Light path structure of laser particle analyzer

Abstract

The utility model discloses a light path structure of a laser particle analyzer. The light path structure comprises a laser (1), a front lens (2), a sample cell (4), a rear lens (5) and a detector (6), the laser emits laser to form a light path, and the front lens, the sample cell, the rear lens and the detector are all arranged on the light path and are sequentially arranged in the light path direction; the light path structure further comprises a prism (3), and the prism is arranged on a light path between the front lens and the sample cell; and the prism is used for guiding a part of light on a light path into the sample cell in an inclined direction through reflection. According to the light path structure, the detection lower limit of the laser particle analyzer can be extended only by adding one prism in the light path, and the light path structure has the advantages of simple structure, low cost, small space and high stability.

Description

TECHNICAL FIELD

[0001] The utility model relates to a laser particle size instrument, especially a laser particle size instrument light path structure. BACKGROUND

[0002] The laser particle size instrument is an instrument for measuring particle size and distribution based on scattering theory, and has been widely used in the field of particle size measurement. Compared with the traditional sedimentation method and the screen method, the laser measurement can be applied to solid particles, liquid particles and gas particles, and has fast measurement speed and high precision. The earliest laser particle size instrument in the market has a measurement lower limit of about 2 microns. In order to increase the measurement lower limit of the laser particle size instrument, many instrument companies have carried out exploration and improvement. For example, the Frish company in Germany extends the measurement lower limit to 0.2 microns by changing the position of the sample cell and using the inverted Fourier transform technology. Coulter company extends the measurement lower limit to 0.375 microns by using double lens technology. Cilas company extends the measurement lower limit of Cilas 1064 type laser particle size instrument to 0.04 microns by using double laser source.

[0003] Referring to Figure 1 , the measurement lower limit is extended by double lens technology, and a lens b (including a lens and a detector) is added at the position of forward 45° for detecting the scattering light of smaller particles.

[0004] Referring to Figure 2 , one lens receives the scattering light of two lasers, one of which is the forward scattering light of the laser, measuring the signal of large particles, and the other is the forward 45° scattering light of the laser, measuring the signal of small particles.

[0005] The current problem is that

[0006] 1) changing the position of the sample cell has too high requirements for the space and control of the instrument;

[0007] 2) the method of using double lens and double laser source increases the number of precision components such as laser, lens and detector, also increases the space and cost of the instrument, and also has adverse effects on the stability of the instrument. SUMMARY

[0008] The utility model discloses a laser particle size instrument light path structure, which has the advantages of simple structure, low cost, small space and high stability.

[0009] In order to achieve the above technical purpose, the utility model adopts the following technical scheme:

[0010] The light path structure of the laser particle size analyzer comprises a laser, a pre-lens, a sample cell, a post-lens and a detector; the laser emits laser light to form a light path, the pre-lens, the sample cell, the post-lens and the detector are arranged on the light path and are sequentially arranged along the direction of the light path; the light path structure further comprises a prism, and the prism is arranged on the light path between the pre-lens and the sample cell.

[0011] Further, the prism is used for guiding a part of light on the light path to the sample cell by reflection.

[0012] Further, the prism has an incident light surface, a total reflection surface, a half reflection surface and an outgoing light surface; an anti-reflection film is arranged on the incident light surface and the outgoing light surface, a semi-permeable film is arranged on the half reflection surface, and a high reflection film is arranged on the total reflection surface; the prism is arranged in a positive transmission and oblique reflection arrangement form.

[0013] Further, the positive transmission and oblique reflection arrangement form is specifically that the incident light surface and the half reflection surface of the prism are on the light path, and the outgoing light surface of the prism is at an oblique position of the sample cell; after the parallel light formed by the laser emitted by the laser and passing through the pre-lens enters the prism through the incident light surface, a part of the light transmits through the half reflection surface as forward light and reaches the sample cell along the light path, and the other part of the light is reflected by the half reflection surface to the total reflection surface as oblique light, is reflected to the outgoing light surface again and is emitted from the outgoing light surface, and enters the sample cell obliquely.

[0014] Further, the light path structure further comprises a data processing system, and the data processing system is used for processing and analyzing signals received by the detector and calculating the particle size distribution of particles according to the Mie scattering theory.

[0015] Further, the prism is a parallelogram prism.

[0016] The light path structure of the utility model has the advantages that, compared with the prior art, the utility model has the advantages that:

[0017] 1) simple structure, only one prism needs to be added in the light path, and the lower limit of detection of the laser particle size analyzer can be extended;

[0018] 2) low cost, the cost of one prism is much lower than that of a traditional double laser source or a double lens;

[0019] 3) the space of the laser particle size analyzer is reduced, the size of the prism is much smaller than that of a traditional double laser source or a double lens, and thus the space is saved;

[0020] 4) high stability, the prism is a passive device and is not disturbed by external signals, and is stable and reliable in performance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1This is a schematic diagram of the lower limit of optical path extension measurement using dual-lens technology in the existing optical path structure;

[0022] Figure 2 This is a schematic diagram of the lower limit of measurement for dual laser sources in the optical path structure of existing technology;

[0023] Figure 3 This is a schematic diagram of the optical path structure of the laser particle size analyzer of this utility model;

[0024] Figure 4 This is a schematic diagram showing the arrangement of prisms in the optical path structure of this utility model, with a positive transmission and oblique reflection configuration. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments:

[0026] This embodiment provides an optical path structure for a laser particle size analyzer, which can significantly improve the lower limit of measurement of the laser particle size analyzer.

[0027] See Figure 3 The optical path structure of this embodiment mainly includes a laser 1, a front lens 2, a prism 3, a sample cell 4, a rear lens 5, and a detector 6.

[0028] The laser emitted by the laser 1 forms an optical path. The front lens 2, prism 3, sample cell 4, rear lens 5 and detector 6 are all arranged on the optical path formed by the laser emitted by the laser 1, and are arranged sequentially along the direction of the optical path.

[0029] The sample cell 4 is used to hold the sample to be tested, so that the laser can pass through the sample and generate scattered light.

[0030] The laser 1 generates a laser beam, which serves as the light source for measurement.

[0031] The front lens 2 is used to collimate the laser beam, making it parallel light.

[0032] The rear lens 5 is used to focus parallel light onto the detector 6.

[0033] The prism 3 is used to change the light path, and can guide a portion of the light on the light path to enter the sample cell 4 at an angle through reflection (see below for details).

[0034] The detector 6 is used to receive scattered light signals and convert them into electrical signals.

[0035] It should be noted that a dedicated data processing system is also configured for the detector 6. This data processing system is used to process and analyze the signals received by the detector 6 and calculate the particle size distribution.

[0036] The prism 3 mentioned earlier is placed between the front lens 2 and the sample cell 4. This prism 3 is the main innovation of this embodiment.

[0037] Specifically

[0038] The prism 3 has a special structural configuration; it is a parallelogram prism with two wide, parallel planes. For ease of description, these two planes are designated as the "backlighting planes". Figure 3 (AB side) and "front light side" ( Figure 3 (DC surface in the middle).

[0039] The backlighting surface is further divided into two surfaces. For ease of description, these two surfaces are respectively named "incident light surface" (or "light-receiving surface"). Figure 3 The AE surface and the "total reflection surface" (in the middle) Figure 3 (EB face in the middle).

[0040] The surface facing the light is further divided into two surfaces. For ease of description, these two surfaces are respectively named "semi-reflective surfaces". Figure 3 (DF surface) and "light-emitting surface" ( Figure 3 (FC face in the middle).

[0041] The incident surface of prism 3 corresponds to the semi-reflective surface, or in other words, the two are in a projection relationship with each other. The total reflection surface of prism 3 corresponds to the exiting surface, or in other words, the two are in a projection relationship with each other.

[0042] The light-incident and light-exit surfaces of prism 3 are coated with anti-reflection films, which can enhance the light transmission effect when light strikes the light-incident and light-exit surfaces.

[0043] A semi-transparent film is coated on the semi-reflective surface of prism 3, so that light can be half transmitted and half reflected when it hits the semi-reflective surface.

[0044] A high-reflection coating is applied to the total reflection surface of prism 3, so that light rays hitting the total reflection surface will be completely reflected.

[0045] The prism 3 is positioned in a specific arrangement, such as... Figure 4 As shown. For ease of description, this specific arrangement is defined as the "positive transmission oblique reflection arrangement".

[0046] The specific definition of the positive transmission oblique reflection arrangement is as follows:

[0047] Prism 3 is tilted (45°). The backlighting surface (incident surface and total reflection surface) of prism 3 faces the opposite direction of the light path, while the frontlighting surface (exit surface and semi-reflective surface) faces the same direction. The incident surface and semi-reflective surface of prism 3 are on the forward light path, while the exit surface and total reflection surface are detached from the forward light path, i.e., at an angle to the sample cell 4. Thus, the parallel light formed by the laser emitted from laser 1 after passing through the front lens 2 enters prism 3 through the incident surface. Part of the light, as forward light, passes through the semi-reflective surface and leaves prism 3, continuing forward along the light path until it reaches the sample cell 4. The other part of the light, as oblique light, is reflected by the semi-reflective surface to the total reflection surface, then reflected again to the exit surface and emitted. This oblique light undergoes two reflections inside prism 3 before exiting through the exit surface and entering the sample cell 4 at a 45° angle.

[0048] Two beams of light (a forward beam and an oblique beam) are irradiated onto the particles in sample cell 4, and the particles scatter the light. The scattered light from the forward beam mainly represents the signal from large particles, while the scattered light from the oblique beam mainly represents the signal from small particles. The scattered light is focused by the rear lens 5 and received by the detector 6. The data processing system processes and analyzes the electrical signals received by the detector 6, and calculates the particle size distribution based on Mie scattering theory.

[0049] Compared to existing technologies, the optical path structure in this embodiment splits the laser beam by incorporating a prism 3 within the optical path. This allows a portion of the light to enter the detector 6 at a 45° angle, enabling simultaneous measurement of scattered light signals from both large and small particles. This configuration significantly improves the lower limit of the laser particle size analyzer while offering advantages such as simple structure, low cost, small footprint, and high stability.

[0050] The advantages of the optical path structure in this embodiment are:

[0051] 1) The structure is simple. Only one prism 3 needs to be added to the optical path to extend the detection limit of the laser particle size analyzer;

[0052] 2) Reduced costs: the cost of a single prism 3 is much lower than the cost of dual laser sources or dual lenses;

[0053] 3) Reduce the space required for laser particle size analyzers. Prism 3 is small in size, saving more space than traditional optical paths with dual laser sources or dual lenses;

[0054] 4) High stability: Prism 3 is a passive device, while the laser source and lens are active devices. Active devices have various interference signals and the devices cannot be completely consistent. Therefore, using prism 3 is more stable and reliable than adding a laser source or lens.

[0055] The above are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A light path structure of a laser particle size analyzer, comprising a laser (1), a pre-lens (2), a sample cell (4), a post-lens (5) and a detector (6); the laser (1) emits laser light to form a light path, the pre-lens (2), the sample cell (4), the post-lens (5) and the detector (6) are arranged on the light path and are arranged in sequence along the light path direction; the light path structure further comprises a prism (3) arranged on the light path between the pre-lens (2) and the sample cell (4); the prism (3) has an incident light surface, a total reflection surface, a half reflection surface and an exit light surface; an anti-reflection film is arranged on the incident light surface and the exit light surface, a semi-permeable film is arranged on the half reflection surface, and a high reflection film is arranged on the total reflection surface; the prism (3) is arranged in a positive transmission and oblique reflection arrangement form. The prism (3) is used to guide a part of light on the light path to the sample cell (4) by reflection. characterized in that The positive transmission and oblique reflection arrangement form is specifically that: the incident light surface and the half reflection surface of the prism (3) are on the light path, and the exit light surface of the prism (3) is at an oblique position of the sample cell (4); the parallel light formed after the laser (1) passes through the pre-lens (2) enters the prism (3) through the incident light surface, a part of the light passes through the half reflection surface as forward light and reaches the sample cell (4) along the light path, and the other part of the light is reflected by the half reflection surface to the total reflection surface as oblique light, and then is reflected to the exit light surface and is emitted, and enters the sample cell (4) obliquely. The light path structure further comprises a data processing system, which is used to process and analyze the signal received by the detector (6), and calculate the particle size distribution of the particles according to the Mie scattering theory. The prism (3) is a parallelogram prism. ​ 2. The optical path structure of the laser particle size analyzer according to claim 1, characterized in that: ​ 3. The optical path structure of the laser particle size analyzer according to claim 1, characterized in that: ​ ​ ​ 4. The optical path structure of the laser particle size analyzer according to claim 1, characterized in that: ​ 5. The optical path structure of the laser particle size analyzer according to claim 1, characterized in that: ​

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