Compact high-resolution monochromatic light source for measuring concentration of fluid sample

Abstract

A compact light source for coupling to a movable optical probe may include a light emitting diode (LED) to generate a probe signal of a first bandwidth; an optical coupler disposed adjacent to the LED and arranged to couple a probe signal into the movable probe; and a narrowband-pass filter configured to receive the probe signal of the first bandwidth and output the probe signal in the movable probe at a second bandwidth smaller than the first bandwidth.

Description

[0001] BACKGROUND OF THE DISCLOSURE

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority under 35 U.S.C. §119 to U.S. Provisional Application Serial No. 63 / 343,361, filed on May 18, 2022, entitled “COMPACT HIGH RESOLUTION MONOCHROMATIC LIGHT SOURCE FOR FLUID SAMPLE CONCENTRATION MEASUREMENT,” the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] Embodiments of the present disclosure relate generally to spectral analysis, and more particularly, to solution analysis using a light source coupled to a variable path length measurement system. Background Art

[0005] Absorption spectroscopy is used to measure the composition and / or properties of materials in any phase, gas, liquid, solid. For example, the optical absorption spectrum of a liquid substance can be measured to determine the concentration or other properties of a species of interest in the liquid medium. The absorption spectrum can provide a distribution of light attenuation (due to absorbance) as a function of the wavelength of the light. In a known spectrophotometer, the sample material to be studied is placed in a transparent container so that electromagnetic radiation (light) of known wavelength λ (i.e., ultraviolet, infrared, visible, etc.) and intensity I can be measured using a suitable detector after passing through the transparent container.

[0006] Known ultraviolet (UV) / visible spectrophotometers utilize containers such as standard cuvettes, which containers may have a standard cm path length through which incident light is conducted within a liquid containing the substance to be measured. For a sample consisting of a single homogeneous substance with a concentration c, the light transmitted through the sample will follow a relationship known as Beer's law: A=εCL, where A is the absorbance (also known as the optical density (OD) of the sample at wavelength λ, where OD=logarithm of the ratio of transmitted light to incident light), ε is the absorbance or extinction coefficient (usually constant at a given wavelength), C is the concentration of the sample, and L is the path length of the light through the sample. Therefore, in principle, information about the concentration of a homogeneous substance can be determined based on the recorded light intensity of the signal passing through the sample container. However, in some cases, the determination of concentration in such an apparatus may be difficult. Often the compound of interest in the solution is highly concentrated. For example, when measuring absorbance, certain biological samples (such as proteins, DNA or RNA) are often separated at concentrations that fall outside the linear range of the spectrophotometer. Therefore, it is usually necessary to dilute the sample to measure an absorbance value that falls within the linear range of the instrument. It is usually necessary to dilute the sample multiple times, which can lead to dilution errors and removal of the diluted sample for any downstream application. Therefore, it is useful to take existing samples without knowing the possible concentration and measure the absorbance of these samples without dilution. A common result feature of these known ultraviolet (UV) / visible spectrophotometers is that the path length L is very accurately known, allowing accurate concentration measurements to be made.

[0007] To address these challenges, a measurement technique based on a variable path length spectrophotometer has recently been developed. This type of spectroscopy system can typically employ a known light source, such as a source based on a UV / visible spectrophotometer. The light from the UV / visible spectrophotometer is then directed to a special probe in an analytical instrument that is arranged to change the path length L in a special sample chamber in order to perform multiple absorbance measurements. Thus, in a series of measurements, the radiation generated from the UV / visible spectrophotometer source is detected after passing through the sample chamber while the probe is moved through a plurality of different positions to vary the path length L. Thus, a series of measurements is produced that generates a different A value for each different value of L in a manner that does not require knowledge of any particular path length L in order to determine the concentration C.

[0008] Although such variable path length spectroscopy may be suitable for online measurement of samples, the instrumentation required for such measurement scenarios, such as those performed by production systems, may require a large amount of installation effort and excess space. For example, a UV / visible spectrophotometer system used as a light source may occupy several cubic feet of space and may have a weight on the order of tens of kilograms. Therefore, the placement and operation of the spectral system relative to the production system or other experimental system that generates the fluid sample to be measured may be limited. Moreover, even if the UV / visible spectrophotometer system is remotely placed, in order to measure the change in absorbance over multiple path lengths, the collection of data for each measurement of a given path length L will also make the overall measurement time very long. With respect to these and other considerations, the present disclosure is provided. Summary of the invention

[0009] In one embodiment, a compact light source for coupling to a movable optical probe is provided. The compact light source may include: a light emitting diode (LED) for generating a probe signal of a first bandwidth; an optical coupler disposed adjacent to the LED and arranged to couple the probe signal into the movable probe; and a narrow bandpass filter disposed to receive the probe signal of the first bandwidth and output the probe signal in the movable probe with a second bandwidth less than the first bandwidth.

[0010] In another embodiment, a measuring device is provided, comprising: a compact light source comprising a light emitting diode (LED) for generating a probe signal; and a measuring instrument for receiving the probe signal. The measuring instrument may include a sample vessel for accommodating a fluid sample, the sample vessel comprising a vessel wall. The measuring device may also include a probe arranged to guide the probe signal through the sample vessel, wherein the probe is movable in a probe direction relative to the vessel wall so as to reduce the path length of the probe signal through the fluid sample; and a detector arranged to receive the probe signal after passing through the vessel wall.

[0011] In another embodiment, a system for measuring the concentration of a material in a fluid sample is provided. The system may include: a compact light source including a light emitting diode (LED) for generating a probe signal; and a measuring instrument for receiving the probe signal. The measuring instrument may include a sample vessel for accommodating the fluid sample, wherein the sample vessel chamber has a vessel wall. The measuring instrument may also include: a probe having a probe tip, the probe tip being arranged to guide the probe signal through the sample vessel, wherein the probe is movable in a probe direction relative to the vessel wall so as to reduce the path length of the probe signal through the fluid sample; and a detector, which is arranged to receive the probe signal after passing through the vessel wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings show preferred embodiments of the disclosed method as far as has been devised for practical application of its principles, and in which:

[0013] Figure 1A Describes general features of an absorption spectroscopy system according to an embodiment of the present disclosure;

[0014] Figure 1B A reference absorption spectroscopic setup is depicted;

[0015] Figure 2 depicts a side cross-sectional view of a compact light source according to an embodiment of the present disclosure;

[0016] Figure 3 A variation of the system of Figure 1 is depicted;

[0017] Figure 4 Another measurement system according to an embodiment of the present disclosure is depicted; and

[0018] Figure 5 Exemplary absorption spectra according to embodiments of the present disclosure are depicted. DETAILED DESCRIPTION

[0019] The present embodiments present novel methods of variable path length spectroscopy, including compact light source devices and associated measurement systems. In particular, these embodiments may be based on absorption spectroscopy, where changes in absorbance are used to determine the concentration of a material in a fluid sample.

[0020] According to an embodiment of the present disclosure, a compact light source is provided to be coupled to a variable-pathlength-measurement (VPT) device. The compact light source and the VPT device together provide a flexible absorption spectroscopy device that can be easily integrated into various production, research, and measurement systems, including chromatography protein systems, purification systems, filtration systems, and other fluid handling systems. In particular, according to a non-limiting embodiment, the compact light source device in this embodiment may include a size of approximately 4 inches by 1.5 inches by 1.5 inches. In a non-limiting embodiment, the overall system size including the compact light source and the VPT device may be approximately 12 inches by 12 inches by 6 inches.

[0021] Figure 1A An absorption spectroscopy apparatus according to an embodiment of the present disclosure is depicted, shown as system 100. System 100 may include a compact light source 102, and a measuring instrument 110 coupled to the compact light source 102, and a detector 112 disposed beside the measuring instrument 110.

[0022] The compact light source 102 may include a light emitting diode (LED) 104, an optical coupler 106 disposed adjacent to the LED 104, and a narrow bandpass filter 108 disposed adjacent to the optical coupler 106. According to embodiments of the present disclosure, the LED 104 may represent a single LED or an array of LEDs that emit radiation at a single wavelength. In other embodiments, a plurality of LEDs may be provided, wherein a given LED emits radiation at a wavelength that is different from the wavelength of another LED.

[0023] As in known LEDs, the LED 104 can emit radiation whose intensity as a function of wavelength is characterized by a single peak that can be associated with a given type of LED, such as a 272nm LED, a 310nm LED, and so on. According to various embodiments of the present disclosure, the LED 104 can emit unfiltered radiation 105 having a peak whose bandwidth or half-width is between 10nm and 50nm. According to embodiments of the present disclosure, when the unfiltered radiation 105 from the LED 104 passes through the narrow bandpass filter 108, the bandwidth of the filtered radiation 107 can be reduced to less than 1nm, essentially monochromatic radiation. Therefore, the compact light source 102 can be referred to as a monochromatic light source. In various embodiments of the present disclosure, the filtered radiation can have a peak wavelength in the ultraviolet (UV) to infrared (IR) wavelength range, and more specifically, between 250nm and 1000nm, and can have a bandwidth of less than 1nm after leaving the compact light source 102.

[0024] In operation, filtered radiation 107 may be conducted through measuring instrument 110, appearing as attenuated radiation 111, which is detected by detector 112. Figure 1A 1 , but according to some embodiments, the detector 112 may also form part of the measuring instrument 110. The operation of the measuring instrument 110 or variations thereof is described in detail as follows.

[0025] Briefly, however, the measuring instrument 110 employs a movable optical probe (not separately shown) to vary the path length L of filtered radiation 107 transmitted through a given fluid sample (not shown) present in the measuring instrument 110. The detector 112 is arranged to detect the intensity of the radiation transmitted through the given fluid sample, which is shown as attenuated radiation 111. According to the Beer Lamber law, the concentration C of the material in the sample can be determined as A / eL, where A is the absorbance and e is the molar absorptivity. In turn, A is determined as log 10(I0 / I), where I0 is the intensity of the filtered radiation 107 and I is the intensity of the attenuated radiation 111. Because the intensity of the attenuated radiation 111 will change as a function of the change in path length L, the change in I as a function of the change in path length L can be used to directly determine the change in absorbance A as a function of the change in path length L. For example, assuming that the change in I0 between the intensity measurement at a first path length L1 (I1) and the intensity measurement at a second path length L2 (I2) can be ignored, DA can be directly determined as log I1–log I2. In turn, according to Beer Lambert's law, DA / DL equals eC, where DL or its absolute value equals L1–L2. Therefore, the system 100 can be used to easily determine the concentration C of a material in a fluid sample by varying the path length of the filtered radiation 107 (to determine DL) and detecting the change in the intensity of the attenuated radiation 111 (to determine DA) as the radiation passes through the measuring instrument 110.

[0026] Note that in accordance with embodiments of the present disclosure, where the bandwidth of the filtered radiation 107 is less than 1 nm, the system 100 is able to determine the concentration of a sample in the measurement instrument 110 at a sufficiently narrow wavelength range to be considered as a single wavelength or monochromatic radiation.

[0027] By emphasizing Figure 1A The advantages of the system are as follows: Figure 1B A reference absorption spectroscopy device is depicted, shown as system 150. System 150 includes a known light source, where light source 152 may be referred to as a UV / visible spectrophotometer. Light source 152 may generate radiation over a range of wavelengths extending from the near ultraviolet to the visible wavelength range. The radiation may be directed through an optical fiber or similar structure to reach a measuring device 158. In some embodiments, measuring device 158 may be operable to vary the path length L of radiation from light source 152 that is transmitted through a fluid sample in measuring device 158. For each path length L, an absorption spectrum may be collected over a range of wavelengths, such as between 200nm and 700nm, or any suitable wavelength. Likewise, concentration C may be determined by determining changes in absorbance. However, compared to the intensity detection of monochromatic radiation of system 100, the collection of intensity information at detector 112 for a given path length L may require a much longer duration over the spectral range of 200nm to 700nm. For example, in Figure 1B The collection of the absorption spectrum in the device can be performed by continuously scanning the grating to generate different wavelengths of light, which are transmitted through the fluid sample as a function of time. As an example, using Figure 1B The device shown may take about 20 seconds to make an absorbance measurement.

[0028] The present inventors have recognized that, for the purpose of measuring the concentration of a material of interest, in many instances it is desirable to measure the intensity variation of the absorbance of a fluid sample containing the material of interest using substantially monochromatic radiation only over a narrow spectral range. Figure 1A The system 100 can collect absorbance data almost instantaneously after triggering the LED, and the duration required to obtain each new absorbance measurement at the new path length L is limited to the time required to adjust the radiation's path length L. Moreover, by virtue of having a compact size, the system 100 can provide advantages in terms of flexibility in integration into processing systems, including chromatography systems, protein purification systems, filtration systems, and other fluid handling systems, as previously described.

[0029] Figure 2 A side cross-sectional view of a compact light source according to an embodiment of the present disclosure is depicted. The compact light source 102A can be a variation of the compact light source 102 described above. In this embodiment, the compact light source 102A includes a housing 202 that includes an LED 104, an optical coupler 106, and a narrow bandpass filter 108.

[0030] The compact light source 102A may also include a connector 204 to reversibly couple to a measuring instrument, such as the measuring instrument 110. In particular, the connector 204 functions as an adapter configured to reversibly couple the light source 102A to a movable optical probe, as discussed further below. According to some embodiments, the compact light source 102A may represent a light source and a group of similar light sources that are interchangeably connected to the measuring instrument 110. Each light source in a group of light sources may include an LED configured to emit radiation of a selected wavelength. Thus, according to non-limiting embodiments of the present disclosure, the compact light source 102A may represent a 272nm light source, a 280nm light source, a 310nm light source, and the like. In this way, the compact light source 102A may be easily interchangeable so as to customize the wavelength of the filtered radiation 107 according to a given application. Thus, for detecting the absorbance of a first material, a radiation source with a wavelength of 272nm would be appropriate, while for detecting the absorbance of a second material, a radiation source with a wavelength of 310nm would be appropriate. Of course, the characteristics of the narrow bandpass filter 108 may also be tailored in conjunction with the selection of the wavelength of the LED 104 .

[0031] Figure 3 A variation of the system of FIG. 1 is depicted. The system 100A includes a compact light source 102 and a measurement device 110A connected to the compact light source 102. In some embodiments, the compact light source 102 may be as Figure 2The configuration shown, wherein the housing 202 contains the LED, the optical coupler, the narrow bandpass filter and the connector. Thus, the compact light source 102 can be reversibly connected and disconnected from the measurement device 110A.

[0032] The measuring device 110A may include a movable optical probe, wherein the following reference is made to Figure 4 The operation of the movable optical probe is described in detail. The measuring device 110A can include a sample vessel 160, an inlet port 161 for allowing a fluid sample to enter, and an outlet port 163 for conducting the fluid sample out of the sample chamber vessel 160. Therefore, the measuring device 110A can be used to couple to a processing system (not shown separately) to provide a dynamic measurement of the concentration C of a material in a sample fluid as the sample fluid passes through the measuring instrument 110A.

[0033] Figure 4 A measurement system according to another embodiment of the present disclosure is depicted, shown as measurement system 250. Measurement system 250 is depicted as being coupled to an external processing system, which is represented as processing system 180. Thus, processing system 180 can represent any suitable system that generates a fluid sample to be measured, such as a chromatography system, a protein purification system, a filtration system, or other fluid processing system, as previously noted. The measurement system includes a measurement instrument 110B, and a compact light source 102A coupled to the measurement device, and a drive component 176. According to some embodiments, drive component 176 can be considered to be part of measurement instrument 110B.

[0034] exist Figure 4In the scenario of FIG. 1 , the processing system 180 is depicted as generating a fluid sample 182 that is conducted through the measuring instrument 110B so as to measure the concentration C of the material in the fluid sample 182. In operation, the compact light source 102A will emit radiation from an LED selected to emit radiation of a target wavelength that is suitable for measuring the material in the fluid sample 182. As a result of passing through a narrow bandpass filter in the compact light source 102A, the radiation can be provided as monochromatic radiation, as discussed above. The radiation is guided into and through the movable probe 172 along the probe axis 178. The movable probe 172 can be formed of a single optical fiber or a plurality of optical fibers suitable for transmitting radiation within an appropriate wavelength range generated by the compact light source 102A. These optical fibers can have different diameters depending on the use of the measuring instrument 110B. In various non-limiting embodiments, the optical fiber diameter is in the range of about 0.005 mm to about 20.0 mm. The movable probe 172 may be fused silica, glass, plastic, or any transmissive material suitable for the wavelength range of the compact light source 102A and the detector 112. After passing through the window 170, the radiation is detected using the detector 112, where suitable examples of the detector 112 include a photomultiplier tube, a photodiode, an avalanche photodiode, a charge-coupled device (CCD), an intensified CCD, and the like.

[0035] The movable probe 172 is particularly translatable along a probe axis 178 so as to move within the sample vessel 160. Figure 4 As shown, the movable probe can translate relative to the vessel wall 162 of the sample vessel 160, thereby changing the path length L of the radiation. In particular, the path length L represents the distance between the probe tip 172A and the lower portion of the vessel wall 162. Therefore, the value of L corresponds to the distance that the radiation can travel through the fluid sample 182 when the fluid sample is arranged in the sample vessel 160.

[0036] According to various embodiments of the present disclosure, a transparent window (shown as window 170) can be arranged relative to the probe tip 172A. Window 170 can, for example, form a portion of the lower portion of the vessel wall 162, and can be suitable for wavelengths within the range of the transmission measuring instrument 110B, such as from 200nm to 1100nm. For example, in embodiments where the wavelength of radiation is within the ultraviolet range, a quartz window may be required. In various non-limiting embodiments where the sample vessel 160 is coupled to an external fluid circuit of a processing system or device, the volume of the fluid sample in the sample vessel 160 can be in the range of microliters to many milliliters, and the path length L can be variable between 0cm and several cm.

[0037] To facilitate concentration measurements using the DA / DL equals eC method, the drive component 176 can be a motor that translates the probe tip 172A along the probe axis 178. The drive component 176 can provide continuous motion or can be set to change the path length L in precise steps. In various non-limiting embodiments, suitable examples of the drive component 176 include stepper motors, servo, piezoelectric, electric and magnetic motors or any device that can be controlled to provide a variable path length L through the sample. Although the drive component 176 can be coupled to translate the movable probe 172 relative to the sample vessel 160, in some embodiments, the drive component 176 can drive the stage on which the sample vessel 160 rests to move the probe tip 172A relative to the sample vessel 160. In some embodiments of incremental or step-like motion, the movable probe 172 moves relative to the sample vessel 160 in increments ranging from 0.2 μm to 1 cm, and more particularly in increments ranging from 1 μm to 50 μm.

[0038] Notice, Figure 4 An embodiment of the measuring instrument 110B is depicted in a "vertical orientation" in which the sample vessel 160 is disposed above the detector 112 and the probe tip 172A can move up and down, into and out of the sample vessel 160, so that radiation exiting from the probe tip 172A moves through the fluid sample 182 within the sample vessel 160 and impinges on the detector 112 disposed below. In further embodiments, other orientations are possible, such as in a flow cell system in which the detector and the probe tip are in a substantially horizontal orientation relative to each other and the probe axis lies horizontally. Regardless of the absolute spatial orientation or movable probe 172 and detector 112, according to various embodiments of the present disclosure, the probe axis will generally extend perpendicularly relative to the major plane of the detector 112.

[0039] Advantages provided by the foregoing embodiments include the ability to provide higher quality light to the sample being measured than systems based on known broadband spectrophotometers. The improved qualities include a more stable light source and a narrower half-width for a given radiance. The monochromatic light source of the present embodiment can achieve better spectral resolution than a broadband spectrometer while maintaining a much smaller form factor, making such light source devices particularly useful for applications that use only a few selected wavelengths per day.

[0040] Additionally, the reduced size and environmental design requirements (IP65+ / chemical compatibility) that are unique to this type of device allow such devices to be placed into GMP manufacturing environments where such placement would be impractical for traditional broadband spectrophotometers.

[0041] Figure 5 Depicts an exemplary absorption spectrum according to an embodiment of the present disclosure. In this example, Figure 5 The graph of FIG. 5 depicts detected radiation intensity as a function of wavelength in the near UV range. Three spectra are shown, a spectrum shown as curve 502, a spectrum shown as curve 504, and a spectrum shown as curve 506, each consisting of a single monochromatic peak showing the detected intensity of UV light emitted from a monochromatic source emitting at 272 nm.

[0042] According to various embodiments of the present disclosure, and consistent with the aforementioned embodiments, the peak may have a half width of less than 1 nm. The spectra represent data collected after emitting radiation from the UV LED source and passing through a narrow bandpass filter. Thus, spectrum 502 presents data collected at a first instance when the path length of the polymonochromatic radiation is directed through a probe disposed at a first position, the first position defining a path length L1 through the fluid sample. Similarly, curve 504 presents data collected at a second instance when the path length of the polymonochromatic radiation is directed through a probe disposed at a second position, the second position defining a path length L2 through the fluid sample, and curve 506 presents data collected at a third instance when the path length of the polymonochromatic radiation is directed through a probe disposed at a third position, the third position defining a path length L3 through the fluid sample. Given that, as noted above, the concentration C will be equal to DA / (DLe), the determination of the absorbance difference (DA) between curve 504 and spectrum 502 will directly result in C, since DL is given by L2-L1. Furthermore, determination of the absorbance difference (DA) between curve 506 and curve 504 will also lead directly to C since DL is given by L3 - L2.

[0043] Note that the intensity of the 272 nm peak substantially corresponds to the intensity I, as discussed above, and the rate at which the intensity of the 272 nm peak increases with changes in the value of L is proportional to the change in absorbance DA / DL or slope coefficient m. Thus, in one example, the value of DA / DL or m can be determined by measuring the difference in I (curve 504 - curve 502) and L between the first and second examples. Similarly, the value of m can be determined by measuring I (curve 506 - curve 504) between the second and third examples.

[0044] In summary, by providing a compact monochromatic light source in conjunction with a VPT device, the present embodiment demonstrates a novel and useful alternative to known broadband spectrometer-based systems, particularly for certain applications. While measurements performed using broadband light scanning can provide the user with all the information needed to analyze a sample, such measurements come at the expense of increased data acquisition time and data analysis time. By providing discrete wavelengths for analysis, the present embodiment allows the user to obtain only the information needed and no extraneous information. This focus on a single discrete wavelength reduces acquisition time, allowing the user to make real-time process decisions to ensure the quality of the product being measured.

[0045] Although the present arrangement has been disclosed with reference to certain embodiments, many modifications, changes and variations of the described embodiments are possible without departing from the spirit and scope as defined in the appended claims. Therefore, it is intended that the present arrangement is not limited to the described embodiments, but rather has the full scope defined by the language of the following claims and their equivalents.

Claims

1. A compact light source for coupling to a movable probe, comprising: a light emitting diode (LED) for generating a probe signal of a first bandwidth; an optical coupler disposed adjacent the LED and arranged to couple the probe signal into the movable probe; as well as A narrow band pass filter is configured to receive the probe signal of the first bandwidth and output the probe signal in the movable probe with a second bandwidth smaller than the first bandwidth.

2. The compact light source according to claim 1, wherein: The first bandwidth is at least 10 nm, and wherein the second bandwidth is less than 1 nm.

3. The compact light source of claim 1, further comprising a housing for housing the LED, the optical coupler, and the narrow bandpass filter.

4. The compact light source of claim 3, further comprising a connector for reversibly coupling to a movable optical probe.

5. The compact light source of claim 1, the LED, the optical coupler, and the narrow bandpass filter forming a monochromatic light source.

6. The compact light source of claim 5, wherein the probe signal comprises a monochromatic signal characterized by a wavelength in the ultraviolet (UV) to infrared (IR) wavelength range and having a bandwidth of less than 1 nm after leaving the compact light source.

7. A measuring device comprising: a compact light source including a light emitting diode (LED) for generating a probe signal; as well as A measuring instrument, used to receive the probe signal, the measuring instrument comprising: a sample vessel for containing a fluid sample, the sample vessel comprising a vessel wall; a probe arranged to direct the probe signal through the sample vessel, wherein the probe is movable in a probe direction relative to the vessel wall so as to reduce a path length of the probe signal through the fluid sample; and A detector is arranged to receive the probe signal after passing through the vessel wall.

8. The measuring device according to claim 7, wherein the compact light source further comprises: an optical coupler disposed adjacent to the LED; as well as A narrow bandpass filter is configured to receive the probe signal of a first bandwidth and output the probe signal of a second bandwidth smaller than the first bandwidth.

9. The measuring device according to claim 8, wherein: The second bandwidth is less than 1 nm.

10. The measuring device according to claim 8, wherein: The LED, the optical coupler and the narrow bandpass filter are disposed within a common housing.

11. The measuring device according to claim 10, wherein: The compact light source is reversibly attachable and detachable relative to the measuring instrument.

12. The measuring device according to claim 7, wherein: The analytical instrument is arranged to direct the sample fluid through the sample vessel.

13. The measurement device of claim 7, the probe signal comprising a monochromatic signal characterized by a wavelength in the ultraviolet (UV) to infrared (IR) wavelength range and having a bandwidth of less than 1 nm after leaving the compact light source.

14. A system for measuring the concentration of a material in a fluid sample, comprising: a compact light source including a light emitting diode (LED) for generating a probe signal; A measuring instrument, used to receive the probe signal, the measuring instrument comprising: a sample vessel for containing a fluid sample, the sample vessel comprising a vessel wall; a probe having a probe tip, the probe being arranged to direct the probe signal through the sample vessel, wherein the probe is movable in a probe direction relative to the vessel wall so as to reduce a path length of the probe signal through the fluid sample; and A detector is arranged to receive the probe signal after passing through the vessel wall.

15. The system of claim 14, wherein the compact light source further comprises: an optical coupler disposed adjacent to the LED; as well as A narrow bandpass filter is configured to receive the probe signal of a first bandwidth and output the probe signal of a second bandwidth smaller than the first bandwidth.

16. The system of claim 15, wherein the probe signal comprises a monochromatic signal characterized by a wavelength in the ultraviolet (UV) to infrared (IR) wavelength range and having a bandwidth of less than 1 nm after leaving the compact light source.

17. The system of claim 15, wherein: The LED, the optical coupler and the narrow bandpass filter are disposed within a common housing.

18. The system of claim 14, wherein: The compact light source is reversibly attachable and detachable relative to the measuring instrument.

19. The system of claim 14, wherein: The measuring instrument is arranged to direct the fluid sample through the sample vessel.

20. The system of claim 14, wherein the sample vessel further comprises: an inlet port for allowing entry of the fluid sample; an outlet port for conducting the fluid sample out of the sample chamber vessel; as well as A transparent window is disposed between the probe tip and the detector.

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