ , I Ｄｎ ) and a first signal (s Ｒ a reference photodetector (151) configured to record the A second signal (s) representing the intensity of the light beam (LB) passing through the sample cell (140) Ｄ a sample cell photodetector (152) configured to record a light beam generated based on light emitted by at least one of the at least two light sources (D1, D2, Dn); In an apparatus (100), the apparatus (100) comprises: At least two optical fiber bundles (BF1, BF2, BFn), each optical fiber bundle (BF1, BF2, BFn) comprising: receiving light emitted by each of the at least two light sources (D1, D2, Dn) via a starting point (BFi); outputting light through the termination; At least two optical fiber bundles (BF1, BF2, BFn) configured to Equipped with The apparatus (100) is characterized in that the ends of the at least two optical fiber bundles are arranged in a common optical fiber bundle (BFC) to form an output interface (BFo) configured to supply light to a light beam (LB) passing through the sample cell (140) and to the reference photodetector (151).

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

3. 3. The apparatus (100) of claim 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 output interface (BFo) includes a terminal-side optical filter (120) arranged in the output interface (BFo), the terminal-side optical filter (120) being configured to pass only light of a first specific wavelength band, the first specific wavelength band being a wavelength band (λ 1 ) of each of the light emitted from the at least two light sources (D1, D2, Dn). １ , λ ２ , λ ｎ 4. The apparatus (100) of claim 1, comprising:

5. The at least two optical fiber bundles (BF1, BF2, BFn) each include a start-side optical filter (121, 122, 12n) disposed at the start end (BFi) of each of the optical fiber bundles (BF1, BF2, BFn), and the start-side optical filter (121, 122, 12n) is configured to filter a second specific wavelength band (λ １ ;λ ２ ;λ ｎ ) and each of the second specific wavelength bands (λ １ ;λ ２ ;λ ｎ 5. The device (100) according to claim 1, wherein each of the at least two light sources (D1, D2, Dn) of emitted light received by the starting end (BFi) is specific to a respective one of the at least two light sources (D1, D2, Dn).

6. 6. The apparatus (100) of claim 1, further comprising a beam splitter (131) configured to split a portion of the output light from the output interface (BFo) to the reference light detector (151).

7. 6. The apparatus (100) of claim 1, further comprising an optical waveguide (132) configured to split a portion of the output light from the output interface (BFo) to the reference light detector (151).

8. 8. The apparatus (100) of claim 1, wherein the sample cell (140) comprises a collimating lens (141) configured to receive light from the output interface (BFo) and generate the light beam (LB) that is supplied through the sample cell (140).

9. The first signal (s) recorded by the reference photodetector (151) while each of the at least two light sources (D1, D2, Dn) emits light. Ｒ ) and in response to this, The intensity (I) of the light emitted from the at least two light sources (D1, D2, Dn) Ｄ１ , I Ｄ２ , I Ｄｎ Calibrating the sample cell photodetector (152) for any changes in The apparatus (100) of any one of claims 1 to 8, comprising a controller (110) configured to:

10. 10. The apparatus of claim 9, wherein the controller is further configured to calibrate the sample cell photodetector with respect to a dark current recorded by the sample cell photodetector when none of the at least two light sources is emitting light.

11. 11. The device (100) according to any one of claims 1 to 10, wherein each optical fiber in said at least two optical fiber bundles (BF1, BF2, BFn) is of the multimode type.

12. 12. The apparatus (100) according to any one of claims 1 to 11, wherein each optical fiber in the at least two optical fiber bundles (BF1, BF2, BFn) has a non-circular core.

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

14. A computer-implemented method for operating the apparatus (100) of any one of claims 1 to 13, performed in at least one processor (113), comprising: Controlling the light emitted from the at least two light sources (D1, D2, Dn), wherein each light source emits a respective wavelength band (λ １ , λ ２ , λ ｎ ) emitting light; A first signal (s Ｒ ), wherein said first signal (s Ｒ ) is the reference light intensity (I) of each of the light emitted by the at least two light sources (D1, D2, Dn). Ｄ１ , I Ｄ２ , I Ｄｎ ), and A second signal (s Ｄ ), wherein said second signal (s Ｄ ) represents the intensity of a light beam (LB) passing through the sample cell (140), the light beam (LB) being generated based on light emitted by at least one of the at least two light sources (D1, D2, Dn); A computer-implemented method comprising:

1. A computer-implemented method of controlling 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 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 greater than 5 Hz.

15. The first signal (s) is generated while each of the at least two light sources (D1, D2, Dn) is emitting light. Ｒ The intensity (I) of the light emitted from the at least two light sources (D1, D2, Dn) reflected by the Ｄ１ , I Ｄ２ , I Ｄｎ 15. The computer-implemented method of claim 14, further comprising calibrating the sample cell photodetector (152) for any changes in

16. When none of the at least two light sources (D1, D2, Dn) emits light, the second signal (s Ｄ 16. The computer-implemented method of claim 14 or 15, further comprising calibrating the sample cell photodetector (152) for dark current reflected by the sample cell photodetector (152).

17. A computer program (117) loadable onto a non-volatile data carrier (115) communicatively connected to a processing device (113), the computer program (117) comprising software for performing the computer-implemented method of any one of claims 14 to 16 when executed on the processing device (113).

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

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