Ultraviolet and visible spectrophotometer

Abstract

The invention discloses an ultraviolet and visible spectrophotometer, and relates to the field of analytical instruments. A light source switching mirror, a monochromator, a first spherical mirror, a plane mirror, a semi-transparent reflecting mirror, a second spherical mirror, a third spherical mirror, a sample chamber, a first light detector and a second light detector are sequentially arranged on an output main light path of the light source; the optical filter wheel is arranged on the light inlet side or the light outlet side of the monochromator; the optical filter wheel comprises a wheel body, the wheel body is sequentially divided into a first optical filter section, a second optical filter section, a third optical filter section, a fourth optical filter section and a fifth optical filter section, the second through hole, the third through hole, the fourth through hole and the fifth through hole are covered with a second substrate, a third substrate, a fourth substrate and a fifth substrate respectively, a notch optical filter film system is stacked on the fourth substrate, and a notch optical filter film system is stacked on the fifth substrate. The notch filtering film system comprises a high-refractive-index film layer and a low-refractive-index film layer. According to the invention, consumption of computing resources is avoided.

Description

Technical Field

[0001] The present application relates to the field of analytical instruments, and in particular to an ultraviolet-visible spectrophotometer. Background Art

[0002] In the field of optical analysis instruments, UV-visible spectrophotometer is an indispensable tool in the laboratory. Among the many technical indicators of UV-visible spectrophotometer, baseline flatness is one of the most concerned focuses of users. Baseline flatness is an important indicator to measure the performance of the spectrometer. It reflects the stability and consistency of the output signal (such as absorbance) of the spectrometer without sample or background interference.

[0003] Too high a spectral energy peak is an important factor affecting baseline flatness. When the existing UV-visible spectrophotometer performs a tungsten lamp spectral energy scan, due to the superposition effect of different components in the optical path system on the light, the spectrum has a peak in the 652nm to 682nm band. When the system spectral energy has a peak value, when performing a baseline flatness scan at the band where the peak value is located, due to the wavelength repeatability error, in this band, the absorbance values ​​before and after the baseline flatness scan will have a large difference, which leads to a poor baseline flatness index.

[0004] In practical applications, a polynomial function similar to the original spectral curve is constructed to approximate and replace the original curve, and the shape of the spectral curve is finely adjusted by adjusting the coefficients of the polynomial. However, this method increases the complexity of the algorithm and the consumption of computing resources. Summary of the invention

[0005] The purpose of the present application is to provide a UV-visible spectrophotometer, which can solve the problem of poor baseline flatness index by changing the structure of the filter wheel, thereby avoiding the consumption of computing resources.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a UV-visible spectrophotometer, comprising:

[0008] A light source, wherein a light source switching mirror, a monochromator, a first spherical mirror, a plane mirror, a semi-transparent reflecting mirror, a second spherical mirror, a third spherical mirror, a sample chamber, a first light detector and a second light detector are sequentially arranged on the output main light path of the light source;

[0009] A filter wheel, the filter wheel being arranged on the light incident side or the light exiting side of the monochromator;

[0010] The filter wheel comprises a wheel body, on which a first filter section, a second filter section, a third filter section, a fourth filter section and a fifth filter section are sequentially divided; a first through hole, a second through hole, a third through hole, a fourth through hole and a fifth through hole are respectively arranged on the first filter section, the second filter section, the third filter section, the fourth filter section and the fifth filter section; a second substrate, a third substrate, a fourth substrate and a fifth substrate are respectively covered on the second through hole, the third through hole, the fourth through hole and the fifth through hole; a notch filter film system is stacked on the fourth substrate, and the notch filter film system comprises a high refractive index film layer and a low refractive index film layer with a cross-stacked optical thickness of one quarter wavelength.

[0011] Optionally, the fourth substrate includes a substrate A, a substrate B and a substrate C which are connected in sequence, the substrate A is adjacent to the third substrate, the substrate C is adjacent to the fifth substrate, and a notch filter film system is stacked on the substrate B.

[0012] Optionally, the fourth substrate is used to transmit a light beam with a wavelength between 490 nm and 760 nm, the substrate A and the substrate C are yellow glass, and the substrate B is quartz glass or K9 glass.

[0013] Optionally, the monochromator includes an incident slit, a collimating mirror, a grating, a condenser and an exit slit arranged in sequence along the light path direction, the light incident side is located between the light source switching mirror and the incident slit, close to the incident slit, and the light exit side is located between the first spherical mirror and the exit slit, close to the exit slit.

[0014] Optionally, the first filter segment is used to transmit light beams of the entire wavelength band, the second filter segment is used to transmit light beams with wavelengths between 356nm and 390nm, the third filter segment is used to transmit light beams with wavelengths between 390nm and 490nm, and the fifth filter segment is used to transmit light beams with wavelengths between 760nm and 1100nm.

[0015] Optionally, the material of the high refractive index layer is oxide or fluoride, and the material of the low refractive index layer is oxide or fluoride.

[0016] Optionally, the high refractive index film layer includes at least one of a LaF3 film layer, a GdF3 film layer, a NdF3 film layer, a YF3 film layer, a YbF3 film layer, an Al2O3 film layer, a TiO2 film layer, a Nb2O5 film layer, a Ta2O5 film layer, a ZrO2 film layer, and a HfO2 film layer, and the low refractive index film layer includes at least one of a MgF2 film layer, a Na3AlF6 film layer, an AlF3 film layer, a SiO2 film layer, and an Al2O3 film layer.

[0017] Optionally, the number of layers of the low-refractive-index film layer and the high-refractive-index film layer are both greater than or equal to 2.

[0018] Optionally, the second substrate is purple glass, the third substrate is cyan glass, and the fifth substrate is red glass.

[0019] Optionally, the light source includes a deuterium lamp and a tungsten lamp, the deuterium lamp and the tungsten lamp are respectively arranged on the light incident side of the light source switching mirror, the tungsten lamp is used to emit a visible light beam, and the deuterium lamp is used to emit an ultraviolet light beam.

[0020] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0021] The present application provides a UV-visible spectrophotometer, comprising:

[0022] A light source, wherein a light source switching mirror, a monochromator, a first spherical mirror, a plane mirror, a semi-transparent reflecting mirror, a second spherical mirror, a third spherical mirror, a sample chamber, a first light detector and a second light detector are sequentially arranged on the output main light path of the light source; a filter wheel, wherein the filter wheel is arranged on the light incident side or the light exiting side of the monochromator; the filter wheel comprises a wheel body, wherein a first filter section, a second filter section, a third filter section, a fourth filter section and a fifth filter section are sequentially divided on the wheel body, a first through hole, a second through hole, a third through hole, a fourth through hole and a fifth through hole are respectively arranged on the first filter section, the second filter section, the third filter section, the fourth filter section and the fifth filter section, a second substrate, a third substrate, a fourth substrate and a fifth substrate are respectively covered on the second through hole, the third through hole, the fourth through hole and the fifth through hole, a notch filter film system is stacked on the fourth substrate, and the notch filter film system comprises a high refractive index film layer and a low refractive index film layer of a quarter wavelength optical thickness cross-stacked. Among them, after the visible light beam or ultraviolet light beam passes through the light source switching mirror, it enters the monochromator and the filter wheel in turn. The monochromator decomposes the mixed light into monochromatic light of different wavelengths, and the filter wheel is used to remove stray light that does not meet the requirements. By applying a notch filter film on the filter wheel, the peak energy of the wavelength band between 652nm and 682nm in the optical path is reduced, which not only effectively eliminates the interference peak in the spectrum, but also significantly improves the baseline flatness index of the ultraviolet visible spectrophotometer, making the measurement results more accurate and reliable. Subsequently, the screened and adjusted light beam is incident on the first spherical mirror and the plane mirror in turn, and finally splits the light through the semi-transparent and semi-reflective mirror. The semi-transparent and semi-reflective mirror divides the light beam into two. One part of the light beam passes through the sample chamber through the second spherical mirror and irradiates the first light detector; while the other part of the light beam is guided by the third spherical mirror, also passes through the sample chamber, and finally reaches the second light detector. This process realizes the efficient use of the light beam and improves the accuracy and stability of spectral analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic structural diagram of an ultraviolet-visible spectrophotometer according to an exemplary embodiment;

[0025] Figure 2 is a schematic structural diagram of a filter wheel according to an exemplary embodiment;

[0026] Figure 3 is a schematic structural diagram of a filter wheel according to yet another exemplary embodiment;

[0027] Figure 4 It is a relative spectrum energy scanning curve diagram of the tungsten lamp used in the ultraviolet visible spectrophotometer provided by the prior art;

[0028] Figure 5 It is a baseline flatness scanning curve diagram of a UV-visible spectrophotometer provided by the prior art;

[0029] Figure 6 This is a transmittance test chart of a yellow glass coated with a notch filter film using an ultraviolet-visible spectrophotometer according to an exemplary embodiment;

[0030] Figure 7 is a baseline flatness scanning curve diagram of a yellow glass coated with a notch filter film tested by an ultraviolet-visible spectrophotometer according to an exemplary embodiment;

[0031] Figure 8 is a transmittance test chart of a UV-visible spectrophotometer testing quartz glass or K9 glass coated with a notch filter film according to another exemplary embodiment;

[0032] Fig. 9 is a baseline flatness scanning curve diagram of a quartz glass or K9 glass coated with a notch filter film tested by an ultraviolet-visible spectrophotometer according to another exemplary embodiment;

[0033] Fig.10 is a relative spectral energy scanning curve diagram of a tungsten lamp used in an ultraviolet visible spectrophotometer after a notch filter reduces the spectral energy of the tungsten lamp according to another exemplary embodiment;

[0034] Description of reference numerals:

[0035] 1-light source switching mirror; 2-first spherical mirror; 3-plane mirror; 4-semi-transparent reflecting mirror; 5-second spherical mirror; 6-third spherical mirror; 7-sample chamber; 8-first light detector; 9-second light detector; 10-deuterium lamp; 11-tungsten lamp; 12-incident slit; 13-collimating mirror; 14-grating; 15-condenser; 16-exit slit; 17-wheel body; 171-first filter section; 172-second filter section; 173-third filter section; 174-fourth filter section; 175-fifth filter section; 174a-first area; 174b-second area; 174c-third area; 1711-fourth area; 1712-fifth area. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0038] Figure 1 is a schematic diagram of the structure of a UV-visible spectrophotometer according to an exemplary embodiment. Figure 1 As shown, the UV-Vis spectrophotometer includes:

[0039] The light source, on the output main light path of the light source, is sequentially provided with a light source switching mirror 1, a monochromator, a first spherical mirror 2, a plane mirror 3, a semi-transparent reflecting mirror 4, a second spherical mirror 5, a third spherical mirror 6, a sample chamber 7, a first light detector 8 and a second light detector 9.

[0040] For example, a high-intensity, high-stability deuterium lamp 10 and a tungsten lamp 11 are used as light sources, wherein the deuterium lamp 10 is used to emit an ultraviolet light beam, and the tungsten lamp 11 is used to emit a visible light to near-infrared light beam. The continuous spectrum emitted by the deuterium lamp 10 covers the ultraviolet region from 190nm to 400nm, while the tungsten lamp 11 covers the visible light to near-infrared region from 400nm to 1100nm.

[0041] The light source switching mirror 1 is arranged on the main output path of the light source to realize smooth switching between the ultraviolet light region and the visible light region. The monochromator is used to decompose the composite light emitted by the light source into monochromatic light and allow light of a specific wavelength to pass through. After the light source passes through the monochromator, the light will be reflected and focused by a series of spherical mirrors and plane mirrors 3 to ensure that the light can propagate to the sample chamber 7 along a predetermined path. The semi-transparent reflector 4 divides the light into two, one part of the light is reflected to the first light detector 8 for measuring the reference light intensity, and the other part is transmitted and continues to propagate to the sample chamber 7. The sample chamber 7 is used to place the sample to be tested, and is usually made of a highly light-transmitting material, and a temperature control system is configured to keep the sample temperature constant. The first light detector 8 and the second light detector 9 are used to receive the optical signals of the reference light and the sample light, respectively, and convert them into electrical signals.

[0042] The filter wheel 17 is arranged on the light incident side or the light exiting side of the monochromator and is used to filter out other unnecessary spectral components.

[0043] like Figure 2 As shown, the filter wheel 17 includes a wheel body, on which a first filter segment 171, a second filter segment 172, a third filter segment 173, a fourth filter segment 174 and a fifth filter segment 175 are sequentially divided; a first through hole, a second through hole, a third through hole, a fourth through hole and a fifth through hole are respectively arranged on the first filter segment 171, the second filter segment 172, the third filter segment 173, the fourth filter segment 174 and the fifth filter segment 175; a second substrate, a third substrate, a fourth substrate and a fifth substrate are respectively covered on the second through hole, the third through hole, the fourth through hole and the fifth through hole; no substrate is arranged on the first through hole; a notch filter film system is stacked on the fourth substrate, wherein the notch filter film system includes a cross-stacked high refractive index film layer and a low refractive index film layer with a quarter wavelength optical thickness.

[0044] In each filter segment, the first through hole to the fifth through hole are used for light to enter, and the shapes of the first through hole to the fifth through hole are not limited. Figure 2 The fan-shaped hole is used as an example for illustration, and it can also be set to a circular hole, a square hole, a polygonal hole or an irregular hole.

[0045] The corresponding second to fifth substrates are covered on each through hole. These substrates not only provide stable support for the filter wheel 17, but also filter the light passing through by their materials. There is no limitation on the fixing method of the substrate on the wheel body. For example, the substrate can be connected to the wheel body 17 by bonding or snap-fitting, so that the substrate covers each through hole.

[0046] It should be noted that the materials of the second substrate, the third substrate, the fourth substrate and the fifth substrate are not limited in the present application, as long as the substrate can transmit a light beam of a corresponding wavelength during scanning.

[0047] A notch filter film system is stacked on the fourth substrate. The notch filter film system is composed of alternating high-refractive index film layers and low-refractive index film layers with a quarter-wavelength optical thickness. This alternating stacking structure utilizes the interference principle of light, so that light of a specific wavelength undergoes destructive interference when passing through the film system, thereby achieving the purpose of filtering out the light of that wavelength. When light passes through the notch filter film system, the high-refractive index film layer and the low-refractive index film layer will produce different phase delays for the light. By controlling the thickness and refractive index of the film layer, light of a specific wavelength is reflected and interfered multiple times inside the film system, and eventually cancels each other out.

[0048] In one achievable manner, Figure 2 As shown, the first filter segment is used to transmit the light beam of the full wavelength band during scanning, the second filter segment is used to transmit the light beam of wavelength between 356nm and 390nm during scanning, the third filter segment is used to transmit the light beam of wavelength between 390nm and 490nm during scanning, and the fifth filter segment is used to transmit the light beam of wavelength between 760nm and 1100nm during scanning. The light beam of the full wavelength band refers to the light beam of wavelength between 190nm and 1100nm. That is, the wavelength of the UV-visible spectrophotometer is 190nm to 1100nm, and the first filter band has no base, so it can transmit light beams of all wavelength bands.

[0049] A notch filter film system is stacked on the fourth substrate, and the notch filter film adopts a method of alternating arrangement of high refractive index film layers and low refractive index film layers.

[0050] For example, the second substrate is set to purple glass, the third substrate is set to cyan glass, and the fifth substrate is set to red glass. The present application does not limit the setting of the substrate in the first filter segment 171, as long as the first through hole of the filter segment can pass through the full-band light beam. The present application does not limit the specific material of the fourth substrate, as long as the light beam with a wavelength between 490nm and 760nm can pass through the fourth substrate. The fourth substrate on the fourth filter segment 174 is yellow glass, such as JB6.

[0051] When the UV-visible spectrophotometer performs spectral analysis, it controls the rotation of the filter wheel to filter the light beam within a specific wavelength range. When the instrument needs to scan within the wavelength range of 190nm to 356nm, the filter wheel will rotate accordingly so that the light beam passes through the first filter segment 171. In this process, the wavelength range of the light beam is subdivided into two different areas: the wavelength range of 190nm to 296nm corresponds to the fourth area 1711 of the first filter segment 171, and the wavelength range of 296nm to 356nm corresponds to the fifth area 1712 of the first filter segment 171. This distinction is based on the fact that the filter wheel used by the company is a standard part and is suitable for different models of instruments. Since different models of instruments may have a substrate or no substrate in the 1711 area, when performing spectral scanning, the program will be executed according to the established standards to ensure that the light beam can accurately pass through the corresponding filter area.

[0052] During the operation of the instrument, when it is necessary to scan light of different wavelengths, the filter wheel will be positioned to the corresponding band. For example, when the instrument needs ultraviolet light from 190nm to 256nm, since the light in this wavelength range belongs to ultraviolet light, if there is a substrate, it will be absorbed, so no substrate is needed when passing ultraviolet light. This process ensures that the instrument can accurately control the wavelength of the light beam according to different analysis requirements, thereby providing accurate conditions for the spectral analysis of the sample.

[0053] When the wavelength of the light beam is between 356nm and 390nm, it enters the second filter segment 172; when the wavelength of the light beam is between 390nm and 490nm, it enters the third filter segment 173; when the wavelength of the light beam is between 490nm and 760nm, it enters the fourth filter segment 174; when the wavelength of the light beam is between 760nm and 1100nm, it enters the fifth filter segment 175. As the color filter wheel enters the optical path in the 490nm to 760nm band, that is, the filter wheel works in the fourth filter segment 174, the contrast Figure 4 and Figure 6 , Figure 4 FIG. 1 shows a relative spectrum energy scanning curve of a tungsten lamp 11 used in a UV-visible spectrophotometer provided in the prior art. Figure 6 The figure shows the transmittance test of yellow glass coated with notch filter film by UV-visible spectrophotometer after applying the filter wheel provided by the present application. Figure 4 It can be concluded that the light energy emitted by the tungsten lamp 11 reaches a significant peak in the wavelength range of 652nm to 682nm. However, due to the wavelength repeatability error, in this wavelength range, there will be a large difference between the absorbance values ​​before and after the baseline flatness scan, resulting in a poor baseline flatness index, affecting the stability and accuracy of the measurement. The filter wheel in this application is used in a UV-visible spectrophotometer. Figure 6It can be seen that the transmittance of the instrument in the band of 652nm to 682nm is significantly reduced, thereby effectively reducing the peak energy of the tungsten lamp 11 and improving the baseline flatness index. This improvement not only reduces the light interference during the measurement process, but also improves the measurement accuracy and stability of the instrument.

[0054] Baseline flatness is a key parameter to measure the stability of a spectrophotometer and is directly related to the accuracy of the measurement results. Figure 5 This is a baseline flatness scanning curve diagram of a UV-visible spectrophotometer in the prior art. It can be clearly seen from the figure that the absorbance value fluctuates between -0.0006Abs and 0.00057Abs, and this range of fluctuation is sufficient to cause significant errors in the measurement results in high-precision analysis. Figure 7 This is a test chart of the transmittance of yellow glass coated with a notch filter film by a UV-visible spectrophotometer shown in this application. It can be seen that the fluctuation range of the absorbance value is greatly reduced to between -0.00015Abs and 0.00015Abs. Obviously, the baseline flatness index of the UV-visible spectrophotometer has been significantly improved.

[0055] In another achievable manner, the fourth substrate includes a substrate A, a substrate B and a substrate C which are connected in sequence, the substrate A is adjacent to the third substrate, the substrate C is adjacent to the fifth substrate, and a notch filter film system is stacked on the substrate B.

[0056] like Figure 3 As shown, the fourth filter segment 174 is divided into a first area 174a, a second area 174b and a third area 174c in sequence, and a substrate A, a substrate B and a substrate C are respectively arranged on the first area 174a, the second area 174b and the third area 174c. The wheel body is provided with a second through hole, a third through hole and a fifth through hole in the second filter segment 172, the third filter segment 173 and the fifth filter segment 175 in a one-to-one correspondence, and the filter wheel 17 also includes a purple glass covering the second through hole, a cyan glass covering the third through hole, and a red glass covering the fifth through hole. No substrate is arranged at the first through hole. The fourth substrate includes a substrate A, a substrate B and a substrate C adjacent to each other in sequence, the substrate A is adjacent to the cyan glass, and the substrate C is adjacent to the red glass. The above adjacent arrangement is conducive to the smooth transition of light. Among them, the notch filter film is evaporated on the substrate B, and the substrate A and the substrate C are set to yellow glass. Through precise wavelength selection, the filtering effect of light is further refined. Relative Figure 2 The arrangement method reduces the cost.

[0057] It should be noted that if the filter film is coated on substrate A and substrate C, although the yellow glass itself has certain filtering properties and can absorb some blue light and purple light, this approach will bring a problem. Yellow glass will not only reduce the light in the 652nm to 682nm band, but also reduce the light in the 490nm to 652nm and 682nm to 762nm bands. This means that in addition to the target band, the light in other bands will also be affected, which may cause distortion or inaccuracy of the experimental data. Therefore, compared to coating the filter film on substrate A and substrate C, it is more ideal to directly coat the notch filter film on substrate B, and the material of substrate B can be quartz glass or K9 glass. These two materials have good optical properties and stability. When scanning the wavelength, the notch filter film will only work in the 652nm to 682nm band, effectively filtering out the light in the target band without causing unnecessary effects on the light in other bands. This treatment method ensures the accuracy and reliability of the experimental results. Figure 6 A transmittance test chart of yellow glass coated with a notch filter film is shown after using the filter wheel provided by the present application with an ultraviolet-visible spectrophotometer. Figure 8 The figure shows the transmittance test of quartz glass or K9 glass coated with notch filter film by UV-visible spectrophotometer. Figure 6 compared to, Figure 8 The light bandwidth cut by quartz glass or K9 glass is narrower and the cutting effect is better.

[0058] When the UV-visible spectrophotometer is working, as the filter wheel 17 cuts into the light path in the 490nm to 760nm band, that is, when the filter wheel 17 works in the fourth filter segment 174, it cuts into the filter segment corresponding to substrate A in the 490nm to 652nm band, cuts into the filter segment corresponding to substrate B in the 652nm to 682nm band, and cuts into the filter segment corresponding to substrate C in the 682nm to 760nm band. The region from 652nm to 682nm is where the spectral energy of the tungsten lamp 11 is most concentrated. The peak energy of this band needs to be reduced to make the spectral curve smoother. In order to more intuitively demonstrate the changes of the UV-visible spectrophotometer of the present application, a comparative analysis is performed. Figure 4 and Fig.10 The relevant data in Figure 4 The relative spectral energy scanning curve of the tungsten lamp 11 of the UV-visible spectrophotometer in the prior art is shown. Fig.10The figure is a relative spectral energy scanning curve of the tungsten lamp 11 after applying the filter wheel provided by the present application. Through careful comparison, it can be clearly seen that in the key band of 652nm to 682nm, the UV-visible spectrophotometer using the filter wheel 17 successfully reduces the peak energy of the tungsten lamp, making the spectrum curve in this area present a more ideal shape, and improving the baseline flatness of the instrument. The present application combines the characteristics of the spectrum of the tungsten lamp 11, the mechanical structure of the filter wheel 17 and the actual needs of spectrum scanning, and fits the tungsten lamp peak energy reduction curve through precise calculation, and imports the fitted peak reduction curve into the TFCalc software. Through software design, a film system that reduces the peak energy of the tungsten lamp can be realized. The designed film system is plated with the company's own electron beam evaporation coating machine. The substrate is yellow glass and quartz glass. The peak energy is effectively reduced through the plated notch filter film.

[0059] As one of the important indicators to measure instrument performance, baseline flatness is directly related to the accuracy and reliability of measurement results. An ideal baseline flatness scanning curve should be smooth and close to zero baseline. Any deviation may introduce errors and affect the accuracy of analysis results. Figure 5 The baseline flatness scanning curve of the UV-visible spectrophotometer under the existing technical conditions is shown. As can be seen from the figure, its absorbance value fluctuates between -0.0006Abs and 0.00057Abs. This fluctuation may become an interference factor that cannot be ignored in high-precision analysis. In contrast, Fig. 9 The scanning curve of the baseline flatness of the ultraviolet visible spectrophotometer of the present application for testing the quartz glass or K9 glass coated with the notch filter film is shown. By improving the structure of the filter wheel 17 in the ultraviolet visible spectrophotometer, that is, setting the fourth substrate to be the substrate A, substrate B and substrate C adjacent to each other in sequence, and evaporating the notch filter film on the substrate B. The baseline flatness of the ultraviolet visible spectrophotometer is significantly improved. At this time, the fluctuation range of the absorbance value is reduced to -0.000085Abs to 0.000125Abs. This change means that the performance of the instrument has been significantly improved.

[0060] In one feasible manner, the monochromator includes an incident slit 12, a collimating lens 13, a grating 14, a condenser 15 and an exit slit 16 arranged in sequence along the light path direction, the light incident side is located between the light source switching mirror 1 and the incident slit 12, close to the incident slit 12, and the light exiting side is located between the first spherical mirror 2 and the exit slit 16, close to the exit slit 16.

[0061] This embodiment takes the placement of the filter wheel on the light-emitting side of the monochromator (i.e., after the exit slit 16) as an example to explain the working principle of the UV-visible spectrophotometer provided by the present application as follows:

[0062] The light emitted by the deuterium lamp 10 or the tungsten lamp 11 is reflected by the light source switching mirror 1 and then projected to the incident slit 12. The width of the incident slit 12 determines the divergence angle of the light beam entering the monochromator. After passing through the incident slit 12, the light beam enters the collimator 13, grating 14, and condenser 15 inside the monochromator in sequence. The collimator is used to correct the divergent light into parallel light to ensure that the light can be accurately projected onto the grating 14. The grating 14 disperses the parallel light into spectra of different wavelengths according to its diffraction effect. Subsequently, the condenser 15 refocuses these dispersed spectra to form a series of clear light beams, which are output through the exit slit 16. At this point, the light has been converted into monochromatic light of a specific wavelength, which passes through the filter wheel and enters the spectroscopic system. In this embodiment, the filter wheel is located after the exit slit 16, and can selectively transmit or block light of a specific wavelength as needed. The filter wheel can also be set before the incident slit 12. Then, the light is split into two beams by the first spherical mirror 2, the plane mirror 3, and the semi-transparent and semi-reflective mirror. One beam passes through the second spherical mirror 5, passes through the sample chamber 7, and is incident on the first light detector 8; the other beam passes through the third spherical mirror 6, also passes through the sample chamber 7, and is incident on the second light detector 9.

[0063] In the sample chamber 7, the sample to be tested is placed in a specific light path. When monochromatic light passes through the sample, part of the light will be absorbed by the sample, and the degree of absorption is closely related to factors such as the composition and concentration of the sample. The first light detector 8 and the second light detector 9 respectively measure the light intensity before and after passing through the sample, and by comparing the difference between the two, the absorbance of the sample can be calculated. According to the Lambert-Beer law, the absorbance is proportional to the sample concentration, thereby achieving quantitative analysis of the sample concentration. In this process, key links such as the switching of the light source, the splitting of the monochromator, the selection of the filter wheel, and the detection of the double beam together constitute the efficient and accurate working system of the UV-visible spectrophotometer.

[0064] In an achievable manner, the notch filter film system includes a cross-stacked high-refractive index film layer and a low-refractive index film layer of a quarter wavelength optical thickness, the material of the high-refractive index layer is an oxide or a fluoride, and the material of the low-refractive index layer is an oxide or a fluoride. The high-refractive index film layer includes at least one of a LaF3 film layer, a GdF3 film layer, a NdF3 film layer, a YF3 film layer, a YbF3 film layer, an Al2O3 film layer, a TiO2 film layer, a Nb2O5 film layer, a Ta2O5 film layer, a ZrO2 film layer, and a HfO2 film layer, and the low-refractive index film layer includes at least one of a MgF2 film layer, a Na3AlF6 film layer, an AlF3 film layer, a SiO2 film layer, and an Al2O3 film layer.

[0065] For example, MgF2, as a low refractive index material, is used in filter film systems from ultraviolet to visible light due to its high transmittance and low absorption characteristics.

[0066] In the design of the notch filter film system, the optical thickness of each film layer is precisely controlled to about a quarter of the wavelength. This design makes it possible for multiple reflections and interferences to occur between different film layers when light waves pass through the filter film system, thus forming a strong absorption or reflection effect at a specific wavelength.

[0067] For example, MgF2 is selected as the low refractive index film material of the notch filter film, and Al2O3 is selected as the high refractive index film material of the notch filter film. Its film system structure can be expressed as: S1.2H1.2LHLH LHLHL1.1H1.1L0.4HA, and the film system structure has 13 layers. Among them, S represents the substrate, A represents air, the numbers 1.2, 1.1 and 0.4 all represent multiples of the optical thickness of one quarter of the center wavelength, H represents a high refractive index film layer with an optical thickness of one quarter of the center wavelength, that is, an Al2O3 layer, and L represents a low refractive index film layer with an optical thickness of one quarter of the center wavelength, that is, a MgF2 layer, and the center wavelength is 662nm.

[0068] For example, Al2O3 is selected as the low refractive index film material of the notch filter film, and HfO2 and TiO2 are selected as the high refractive index film material of the notch filter film. The film system structure can be expressed as: S1.79L1.47H1.49L1.46H1.45L0.43H0.33L0.27H1.22L1.03H1.6L1.04H1.9L0.72H1.8L1.56H0.2L1.89M1.92L1.12M1.71L1.15M1.88L0.97M1.81L1.0 2M2L1.55M1.73L1.93M1.74L1.63M2L1.02M0.47L0.15H1.31L1.89M1.27L1.49H1L1.5H1.67L0.7H1.6L1.28H0.72L1.5H1.44L1.82H0.2L1.15H0.9LA, the film system has 53 layers in total. Among them, S represents substrate, A represents air, the number 1.79 represents the multiple of the optical thickness of one quarter of the central wavelength, H represents the high refractive index film layer of one quarter of the central wavelength optical thickness, i.e. HfO2 layer, L represents the low refractive index film layer of one quarter of the central wavelength optical thickness, i.e. Al2O3 layer, M represents the high refractive index film layer of one quarter of the central wavelength optical thickness, i.e. TiO2 layer, and the central wavelength is 662nm.

[0069] It should be noted that the above two film system structures are only two examples given in the present application, and are not specific limitations on the film system structure of the notch filter film proposed in the present application.

[0070] In one achievable manner, the number of layers of the low refractive index film layer and the high refractive index film layer are both greater than or equal to 2. There is no upper limit on the number of layers of the low refractive index film layer and the high refractive index film layer, and the number of layers of the low refractive index film layer and the high refractive index film layer are the same or differ by one layer. The refractive indexes of two adjacent film layers of the wave-limiting filter film are different, and the high refractive index film layers and the low refractive index film layers are arranged alternately. The combination of the low refractive index film layer and the high refractive index film layer forms a wave-limiting filter film. The key to the wave-limiting filter film being able to achieve a specific wavelength screening function lies in the difference in refractive index between the film layers within it. When light passes through these film layers, due to the different refractive indices, the light will experience different degrees of reflection and transmission.

[0071] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A UV-visible spectrophotometer, characterized in that: The UV-visible spectrophotometer comprises: A light source, wherein a light source switching mirror, a monochromator, a first spherical mirror, a plane mirror, a semi-transparent reflecting mirror, a second spherical mirror, a third spherical mirror, a sample chamber, a first light detector and a second light detector are sequentially arranged on the output main light path of the light source; A filter wheel, the filter wheel being arranged on the light incident side or the light exiting side of the monochromator; The filter wheel comprises a wheel body, on which a first filter segment, a second filter segment, a third filter segment, a fourth filter segment and a fifth filter segment are sequentially divided; a first through hole, a second through hole, a third through hole, a fourth through hole and a fifth through hole are respectively arranged on the first filter segment, the second filter segment, the third filter segment, the fourth filter segment and the fifth filter segment; a second substrate, a third substrate, a fourth substrate and a fifth substrate are respectively covered on the second through hole, the third through hole, the fourth through hole and the fifth through hole; the notch filter film system is stacked on the fourth substrate, and the notch filter film system comprises a high refractive index film layer and a low refractive index film layer with a cross-stacked optical thickness of one quarter wavelength.

2. The UV-visible spectrophotometer according to claim 1, characterized in that: The fourth substrate includes a substrate A, a substrate B and a substrate C which are connected in sequence, the substrate A is adjacent to the third substrate, the substrate C is adjacent to the fifth substrate, and the substrate B is stacked with the notch filter film system.

3. The UV-visible spectrophotometer according to claim 2, characterized in that: The fourth substrate is used to transmit a light beam with a wavelength between 490nm and 760nm during scanning, wherein the substrate A and the substrate C are yellow glass, the substrate B is quartz glass or K9 glass, the substrate A is used to transmit a light beam between 490nm and 652nm during scanning, the substrate B is stacked with the notch filter film and is used to transmit a light beam between 652nm and 682nm during scanning, and the substrate C is used to transmit a light beam between 490nm and 562nm during scanning.

4. The UV-visible spectrophotometer according to claim 1, characterized in that: The monochromator includes an incident slit, a collimating mirror, a grating, a condenser and an exit slit which are arranged in sequence along the light path direction; the light incident side is located between the light source switching mirror and the incident slit, close to the incident slit; the light exit side is located between the first spherical mirror and the exit slit, close to the exit slit.

5. The UV-visible spectrophotometer according to claim 1, characterized in that: The first filter segment is used to pass the full-band light beam when scanning, the second filter segment is used to pass the light beam with a wavelength between 356nm and 390nm when scanning, the third filter segment is used to pass the light beam with a wavelength between 390nm and 490nm when scanning, and the fifth filter segment is used to pass the light beam with a wavelength between 760nm and 1100nm when scanning. The wavelength of the full-band light beam is 190nm to 1100nm.

6. The UV-visible spectrophotometer according to claim 1, characterized in that: The material of the high refractive index film layer is oxide or fluoride, and the material of the low refractive index film layer is oxide or fluoride.

7. The UV-visible spectrophotometer according to claim 1, characterized in that: The high refractive index film layer includes at least one of a LaF3 film layer, a GdF3 film layer, a NdF3 film layer, a YF3 film layer, a YbF3 film layer, an Al2O3 film layer, a TiO2 film layer, a Nb2O5 film layer, a Ta2O5 film layer, a ZrO2 film layer, and a HfO2 film layer; the low refractive index film layer includes at least one of a MgF2 film layer, a Na3AlF6 film layer, an AlF3 film layer, a SiO2 film layer, and an Al2O3 film layer.

8. The UV-visible spectrophotometer according to claim 1, characterized in that: The number of layers of the low refractive index film layer and the high refractive index film layer are both greater than or equal to 2.

9. The UV-visible spectrophotometer according to claim 1, characterized in that: The second substrate is purple glass, the third substrate is cyan glass, and the fifth substrate is red glass.

10. The UV-visible spectrophotometer according to claim 1, characterized in that: The light source includes a deuterium lamp and a tungsten lamp, the deuterium lamp and the tungsten lamp are respectively arranged on the light incident side of the light source switching mirror, the tungsten lamp is used to emit a visible light beam, and the deuterium lamp is used to emit an ultraviolet light beam.

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