Static light scattering detection optical system and device

Abstract

The invention relates to the technical field of light scattering detection, and discloses a static light scattering detection optical system and device, and the system comprises a scattered light collection module which is used for converting scattered light at different angles generated after a to-be-detected solution is irradiated by a measurement light beam into to-be-detected parallel light beams, light beams at different positions in the parallel light beams to be detected correspond to scattered light at different angles; the photoelectric detector is used for receiving the to-be-detected parallel light beams and detecting light intensity information of the to-be-detected parallel light beams at different positions, a scattering light field in a preset scattering angle range is generated according to the light intensity information, and the scattering light field is used for detecting the absolute molecular weight of solute in the to-be-detected solution. According to the invention, continuous angle detection can be carried out on a scattered light field, a plurality of discrete photoelectric detectors are not needed, and the device has the advantages of compact and simple structure and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of light scattering detection, and in particular to a static light scattering detection optical system and device. Background Art

[0002] At present, the mainstream methods for relative molecular weight measurement are viscosity method and size exclusion chromatography. The viscosity method determines the viscosity-average molecular weight based on the pre-calibrated relationship between viscosity and molecular weight; the size exclusion chromatography uses the difference in molecular size to separate components of different molecular weights. This method requires calibration with a standard sample of known molecular weight, and the polymer shape of the standard sample should be as close as possible to the object being measured to ensure the accuracy of the test.

[0003] Static light scattering is an absolute molecular weight measurement method based on elastic light scattering theory. It measures the scattered light intensity at different angles to obtain conformational information of polymers, including molecular weight, mean square radius of gyration, and second virial coefficient. Typical static light scattering techniques can measure a wide range of molecular weights, generally 10 3 to 10 8 Dalton. Existing static light scattering detection devices all use multiple separate photodetectors to synchronously collect scattered light intensities at different angles, reconstruct the scattered light field, and then obtain information such as molecular weight based on theoretical formulas. Because molecular weight is highly dependent on the angle information of the scattered light, the static light scattering detection device must use a complex structure to strictly limit the detection angle, that is, the angular resolution requirement is high. In order to improve measurement accuracy and expand the measurement range, it is generally necessary to arrange more than 10 photodetectors at different angles, such as an 18-angle static light scattering detection device or a 21-angle static light scattering detection device. All of these lead to the complex structure and high cost of the static light scattering detection device. Summary of the Invention

[0004] In view of this, the present invention provides a static light scattering detection optical system and device to solve or partially solve the technical problems of complex structure and high cost of static light scattering solutions in the prior art.

[0005] The technical solutions proposed by the present invention are as follows:

[0006] In the first aspect, the present invention proposes a static light scattering detection optical system, comprising: a scattered light collection module, used to convert scattered light of different angles generated after the solution to be tested is irradiated by a measuring light beam into a parallel light beam to be detected, wherein the light beams at different positions in the parallel light beam to be detected correspond to scattered light at different angles; a photodetector, used to receive the parallel light beam to be detected and detect the light intensity information of the parallel light beam to be detected at different positions, and generate a scattered light field within a preset scattering angle range based on the light intensity information, and the scattered light field is used to detect the absolute molecular weight of the solute in the solution to be tested.

[0007] In some optional embodiments, the scattered light collection module includes:

[0008] The microscope objective lens is used to convert the scattered light at different angles generated by the solution to be tested after being irradiated by the measuring beam into an intermediate parallel beam;

[0009] The beam expansion unit is used to expand the intermediate parallel light beam to obtain the parallel light beam to be detected.

[0010] In some optional embodiments, the microscope objective lens is an infinite conjugate microscope objective lens, and the numerical aperture of the infinite conjugate microscope objective lens is greater than or equal to 0.7.

[0011] In some optional embodiments, the beam expansion unit includes:

[0012] A first convex lens is used to converge the intermediate parallel light beam;

[0013] The second convex lens is used to convert the converged light beam into a parallel light beam to be detected, wherein the focal length of the second convex lens is greater than the focal length of the first convex lens.

[0014] In some optional embodiments, the scattered light collection module further includes an aperture, which is located between the first convex lens and the second convex lens, and is arranged on a common focal plane of the first convex lens and the second convex lens, and is conjugate with the center of the object field of view of the microscope objective lens.

[0015] In some optional embodiments, the aperture of the aperture is between 50 μm and 500 μm.

[0016] In some optional embodiments, the static light scattering detection optical system further includes a sample cell, the sample cell is used to contain the solution to be tested, and a cover glass is provided on a side of the sample cell close to the scattered light collection module.

[0017] In some optional embodiments, the first side surface and the second side surface opposite to each other in the sample cell are polished surfaces, wherein both the first side surface and the second side surface are perpendicular to the measurement beam.

[0018] In some optional embodiments, the photodetector is an array photodetector, and the maximum effective detection size of the photodetector is larger than the aperture of the parallel light beam to be detected.

[0019] In a second aspect, the present invention provides a static light scattering detection device, comprising a static light scattering detection optical system as described in any one of the first aspects of the present invention.

[0020] The present invention has the following beneficial effects:

[0021] The static light scattering detection optical system of the present invention converts scattered light at different angles into a parallel light beam to be detected through a scattered light collection module, and then uses a photodetector to detect the intensity of the parallel light beam to be detected to obtain light intensity information of the parallel light beam to be detected at different positions. Since light beams at different positions in the parallel light beam to be detected correspond to scattered light at different angles, a scattered light field within a preset scattering angle range can be generated based on the light intensity information, and then the absolute molecular weight of the solute in the solution to be tested can be detected based on the scattered light field. The present invention can detect the scattered light field at continuous angles without the need for multiple discrete photodetectors, and has the advantages of compact and simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly express the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the structure of the static light scattering detection optical system in an embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the structure of the sample cell in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the relationship between scattering angle and aperture in an embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 01. Measuring beam; 02. Sample cell; 021. Solution to be tested; 022. Cover glass; 023. First side; 024. Second side; 03. Scattered light; 04. Infinity conjugate microscope objective; 05. First convex lens; 06. Aperture diaphragm; 07. Second convex lens; 08. Photodetector. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two components; it can mean a wireless connection or a wired connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0031] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Cellulose, protein, starch, natural rubber, synthetic rubber, various coatings, and functional polymer materials are all examples of polymers, and they are widely used in production and daily life. The molecular weight of a polymer is a key parameter characterizing its performance, so accurate molecular weight determination is crucial. Molecular weight determination methods include relative and absolute methods. The former requires additional methods to determine the true molecular weight, while the latter allows for independent molecular weight determination.

[0033] The static light scattering detection optical system according to the embodiment of the present invention is mainly used for absolute detection of the molecular weight of polymers.

[0034] Existing static light scattering instruments all use multiple discrete photodetectors 08 to synchronously collect the intensity of scattered light 03 at different angles, reconstruct the scattered light field, and then obtain information such as molecular weight based on theoretical formulas. However, these solutions require many devices, have limited detection angles, and are expensive.

[0035] Based on this, the static light scattering detection optical system of the embodiment of the present invention proposes a solution for converting scattered light 03 at different angles into parallel light, so that only one photodetector 08 is needed to perform continuous angle detection of the scattered light field.

[0036] like Figure 1 As shown, the static light scattering detection optical system of the embodiment of the present invention includes:

[0037] The scattered light collection module is used to convert the scattered light 03 of different angles generated by the solution to be tested 021 after being irradiated by the measuring light beam 01 into a parallel light beam to be detected, wherein light beams at different positions in the parallel light beam to be detected correspond to scattered light 03 of different angles.

[0038] Specifically, the test solution 021 includes polymer molecules such as cellulose, protein, starch or natural rubber.

[0039] The solution to be tested 021 is placed in the sample cell 02, and the measuring light beam 01 is incident on the sample cell 02 from the horizontal direction.

[0040] like Figure 2 As shown, the entire structure of sample cell 02 is made of highly transparent and corrosion-resistant glass. A cover glass 022 is installed on the side of sample cell 02 near the scattered light collection module. In one example, the scattered light collection module is located directly above sample cell 02, and cover glass 022 is placed on the upper side of sample cell 02. An optical bonding process is used to secure cover glass 022 to sample cell 02. This not only aligns with the scattered light collection module, reducing spherical aberration, but also ensures that the test solution 021 is stable and free of contamination.

[0041] Furthermore, the first side surface 023 and the second side surface 024 opposing each other in sample cell 02 are polished surfaces, wherein both first side surface 023 and second side surface 024 are perpendicular to measurement beam 01. First side surface 023 and second side surface 024, i.e., the left and right sides of sample cell 02, are both highly polished surfaces with a surface shape accuracy PV better than λ / 4, where λ is the wavelength of measurement beam 01, to reduce interference with the alignment of measurement beam 01.

[0042] The measuring beam 01 uses monochromatic light with a spectral width less than 0.1 nm. Before entering the sample cell 02, the measuring beam 01 is shaped into a thin beam. The aperture of the measuring beam 01 is Φ laser The optical fiber is preferably 100 μm to 500 μm to prevent scattered light 03 from the non-detection area from interfering with the measurement results.

[0043] The measuring beam 01 passes through the sample cell 02 and irradiates the test solution 021. The polymer structure within the test solution 021 scatters the measuring beam 01. Part of the scattered light 03 is collected by the scattered light collection module and converted into a parallel beam to be detected. Scattered light 03 emitted at different angles passes through the scattered light collection module and is converted into parallel beams to be detected at different positions. In other words, there is a one-to-one correspondence between the angle of the scattered light 03 and the position of the parallel beam to be detected.

[0044] The photoelectric detector 08 is used to receive the parallel light beam to be detected and detect the light intensity information of the parallel light beam to be detected at different positions, and generate a scattered light field within a preset scattering angle range based on the light intensity information. The scattered light field is used to detect the absolute molecular weight of the solute in the solution to be tested 021.

[0045] Specifically, the preset scattering angle range is the angle range of scattered light 03 that can be collected by the scattered light collection module. The maximum angle α of the scattered light 03 that can be collected by the scattered light collection module is maxDetermined by its numerical aperture NA, taking the incident angle of the measuring beam 01 as the reference, that is, the incident angle of the measuring beam 01 is 0°, then the angle range of the scattered light 03 that can be collected by the scattered light collection module is (90°-α max ) to (90°+α max ).

[0046] Furthermore, the photodetector 08 is an array photodetector, and the maximum effective detection size of the photodetector 08 is larger than the aperture of the parallel light beam to be detected.

[0047] Specifically, the photodetector 08 adopts a linear array photodetector or a planar array photodetector, and the maximum effective detection size of the photodetector 08 is larger than the aperture of the parallel light beam to be detected, so that the photodetector 08 can detect the light intensity information of the complete parallel light beam to be detected at each position, thereby obtaining the light intensity of the scattered light 03 at each scattering angle based on the one-to-one correspondence between the angle of the scattered light 03 and the position of the parallel light beam to be detected, generating a scattered light field within a preset scattering angle range, and then using the scattered light field to calculate the absolute molecular weight of the polymer in the solution to be tested 021.

[0048] In addition, the pixel of the photodetector 08 should be as small as possible to improve the angular resolution of the measurement.

[0049] The static light scattering detection optical system of the embodiment of the present invention converts scattered light 03 at different angles into a parallel light beam to be detected through a scattered light collection module, and then uses a photodetector 08 to detect the intensity of the parallel light beam to be detected to obtain light intensity information of the parallel light beam to be detected at different positions. Since light beams at different positions in the parallel light beam to be detected correspond to scattered light 03 at different angles, a scattered light field within a preset scattering angle range can be generated based on the light intensity information, and then the absolute molecular weight of the solute in the solution to be tested 021 can be detected based on the scattered light field. The present invention can detect the scattered light field at continuous angles without the need for multiple discrete photodetectors 08, and has the advantages of compact and simple structure and low cost.

[0050] In some embodiments, the scattered light collection module includes:

[0051] The microscope objective lens is used to convert the scattered light 03 at different angles generated by the solution to be tested 021 after being irradiated by the measuring light beam 01 into an intermediate parallel light beam;

[0052] The beam expansion unit is used to expand the intermediate parallel light beam to obtain the parallel light beam to be detected.

[0053] Specifically, the microscope objective lens adopts an infinite conjugate microscope objective lens 04 , and the numerical aperture of the infinite conjugate microscope objective lens 04 is greater than or equal to 0.7.

[0054] It should be understood that the infinite conjugate microscope objective lens 04 should be an objective lens with minimal aberration, and its operating band covers the measurement beam 01. The infinite conjugate microscope objective lens 04 can convert scattered light 03 at different angles into an intermediate parallel beam for output.

[0055] The numerical aperture of the infinite conjugate microscope objective lens 04 can be 0.7, 0.8 or 0.95, etc. By setting a larger numerical aperture, the angle range of the collected scattered light 03 can be increased, thereby increasing the scattering angle measurement range.

[0056] According to the design principle of infinite conjugate microscope objective 04, Figure 3 As shown, the object side ray angle α and the objective lens exit pupil ray diameter r satisfy the following relationship:

[0057] r=f o ×n×sinα

[0058] Among them, f o is the focal length of the microscope objective lens, and n is the object space refractive index. According to the above formula, there is a one-to-one correspondence between the angle of the scattered light 03 and the intermediate parallel beam emitted by the microscope objective lens. Since the parallel beam to be detected is obtained by expanding the intermediate parallel beam, the angle of the scattered light 03 also has a one-to-one correspondence with the position of the final parallel beam to be detected.

[0059] The maximum angle α of light that can be collected by the microscope objective max It is determined by the numerical aperture NA of the microscope objective lens, that is:

[0060] NA=n×sinα max

[0061] Taking the incident angle of the measuring beam 01 as the reference, that is, the incident angle of the measuring beam 01 is 0°, the angle range of the scattered light 03 that can be collected by the scattered light collection module is (90°-α max ) to (90°+α max ). Therefore, in order to maximize the detection range of scattered light O3, a microscope objective with a larger numerical aperture should be used as much as possible.

[0062] The beam expansion unit adopts a Kepler telescope optical beam expansion system. The telescope optical beam expansion system is usually composed of two coaxially placed lenses, one is a converging lens with a shorter focal length, and the other is a diverging lens with a longer focal length.

[0063] Specifically, the beam expansion unit includes a first convex lens 05 and a second convex lens 07. The first convex lens 05 is used to converge the intermediate parallel light beam. The second convex lens 07 is used to convert the converged light beam into a parallel light beam to be detected, wherein the focal length of the second convex lens 07 is greater than the focal length of the first convex lens 05.

[0064] The first convex lens 05 and the second convex lens 07 cooperate to amplify the intermediate parallel light beam emitted by the microscope objective lens. The magnification is M, and the aperture of the parallel light beam to be detected after amplification is Φ. test It can be expressed as:

[0065] M=f2 / f1

[0066] Ф test =2Mf o n sinα

[0067] Wherein, f1 is the focal length of the first convex lens 05, and f2 is the focal length of the second convex lens 07. From the above formula, it can be seen that in order to expand and amplify the light beam, the focal length of the second convex lens 07 should be greater than the focal length of the first convex lens 05.

[0068] In some embodiments, the scattered light collection module further includes an aperture 06, which is located between the first convex lens 05 and the second convex lens 07, and is set on the common focal plane of the first convex lens 05 and the second convex lens 07. The aperture 06 is conjugate with the center of the object field of view of the microscope objective lens.

[0069] Specifically, a small hole is set at the center of the aperture 06, and the center of the small hole is on the same straight line as the center of the first convex lens 05, the center of the second convex lens 07 and the center of the microscope objective lens, so that the aperture 06 is conjugate with the center of the object field of view of the microscope objective lens.

[0070] The aperture 06 can filter out scattered light 03 outside the focal plane of the objective lens, that is, out-of-focus light, and can also filter out off-axis scattered light 03 outside the central field of view. This can limit the detection volume of scattered light 03 to a very small range and improve measurement accuracy. In practical applications, considering the beam alignment, signal strength, processing difficulty, etc., the aperture 06 is generally required to have a diameter of Φ hole At the order of hundreds of microns, the scattered light 03 detection volume V defined by the aperture 06 can be expressed as:

[0071]

[0072] Among them, Ф laser is the aperture of the measurement beam 01.

[0073] Specifically, the aperture of the aperture 06 is between 50 μm and 500 μm to suppress non-central viewing fields and out-of-focus scattered light 03 , further limiting the scattered light 03 measurement volume, thereby improving measurement accuracy.

[0074] The working process of the static light scattering detection optical system according to the embodiment of the present invention is described below with reference to a specific example.

[0075] Monochromatic light with a spectral width less than 0.1 nm is used as the measuring beam 01 , and the measuring beam 01 is shaped into a thin beam. The beam diameter of the shaped measuring beam 01 is 200 μm.

[0076] The measuring light beam 01 is horizontally incident on the sample cell 02, and then passes through the sample cell 02 to irradiate the solution to be tested 021. The polymer structure in the solution to be tested 021 scatters the measuring light beam 01, and part of the scattered light 03 is collected by the infinite conjugate microscope objective lens 04 set in the vertical direction and converted into an intermediate parallel light beam. The light beam is then converged by the first convex lens 05, and an aperture 06 is placed at the common focal plane of the first convex lens 05 and the second convex lens 07 to filter out the out-of-focus and non-field-of-view light beams. The converged light beam passes through the second convex lens 07 and is converted into a parallel light beam to be detected, and is finally received by the photodetector 08.

[0077] Assuming the pixel size of the photodetector 08 is P, the angular resolution δ of the static light scattering detection optical system is determined as:

[0078]

[0079] The maximum effective detection size Φ of the target surface of the photoelectric detector 08 CCD Should be larger than the diameter of the parallel light beam to be detected test , and the pixel should be as small as possible to improve the angular resolution of the static light scattering detection optical system.

[0080] Taking NA0.95, 40X microscope objective lens as an example, its working medium is air, that is, n=1, and the focal length of the microscope objective lens is f o The maximum angle α of light that can be collected by the microscope objective lens is calculated according to the formula max It is 71.8°, that is, the microscope objective can collect scattered light 03 in the range of 18.2° to 161.8°.

[0081] When the aperture 06 is Φ hole The diameter of the measuring beam 01 is 100 μm. laser When the diameter is 200 μm, the scattered light 03 detection volume V is about 1.6 nL according to the formula.

[0082] In order to improve the angular resolution of the photoelectric detector 08, the beam magnification M should be increased as much as possible in combination with the target surface size of the photoelectric detector 08. When the focal length of the second convex lens 07 is 180mm and the focal length of the first convex lens 05 is 20mm, the final aperture Φ of the parallel light beam to be detected is calculated. test The maximum effective detection size of the target surface of the photoelectric detector 08 should be greater than 76.95mm, and its pixel size is 5μm. According to the formula The calculated maximum angular resolution δ is 0.023° and the minimum is 0.007°, which fully meets the requirements of multi-angle static light scattering detection.

[0083] Finally, based on the light intensity information collected by the photodetector 08, the light field distribution of the scattered light 03 within the scattering angle range of 18.2° to 161.8° can be reconstructed, and the absolute molecular weight of the polymer in the test solution 021 can be calculated.

[0084] The static light scattering detection optical system of the present invention utilizes an infinitely conjugated microscope objective lens 04 as a scattered light collection device. A beam expansion unit converts scattered light 03 at varying angles into a parallel beam to be detected. The beam intensity is then detected using a linear or planar array of photodetectors 08. This system can detect scattered light at varying angles without requiring multiple discrete photodetectors 08, resulting in a compact, simple structure and low cost.

[0085] In addition, in order to suppress the non-central field of view and out-of-focus scattered light 03, an aperture 06 is arranged in the optical path to further limit the detection volume of the scattered light 03 and improve the measurement accuracy.

[0086] An embodiment of the present invention further provides a static light scattering detection device, comprising the static light scattering detection optical system according to any one of the above embodiments of the present invention.

[0087] Although example embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit and scope of protection of the present invention, and such modifications and variations are all within the scope defined therein.

Claims

1. A static light scattering detection optical system, characterized in that: include: A scattered light collection module is used to convert scattered light at different angles generated by the solution to be tested after being irradiated by the measuring light beam into a parallel light beam to be detected, wherein light beams at different positions in the parallel light beam to be detected correspond to scattered light at different angles; A photoelectric detector is used to receive the parallel light beam to be detected and detect the light intensity information of the parallel light beam to be detected at different positions, and generate a scattered light field within a preset scattering angle range based on the light intensity information. The scattered light field is used to detect the absolute molecular weight of the solute in the solution to be tested.

2. The static light scattering detection optical system according to claim 1, characterized in that: The scattered light collection module includes: The microscope objective lens is used to convert the scattered light at different angles generated by the solution to be tested after being irradiated by the measuring beam into an intermediate parallel beam; The beam expansion unit is used to expand the intermediate parallel light beam to obtain the parallel light beam to be detected.

3. The static light scattering detection optical system according to claim 2, characterized in that: The microscope objective lens adopts an infinite conjugate microscope objective lens, and the numerical aperture of the infinite conjugate microscope objective lens is greater than or equal to 0.

7.

4. The static light scattering detection optical system according to claim 2, characterized in that: The beam expansion unit comprises: a first convex lens, configured to converge the intermediate parallel light beam; The second convex lens is used to convert the converged light beam into a parallel light beam to be detected, wherein the focal length of the second convex lens is greater than the focal length of the first convex lens.

5. The static light scattering detection optical system according to claim 4, characterized in that: The scattered light collection module further includes an aperture, which is located between the first convex lens and the second convex lens, and is set on a common focal plane of the first convex lens and the second convex lens. The aperture is conjugate with the center of the object plane field of view of the microscope objective lens.

6. The static light scattering detection optical system according to claim 5, characterized in that: The aperture of the aperture is between 50 μm and 500 μm.

7. The static light scattering detection optical system according to claim 1, characterized in that: It also includes a sample pool, which is used to accommodate the solution to be tested. A cover glass is provided on one side of the sample pool close to the scattered light collection module.

8. The static light scattering detection optical system according to claim 7, characterized in that: The first side surface and the second side surface opposite to each other in the sample cell are polished surfaces, wherein the first side surface and the second side surface are both perpendicular to the measuring light beam.

9. The static light scattering detection optical system according to claim 1, characterized in that: The photoelectric detector is an array photoelectric detector, and the maximum effective detection size of the photoelectric detector is larger than the aperture of the parallel light beam to be detected.

10. A static light scattering detection device, characterized in that: The method comprises the static light scattering detection optical system according to any one of claims 1 to 9.

Images