Vortex polarimeter

Abstract

The utility model relates to the technical field of polarimeters, in particular to a vortex polarimeter, which comprises a polarization state generator, a first diaphragm, a polarization analyzer, a 4F imaging system and a computer, the polarization state generator is used for converting a light beam into a linear polarization vortex light beam, a to-be-measured optical rotation solution is placed on an emergent light path of the polarization state generator, the first diaphragm is mounted on an incident light path of the to-be-measured optical rotation solution, and the polarization analyzer is mounted on the emergent light path of the to-be-measured optical rotation solution; the linear polarization vortex light beam passes through a to-be-detected optical rotation solution and then enters the polarization analyzer, the 4F imaging system is installed on an emergent light path of the polarization analyzer, and the 4F imaging system is used for imaging the polarization analyzer and sending a collected polarized light image to the computer for analysis. According to the vortex polarimeter, a transmission-type light path is adopted and combined with a 4F imaging system, so that the accuracy of optical rotation measurement is effectively improved, the detection work of a to-be-detected optical rotation solution with relatively high concentration can be realized, and in addition, the vortex polarimeter is simple in structure and relatively low in cost.

Description

Technical Field

[0001] This utility model relates to the field of polarimeter technology, and more specifically, to a vortex polarimeter. Background Technology

[0002] A polarimeter is an instrument used to determine the optical rotation of substances. By measuring the optical rotation of a sample, the concentration, content, and purity of the substance can be analyzed and determined. It is widely used in pharmaceutical, drug testing, sugar refining, food, flavoring, monosodium glutamate, chemical, and petroleum industries. It can also be used in scientific research and teaching departments for laboratory analysis or process quality control.

[0003] Existing polarimeters, such as the vortex polarimeter disclosed in CN116438445A, utilize multi-wavelength beams with varying polarization and / or phase states at azimuth angles to focus a vortex beam onto the sample under test within a wide range of incident angles for sample characteristic detection. This prior art employs reflective signal processing, which suffers from low detection accuracy for solutions with high concentrations due to the weak reflected signal. Furthermore, the vortex polarimeter has a complex overall structure and high cost.

[0004] Therefore, how to accurately measure the optical rotation of solutions with high concentrations while reducing costs is a technical problem that urgently needs to be solved. Utility Model Content

[0005] The purpose of this invention is to provide a vortex polarimeter that uses a transmission optical path combined with a 4F imaging system to solve the technical problem of how to accurately measure the optical rotation of solutions with high concentrations and reduce costs.

[0006] This utility model is achieved through the following technical solution: a vortex polarimeter, including a light source, a polarization state generator, a first aperture, an analyzer, a 4F imaging system, and a computer, wherein the light source, polarization state generator, first aperture, analyzer, and 4F imaging system are arranged and installed in a coaxial configuration with equal height.

[0007] The light source is used to generate a light beam, the polarization state generator is used to convert the light beam into a linearly polarized vortex beam, the optically active solution to be tested is placed in the output light path of the polarization state generator, the first aperture is installed in the incident light path of the optically active solution to be tested, the analyzer is installed in the output light path of the optically active solution to be tested, the linearly polarized vortex beam passes through the optically active solution to be tested and then enters the analyzer, the 4F imaging system is installed in the output light path of the analyzer, the 4F imaging system is used to image the analyzer and send the acquired polarized light image to a computer for analysis.

[0008] According to a preferred embodiment, the polarization state generator includes a first polarizer, a quarter-wave plate, a vortex wave plate, and a second polarizer. The first polarizer is used to modulate the light beam into linearly polarized light. The quarter-wave plate is installed in the output light path of the first polarizer to convert the linearly polarized light into a circularly polarized light beam. The vortex wave plate is installed before the second polarizer to convert the circularly polarized light into a circularly polarized vortex beam. The second polarizer is used to convert the circularly polarized vortex beam into a linearly polarized vortex beam.

[0009] According to a preferred embodiment, the 4F imaging system includes a first convex lens, a second convex lens, and a second aperture stop. The analyzer is installed at the focal point of the first convex lens, the second aperture stop is installed at the Fourier plane position of the 4F imaging system, and the second convex lens is installed on the incident light path of the CCD sensor image plane.

[0010] According to a preferred embodiment, the focal length of both the first convex lens and the second convex lens is 125mm.

[0011] According to a preferred embodiment, a collimating beam expander is installed on the outgoing light path of the light source. The collimating beam expander is installed on the incident light path of the polarization state generator, so that the light beam emitted from the light source is expanded and converted into parallel light that enters the polarization state generator.

[0012] According to a preferred embodiment, the light source is a HE-NE laser.

[0013] The technical solution of the vortex polarimeter provided by this utility model has at least the following advantages and beneficial effects: (1) The vortex polarimeter adopts a transmission optical path and is combined with a 4F imaging system, which effectively improves the accuracy of optical rotation measurement; (2) For optically active solutions with high concentrations, the measurement error is low by using linearly polarized vortex light, which further improves the accuracy of optical rotation measurement; (3) The vortex polarimeter has a simple structure and low cost. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the optical path of the vortex cyclotron provided in Embodiment 1 of this utility model;

[0015] Figure reference numerals: 1-He-Ne laser, 2-collimating beam expander, 3-first polarizer, 4-1 / 4 wave plate, 5-vortex wave plate, 6-second polarizer, 7-first aperture, 8-solution to be tested, 9-analyzer, 10-first convex lens, 11-second aperture, 12-second convex lens, 13-CCD sensor, 14-computer. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Example 1

[0018] Figure 1 This is a schematic diagram of the optical path of the vortex vortexer provided in an embodiment of this utility model. See also... Figure 1 As shown, the vortex cyclotron includes a light source, a collimating beam expander 2, a polarization state generator, a first aperture 7, an analyzer 9, a 4F imaging system, and a computer 14.

[0019] In some embodiments, the light source is a laser, such as a solid-state laser, gas laser, liquid laser, semiconductor laser, etc. Specifically, in this embodiment, a HE-NE laser 1 is used, that is, the HE-NE laser 1 is used as the light source to provide a stable, scatter-free, and high-precision beam. In this embodiment, a collimating beam expander 2 is installed on the output optical path of the HE-NE laser 1. The collimating beam expander 2 is installed on the incident optical path of the polarization state generator, so that the beam emitted from the HE-NE laser 1 is expanded and converted into parallel light that enters the polarization state generator.

[0020] In some embodiments, the polarization state generator can be generated by a combination of a spiral phase plate and a half-wave plate. The polarization state generator is used to convert the light beam into a linearly polarized vortex beam. For the optically active solution 8 with a high concentration, the measurement error is low by using linearly polarized vortex light, which further improves the accuracy of optical rotation measurement. Specifically, in this embodiment, the optically active solution 8 is placed in the output light path of the polarization state generator, and a first aperture 7 is also installed in the incident light path of the optically active solution 8. The first aperture 7 controls the number and direction of the linearly polarized vortex beam entering the optically active solution 8, thereby filtering stray light. Specifically, in this embodiment, the first aperture 7 is an aperture stop to limit the solid angle of the linearly polarized vortex beam. The aperture stop is used to block stray light, preventing it from entering the subsequent light path.

[0021] Specifically, in this embodiment, the polarization state generator includes a first polarizer 3, a quarter-wave plate 4, a vortex wave plate 5, and a second polarizer 6. The first polarizer 3 is used to modulate the beam into linearly polarized light. The quarter-wave plate 4 is installed on the outgoing light path of the first polarizer 3 to convert the linearly polarized light into a circularly polarized beam. Specifically, in this embodiment, the quarter-wave plate 4 is made of a birefringent material. By precisely controlling the thickness, a phase difference of π / 2 radians is generated when the beam passes through, thereby converting the linearly polarized light into circularly polarized light. The vortex wave plate 5 is installed before the second polarizer 6 to convert the circularly polarized light into a circularly polarized vortex beam. Specifically, in this embodiment, the vortex wave plate 5 is based on an N-BK7 glass substrate and a liquid crystal polymer birefringent material, supported by a light-controlled alignment process, presenting a "sandwich structure of front and rear glass substrates and an intermediate LCP functional film layer". When the incident light is circularly polarized light, the vortex wave plate 5 can generate a circularly polarized vortex beam with a spiral phase wavefront. The second polarizer 6 is used to convert the circularly polarized vortex beam into a linearly polarized vortex beam.

[0022] Furthermore, the analyzer 9 is installed in the output optical path of the optically polarized solution 8 to be tested. The linearly polarized vortex beam enters the analyzer 9 after passing through the optically polarized solution 8. The analyzer 9 is used to detect the polarization state of the linearly polarized vortex beam after passing through the optically polarized solution 8. The 4F imaging system is installed in the output optical path of the analyzer 9. The 4F imaging system is used to image the analyzer 9 and realize the function of spatial frequency filtering. The 4F imaging system forms a clear image on the output plane by performing Fourier transform and inverse Fourier transform, and sends the acquired polarized light image to the computer 14 for light intensity analysis. This can effectively reduce noise in the imaging and enhance the features. The vortex polarimeter adopts a transmission optical path and combines it with the 4F imaging system, which effectively improves the accuracy of optical rotation measurement.

[0023] To further simplify the overall structure of the vortex polarimeter, the light source, polarization state generator, first aperture 7, analyzer 9, and 4F imaging system are arranged and installed in a coaxial configuration at the same height.

[0024] The following describes the operation of the vortex polarimeter:

[0025] In this embodiment, the following steps are included:

[0026] Step A: Turn off indoor light sources and use light intensity analysis software to test the indoor background light to obtain the initial background light intensity;

[0027] Step B: Open the device, including the light source and CCD sensor 13;

[0028] Step C: Adjust the polarizer and analyzer 9 so that their polarization states are orthogonal to each other. The angle of the analyzer 9 at this time is denoted as .

[0029] Step D: Place the optically active solution 8 to be tested in the output light path of the polarization state generator, receive the polarized light image through the CCD sensor 13, and send the polarized light image to the computer 14 for light intensity analysis, according to the preset light intensity threshold of 4×10. -3 Adjust the angle of the analyzer 9 to minimize the light intensity. The angle of the analyzer 9 at this time is denoted as θ1.

[0030] Step E: Obtain the optical rotation θ of the optically active solution 8 to be tested. i =θ1-θ0.

[0031] In summary, the vortex polarimeter provided in this embodiment improves the accuracy of optical rotation measurement, and has a simple overall structure, reducing costs.

[0032] Example 2

[0033] This embodiment further explains the 4F imaging system based on the technical solution provided in Embodiment 1:

[0034] In this embodiment, the 4F imaging system includes a first convex lens 10, a second convex lens 12, and a second aperture 11. An analyzer 9 is installed at the focal point of the first convex lens 10. The first convex lens 10 performs a Fourier transform to convert the spatial distribution of the input image into a frequency domain distribution. The second aperture 11 is installed in the Fourier plane of the 4F imaging system to limit the aperture and direction of the imaging beam. The second convex lens 12 is installed on the incident light path of the image plane of the CCD sensor 13. The second convex lens 12 performs an inverse Fourier transform to convert the frequency domain distribution back to a time domain distribution, ultimately forming a clear image on the image plane of the CCD sensor 13. In some embodiments, for the optically active solution 8 to be tested, which is a glucose solution, the focal lengths of both the first convex lens 10 and the second convex lens 12 are 125 mm.

[0035] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A vortex polarimeter characterized by, The system comprises a light source, a polarization state generator, a first diaphragm (7), a polarimeter (9), a 4F imaging system and a computer (14), and the light source, the polarization state generator, the first diaphragm (7), the polarimeter (9) and the 4F imaging system are arranged in the same height and are coaxially installed. The light source is used to generate a light beam, the polarization state generator is used to convert the light beam into a linearly polarized vortex light beam, the solution to be measured (8) is placed on the outgoing light path of the polarization state generator, the first diaphragm (7) is installed on the incident light path of the solution to be measured (8), the polarimeter (9) is installed on the outgoing light path of the solution to be measured (8), the linearly polarized vortex light beam passes through the solution to be measured (8) and then enters the polarimeter (9), the 4F imaging system is installed on the outgoing light path of the polarimeter (9), and the 4F imaging system is used to image the polarimeter (9) and send the collected polarized light image to the computer (14) for analysis.

2. A polarimeter according to claim 1, wherein The polarization state generator comprises a first polarizer (3), a 1 / 4 wave plate (4), a vortex wave plate (5) and a second polarizer (6), the first polarizer (3) is used to modulate the light beam into linearly polarized light, the 1 / 4 wave plate (4) is installed on the outgoing light path of the first polarizer (3) and is used to convert the linearly polarized light into a circularly polarized light beam, the vortex wave plate (5) is installed on the outgoing light path of the 1 / 4 wave plate (4) and is used to convert the circularly polarized light into a circularly polarized vortex light beam, and the second polarizer (6) is installed on the outgoing light path of the vortex wave plate (5) and is used to convert the circularly polarized vortex light beam into a linearly polarized vortex light beam.

3. The polarimeter of claim 1, wherein the polarimeter is configured to determine the polarization state of the light beam by determining the phase shift of the light beam. The 4F imaging system comprises a first convex lens (10), a second convex lens (12) and a second diaphragm (11), the polarimeter (9) is installed at the focal point of the first convex lens (10), the second diaphragm (11) is installed at the Fourier plane of the 4F imaging system, and the second convex lens (12) is installed on the incident light path of the image plane of the CCD sensor (13).

4. A polarimeter according to claim 3, wherein The focal length of the first convex lens (10) and the second convex lens (12) is 125mm.

5. The polarimeter of claim 1, wherein, A collimating and expanding mirror (2) is installed on the outgoing light path of the light source, the collimating and expanding mirror (2) is installed on the incident light path of the polarization state generator, so that the light beam emitted by the light source is expanded and converted into parallel light and enters the polarization state generator.

6. A polarimeter according to claim 5, wherein the optical element is a quarter wave plate. The light source is an HE-NE laser (1).

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