CN106644858B - A kind of laser particle size analyzer and particle size distribution testing method - Google Patents

Abstract

The invention discloses a laser particle analyzer, which comprises: a laser light source for emitting a laser beam; the sample cell is used for containing a sample to be detected; the charge coupled photoelectric detector is used for receiving scattered light generated after the laser beam passes through the sample to be detected and converting the scattered light into a scattered light energy distribution graph, and the surface of the charge coupled photoelectric detector is provided with a circular ring mask plate; and the calculator is used for calculating the particle size distribution of the sample to be detected according to the scattered light energy distribution diagram. The purpose of using the circular ring mask plate is to more intuitively obtain the corresponding positions of the pixel points for receiving the scattered light, so that the energy of the scattered light can be conveniently extracted according to the corresponding positions of the pixel points, further the scattered light energy distribution map is rapidly drawn, and the calculation speed for calculating the particle size distribution of the sample to be detected is increased. The invention also provides a particle size distribution testing method, which has the above effects.

Description

A kind of laser particle size analyzer and particle size distribution testing method

technical field

The invention relates to the technical field of instruments and meters, in particular to a laser particle size analyzer, and also to a particle size distribution testing method.

Background technique

The laser particle size analyzer is an instrument for testing the particle size distribution and particle size based on the particle's ability to diffract or scatter laser light to obtain a scattering spectrum. Its specific working principle is as follows: Since the laser has good monochromaticity and strong directionality, a beam of parallel laser light will irradiate to an infinite distance in an infinite space without hindrance, and it will be very fast during the propagation process. There is little divergence; when the beam is blocked by particles, part of the light will be scattered, and the propagation direction of the scattered light will form an angle θ with the propagation direction of the main beam. Scattering theory and experimental results tell us that the size of the scattering angle θ is related to the size of the particle. The larger the particle, the smaller the θ angle of the scattered light; the smaller the particle, the larger the θ angle of the scattered light. At the same time, the intensity of scattered light represents the number of particles of that size. By measuring the intensity of scattered light at different angles, the particle size distribution of the sample can be obtained.

In the existing technology, most of the laser particle size analyzers sold on the market use photoelectric elements such as silicon photodiodes or CCDs and CMOSs as detectors. The silicon photodiode detector can directly process the photoelectric signal received by the ring detection unit in the later stage. The disadvantage is that it directly uses photoelectric components such as CCD or CMOS, and needs to add a centering adjustment program to the system, occupying computer computing memory, and reducing Computing speed, complex operation.

Therefore, how to improve the calculation speed of the particle size distribution is a technical problem to be solved by those skilled in the art.

Contents of the invention

The object of the present invention is to provide a laser particle size analyzer, which uses a ring mask to obtain the corresponding position of the pixel point where the charge-coupled photodetector receives scattered light, thereby increasing the calculation speed of the particle size distribution.

In order to solve the above technical problems, the present invention provides a laser particle size analyzer, comprising:

a laser light source for emitting a laser beam;

A sample cell for holding the sample to be tested;

A charge-coupled photodetector for receiving the scattered light generated after the laser beam passes through the sample to be tested, and converting it into a scattered light energy distribution diagram, with a ring mask on the surface;

A calculator for calculating the particle size distribution of the sample to be tested according to the scattered light energy distribution diagram.

Preferably, in the above-mentioned laser particle size analyzer, the ring mask includes a plurality of concentric rings, and the center of the ring with the smallest radius coincides with the optical center of the charge-coupled photodetector.

Preferably, the above-mentioned laser particle size analyzer further includes a collimating beam expander arranged between the laser light source and the sample cell.

Preferably, in the above-mentioned laser particle size analyzer, the collimating beam expanding device is a Keplerian laser beam expanding device, including a converging lens and a collimating lens.

Preferably, in the above-mentioned laser particle size analyzer, a spatial filter located at the focal point of the converging lens is further included.

Preferably, the above-mentioned laser particle size analyzer further includes an imaging lens arranged between the sample cell and the photodetector, the focal point of the imaging lens coincides with the center of the photodetector.

The present invention also includes a particle size distribution testing method, comprising:

Step S1: setting the ring mask on the charge-coupled photodetector of the laser particle size analyzer, and adjusting the center of the ring with the smallest radius to coincide with the optical center of the charge-coupled photodetector;

Step S2: The laser beam emitted by the laser light source passes through the sample cell containing the sample to be tested to form scattered light;

Step S3: the charge-coupled photodetector receives the scattered light, and obtains the coordinates of the pixel point receiving the scattered light according to the circular mask;

Step S4: draw the scattered light energy distribution diagram according to the coordinates of the pixel points, and calculate the particle size distribution of the sample to be tested.

Preferably, in the above particle size distribution testing method, before the step S2, it also includes:

Step S11: adjusting the center of the circle with the smallest radius in the circle mask to coincide with the optical center of the charge-coupled photodetector;

Step S12: the laser beam is incident on the charge-coupled photodetector through the sample cell without the sample to be tested;

Step S13: judging whether the spot of the laser beam on the charge-coupled photodetector falls on the center of the circle with the smallest radius, if not, adjusting the spot of the laser beam on the charge-coupled photodetector If yes, execute the step S2.

The invention provides a laser particle size analyzer, comprising: a laser light source for emitting a laser beam; a sample cell for holding a sample to be tested; and a sample pool for receiving the scattered light generated after the laser beam passes through the sample to be tested. Light, and convert it into a scattered light energy distribution map, a charge-coupled photodetector with a ring mask plate on the surface; used to calculate the particle size distribution of the sample to be measured according to the scattered light energy distribution map device. The purpose of using the ring mask in the present invention is to obtain the position corresponding to each pixel point receiving scattered light more intuitively, to facilitate the extraction of scattered light energy energy according to the position corresponding to each pixel point, and then to quickly draw the scattered light energy distribution diagram to speed up the calculation speed of calculating the particle size distribution of the sample to be tested.

The invention also provides a particle size distribution testing method, which has the above effects.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is the schematic diagram of the laser particle size analyzer provided by the embodiment of the present invention;

FIG. 2 is a schematic diagram of a charge-coupled photodetector provided with a ring mask on the surface provided by an embodiment of the present invention;

Fig. 3 is a schematic diagram of a particle size distribution testing method provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Figure 1 and Figure 2, Figure 1 is a schematic diagram of a laser particle size analyzer provided by an embodiment of the present invention; Figure 2 is a schematic diagram of a charge-coupled photodetector provided with a ring mask on the surface provided by an embodiment of the present invention.

In a specific embodiment, the present invention provides a laser particle size analyzer, comprising:

A laser light source 1 for emitting a laser beam;

A sample cell 3 for holding the sample to be tested;

Used to receive the scattered light generated after the laser beam passes through the sample to be tested, and convert it into a scattered light energy distribution map, and a charge-coupled photodetector 5 with a ring mask on the surface;

A calculator 6 for calculating the particle size distribution of the sample to be tested according to the scattered light energy distribution diagram.

Specifically, for the laser particle size analyzer provided in this embodiment, please refer to the prior art for its specific setting method and working method, and details will not be repeated here. Using the charge-coupled photodetector 5 to replace the detector composed of silicon photodiodes can realize the collection of all data within the range of the measured particle size, which is no longer limited by photolithography technology and processing technology, and has a wider range of applications.

The charge-coupled photodetector 5 is an optoelectronic device that utilizes the internal photoelectric effect to achieve photoelectric conversion to generate signal charges, and is composed of multiple charge-coupled units. A metal oxide semiconductor transistor (English name: Metal Oxide Semiconductor, MOS for short) capacitor is used as its basic unit. MOS capacitors are oxidized to form a silicon dioxide layer on the surface of a P-type or N-type silicon substrate, and then a metal film is evaporated on the silicon dioxide layer, and finally the gate is made by photolithography. Shaped electrodes constitute a MOS capacitive transfer device, and its single MOS capacitor is a pixel or a photosensitive element of the CCD detector.

The use of photolithography to make a mask is a process in which a specific part of the wafer surface film is removed through a series of production steps. After this, a film with a micropatterned structure remains on the wafer surface. Through the photolithography process, what is finally reserved on the wafer is the characteristic pattern part. The purpose of setting the ring mask on the surface of the charge-coupled photodetector 5 is to more intuitively obtain the corresponding position of each pixel point receiving scattered light, so as to facilitate the extraction of scattered light energy according to the position corresponding to each pixel point, and then quickly Draw a scattered light energy distribution diagram to speed up the operation speed of calculating the particle size distribution of the sample to be tested.

It should be pointed out that the laser light source 1 can be selected according to requirements, for example, it can be an infrared laser light source 1 or a blue light laser light source 1, etc., all of which are within the scope of protection.

On the basis of the above-mentioned laser particle size analyzer, the ring mask includes a plurality of concentric rings 10 , and the center of the ring with the smallest radius coincides with the optical center of the charge-coupled photodetector 5 .

As shown in FIG. 2 , the ring mask includes a plurality of concentric rings 10 . The rings can be made of steel rings and other materials. The number and radius of the concentric rings 10 are not specifically limited, and they are all within the scope of protection.

On the basis of the above-mentioned laser particle size analyzer, it also includes a collimating beam expander 2 arranged between the laser light source 1 and the sample cell.

Further, in the above-mentioned laser particle size analyzer, the collimating beam expanding device 2 is a Keplerian laser beam expanding device, including a converging lens 7 and a collimating lens 8 .

Further, in the above-mentioned laser particle size analyzer, a spatial filter 9 located at the focal point of the converging lens is also included.

General laser collimation beam expander 2 is divided into two classes, Kepler type laser beam expander and Galileo type laser beam expander, present embodiment preferably adopts Kepler type laser beam expander, and in the beam expander system A spatial filter 9 is added to the focal point, which can filter out all high-order scattered light. What passes through the spatial filter 9 is a spatially low-frequency laser beam, which is a divergent beam, and then becomes a parallel single beam after passing through the collimating lens 8. colored beams. The purpose is to achieve uniform illumination of the laser beam incident into the sample cell 3, reduce the influence of stray light on the monitoring results, and reduce system errors.

On the basis of the above-mentioned laser particle size analyzer, it also includes an imaging lens 4 arranged between the sample cell 3 and the charge-coupled photodetector 5, the focal point of the imaging lens 4 is connected to the charge-coupled photodetector 5 centers coincide.

Wherein, the charge-coupled photodetector 5 is placed at the focal point of the imaging lens 4, because a part of the parallel light beam is scattered, and the imaging lens 4 converges the scattered light on its focal plane, and the imaging lens 4 at the focal plane receives the scattered light. The imaging lens 4 can be a lens such as a Fourier lens, which can be selected according to needs, and all of them are within the scope of protection.

As shown in FIG. 3 , FIG. 3 is a schematic diagram of a particle size distribution testing method provided by an embodiment of the present invention.

The present invention also includes a particle size distribution testing method, comprising:

Step S1: setting the ring mask on the charge-coupled photodetector 5 of the laser particle size analyzer,

Step S2: The laser beam emitted by the laser light source 1 passes through the sample cell 3 containing the sample to be tested to form scattered light;

Step S3: the charge-coupled photodetector 5 receives the scattered light, and obtains the coordinates of the pixel point receiving the scattered light according to the circular mask;

Step S4: draw the scattered light energy distribution diagram according to the coordinates of the pixel points, and calculate the particle size distribution of the sample to be tested.

Further, in the above particle size distribution testing method, before the step S2, it also includes:

Step S11: adjusting the center of the circle with the smallest radius in the circle mask to coincide with the optical center of the charge-coupled photodetector 5;

Step S12: the laser beam is incident on the charge-coupled photodetector 5 through the sample cell 3 without the sample to be measured;

Step S13: judging whether the spot of the laser beam on the charge-coupled photodetector 5 falls on the center of the circle with the smallest radius, if not, adjusting the laser beam on the charge-coupled photodetector 5 above, if yes, execute the step S2.

Wherein, the ring mask is fixed on the surface of the charge-coupled photodetector 5, and the centering of the optical path of the laser particle size analyzer on the photodetector can be completed through mechanical adjustment, that is, to adjust the laser beam at the surface of the photodetector. Whether the light spot on the charge-coupled photodetector 5 falls on the center of the circular ring with the smallest radius makes the light energy background of the laser particle size analyzer meet the test requirements, so that it is more intuitive and clear to know that each light spot on the charge-coupled photodetector 5 A pixel corresponds to the divergent beam scattering angle, and then the particle size distribution is calculated using an inversion algorithm.

Each embodiment in the description is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related part, please refer to the description of the method part.

In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (7)

1. A laser particle size analyzer, characterized in that, comprising: a laser light source for emitting a laser beam; A sample cell for holding the sample to be tested; A charge-coupled photodetector for receiving the scattered light generated after the laser beam passes through the sample to be tested, and converting it into a scattered light energy distribution diagram, with a ring mask on the surface; A calculator for calculating the particle size distribution of the sample to be tested according to the scattered light energy distribution diagram; The ring mask plate includes a plurality of concentric rings, and the center of the ring with the smallest radius coincides with the optical center of the charge-coupled photodetector. 2. The laser particle size analyzer according to claim 1, further comprising a collimating beam expander arranged between the laser light source and the sample cell. 3. The laser particle size analyzer according to claim 2, wherein the collimating beam expanding device is a Keplerian laser beam expanding device, comprising a converging lens and a collimating lens. 4. The laser particle size analyzer according to claim 3, further comprising a spatial filter located at the focal point of the converging lens. 5. laser particle size analyzer as claimed in claim 4, is characterized in that, also comprises the imaging lens that is arranged between described sample pool and described photodetector, the focal point of described imaging lens and described photodetector The centers coincide. 6. A particle size distribution testing method, characterized in that, comprising: Step S1: Set the ring mask plate on the charge-coupled photodetector of the laser particle size analyzer, and adjust the center of the ring with the smallest radius to coincide with the optical center of the charge-coupled photodetector; wherein, the ring mask the plate includes a plurality of concentric rings; Step S2: The laser beam emitted by the laser light source passes through the sample cell containing the sample to be tested to form scattered light; Step S3: the charge-coupled photodetector receives the scattered light, and obtains the coordinates of the pixel point receiving the scattered light according to the circular mask; Step S4: draw the scattered light energy distribution diagram according to the coordinates of the pixel points, and calculate the particle size distribution of the sample to be tested. 7. particle size distribution test method as claimed in claim 6, is characterized in that, before described step S2, also comprises: Step S11: adjusting the center of the circle with the smallest radius in the circle mask to coincide with the optical center of the charge-coupled photodetector; Step S12: the laser beam is incident on the charge-coupled photodetector through the sample cell without the sample to be tested; Step S13: judging whether the spot of the laser beam on the charge-coupled photodetector falls on the center of the circle with the smallest radius, if not, adjusting the spot of the laser beam on the charge-coupled photodetector If yes, execute the step S2.