A multi-wavelength photometer for time-sequential light emitting diode (LED) light sources

Abstract

The application provides a kind of multi-wavelength photometer of time-sharing sequential light-emitting LED light source, linear array consisting of N (N >= 4) different wavelength LEDs constitutes the light source of the photometer, the light-emitting surface of LED is close to the side of light guide rod, the light-emitting end surface of light guide rod emits LED light, and the emitted light enters sample cell through the emitted light window and enters the detection window on the opposite side. A light detector is placed behind the detection window, and the light detector is connected to a preamplifier, an analog-to-digital conversion circuit, a sampling and filtering circuit, a background subtraction circuit, a timing control circuit, an LED light source array driving circuit, an LED light source array temperature measurement circuit, a light detector temperature measurement circuit, a response value data correction circuit and an interface circuit. The shell provides mechanical support and overall protection for the above-mentioned devices. The timing and pulse width of the control LED array light-emitting are such that each LED is turned off after the lighting time ΔT ends, then delayed for Δt, and then the next LED is turned on, and so on, and the entire measurement period H >= N x (ΔT + Δt).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photometric measurement in small analytical instruments, and more particularly, to a multi-wavelength photometer with time-sequential light-emitting diode (LED) light source. BACKGROUND

[0002] Photometers are widely used in chemical and material research laboratories, and also in biological, pharmaceutical, chemical, food, cosmetic, environmental monitoring, and other fields. In addition, they are also used in marine environmental investigation and monitoring, deep-sea scientific research, and in the detection of faults in seabed oil exploration, oil pipeline leaks, and optical fiber protective layer leaks.

[0003] Existing commercial spectrophotometers or ultraviolet-visible photometers use a continuous wavelength light source with an ultraviolet lamp (deuterium lamp / xenon lamp) + tungsten lamp, a grating spectrometer, and a slit light source. The wavelength of the light source can be adjusted by rotating the grating, and the absorbance value is obtained after passing through a sample cell and a detector. These devices are difficult to miniaturize, low-power, and field applications due to the large size, high power consumption, and vulnerability to vibration and impact of the traditional light source, and the need for grating spectrometry to obtain a wide spectral range scan.

[0004] The earliest report of photometric device using LED as light source is the paper "Light emitting diodes and phototransistors in photometric modules" published in Anal, Lett., 1973, 6, 585 by H Flaschka, CMcKeithan, R Barnes in 1973. After that, many researchers from different countries published papers using LED as light source and silicon photodiode as detector. Since 1995, there are research reports on special photometers using multiple LEDs and array LEDs as light source [AMULTIWAVELENGTH PHOTOMETER BASED ON LIGHT-EMITTING-DIODES]. However, this technology did not gain commercial application until the last decade, thanks to the improvement of LED quality and the maturity of UV LED technology, and the significant price reduction. Compared with traditional light sources, LED has the advantages of small size, low power consumption, low light intensity fluctuation, low noise, and long life. In existing academic reports and patent technologies, photometers using LED as light source are mainly applied in special fields. Patent numbers JP2021082610, JP2019506607A, JP2021139908A, JP2021139907A, and JP2021139906A disclose portable instruments for measuring parameters such as whole blood hemoglobin, whole blood bilirubin, glucose, and lactic acid concentration. Patent number CN216386741U discloses the determination of specific pollutants in wastewater, the determination of specified agricultural residues in vegetables, and patent number CN109709040A discloses the use of microfluidic chips for detection. In the above applications, it is usually necessary to cooperate with color reagents to react with the measured components to produce colored substances, and to use a given wavelength photometer for quantitative measurement. In such applications, 1 to 7 LEDs of different wavelengths are usually used, for example, patent numbers CN114460022A and CN109709040A disclose the use of gratings or moving LEDs for wavelength selection; there are also methods of selecting the wavelength of the emitted light by lighting different wavelength LEDs separately and selecting appropriate filters simultaneously to measure the absorbance at that wavelength; and there are also methods of using multiple independent measurement cells, each with an independent LED and light detector.

[0005] Since the wavelength of light emitted by a single-color LED has a wavelength distribution of about ±15-20 nm, in applications requiring narrow-band wavelength, a grating + slit or a narrow-band filter is often used to limit the bandwidth. However, such applications are mainly in the laboratory. In various applications outside the laboratory, such as portable, online, in-situ detection, etc., there are higher requirements for detection sensitivity, repeatability, long-term stability and environmental adaptability, while low power consumption, resistance to vibration and electromagnetic interference are also required, and the bandwidth of the outgoing light source is not high. This is because the absorbance-wavelength characteristics of most components are not sharp peaks, but relatively wide peaks, so monitoring such components does not require a narrow bandwidth.

[0006] For applications that need to adapt to wide environmental temperature changes, the current mainstream technology is to monitor the outgoing light intensity of one LED with one silicon photodiode (PD) and compensate for it, so as to stabilize the output light intensity of the LED. However, since the response value of the PD is also affected by temperature, this compensation scheme only reduces the impact of temperature changes on the outgoing light intensity of the LED, and cannot fully compensate. SUMMARY

[0007] According to the technical problems mentioned above, a multi-wavelength photometer of a time-sequential light-emitting LED light source is provided. The present application uses an LED array to replace the traditional ultraviolet lamp and tungsten lamp as the light source, without using a grating spectrometer or a filter to select the wavelength. A combination of multiple single-wavelength LEDs from deep ultraviolet to near infrared (usually 26 LEDs of different wavelengths are needed) is used to realize an uninterrupted wide-spectrum light source, which can measure the luminosity value from deep ultraviolet to near infrared wavelength distribution. By lighting only one LED at a time, monochromatic light with a bandwidth of about 30 nm is obtained, and by sequentially lighting and extinguishing the LED, wavelength scanning in a wide spectral range is realized. By collecting the background light after the LED (i) is extinguished for a delay time Δt and subtracting the absorbance value of the wavelength measured during the lighting time ΔT of the LED (i), the absorbance of the bright field can be measured. In addition, because the light intensity E of the LED is related to the junction temperature Temp of the LED [E=f LEDi (Temp)], the response value S of the light detection device is also related to the temperature [S=f d (Temp)]. The present application can also measure the LED temperature and the light detector temperature in real time and correct the response value, thereby improving the resistance to large temperature changes in the environment and the measurement accuracy, and can be used in wide temperature range field environments.

[0008] The technical means adopted by the present application are as follows:

[0009] A kind of multi-wavelength spectrometer of time-sharing sequential light-emitting LED light source, comprising: LED line light source array, light guide rod, exit window, sample cell, receiving light window, light detector, sealed housing and circuit part, wherein:

[0010] The LED line light source array is arranged on the side of the light guide rod and close to the light guide rod;The light exit end surface of the light guide rod is close to the exit window;The sample cell to be measured is arranged between the exit window and the receiving light window;The light detector is arranged at the rear of the receiving light window;

[0011] The circuit part includes preamplifier, analog-digital conversion circuit, sampling and filtering circuit, background deduction circuit, timing control circuit, LED line light source array driving circuit, LED substrate temperature measurement circuit, light detector temperature measurement circuit, response value data correction circuit and interface circuit, wherein:

[0012] The LED line light source array driving circuit time-sharing sequentially lights up and turns off each LED in the LED line light source array, the light emitted by the lit LED is guided out through the light guide rod, respectively passes through the exit light window and the medium in the sample cell, enters the receiving light window and reaches the light detector, and after passing through the preamplifier, analog-digital conversion circuit, sampling and filtering circuit and background deduction circuit, the uncorrected absorbance signal I and background light signal I b The LED substrate temperature measurement circuit and the light detector temperature measurement circuit transmit the measured temperature data to the response value data correction circuit to correct the influence of temperature on the light-emitting intensity of LED and the sensitivity of light detector respectively, so that the measurement data is corrected in a wide temperature range;The sampling and filtering circuit, the background deduction circuit, the LED light source array driving circuit, the response value data correction circuit and the interface circuit are controlled in time sequence by the timing control circuit;

[0013] The sealed housing is used to shield the external background light and dust from entering the interior of the device to protect the above optical devices and circuits.

[0014] Further, the LED line light source array includes a linear array light source composed of N different wavelength LEDs, N≥4, and the LED emission wavelength is not limited, depending on the product performance of LED, wherein:

[0015] When N≤8, the LEDs are arranged in a line and welded on a 1 aluminum-based PCB board or a common PCB board, the LED light-emitting surface is close to the light guide rod and completely parallel to the light guide rod, so that the LED exit light can enter the light guide rod as much as possible;

[0016] When N>8, the LEDs are divided into 2 LED light source array strips, and the 2 LED light source array strips are respectively close to the 2 side faces of the light guide rod;

[0017] When N≥20, the LEDs are divided into 4 LED light source array strips, and the 4 LED light source array strips are respectively close to the 4 side faces of the light guide rod.

[0018] Further, the LEDs in the LED linear light source array are sequentially lighted or extinguished by the LED linear light source array driving circuit, wherein:

[0019] Each LED in the LED linear light source array is lighted for a period of time ΔT and then extinguished, and is kept for a period of time Δt; then the next LED is lighted for a period of time ΔT and then extinguished, and is kept for a period of time Δt; then the third LED is lighted, and so on until the Nth LED is lighted for a period of time ΔT and then extinguished, and is kept for a period of time Δt, thus completing a multi-wavelength light emitting cycle, and the time used is T C .

[0020] Further, the light emitted by the LED light source array strips in the LED linear light source array enters the light guide rod, and the light is transmitted to the two ends of the light guide rod; one end face of the light guide rod is a light emitting face, and the other end face is provided with a reflector, the reflector reflects the light emitted by the end face back to the light guide rod, so that the light is emitted from the light emitting face, and the intensity of the emitted light is enhanced.

[0021] Further, the light guide rod is used for guiding the light emitted by the LED light source array strips close to the side faces of the light guide rod to the same light emitting face, the side faces and the end faces of the light guide rod are optical planes; the light guide rod is made of transparent optical material, the transparent optical material includes transparent high molecular material or transparent inorganic optical material, the transparent high molecular material includes PMMA and polycarbonate; the transparent inorganic optical material includes optical glass, optical quartz glass or transparent optical ceramic; the cross-sectional shape of the light guide rod includes triangle, rectangle or polygon.

[0022] Further, the light emitting axis of the light guide rod is coaxial with the axis of the light emitting window and the axis of the light receiving window, so that the light signal after the emitted light passes through the sample cell can as much as possible reach the light receiving window and finally be detected by the light detector;

[0023] Further, the axis of the exit light window intersects with the entrance axis of the sample cell at an angle of a; the axis of the receiving light window intersects with the axis of the sample cell at an angle of 180°-a, and a tube made of light-reflecting material is arranged between the two windows, the tube is filled with the liquid sample to be measured; the exit light is emitted into the sample solution to be measured at an angle of a, irradiates the inner wall of the light-reflecting material tube, and is then totally reflected to enter the sample solution to be measured again and reach the opposite inner wall of the tube, and so on until the light is received by the receiving light window at the tube outlet position and detected by the light detector; wherein the light-reflecting material comprises PTFE-AF or a light-reflecting layer.

[0024] Further, the sample cell comprises a closed space or an open space, the closed space comprises a cuvette, a transparent liquid pipeline or a sample cell with totally-reflecting inner wall, and the open space is that the water-tight shell, the exit light window and the receiving light window are all immersed in the liquid to be measured.

[0025] Further, the light detector, the pre-logarithmic amplifier, the analog-to-digital conversion circuit and the sampling and filtering circuit measure the absorbance value I within a time ΔT and the background light value I within a time Δt. b The background deduction circuit deducts the background light signal according to the absorbance value I and the background light value I b to obtain the corrected absorbance value I R , and the correction formula is I R (i) = I(i) - (I b (i-1) + I b (i)) / 2, wherein i represents the i-th LED.

[0026] Further, the substrate of the LED linear light source array is provided with an LED substrate temperature sensor and an LED substrate temperature measurement circuit; the light detector is provided with a light detector temperature sensor and a light detector temperature measurement circuit, and the data are transmitted to the response value data correction circuit; the relationship f i (Temp) between the light-emitting intensity of the LED linear light source array and the light source temperature and the relationship f d (Temp) between the response value S of the light detector and the temperature are both stored in the response value data correction circuit, and the absorbance value is temperature-corrected.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] 1. The multi-wavelength photometer of the time-division sequential light-emitting LED light source provided by the present application adopts an LED linear array light source, each LED is sequentially lighted and turned off, and only one LED is lighted at any moment, so that the power consumption is extremely low.

[0029] 2. The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source can realize large light flux design, and thus has similar sensitivity to commercial photometers using traditional light sources.

[0030] 3. The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source can collect background light signals and deduct them, and thus can realize bright field detection of absorbance.

[0031] 4. The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source does not need filters and gratings, greatly reduces the size and cost of the device, improves the performance of resisting vibration and impact, improves long-term reliability, and is suitable for portable, field and in-situ online use. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The photometer principle diagram of the time-sharing sequential light-emitting multi-wavelength LED light source of the present application.

[0034] Figure 2 The cooperation schematic diagram of the LED linear light source array and the light guide rod in the photometer of the time-sharing sequential light-emitting multi-wavelength LED light source provided by the embodiment of the present application.

[0035] Figure 3 The control timing and sampling timing diagram of the time-sharing sequential light-emitting LED light source of the photometer of the time-sharing sequential light-emitting multi-wavelength LED light source provided by the embodiment of the present application.

[0036] Figure 4 The circuit principle diagram of the photometer of the time-sharing sequential light-emitting multi-wavelength LED light source of the present application.

[0037] In the figure: 1, LED linear light source array; 2, light guide rod; 201, light-emitting surface; 202, end surface; 203, reflector; 3, light-emitting window; 4, sample cell; 5, light receiving window; 6, light detector; 7, preamplifier; 8, analog-to-digital conversion circuit; 9, sampling and filtering circuit; 10, background deduction circuit; 11, timing control circuit; 12, LED linear light source array driving circuit; 13, LED substrate temperature measurement circuit; 1301, LED substrate temperature sensor; 14, light detector temperature measurement circuit; 1401, light detector temperature measurement circuit; 15, response value data correction circuit; 16, interface circuit; 17, sealed shell. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0042] In the description of the application, it needs to be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship is generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the device or element indicated must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application: the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0043] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0044] In addition, it should be noted that the use of "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore, it cannot be understood as a limitation on the scope of protection of the application.

[0045] Embodiment 1

[0046] As Figure 1 shown, the application provides a multi-wavelength photometer of time-sharing sequential light-emitting LED light source, comprising: an LED linear light source array 1, a light guide rod 2, an exit light window 3, a sample cell 4, a receiving light window 5, a light detector 6, a sealed shell 17 and a circuit part, wherein:

[0047] The LED linear light source array 1 is arranged on the side of the light guide rod 2 and close to the light guide rod 2; the light-emitting end surface of the light guide rod 2 is close to the exit window 3; the measured sample cell 4 is arranged between the exit window 3 and the receiving light window 5; the light detector 6 is arranged at the rear of the receiving light window 5;

[0048] The circuit part comprises a pre-logarithmic amplifier 7, an analog-digital conversion circuit 8, a sampling and filtering circuit 9, a background deduction circuit 10, a timing control circuit 11, an LED linear light source array driving circuit 12, an LED substrate temperature measuring circuit 13, a light detector temperature measuring circuit 14, a response value data correction circuit 15 and an interface circuit 16, wherein:

[0049] The LED linear light source array driving circuit 12 sequentially turns on and off each LED in the LED linear light source array 1 in time-sharing mode, the light emitted by the turned-on LED is guided out through the light guide rod 2, enters the receiving light window 5 through the medium in the sample cell 4 and reaches the light detector 6 after passing through the light exit window 3, and then the uncorrected absorbance signal I and the background light signal I are obtained through the pre-logarithmic amplifier 7, the analog-digital conversion circuit 8, the sampling and filtering circuit 9 and the background deduction circuit 10. b The LED substrate temperature measuring circuit 13 and the light detector temperature measuring circuit 14 transmit the measured temperature data to the response value data correction circuit 15 for correcting the influence of temperature on the light emitting intensity of the LED and the sensitivity of the light detector respectively, so that the measurement data is corrected in a wide temperature range; the sampling and filtering circuit 9, the background deduction circuit 10, the LED light source array driving circuit 12, the response value data correction circuit 15 and the interface circuit 16 are all controlled in timing by the timing control circuit 11.

[0050] The sealed shell 17 is used to shield the external background light and dust from entering the inside of the device to protect the above-mentioned optical devices and circuits.

[0051] In the specific implementation, as a preferred embodiment of the present application, the LED linear light source array 1 comprises a linear array light source composed of N groups of LEDs with different wavelengths, N≥4, and the LED emission wavelength is not limited and depends on the product performance of the LED, wherein:

[0052] When N≤8, the LEDs are arranged in a line and welded on one aluminum-based PCB board or common PCB board, the LED light emitting surface is close to the light guide rod 2 and completely parallel to the light guide rod 2, so that the LED emitted light can enter the light guide rod as much as possible;

[0053] When N>8, the LEDs are divided into two LED light source array strips, and the two LED light source array strips are close to the light guide rod 2 from two sides of the light guide rod 2 respectively;

[0054] When N≥20, the LEDs are divided into four LED light source array strips, and the four LED light source array strips are close to the light guide rod 2 from four sides of the light guide rod 2 respectively.

[0055] In the embodiment, the wavelength range covers 255-980nm, including 26 LEDs with wavelengths of 255, 275, 285, 300, 320, 365, 380, 405, 440, 465, 485, 510, 530, 560, 590, 610, 630, 650, 670, 685, 700, 750, 800, 850, 920, 980nm, respectively, which form four linear array light sources. The six LEDs with wavelengths of 255-365nm form the first linear array light source, the six LEDs with wavelengths of 380-510nm form the second linear array light source, the seven LEDs with wavelengths of 530-670nm form the third linear array light source, and the seven LEDs with wavelengths of 685-980nm form the fourth linear array light source. The light emitting surfaces of the four linear array light sources are close to the four sides of the light guide rod 2, respectively. Figure 2 .

[0056] In the embodiment, the LEDs in the LED linear light source array 1 are sequentially lighted or extinguished by the LED linear light source array driving circuit 12, which is the preferred embodiment of the present application.

[0057] Each LED in the LED linear light source array 1 is lighted for a period of time ΔT and then extinguished, and remains off for a period of time Δt. Then the next LED is lighted for a period of time ΔT and then extinguished, and remains off for a period of time Δt. Then the third LED is lighted for a period of time ΔT and then extinguished, and remains off for a period of time Δt. The above process is repeated until the Nth LED is lighted for a period of time ΔT and then extinguished, and remains off for a period of time Δt. Thus, a multi-wavelength light emitting cycle is completed, and the time used is T C In the embodiment, the control timing and sampling timing of the LED light source are shown in Figure 3 The driving circuit of the LED array light source lights each LED for a period of time ΔT=2ms and remains off for a period of time Δt=1ms. A full wavelength measurement cycle is 78ms.

[0058] In a specific implementation, as a preferred embodiment of the present application, the light emitted by the LED light source array strips in the LED light source array 1 enters the light guide rod 2, and then is transmitted to both ends of the light guide rod 2; one end surface of the light guide rod 2 is the light exit surface 201, and the other end surface 202 is provided with a reflector 203, which reflects the light exiting from the end surface 202 back to the light guide rod 2, so that the light exits from the light exit surface 201 and the intensity of the exiting light is enhanced. The light guide rod 2 is used to guide the light emitted by the LED light source array strips close to the side surface of the light guide rod 2 to the same light exit surface, and the side surface and the end surface of the light guide rod 2 are both optical planes; the light guide rod 2 is made of transparent optical material, which includes transparent high molecular material or transparent inorganic optical material, the transparent high molecular material includes PMMA and polycarbonate, the transparent inorganic optical material includes optical glass, optical quartz glass or transparent optical ceramic, and the cross-sectional shape of the light guide rod 2 includes triangle, rectangle or polygon. In this embodiment, the cross section of the light guide rod 2 is rectangular and is made of JGS1 optical quartz.

[0059] In a specific implementation, as a preferred embodiment of the present application, the light exit axis of the light guide rod 2 is coaxial with the axis of the light exit window 3 and the axis of the light receiving window 5, so that the light signal after the exiting light passes through the sample cell 4 can reach the light receiving window 5 as much as possible and is finally detected by the light detector 6.

[0060] In a specific implementation, as a preferred embodiment of the present application, the axis of the light exit window 3 intersects with the axis of the sample cell 4 at an angle of α; the axis of the light receiving window 5 intersects with the axis of the sample cell 4 at an angle of 180°-α, and a tube made of light reflecting material is arranged between the two windows, and the tube is filled with the measured liquid sample; the exiting light is incident into the measured sample solution at an angle of α, irradiates the inner wall of the light reflecting material tube, and then is totally reflected to enter the measured sample solution again and reaches the inner wall of the opposite tube, and so on until the light is received by the light receiving window 5 at the tube outlet position and is detected by the light detector 6; wherein the light reflecting material includes PTFE-AF or a light reflecting layer.

[0061] In a preferred embodiment, the sample cell 4 is a closed space or an open space. The closed space includes a cuvette, a transparent liquid conduit or a sample cell with total internal reflection. The open space is that the water-tight housing 17, the light exit window 3 and the light receiving window 5 are all immersed in the liquid to be measured. In this embodiment, the sample cell is a cuvette made of JGS1 material, the light receiving window and the light exit window are both made of JGS1 material, the light detector is a photodiode (PD), and the pre-amplification and logarithmic amplification circuit, the analog-to-digital conversion circuit, the sampling and filtering circuit, the background subtraction circuit, the timing control circuit, the LED linear array light source driving circuit, the LED substrate temperature measurement circuit in the LED linear array light source array, the light detector temperature measurement circuit, the response value data correction circuit, the interface circuit and the power management module are all installed in the sealed housing, as shown in Figure 4 .

[0062] In a preferred embodiment, the light detector 6, the pre-amplification and logarithmic amplification circuit 7, the analog-to-digital conversion circuit 8 and the sampling and filtering circuit 9 measure the absorbance value I within a time ΔT and the background light value I b within a time Δt; the background subtraction circuit 10 subtracts the background light signal according to the absorbance value I and the background light value I b to obtain the corrected absorbance value I R , and the correction formula is I R (i) = I(i) - (I b (i-1) + I b (i)) / 2, where i represents the i-th LED. In this embodiment, the linear range of the pre-amplification and logarithmic amplification circuit is not less than 5 orders of magnitude, the analog-to-digital conversion circuit uses a 24-bit ADC, the filtering part of the sampling and filtering circuit uses active filtering followed by digital filtering or separate digital filtering, and the background subtraction circuit uses the formula I R (i) = I(i) - (I b (i-1) + I b (i)) / 2 to perform background light subtraction operation.

[0063] In a specific implementation, as a preferred embodiment of the present application, the LED linear light source array 1 is provided with an LED substrate temperature sensor 1301 and an LED substrate temperature measuring circuit 13; the light detector 6 is provided with a light detector temperature sensor 1401 and a light detector temperature measuring circuit 14, and data are transmitted to the response value data correction circuit 15. In this embodiment, the temperature probe in the LED substrate temperature measuring circuit is attached to the heat-conducting layer on the PCB on which the LED linear array is mounted, so that the temperature of the substrate can be measured in time and accurately. The temperature measuring probe in the light detector temperature measuring circuit is attached to the PD, so as to measure the temperature of the PD. The response value data correction circuit obtains the absorbance value when each LED is lit, and uses the stored brightness data of each LED and the response characteristic data of the PD, as well as the data of the influence of temperature on the LED and the PD, to comprehensively correct the response value. The temperature measuring and correction circuit contained therein enables the photometer of the present application to normally work within the range of +50℃ of the working temperature of the LED device used, and the data are corrected.

[0064] In a specific implementation, as a preferred embodiment of the present application, the relationship f i (Temp) between the luminous intensity of the LED linear light source array 1 and the temperature of the light source and the relationship f d (Temp) between the response value S of the light detector 6 and the temperature are both stored in the response value data correction circuit 15, and the absorbance value is temperature-corrected.

[0065] The photometer in the above embodiment meets the requirements of dark field and bright field detection, and is suitable for use in field environment and laboratory.

[0066] Embodiment 2

[0067] The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source provided in Embodiment 1 above, wherein the pre-logarithmic amplifier 7 is simplified into a simple linear amplification circuit, and a single-chip microcomputer is added in the response value data correction circuit 15, so as to convert the linear signal into a logarithmic signal output by using numerical method. In this embodiment, the sample cell is a pipeline made of JGS1 material, and the sample liquid continuously or intermittently flows through the sample cell. The driving circuit of the LED array light source lights each LED for a time length ΔT=1ms, Δt=0.5ms, and a full-wavelength measurement period is 39ms.

[0068] The multi-wavelength photometer provided in this embodiment meets the requirement of online continuous measurement, is suitable for online spectral detection in chemical and pharmaceutical enterprises, is also suitable for online water quality monitoring in field environment, and meets the requirements of dark field and bright field detection.

[0069] Embodiment 3

[0070] The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source provided in Embodiment 1 is used in this embodiment, wherein the sample cell is an open space, the whole machine is designed as a water-tight structure, and the water-tight joint is used for electrical connection. The driving circuit of the LED array light source lights up each LED for a time period of ΔT=3 ms and Δt=1 ms, and a full-wavelength measurement cycle is 104 ms. In this embodiment, the whole multi-wavelength photometer is immersed in the measured liquid, and the liquid between the light-emitting window and the light-receiving window is the measured sample, and the light-absorbing distance is the distance between the two windows and the outer surface.

[0071] The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source provided in this embodiment is suitable for in-situ online monitoring of the optical environment of rivers, lakes and seas, such as water pollution and eutrophication, and meets the light environment and temperature conditions of in-situ bright field measurement.

[0072] Embodiment 4

[0073] On the basis of Embodiment 3, this embodiment provides an underwater in-situ photometer, wherein the driving circuit of the LED array light source lights up each LED for a time period of ΔT=30 ms and Δt=8 ms, and a full-wavelength measurement cycle is 988 ms. The whole machine shell and optical window are designed as a high-pressure-resistant structure, and the water-tight joint is of a high-pressure-resistant type.

[0074] The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source provided in this embodiment is suitable for in-situ online monitoring of the optical environment of deep sea water.

[0075] As described above, the time sequence and pulse width of the LED array light-emitting are controlled so that each LED is extinguished after the lighting time (ΔT) ends, and then delayed for Δt, and then the next LED is lighted, and so on. The whole measurement cycle is H≥N×(ΔT+Δt). This design ensures that any time, two LEDs cannot be lighted at the same time, and also ensures that when all the N LEDs are extinguished, the light detection circuit can collect the background light signal. Because only one LED is lighted at each light-emitting time, the wavelength selection is not needed at the detection end, the use of filters is avoided, and the use of a grating spectrometer is also avoided. The multi-wavelength photometer of the present application has a large light flux, high sensitivity, small size, low power consumption, and is suitable for portable or field use, and is also suitable for laboratory use.

[0076] The detection lower limit of the time-sharing multi-wavelength photometer of the present application is from sub-ppm (10 -6 v / v) to dozens of ppm, the dynamic range is not less than 5 orders of magnitude, the detection sensitivity can be similar to that of a laboratory commercial ultraviolet-visible spectrophotometer, the total power consumption is not more than 1.5 W, the size is small, and the present application is suitable for laboratory and field portable applications as a general or special photometer.

[0077] The multi-wavelength photometer of the time-sharing sequential light-emitting LED light source provided by the application can be loaded on a deep-sea submersible vehicle to perform deep-sea salvage search, submarine optical cable protection layer damage leakage protection exploration, oil pipeline leakage exploration and submarine oil spill exploration, and can also be used for in-situ detection of the influence of marine plant and animal residues and other substances stirred by a propeller on an underwater optical environment, search for a submarine hydrothermal vent, measurement of a hydrothermal plume distribution and other scientific research work. Another application is in-situ measurement of seawater absorbance, and the sensitivity of the seawater absorbance change in the visible light band is 2-3 orders of magnitude higher than that of a video probe.

[0078] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A multi-wavelength photometer for a time-sequential light emitting diode (LED) light source, comprising: It comprises: LED linear light source array (1), light guide rod (2), light exit window (3), sample cell (4), light receiving window (5), light detector (6), sealed shell (17) and circuit part, wherein: The LED linear light source array (1) comprises a linear array light source composed of N groups of LEDs with different wavelengths, N 4, and the LED emission wavelength is not limited; the LED linear light source array (1) is arranged on the side of the light guide rod (2) and close to the light guide rod (2); the light emitting end face of the light guide rod (2) is close to the light exit window (3); the sample cell (4) is arranged between the light exit window (3) and the light receiving window (5); the light detector (6) is arranged at the rear of the light receiving window (5); The circuit part comprises preamplifier (7), analog-to-digital conversion circuit (8), sampling and filtering circuit (9), background subtraction circuit (10), timing control circuit (11), LED linear light source array driving circuit (12), LED substrate temperature measurement circuit (13), light detector temperature measurement circuit (14), response value data correction circuit (15) and interface circuit (16), wherein: The LED linear light source array driving circuit (12) sequentially turns on and off each LED in the LED linear light source array (1) in time, the light emitted by the turned-on LED is guided out through the light guide rod (2), enters the receiving light window (5) and reaches the light detector (6) after passing through the medium in the sample cell (4) and the exit light window (3), and is obtained after passing through the pre-logarithmic amplifier (7), the analog-digital conversion circuit (8), the sampling and filtering circuit (9) and the background deduction circuit (10) and the background light signal ; the LED substrate temperature measurement circuit (13) and the light detector temperature measurement circuit (14) transmit the measured temperature data to the response value data correction circuit (15) to correct the influence of temperature on the light emitting intensity of the LED and the sensitivity of the light detector respectively, so that the measurement data is corrected in a wide temperature range; the sampling and filtering circuit (9), the background deduction circuit (10), the LED linear light source array driving circuit (12), the response value data correction circuit (15) and the interface circuit (16) are all controlled in time by the time sequence control circuit (11). The LEDs in the LED linear light source array (1) are sequentially lighted or extinguished by the LED linear light source array driving circuit (12), wherein each LED in the LED linear light source array (1) is lighted for a period of time then extinguished, and kept for a period of time; then the next LED is lighted for a period of time then extinguished, and kept for a period of time; then the third LED is lighted again, and so on until the th LED is lighted for a period of time, then extinguished, and kept for a period of time, thus completing a multi-wavelength light emitting cycle, and the total time is . The LED substrate temperature sensor (1301) and the LED substrate temperature measuring circuit (13) are arranged on the substrate of the LED linear light source array (1); the light detector (6) is provided with a light detector temperature sensor (1401) and a light detector temperature measuring circuit (14), and data are transmitted to the response value data correction circuit (15); the relationship between the luminous intensity of the LED linear light source array (1) and the light source temperature and the relationship between the response value S of the light detector (6) and the temperature are stored in the response value data correction circuit (15) and are used for temperature correction of the absorbance value. The sealed shell (17) is used to shield the external background light and dust from entering the inside of the device to protect the optical devices and circuits.

2. The multi-wavelength photometer of time-sequential light-emitting diode (LED) light source according to claim 1, wherein, The line array light source composed of different wavelength LEDs depends on the product performance of the LEDs, wherein: When 8, LED one character line welding in 1 aluminum base PCB board or common PCB board, LED light surface close to the light bar (2) and the light bar (2) is completely parallel, so that the LED exit light into the light bar; When 8, the LED is divided into 2 LED light source array strips, and the 2 LED light source array strips are respectively close to the light guide rod (2) from the 2 sides of the light guide rod (2). When 20, the LED is divided into 4 LED light source array strips, and the 4 LED light source array strips are respectively close to the light guide rod (2) from the 4 sides of the light guide rod (2).

3. The multi-wavelength photometer of time-sequential light-emitting diode (LED) light source according to claim 1, wherein, The light emitted by the LED light source array strip in the LED linear light source array (1) enters the light guide rod (2), and the light is transmitted to both ends of the light guide rod (2); one end face of the light guide rod (2) is a light exit face (201), and the other end face (202) is provided with a reflector (203), the reflector (203) reflects the light emitted by the end face (202) back to the light guide rod (2), so that the light is emitted from the light exit face (201), and the intensity of the emitted light is enhanced.

4. The multi-wavelength photometer of time-sequential light-outputting LED light sources according to claim 1, characterized in that, The light guide rod (2) is used to guide the light emitted by the LED light source array strip close to the side face of the light guide rod (2) to the same light exit face, and the side face and the end face of the light guide rod (2) are optical planes; the light guide rod (2) is made of transparent optical material, and the transparent optical material includes transparent high molecular material or transparent inorganic optical material, the transparent high molecular material includes PMMA and polycarbonate; the transparent inorganic optical material includes optical glass, optical quartz glass or transparent optical ceramic; the cross-sectional shape of the light guide rod (2) includes triangle, rectangle or polygon.

5. The multi-wavelength photometer of time-sequential light-emitting diode (LED) light source according to claim 1, wherein, The light exit axis of the light guide rod (2) is coaxial with the axis of the light exit window (3) and the axis of the light receiving window (5), so that the light signal after the emitted light passes through the sample cell (4) reaches the light receiving window (5) and is finally detected by the light detector (6).

6. The multi-wavelength photometer of time-sequential light-outputting LED light sources according to claim 1, characterized in that, The axis of the exit light window (3) intersects the inlet axis of the sample cell (4) at an angle of ; the axis of the receiving light window (5) intersects the axis of the sample cell (4) at an angle of ; a tube made of light-reflecting material is arranged between the two windows, and the tube is filled with the liquid sample to be measured; the exit light is emitted into the sample solution to be measured at an angle of , illuminates the inner wall of the light-reflecting material tube, is then totally reflected and enters the sample solution to be measured again, and reaches the opposite inner wall of the tube, and so on, until it is received at the tube outlet position by the receiving light window (5) and detected by the light detector (6); wherein the light-reflecting material comprises PTFE-AF or a light-reflecting layer.

7. The multi-wavelength photometer of time-sequential light-outputting LED light sources according to claim 1, characterized in that, The sample cell (4) comprises a closed space or an open space, the closed space comprises a cuvette, a transparent liquid pipeline or a sample cell with full internal wall reflection, and the open space is that the water-tight shell (17), the light exit window (3) and the light receiving window (5) are all immersed in the measured liquid.

8. The multi-wavelength photometer of time-sequential light-outputting LED light sources according to claim 1, characterized in that, The photodetector (6), the pre-logarithmic amplifier (7), the analog-to-digital converter (8), and the sampling and filtering circuit (9) are in time The absorbance value was measured internally. ,exist Background light value measured within a time period The background subtraction circuit (10) is based on the absorbance value. and background light value After subtracting the background light signal, the corrected absorbance value is obtained. The correction formula is ， in, Indicates the first LED only.

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