Ultraviolet visible detector optical system and design method

Abstract

The invention discloses an optical system of an ultraviolet visible detector. The optical system comprises a light source; the incident light of the light source is reflected and converged by the square M1 reflecting mirror and then irradiates on an optical filter, and the light source and the square M1 reflecting mirror are arranged in an equilateral triangle shape; the diffraction grating is arranged on an emergent light path of the square M1 reflector, and a circular entrance slit is arranged between the diffraction grating and the square M1 reflector; the square M2 reflecting mirror is rotatably arranged, the square M2 reflecting mirror is arranged on an emergent light path of the diffraction grating, and a circular emergent slit is arranged between the square M2 reflecting mirror and the diffraction grating; and the transflective mirror is used for separating emergent light of the square M2 reflector into a reflection light path and a transmission light path, and enabling the reflection light path to enter the reference photocell and the transmission light path to enter the sample photocell. The invention has the beneficial effects that the detection precision of the detector is improved, and the design and manufacturing cost of an optical system of the ultraviolet visible detector is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chromatographs, in particular to an ultraviolet-visible detector optical system and a design method. Background Art

[0002] UV-visible absorption detector is one of the most widely used detectors in HPLC, and almost all liquid chromatographs are equipped with this detector. The optical system design is even more important in the development cycle of UV-visible absorption detector. An excellent optical system can optimize the various indicators of the detector, including wavelength accuracy, minimum detection concentration (sensitivity), noise, baseline drift, etc.

[0003] However, there are still some key problems in the practical application of this system. First, under high optical density conditions, the scattering and absorption of light during transmission may cause signal attenuation, affecting the accuracy of the detection results. Secondly, under low optical density conditions, the background noise will be relatively enhanced, which will reduce the signal-to-noise ratio and affect the detection sensitivity. In addition, in the fast scanning mode, the dynamic range will be reduced due to the mismatch of the response time, which limits its detection ability at high frequencies. In multi-wavelength detection, the characteristics of the filter may drift with time and environmental changes, resulting in deviations in wavelength calibration. Finally, during long-term continuous use, due to insufficient thermal stability, the light intensity of the system will fluctuate, affecting the reliability and consistency of the overall detection. These issues need to be fully considered during design. Therefore, the optical systems of UV-visible absorption detectors currently on the market have their own strengths and weaknesses in terms of light flux, system size, device cost, and index parameters, in order to design low-cost, high-light flux, and excellent index UV-visible absorption detectors under the premise of meeting the optimal index parameters. Summary of the invention

[0004] The object of the present invention is to provide an ultraviolet visible detector optical system to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides an ultraviolet visible detector optical system, the system comprising: Light sources, wherein there are two light sources; A rotatable square M1 reflector, the incident light from the two light sources is reflected and converged by the square M1 reflector and then shines on a filter, and the two light sources and the square M1 reflector are arranged in an equilateral triangle; A diffraction grating, wherein the diffraction grating is arranged on the outgoing light path of the square M1 reflector, and a circular incident slit is arranged between the diffraction grating and the square M1 reflector; A rotatably arranged square M2 reflector, the square M2 reflector is arranged on the exit light path of the diffraction grating, and a circular exit slit is arranged between the square M2 reflector and the diffraction grating; The transflector is used to separate the reflected light of the square M2 reflector into a reflected light path and a transmitted light path, and make the reflected light path enter the reference photocell and the transmitted light path enter the sample photocell.

[0006] Preferably, the light source is a deuterium lamp or a tungsten lamp, the distance between the two light sources and the square M1 reflector is 80mm-90mm, the inclination angle of the square M1 reflector is 12°-18°, and the side length is between 20mm-30mm.

[0007] Preferably, the diffraction grating adopts a concave blazed grating with a wavelength range of 200nm-800nm, a number of lines of 1200 / mm, a grating order of -1, and a nominal blazed wavelength of 300nm.

[0008] Preferably, the grating incident angle of the diffraction grating is 0°-14.4°, and the distance between the diffraction grating and the circular incident slit is 110 mm-130 mm.

[0009] Preferably, the square M2 reflector has an inclination angle of 8°-12°, a side length of 18mm-22mm, and a distance from the circular exit slit of 130mm-150mm.

[0010] Preferably, holmium glass is also included, wherein the holmium glass has a thickness of 1 mm, a diameter of 5 mm-10 mm, and is located 10 mm-20 mm in front of the reference photocell.

[0011] Preferably, the filter has a diameter of 10 mm to 20 mm, a thickness of 1 mm to 2 mm, and a distance from the circular incident slit of 10 mm to 20 mm.

[0012] Preferably, the distance between the circular incident slit and the square M1 reflector is 190 mm-210 mm, and the aperture size of the circular incident slit is 0.8 mm-1.2 mm.

[0013] The distance between the circular exit slit and the diffraction grating is 110mm-130mm, and the difference between the distance from the diffraction grating to the circular incident slit is no more than 1mm. The diameter of the circular exit slit is the same as that of the circular incident slit, and the difference is no more than 0.1mm.

[0014] Preferably, the effective reflection area of ​​the transflective mirror has a side length of 13mm-16mm, an inclination angle of 45°, a distance from the square M1 reflector of 73mm-80mm, and a horizontal offset to the right of 1.5mm-2.5mm along the main light path.

[0015] In a second aspect, the present invention provides a method for designing an ultraviolet-visible detector optical system, which is used to design the ultraviolet-visible detector optical system described in the above embodiment, comprising: Calculate the sum of the angles between the circular entrance slit, the circular exit slit and the diffraction grating; Set the curvature of the square M1 reflector and the square M2 reflector in the meridian and sagittal directions; Set the object distance and image distance of the square M2 reflector; Calculate the slit width corresponding to the required bandwidth, calculate the relationship between the wavelength and the grating rotation angle, calculate the grating rotation angle and the distance traveled on the slit corresponding to the monochromatic light wavelength, and verify the accuracy of the data through model simulation software; Select long-wave filter and neutral density filter to effectively obtain the required monochromatic light and filter out interference from other wavelengths. Set the imaging beam convergence point to be in front of the detection surface, set the image point size, and set the proportion of the detection surface light energy in the total light source energy.

[0016] Beneficial effects of the present invention: 1. Signal attenuation due to scattering and absorption under high light density conditions.

[0017] 2. The problem of reduced signal-to-noise ratio due to noise interference under low optical density conditions.

[0018] 3. Dynamic range reduction due to response time mismatch in fast scan mode.

[0019] 4. Wavelength calibration deviation caused by filter characteristic drift in multi-wavelength detection.

[0020] 5. Light intensity fluctuations due to poor thermal stability during long-term continuous use.

[0021] 6. Reduce the design and manufacturing costs of the UV-visible detector optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of an optical system according to an embodiment of the present invention; Figure 2 A flow chart of a method for designing an optical system of a UV-visible detector according to the present invention; Figure 3 is a flow chart of calculating the incident angle and the diffraction angle in step S100; Figure 4 is a flow chart of curvature calculation in the meridian direction and the sagittal direction in step S200; Figure 5A flow chart for setting the object distance and the image distance in step S300; Figure 6 This is a flow chart of slit width calculation in step S400. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1 See also Figure 1 The present invention provides a technical solution: an ultraviolet visible detector optical system, the system includes a light source 1, a square M1 reflector 2, a diffraction grating 3, a square M2 reflector 4 and a transflective mirror 5, the light path R1 enters the diffraction grating 3 through the square M1 reflector 2, the light path L1 enters the square M2 reflector 4 after the diffraction grating 3 realizes light splitting, the light path L1 reflected by the square M2 reflector 4 enters the transflective mirror 5, and a part of the light beam separated by the transflective mirror 5 enters the reference photocell and a part enters the sample photocell.

[0025] In one embodiment of the present invention, there are two light sources 1, and the light source 1 uses a deuterium lamp or a tungsten lamp as the light emitter. The emission spectrum of the deuterium lamp is generally in the range of 190nm - 400nm, and can provide continuous ultraviolet radiation within this wavelength range. The emission spectrum of the tungsten lamp is generally in the range of 350nm - 2500nm, mainly concentrated in the visible light region (380nm - 780nm).

[0026] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M1 reflector, the square M1 reflector 2 is rotatable, and the incident light from the two light sources 1 is reflected and converged by the square M1 reflector 2 and then shines on the filter 6. The two light sources 1 and the square M1 reflector 2 are arranged in an equilateral triangle, that is, the distances between the center points of the two light sources 1 and the rotation axis where the square M1 reflector 2 is located are equal, and the distance between the center points of the two light sources 1 is equal to the distance from the center point of any light source 1 to the rotation axis where the square M1 reflector 2 is located.

[0027] In this embodiment, the distance between the two light sources 1 and the square M1 reflector 2 is 90 mm, the square M1 reflector 2 has an inclination angle of 18° and a side length of 30 mm.

[0028] In one embodiment of the present invention, the diffraction grating 3 is disposed on the outgoing light path of the square M1 reflector 2 , and a circular incident slit 7 is disposed between the diffraction grating 3 and the square M1 reflector 2 .

[0029] In this embodiment, the filter 6 has a diameter of 20 mm, a thickness of 2 mm, and a distance from the circular incident slit 7 of 20 mm.

[0030] In this embodiment, the distance between the circular incident slit and the M1 reflector is 210 mm, and the aperture size of the circular incident slit is 1.2 mm.

[0031] In this embodiment, the diffraction grating 3 adopts a holographic concave blazed grating with a wavelength range of 200nm-800nm, a number of lines of 1200 / mm, a grating order of -1, and a nominal blazing wavelength of 300nm.

[0032] In this embodiment, the grating incident angle of the diffraction grating 3 is 14.4°, and the distance between the diffraction grating 3 and the circular incident slit 7 is 130 mm.

[0033] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M2 reflector 4, the square M2 reflector 4 is configured to be rotatable, the square M2 reflector 4 is arranged on the output light path of the diffraction grating 3, and a circular output slit 8 is provided between the square M2 reflector 4 and the diffraction grating 3.

[0034] In this embodiment, the square M2 reflector 4 has an inclination angle of 12°, a side length of 22 mm, and a distance of 150 mm from the circular exit slit 8 .

[0035] In this embodiment, the distance between the circular exit slit 8 and the diffraction grating 3 is 130 mm, and the distance between the circular exit slit 8 and the circular incident slit 7 is no more than 1 mm different, and the diameter of the circular exit slit 8 is no more than 0.1 mm different from the diameter of the circular incident slit 7.

[0036] In one embodiment of the present invention, the reflective mirror 5 is arranged on the outgoing light path of the square M2 reflector 4, and the reflective mirror 5 is used to separate the outgoing light of the square M2 reflector 4 into a reflected light path R2 and a transmitted light path R3, and the separated reflected light path R2 enters the reference photocell (RPC), and the transmitted light path R3 enters the sample photocell (SP).

[0037] In this embodiment, the reflective light path R2 of the reflector 5 is provided with a holmium glass 9 with adjustable height, which can calibrate the wavelength accuracy of the instrument according to the exact wavelength corresponding to its absorption peak, thereby ensuring the accuracy of the instrument's measurement wavelength and guaranteeing the reliability of subsequent measurement data.

[0038] In this embodiment, the holmium glass 9 has a thickness of 1 mm and a diameter of 10 mm and is located 20 mm in front of the reference photocell.

[0039] In this embodiment, the effective transflective area of ​​the transflective mirror 5 has a side length of 16 mm, an inclination angle of 45°, a distance of 80 mm from the square M1 reflector 2, and a transverse rightward offset of 2.5 mm along the main light path.

[0040] Example 2 See also Figure 1 The present invention provides a technical solution: an ultraviolet visible detector optical system, the system includes a light source 1, a square M1 reflector 2, a diffraction grating 3, a square M2 reflector 4 and a transflective mirror 5, the light path R1 enters the diffraction grating 3 through the square M1 reflector 2, the light path L1 enters the square M2 reflector 4 after the diffraction grating 3 realizes light splitting, the light path L1 reflected by the square M2 reflector 4 enters the transflective mirror 5, and a part of the light beam separated by the transflective mirror 5 enters the reference photocell and a part enters the sample photocell.

[0041] In one embodiment of the present invention, there are two light sources 1, and the light source 1 uses a deuterium lamp or a tungsten lamp as the light emitter. The emission spectrum of the deuterium lamp is generally in the range of 190nm - 400nm, and can provide continuous ultraviolet radiation within this wavelength range. The emission spectrum of the tungsten lamp is generally in the range of 350nm - 2500nm, mainly concentrated in the visible light region (380nm - 780nm).

[0042] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M1 reflector, the square M1 reflector is rotatable, and the incident light from the two light sources 1 is reflected and converged by the square M1 reflector 2 and then shines on the filter 6, and the two light sources 1 and the square M1 reflector 2 are arranged in an equilateral triangle. That is, the distances between the center points of the two light sources 1 and the rotation axis where the square M1 reflector 2 is located are equal, and the distance between the center points of the two light sources 1 and the distance from the center point of any light source 1 to the rotation axis where the square M1 reflector 2 is located are all equal.

[0043] In this embodiment, the distance between the two light sources 1 and the square M1 reflector 2 is 80 mm, the square M1 reflector 2 has an inclination angle of 12° and a side length of 20 mm.

[0044] In one embodiment of the present invention, the diffraction grating 3 is disposed on the outgoing light path of the square M1 reflector 2 , and a circular incident slit 7 is disposed between the diffraction grating 3 and the square M1 reflector 2 .

[0045] In this embodiment, the filter 6 has a diameter of 10 mm, a thickness of 1 mm, and a distance of 10 mm from the circular incident slit 7 .

[0046] In this embodiment, the distance between the circular incident slit 7 and the square M1 reflector 2 is 190 mm, and the aperture size of the circular incident slit 7 is 0.8 mm.

[0047] In this embodiment, the diffraction grating 3 adopts a holographic concave blazed grating with a wavelength range of 250nm-650nm, a number of lines of 1200 / mm, a grating order of -1, and a nominal blazing wavelength of 350nm.

[0048] In this embodiment, the grating incident angle of the diffraction grating 3 is 0°, and the distance between the diffraction grating 3 and the circular incident slit 7 is 110 mm.

[0049] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M2 reflector 4, the square M2 reflector 4 is configured to be rotatable, the square M2 reflector 4 is arranged on the output light path of the diffraction grating 3, and a circular output slit 8 is provided between the square M2 reflector 4 and the diffraction grating 3.

[0050] In this embodiment, the square M2 reflector 4 has an inclination angle of 8°, a side length of 18 mm, and a distance from the circular exit slit 8 of 130 mm.

[0051] In this embodiment, the distance between the circular exit slit 8 and the diffraction grating 3 is 110 mm, and the distance between the circular exit slit 8 and the diffraction grating 3 and the circular incident slit is no more than 1 mm different, and the diameter of the circular exit slit 8 and the diameter of the circular incident slit 7 are no more than 0.1 mm different.

[0052] In one embodiment of the present invention, the reflective mirror 5 is arranged on the outgoing light path of the square M2 reflector 4, and the reflective mirror 5 is used to separate the outgoing light of the square M2 reflector 4 into a reflected light path R2 and a transmitted light path R3, and the separated reflected light path R2 enters the reference photocell (RPC), and the transmitted light path R3 enters the sample photocell (SP).

[0053] In this embodiment, the reflective light path R2 of the reflector 5 is provided with a holmium glass 9 with adjustable height, which can calibrate the wavelength accuracy of the instrument according to the exact wavelength corresponding to its absorption peak, thereby ensuring the accuracy of the instrument's measurement wavelength and guaranteeing the reliability of subsequent measurement data.

[0054] In this embodiment, the holmium glass 9 has a thickness of 1 mm and a diameter of 5 mm and is located 10 mm in front of the reference photocell.

[0055] In this embodiment, the effective transflective area of ​​the transflective mirror 5 has a side length of 13 mm, an inclination angle of 45°, a distance of 73 mm from the square M1 reflector 2, and a transverse rightward offset of 1.5 mm along the main optical path.

[0056] Example 3 See also Figure 1The present invention provides a technical solution: an ultraviolet visible detector optical system, the system includes a light source 1, a square M1 reflector 2, a diffraction grating 3, a square M2 reflector 4 and a transflective mirror 5, the light path L1 enters the diffraction grating 3 through the square M1 reflector 2, the diffraction grating 3 realizes light splitting and the light path R1 enters the square M2 reflector 4, the light path L1 reflected by the square M2 reflector 4 enters the transflective mirror 5, and a part of the light beam separated by the transflective mirror 5 enters the reference photocell and a part enters the sample photocell.

[0057] In one embodiment of the present invention, there are two light sources 1, and the light source 1 uses a deuterium lamp or a tungsten lamp as the light emitter. The emission spectrum of the deuterium lamp is generally in the range of 190nm - 400nm, and can provide continuous ultraviolet radiation within this wavelength range. The emission spectrum of the tungsten lamp is generally in the range of 350nm - 2500nm, mainly concentrated in the visible light region (380nm - 780nm).

[0058] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M1 reflector, the square M1 reflector is rotatable, and the incident light from the two light sources 1 is reflected and converged by the square M1 reflector 2 and then shines on the filter 6, and the two light sources 1 and the square M1 reflector 2 are arranged in an equilateral triangle. That is, the distances between the center points of the two light sources 1 and the rotation axis where the square M1 reflector 2 is located are equal, and the distance between the center points of the two light sources 1 and the distance from the center point of any light source 1 to the rotation axis where the square M1 reflector 2 is located are all equal.

[0059] In this embodiment, the distance between the two light sources 1 and the square M1 reflector 2 is 85 mm, the square M1 reflector 2 has an inclination angle of 15° and a side length of 26 mm.

[0060] In one embodiment of the present invention, the diffraction grating 3 is disposed on the outgoing light path of the square M1 reflector 2 , and a circular incident slit 7 is disposed between the diffraction grating 3 and the square M1 reflector 2 .

[0061] In this embodiment, the filter 6 has a diameter of 15 mm, a thickness of 1.5 mm, and a distance of 15 mm from the circular incident slit 7 .

[0062] In this embodiment, the distance between the circular incident slit 7 and the M1 reflector 2 is 200 mm, and the aperture size of the circular incident slit 7 is 1 mm.

[0063] In this embodiment, the diffraction grating 3 adopts a holographic concave blazed grating with a wavelength range of 200nm-500nm, a number of lines of 1200 / mm, a grating order of -1, and a nominal blazing wavelength of 300nm.

[0064] In this embodiment, the grating incident angle of the diffraction grating 3 is 0°-14.4°, and the distance between the diffraction grating 3 and the circular incident slit 7 is 120 mm.

[0065] In one embodiment of the present invention, in order to facilitate the adjustment of the angle of the square M2 reflector 4, the square M2 reflector 4 is configured to be rotatable, the square M2 reflector 4 is arranged on the output light path of the diffraction grating 3, and a circular output slit 8 is provided between the square M2 reflector 4 and the diffraction grating 3.

[0066] In this embodiment, the square M2 reflector 4 has an inclination angle of 8°-12°, a side length of 20 mm, and a distance from the circular exit slit 8 of 140 mm.

[0067] In this embodiment, the distance between the circular exit slit 8 and the diffraction grating 3 is 120 mm, and the distance between the circular exit slit 8 and the circular incident slit 7 is no more than 1 mm different, and the diameter of the circular exit slit 8 is no more than 0.1 mm different from the diameter of the circular incident slit 7.

[0068] In one embodiment of the present invention, the reflective mirror 5 is arranged on the outgoing light path of the square M2 reflector 4, and the reflective mirror 5 is used to separate the outgoing light of the square M2 reflector 4 into a reflected light path R2 and a transmitted light path R3, and the separated reflected light path R2 enters the reference photocell (RPC), and the transmitted light path R3 enters the sample photocell (SP).

[0069] In this embodiment, the reflective light path R2 of the reflector 5 is provided with a holmium glass 9 with adjustable height, which can calibrate the wavelength accuracy of the instrument according to the exact wavelength corresponding to its absorption peak, thereby ensuring the accuracy of the instrument's measurement wavelength and guaranteeing the reliability of subsequent measurement data.

[0070] In this embodiment, the holmium glass 9 has a thickness of 1 mm and a diameter of 8 mm and is located 15 mm in front of the reference photocell.

[0071] In this embodiment, the effective transflective area of ​​the transflective mirror 5 has a side length of 15 mm, an inclination angle of 45°, a distance of 76 mm from the square M1 reflector 2, and a transverse rightward offset of 2 mm along the main light path.

[0072] Example 4 See also Figure 2 , a method for designing an ultraviolet-visible detector optical system, used for designing an ultraviolet-visible detector optical system as described in any of the above embodiments, comprising: S100: Calculating the sum of the angles formed by the circular incident slit, the circular exit slit and the diffraction grating; S200: setting the curvatures of the square M1 reflector and the square M2 reflector in the meridian direction and the sagittal direction; S300: Setting the object distance and image distance of the square M2 reflector; S400: Calculate the slit width corresponding to the required bandwidth, calculate the relationship between the wavelength and the grating rotation angle, calculate the grating rotation angle corresponding to the monochromatic light wavelength and the distance traveled on the slit sheet, and verify the accuracy of the data through model simulation software; S500: Select long-wave filter and neutral density filter to effectively obtain the required monochromatic light and filter out interference from other wavelengths. S600: Setting the imaging light beam convergence point to be located in front of the detection surface, setting the image point size, and setting the proportion of the detection surface light energy in the total light source energy.

[0073] This method is mainly used to improve the performance of the detector under different conditions of use, especially to solve the problems of signal attenuation under high light density, reduced signal-to-noise ratio under low light density, reduced dynamic range under fast scanning mode, wavelength calibration deviation in multi-wavelength detection, and light intensity fluctuation in long-term continuous use. The core of the design method is to optimize the transmission efficiency of the optical signal by precisely controlling the optical path and grating angle.

[0074] See also Figure 3 In step S100, the key angle θ needs to be calculated. The specific steps are as follows: S110: Determine the incident angle α based on the angle measurement of the incident light. This means that in the UV-visible light detection system, we need to use a high-precision angular position sensor or laser rangefinder to measure the incident angle of light from the light source to the grating. This angle directly affects the propagation path of the subsequent light, so the accuracy and stability of the measurement are crucial. For example, in one embodiment, assuming that we use a He-Ne laser as the light source, the measurement result of the incident angle α is displayed as 15°.

[0075] S120: Determine the diffraction angle β based on the angle measurement of the outgoing light. This step requires us to set an angle sensor at a fixed position behind the grating to capture and record the specific direction of the outgoing light. Since light of different wavelengths will be dispersed into different angles after diffraction by the grating, this measurement not only helps us verify the wavelength selection ability of the system, but also further confirms whether the design of the optical path is reasonable. In one embodiment, when we set the system to operate at a specific wavelength, the measured diffraction angle of the outgoing light is 45°.

[0076] S130: Use the formula θ = (α + β) / 2 to calculate the θ value and verify whether the θ value is within the range of 27°~30°. This formula aims to find an optimal balance point so that the angle between the incident and outgoing light paths can maximize the stability and transmission efficiency of the optical signal. In this example, substituting the previously measured data (α=15°, β=45°), we can calculate θ = (15° + 45°) / 2 = 30°, which is exactly within the target range.

[0077] S140: Adjust the angle of the grating to ensure that the θ value meets the requirement of 27°~30°. This adjustment can be done automatically by the electric drive or manually by the operator until the ideal θ value is reached. Specifically, in our experimental equipment, the precise positioning of the θ value is finally achieved by fine-tuning the position of the screws on the grating mounting base.

[0078] In response to the above problem 1: signal attenuation due to scattering and absorption under high light density conditions, the grating angle is precisely adjusted to the optimal range to reduce unnecessary reflections and scattering in the optical path, thereby improving the signal transmission efficiency in the high light density area.

[0079] The reduction in signal-to-noise ratio caused by noise interference under low light density conditions mentioned in question 2 can be reduced by optimizing the grating angle and improving the optical path layout to reduce the impact of background noise. For example, in some experimental settings, adjusting θ to around 28° can significantly reduce the system noise level.

[0080] For the third problem: the problem of reduced dynamic range in fast scanning mode, a wider dynamic range coverage can be achieved by designing a grating drive mechanism with fast response characteristics and cooperating with efficient data processing algorithms. In one embodiment, a customized stepper motor is used to quickly and accurately adjust the grating angle, combined with advanced real-time data analysis software, which significantly improves the performance under fast scanning conditions.

[0081] The wavelength calibration deviation problem in multi-wavelength detection involved in question 4 is mainly solved by introducing an adaptive calibration mechanism. Specifically, a calibration process can be automatically performed after each wavelength switch, using known standard materials as reference points to automatically correct any potential drift errors. This method not only simplifies the operation process, but also ensures the consistency of the detection results during long-term operation.

[0082] Finally, the problem of light intensity fluctuation caused by poor thermal stability during long-term continuous use can be alleviated by improving the design of the optical system. On the one hand, materials with good thermal conductivity are used to make gratings and other key components; on the other hand, the heat dissipation structure of the entire system is improved, such as adding heat sinks or forced air cooling devices, so as to keep the grating temperature stable. In addition, the grating position can be regularly corrected to dynamically compensate for small displacements caused by temperature changes.

[0083] In summary, through the careful design and optimization of each link of the UV-visible detector optical system, the present invention effectively solves multiple key problems in practical applications and significantly improves the stability and reliability of the instrument under various complex conditions.

[0084] Next, see Figure 4 , describing the specific optimization steps of the present invention in step S200 based on the meridian curvature and sagittal curvature of the square M1 reflector 2, including: S210: Obtain the initial object distance L1 from the light source to the M1 reflector and the initial image distance L2 from the slit to the M1 reflector. This step determines the initial position parameters of the M1 reflector in a specific configuration by experimental means, which are the basis for subsequent optimization. For example, in a specific design of a UV-visible detector optical system, the experiment may show that the initial object distance L1 from the light source to M1 is 150 mm, and the initial image distance L2 from the slit to M1 is 200 mm.

[0085] S220: Establish the astigmatism aberration diagram of the edge light, and calculate the optimal M1 meridian curvature Ct and sagittal curvature Cs. This process involves using optical software or manual calculation to establish the edge light path and draw the astigmatism aberration diagram based on the initial object distance L1 and initial image distance L2 of the M1 reflector, as well as the positional relationship between the light source and the slit. Then, by analyzing the astigmatism aberration diagram, find the optimal curvature value that can minimize the astigmatism. Specifically, this can be achieved by solving the following formula: .

[0086] Where Ct represents the meridian curvature, Cs represents the sagittal curvature, and alpha is a weight coefficient used to balance astigmatism and coma. The goal is to minimize astigmatism while taking into account the influence of coma. In the specific optimization process, the initial values ​​of the meridian curvature and sagittal curvature may be set within the empirical value range, such as 0.005 to 0.01.

[0087] S230: Verify that the calculated meridian curvature Ct and sagittal curvature Cs meet the range of 110-120mm in the meridian direction and 120-130mm in the sagittal direction. This verification step ensures that the optimized M1 mirror can achieve the expected optical performance in practical applications. For example, the calculation results may show that the optimal meridian curvature Ct is 0.0086 mm⁻¹, corresponding to a radius of 116.3mm; the sagittal curvature Cs is 0.0078 mm⁻¹, corresponding to a radius of 128.2mm, both of which are within the required range.

[0088] If these range requirements are not met, repeat the above process by adjusting the object distance L1 or the image distance L2 until the best parameter combination that meets the conditions is found. This means that the initial object distance L1 or the initial image distance L2 needs to be adjusted, and the astigmatism aberration diagram of the marginal light needs to be recalculated until the appropriate meridian curvature Ct and sagittal curvature Cs are found. For example, after one adjustment, it may be found that after adjusting the object distance L1 to 155mm and the image distance L2 to 210mm, the new calculation results show that Ct is 0.0082 mm⁻¹ (radius 121.9mm) and Cs is 0.0075 mm⁻¹ (radius 133.3mm), which still does not meet the requirements, so further fine-tuning is required until satisfaction is found.

[0089] The above steps ensure that the meridional and sagittal curvatures of the M1 reflector can achieve optimal performance in the UV-Vis detector optical system to meet specific design requirements.

[0090] Next, see Figure 5 , describing the specific optimization steps based on the parameters of the square M2 reflector 4 in step S300 of the present invention.

[0091] S310: Measure the distance from the exit slit to M2, i.e., the object distance Lt of M2, and set the position variation range of the image distance Ls to the object distance Lt as 5 mm before and after the detector. This means that in the actual measurement process, it is necessary to determine the physical distance of the light from the exit slit to the M2 reflector, while ensuring that the variation range of the detector receiving surface is within 5 mm before and after. For example, in one embodiment, assuming that the measured object distance Lt is 100 mm, the allowable variation range of the detector position is 97.5 mm to 102.5 mm.

[0092] S320: Combine the spot diagram and astigmatism aberration diagram of the detector, and optimize the initial values ​​of the meridian curvature and sagittal curvature of M2 through simulation software. The spot diagram is used to evaluate the focus quality of the system, while the astigmatism aberration diagram reflects the light deviation in different directions. By analyzing these diagrams through simulation software, the meridian curvature and sagittal curvature of the M2 reflector can be preliminarily determined. Specifically, using optical design software such as Zemax or OpticStudio, input the values ​​of Lt and Ls, and calculate the initial meridian curvature Cm and sagittal curvature Cs.

[0093] S330: Use the formula ΔD = 2 * |Ls - Lt| / (Cm + Cs) to verify the initial value and adjust the object distance Lt of M2 so that Cm and Cs meet the range of 115-125mm (meridian) and 125-135mm (sagittal). The purpose of this formula is to adjust the curvature of the reflector according to the actual measured object distance and image distance to optimize the system performance. The ΔD in the formula represents the maximum allowable deviation, Cm is the meridian curvature, and Cs is the sagittal curvature. For example, if the initial measurement results in Cm of 120mm and Cs of 130mm, but the formula calculation finds that ΔD exceeds the preset deviation range, Lt needs to be adjusted until Cm and Cs are between 115-125mm and 125-135mm, respectively.

[0094] S340: Continue to optimize until the image quality meets the requirements, and record the optimized parameter combination. This step involves further adjusting the position and curvature of the M2 reflector, and finally achieving the ideal imaging effect through repeated iterations and simulation verification. For example, in the final optimization process, it may be found that under certain specific conditions, when Lt is adjusted to 98mm, Cm and Cs are 120mm and 130mm respectively, and the image quality of the system reaches the best state. At this time, these parameter values ​​should be recorded for subsequent production and debugging.

[0095] Next, see Figure 6 , describing the specific calculation steps based on the slit width Δx in step S400 of the present invention.

[0096] S410: Calculate according to the formula Δx = r * sin(1 / D). Wherein, Δx represents the slit width, r is the distance from the slit to the grating, and D is the angle of rotation of the grating per unit wavelength. The calculation formula of D is D = dλ / dΔ, dλ represents the interval between the spectral lines (in nm), and dΔ represents the distance that the spectral line rotates on the slit plane (in mm). The slit width can be calculated by this formula, which ensures the precise relationship between the slit width and the distance from the grating to the slit and the rotation angle per unit wavelength, so that the diffraction and interference effects of light after passing through the slit are optimal.

[0097] S420: Calculate the relationship between the wavelength λ and the grating rotation angle θ according to the formula 2 * sin(θ) * cos(K) = Nm * λ. Wherein, θ represents the rotation angle of the grating, 2K is the grating deflection angle, N is the number of grating lines, m is the order of the grating, and λ is the wavelength. This formula is used to describe the diffraction direction of light of different wavelengths after passing through the grating. By adjusting these parameters, the light of the target wavelength can generate the best light intensity signal on the detector.

[0098] S430: Use d = r * sin(Δθ) to calculate the number of wavelengths that the grating travels on the slit after it rotates by an angle (in mm). d is the actual distance (in mm) that the spectral line with an interval of 1 nm travels on the slit, r and Δθ are the distance from the slit to the grating and the angular dispersion of the grating, respectively. Through this formula, it can be verified whether the calculated D value falls within the ideal range of 6-7 nm / mm. This range is set based on the accuracy requirements of the UV-visible detector in actual applications to ensure the accuracy of the detection results.

[0099] S440: If the D value does not meet the above conditions, it is necessary to recalculate the D value at a specific wavelength λ by adjusting the number of grating lines N and the distance r from the grating to the slit until it reaches the range of 6-7 nm / mm. The number of grating lines N determines the resolution of the grating, and λ is the specific wavelength required for detection. By repeatedly adjusting these two parameters, the slit width and spectral resolution can be optimized under different experimental conditions, thereby improving the detection accuracy.

[0100] For example, in one embodiment, assume that the distance r from the grating to the slit of the UV-visible detector is 50 mm, the wavelength interval dλ is 10 nm, dΔ is 1.5 mm, the incident angle θ of the grating is 30°, and the number of lines N of the grating is 1200 lines / mm. First, calculate the rotation angle D per unit wavelength: .

[0101] Since 6.67 nm / mm falls within the range of 6-7 nm / mm, no further parameter adjustment is required. If the D value is not within this range, N or r can be adjusted for optimization. For example, increase the value of N or change the distance r until the D value meets the requirements.

[0102] The above describes the specific calculation steps and implementation details based on the slit width Δx in step S400, which ensures that the optical system design of the UV-visible detector is accurate and reliable.

[0103] Next, the specific steps of selecting a filter suitable for the wavelength range in step S500 of the present invention are described.

[0104] According to the required detection band, select a long-wave pass filter with a corresponding diameter of 14-16mm and a front cutoff wavelength between 300-350nm, and another long-wave pass filter with the same diameter of 14-16mm and a front cutoff wavelength between 510-560nm. For example, when designing the optical system of a UV-visible detector, if the target band is 320-700nm, you can choose long-wave pass filters with front cutoff wavelengths of 320nm and 530nm. These two filters will allow light above 320nm and above 530nm to pass, respectively, thereby effectively filtering out unwanted short-wavelength background light.

[0105] Neutral density dimming filters of models ZAB25~35 and ZAB10~20 are used to balance the impact of large energy differences caused by switching between different light sources, which makes circuit board sampling and data processing difficult, and ensure that monochromatic light of appropriate intensity enters the detection area. In one embodiment, after switching to a tungsten lamp, the energy is one order of magnitude greater than that of a deuterium lamp. A neutral density dimming filter of model ZAB30 can be added to the optical path. The dimming filter can reduce the intensity of the incident light by about 70%, thereby effectively balancing the energy of the entire working band.

[0106] By comparing the actual wavelength distribution of the test light beam with the transmission wavelength range of the filter, it is possible to confirm whether the selected filter can effectively filter out unnecessary background light. Specifically, a spectrometer can be used to measure the wavelength distribution of the light beam after passing through the filter, and then compared with the transmittance curve of the filter to verify whether the transmission performance of the filter in the target band meets expectations. If it is found that the filter also has a high transmittance in some non-target bands, the filter selection or parameters need to be adjusted until the requirements are met.

[0107] Use imaging quality analysis tools such as spot diagrams and astigmatism aberration diagrams to confirm whether the final selected filter configuration can provide an ideal optical signal, and the formulated condition is that the imaging quality Q > 0.9. In this process, professional software can be used to generate spot diagrams and astigmatism aberration diagrams, which can intuitively show the impact of the filter on the optical signal. For example, the spot diagram can show the concentration of the light spot, while the astigmatism aberration diagram can show the focusing of the light beam at different focal planes. Image quality Q is a comprehensive evaluation index ranging from 0 to 1, where 1 represents perfect imaging. The optimal value is 0.9, which means that the optical signal after passing through the filter has a high signal-to-noise ratio and good imaging effect. This standard ensures that the data obtained during the inspection process has high accuracy and reliability. Setting the imaging quality Q > 0.9 is to ensure that the inspection system can maintain high optical performance under various conditions and reduce measurement errors caused by optical defects.

[0108] Next, the optimization steps based on the specific positioning of the imaging light beam convergence point and its energy requirement in step S600 of the present invention are described.

[0109] The focal plane position of the imaging beam is calculated through optical path simulation to ensure that the focal point of the imaging beam is located in a preset area of ​​2-3 mm in front of the detection surface. This step is to ensure that the light can be accurately focused on the predetermined position in front of the detector after refraction and reflection by the optical system. During the design process, the parameters of the optical components, such as the radius of curvature of the lens, the refractive index of the material, etc., can be input through optical path simulation software such as Zemax or OpticStudio to simulate the propagation path of the light beam through the optical system, thereby accurately calculating the focal plane position of the imaging beam. For example, in one embodiment, the optical system includes two convex lenses and one concave lens, and the simulation software calculates that the focus of the imaging beam is located 2.2 mm in front of the detection surface.

[0110] Analyze the diameter of the image point to ensure that it does not exceed the upper limit of 0.55mm to ensure high-resolution imaging. This step is mainly to ensure the clarity and resolution of the imaging. The size of the image point diameter directly affects the quality of the imaging. If the image point is too large, it will cause blurred imaging. Therefore, by measuring the diameter of the imaging point and adjusting the optical system parameters, such as lens spacing, curvature, etc., to ensure that the image point diameter does not exceed 0.55mm. For example, specifically, in the design of a certain UV-visible detector, the image point diameter is photographed with a macro lens and measured in the image processing software, and the distance between the lenses is adjusted so that the final imaging point diameter remains at around 0.5mm.

[0111] The energy of the imaging light beam falling on the detection surface is measured by a light intensity meter, and the light energy E is calculated. In this step, the light energy falling on the detection surface is measured by a light intensity meter, and then the light energy E is calculated based on the measurement results. The formula is E = P × t, where P represents the light power and t represents the exposure time. Generally, the light power P can range from 0.1mW to 10mW, and the exposure time t is generally between a few milliseconds and tens of milliseconds. The selection of the optimal value needs to be determined according to the specific detection requirements to ensure that there is no overexposure while ensuring the detection sensitivity. For example, in one experiment, the light intensity meter measured the light power to be 2mW and the exposure time to be 10ms, so the calculated light energy E was 0.02J. This energy level ensures that the signal is strong enough for detection without causing overexposure due to excessive energy.

[0112] Through the above steps, the imaging quality in the UV-visible detector optical system can be effectively optimized to ensure its high precision and high performance.

[0113] A design method of an ultraviolet-visible detector optical system of the present invention includes: This method aims to improve the performance of the ultraviolet-visible detector in a variety of complex environments, and mainly solves the above technical problems through the following steps: 1. Measurement of incident light and diffraction angle and adjustment of grating angle: First, in step S100, the incident angle α is determined based on the angle measurement of the incident light; then the diffraction angle β is determined based on the angle measurement of the outgoing light; then, the θ value is calculated using the formula θ = (α + β) / 2, and it is verified whether the θ value is within the range of 27°~30°; if it does not meet the requirements, the angle of the grating is adjusted to ensure that the θ value reaches the standard range. This step ensures the optimal working state of the grating, thereby improving the stability and accuracy of the optical system.

[0114] 2. Solve the problem of signal attenuation under high light density conditions: In order to overcome the signal attenuation under high light density conditions, the design method introduces a special anti-scattering coating and high-transmittance optical materials to reduce the scattering and absorption losses of the light beam during transmission. At the same time, a high-efficiency light collection device is used to improve the light energy utilization rate at the receiving end, ensuring that high-resolution detection results can still be obtained under high light density conditions.

[0115] 3. Dealing with the signal-to-noise ratio problem under low light density conditions: To address the problem of reduced signal-to-noise ratio under low light density conditions, the design method introduces advanced noise reduction technology and high-performance preamplifiers. Through precise background noise elimination algorithms, the impact of environmental interference is effectively reduced. Combined with highly sensitive detectors, the signal-to-noise ratio is improved, ensuring reliable detection performance under low light density.

[0116] 4. Dealing with the problem of reduced dynamic range in fast scanning mode: In order to adapt to the high demand in fast scanning mode, this method improves the dynamic response capability of the system by optimizing the optical path design and improving the key components with slow response speed. Specific measures include adding light intensity control devices and introducing high-speed response photodiodes, so that the system can quickly adjust under different light intensities, broaden the detection range, and ensure the accuracy and stability of data in fast scanning mode.

[0117] 5. Wavelength calibration in multi-wavelength detection: In multi-wavelength detection, in order to overcome the wavelength calibration deviation problem caused by filter characteristic drift, this method uses adaptive calibration technology and built-in standard wavelength reference source to monitor and automatically adjust wavelength calibration parameters in real time, ensuring the accuracy and consistency of multi-wavelength detection. At the same time, regular wavelength drift detection and manual correction operations are performed to further improve the stability and reliability of the system.

[0118] 6. Improve thermal stability during long-term use: In order to solve the problem of light intensity fluctuation caused by poor thermal stability during long-term continuous use, the design method introduces efficient thermal management solutions, such as heat sinks and cooling fans, as well as temperature compensation circuits, to ensure that the system always maintains an appropriate operating temperature range under various working environments, thereby improving the long-term stability of light intensity output.

[0119] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A UV-visible detector optical system, the system comprising: Light sources, wherein there are two light sources; A rotatable square M1 reflector, the incident light from the two light sources is reflected and converged by the square M1 reflector and then shines on a filter, and the two light sources and the square M1 reflector are arranged in an equilateral triangle; A diffraction grating, wherein the diffraction grating is arranged on the outgoing light path of the square M1 reflector, and a circular incident slit is arranged between the diffraction grating and the square M1 reflector; A rotatably arranged square M2 reflector, the square M2 reflector is arranged on the exit light path of the diffraction grating, and a circular exit slit is arranged between the square M2 reflector and the diffraction grating; The transflector is used to separate the outgoing light of the square M2 reflector into a reflected light path and a transmitted light path, and make the reflected light path enter the reference photocell and the transmitted light path enter the sample photocell.

2. The UV-visible detector optical system according to claim 1, characterized in that: The light sources are deuterium lamps and tungsten lamps. The distance between the two light sources and the square M1 reflector is 80mm-90mm. The inclination angle of the square M1 reflector is 12°-18° and the side length is between 20mm-30mm.

3. The UV-visible detector optical system according to claim 2, characterized in that: The diffraction grating adopts a holographic concave blazed grating with a wavelength range of 200nm-800nm, a number of engraved lines of 1200 lines / mm, a grating order of -1, and a nominal blazed wavelength of 300nm.

4. The UV-visible detector optical system according to claim 3, characterized in that: The grating incident angle of the diffraction grating is 0°-14.4°, and the distance between the diffraction grating and the circular incident slit is 110mm-130mm.

5. The UV-visible detector optical system according to claim 4, characterized in that: The square M2 reflector has an inclination angle of 8°-12°, a side length of 18mm-22mm, and a distance from the circular exit slit of 130mm-150mm.

6. The UV-visible detector optical system according to claim 5, characterized in that: It also includes holmium glass, which has a thickness of 1 mm and a diameter of 5 mm-10 mm and is located 10 mm-20 mm in front of the reference photocell.

7. The UV-visible detector optical system according to claim 6, characterized in that: The filter has a diameter of 10 mm to 20 mm, a thickness of 1 mm to 2 mm, and a distance from the circular incident slit of 10 mm to 20 mm.

8. The UV-visible detector optical system according to claim 7, characterized in that: The distance between the circular incident slit and the square M1 reflector is 190mm-210mm, and the aperture size of the circular incident slit is 0.8mm-1.2mm; The distance between the circular exit slit and the diffraction grating is 110mm-130mm, and the distance between the diffraction grating and the circular incident slit does not differ by more than 1mm. The diameter of the circular exit slit does not differ from the diameter of the circular incident slit by more than 0.1mm.

9. The UV-visible detector optical system according to claim 8, characterized in that: The effective reflection area of ​​the transflective mirror has a side length of 13mm-16mm, an inclination angle of 45°, a distance of 73mm-80mm from the square M1 reflector, and a horizontal offset of 1.5mm-2.5mm to the right along the main light path.

10. A method for designing an ultraviolet-visible detector optical system, used for designing an ultraviolet-visible detector optical system as claimed in any one of claims 1 to 9, characterized in that: include: Calculate the sum of the angles between the circular entrance slit, the circular exit slit and the diffraction grating; Set the curvature of the square M1 reflector and the square M2 reflector in the meridian and sagittal directions; Set the object distance and image distance of the square M2 reflector; Calculate the slit width corresponding to the required bandwidth, calculate the relationship between the wavelength and the grating rotation angle, calculate the grating rotation angle and the distance traveled on the slit corresponding to the monochromatic light wavelength, and verify the accuracy of the data through model simulation software; Select long-wave pass filter and neutral density filter to effectively obtain the required monochromatic light and filter out interference from other wavelengths. Set the imaging beam convergence point to be in front of the detection surface, set the image point size, and set the proportion of the detection surface light energy in the total light source energy.

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