JP2876255B2 - Particle size distribution analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a particle size for measuring a particle size distribution of sample particles by utilizing a diffraction phenomenon or a scattering phenomenon caused by irradiating dispersed particles with light. The present invention relates to a distribution measuring device.

[Conventional technology]

In a particle size distribution measuring apparatus utilizing the diffraction or scattering of light by particles, the intensity distribution of diffracted light or
That is, the particle size distribution of the sample particles is calculated by measuring the relationship between the diffraction angle or the scattering angle and the light intensity and performing an arithmetic process based on the theory of Fraunhofer diffraction or Mie scattering.

FIG. 4 is a perspective view showing a conventional example of this type of particle size distribution measuring device.

In FIG. 4, a flow cell 1 is a transparent container through which sample particles dispersed in a medium flow, and a parallel laser beam L is applied to the flow cell 1 from a laser optical system 2.

Separately, the single-wavelength optical system 3 irradiates the single-wavelength light M to the flow cell 1.

The laser light L diffracted or scattered by the sample particles in the flow cell 1 is received by the ring-shaped photosensor array 5 via the Fourier transform lens 4 and, based on the distribution of the measured light intensity, sample particles having a relatively large particle size. Is determined.

The single-wavelength light M that is also diffracted or scattered by the sample particles is received by a plurality of photosensors 6a, 6b,... From this, the particle size distribution of the sample particles having a relatively small particle size is determined.

In FIG. 5, 7 is a laser diode, 8 is a collimator lens, 9 is an ultraviolet light source, 10 is a spherical mirror, 11
Is a slit, 12 is a condenser lens, 13 is an interference filter, and 14 is a photometric slit.

In the above particle size distribution measuring device, a laser beam L radiated by the laser optical system 2 and a single wavelength light M by the single wavelength optical system 3 are irradiated on the same flow cell 1 and diffracted or scattered by sample particles in the flow cell 1. The light L is received by the ring-shaped photosensor array 5 and its light intensity distribution is measured. At the same time, the single-wavelength light M also diffracted or scattered by the sample particles is received by the plurality of photosensors 6a, 6b,.
Since the light intensity is measured, a relatively large particle size distribution is measured in the measurement with the laser light L, and a relatively small particle size distribution is measured in the measurement with the single wavelength light M. As a whole, there is an advantage that a particle distribution ranging from a small particle diameter to a large particle diameter can be measured.

[Problems to be solved by the invention]

However, in the case of the above-described conventional particle size distribution measuring device, when the light amount of the laser diode 7 or the ultraviolet light source 9 as the light source of the laser optical system 2 or the single-wavelength optical system 3 fluctuates, the ring-shaped photo sensor array 5 is correspondingly changed. And photo sensors 6a, 6
The received light amount of b ... also fluctuates. However, since no measure is taken for the influence of the fluctuation of the light source light amount on the scattered light amount,
There is a problem that an accurate particle size distribution cannot be obtained.

In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide a particle size distribution measuring device capable of accurately measuring a particle size distribution without being influenced by a light amount variation of a light source.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a laser light irradiation means for irradiating a sample container containing a medium in which sample particles are dispersed with laser light and a scattering angle diffracted or scattered by the sample particles. A large-diameter particle detection optical system including a ring-shaped detector for measuring the light intensity of the laser light, a single-wavelength light irradiating means for irradiating the sample container with single-wavelength light obtained from lamp light, and the sample A small-diameter particle detection optical system including a photosensor group for measuring the light intensity of a single wavelength light for each scattering angle diffracted or scattered by particles, and a part of the laser light before being irradiated on the sample container. A first beam splitter to be separated, a first monitor photosensor for measuring the light intensity of the laser beam split by the beam splitter, and a light source for irradiating the sample container. A second beam splitter for separating a part of the previous single-wavelength light, a second monitor photosensor for measuring the light intensity of the single-wavelength light separated by the beam splitter, and the ring-shaped detector; Data input means for taking in both measurement data of the photo sensor group and the photo sensor for each monitor, and the ring detector and the photo sensor group taken in by the data input means, and the monitor data at the time of measurement of the measurement data And a particle size distribution calculating means for calculating a particle size distribution of the sample particles from the corrected measurement data based on Fraunhofer diffraction or Mie scattering theory. And

[Action]

According to the above configuration, the measurement data by the ring-shaped detector that measures the light intensity of the laser light diffracted or scattered by the sample particles, and the measurement data of the photosensor group that measures the light intensity of the single-wavelength light are measured by the measurement. At this point, the correction unit corrects the amount of the laser light and the single-wavelength light measured by the first and second monitoring photosensors by an amount corresponding to the amount of the light, and the particle size distribution calculating unit calculates the sample based on the corrected measurement data. The particle size distribution of the particles is accurately calculated.

Also, both the data measured by the optical system for detecting large-diameter particles and the data measured by the optical system for detecting small-diameter particles are fetched by the data input unit and used as the data of the particle size distribution calculating unit. A wide range of particle size distribution across the diameter can be easily measured.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing a measuring optical system of a particle size distribution measuring device according to the present invention.

In FIG. 1, a sample cell 21 is a transparent container containing a sample solution in which sample particles are dispersed and present in a medium, and a laser beam irradiation means 22 irradiates the sample cell 21 with a parallel laser beam L. Optical system.

The laser light irradiating means 22 includes a laser light source 27 that outputs a parallel laser light L, a beam expander 28 that expands the light flux of the laser light L, and the like.

A condensing lens for condensing laser light L diffracted or scattered by sample particles on a ring-shaped detector 25 in front of the sample cell 21 on the optical axis of the laser light irradiation means 22.
24 are located.

The ring-shaped detector 25 receives light having a relatively small scattering angle out of the laser light L diffracted or scattered by the sample particles, for each scattering angle, and measures the light intensity thereof. It is arranged in front of the condenser lens 24.

FIG. 2 is a perspective view showing the configuration of the ring-shaped detector 25. The ring-shaped detector 25 includes a plurality of photosensors 25a, 25b for detecting laser light L diffracted or scattered at respective angles according to the particle size of the sample particles.
Are arranged in a ring shape around the optical axis P of the laser beam irradiating means 22.

Each photo sensor 25a, 25b of the ring detector 25
Are connected to a multiplexer 36 via amplifiers 35 respectively associated with each other.

The above-described laser beam irradiating means 22, condensing lens 24, and ring-shaped detector 25 constitute a large-diameter particle detection optical system 19 that receives light diffracted or scattered by sample particles having a relatively large particle diameter.

Between the beam expander 28 and the sample cell 21 on the optical axis of the laser light irradiating means 22, there is provided a first mirror including a half mirror for separating a part of the laser light L irradiated through the beam expander 28. Beam splitter 37 is provided,
A part of the laser light L separated by the beam splitter 37 is received by a first monitoring photosensor 38. The monitoring photosensor 38 is also connected to the multiplexer 36 via the corresponding amplifier 35.

On the other hand, the single-wavelength light irradiating means 23 is an optical system for irradiating the sample cell 21 with single-wavelength light M having a shorter wavelength than the laser light L, and includes a lamp light source 29, a spherical mirror 30, and an aperture 31. , 34, collimator lens 32, interference filter 33
It is constituted by such as.

The spherical mirror 30 emits light emitted backward from the lamp light source 29 to an aperture disposed in front of the lamp light source 29.
The aperture 31 is a mirror for condensing the light from the lamp light source 29 into a sufficiently small light flux.

The collimator lens 32 disposed in front of the aperture 31 is a lens for converting the lamp light whose light flux has been narrowed down by the aperture 31 into parallel rays, and the collimator lens thereof
An interference filter 33 disposed in front of 32 is a filter for extracting only a predetermined single-wavelength light M from the parallel light.

An aperture 34 arranged in front of the interference filter 33
Is for narrowing the luminous flux of the single-wavelength light M from the interference filter 33, and the single-wavelength light M passing through the aperture 34 is located at a position different from the irradiation position of the laser light L on the sample cell 21. Irradiated.

Around the sample cell 21, a photosensor group 26 for individually detecting light having a relatively large scattering angle among the single wavelength light M diffracted or scattered by the sample particles is provided for each scattering angle. A plurality of photo sensors 26a, 26b ...
Are arranged at the respective scattering angle positions. In particular,
Here, photosensors 26a, 26b,... Are arranged not only on the rear side of the sample cell 21, that is, on the side where the single-wavelength light irradiation means 23 is disposed, but also on the front side of the sample cell 21 having a small scattering angle. It is also configured to measure the light intensity of the single-wavelength light M scattered in front of.

Each of the photosensors 26a, 26b,... Receives the diffracted light or the scattered light collected by the corresponding condenser lens 39a, 39b,. These photosensors 26a, 26b are connected to the multiplexer through corresponding amplifiers 35, respectively.
Connected to 36.

The single-wavelength light irradiating means 23, the photosensor group 26, and the condenser lenses 39a, 39b... Are provided with a small-diameter particle detection optical system 20 for receiving light diffracted or scattered by sample particles having a relatively small particle diameter. Constitute.

Further, on the optical axis of the single-wavelength light irradiation means 22, between the aperture 34 and the sample cell 21, a half mirror or the like for separating a part of the single-wavelength light M irradiated through the aperture 34 is provided. A second beam splitter 40 is provided, and a part of the single-wavelength light M separated by the beam splitter 40 is received by a second monitor photosensor 41. The monitor photosensor 41 is also connected to the multiplexer 36 via the corresponding amplifier 35.

The multiplexer 36 converts the measurement data of the light intensity detected by each photo sensor 25a, 26b... Of the ring-shaped detector 25, each photo sensor 26a, 26b. This is a circuit having a function of capturing in a predetermined order, converting the captured measurement data into a serial signal in accordance with the capturing order, and transmitting the serial signal to the A / D converter 42 in the next stage.

The A / D converter 42 is a circuit that converts the transmitted measurement data, that is, analog data, into digital data, and the digital data is transmitted to the processing unit 43 in the next stage.

The arithmetic processing device 43 is a device that performs an arithmetic process for obtaining a particle size distribution of the sample particles in the sample cell 21 based on the transmitted digital data on the light intensity, and has an arithmetic function configured by a computer or the like. Is
Although the particle size distribution is obtained based on the Fraunhofer diffraction or Mie scattering theory, a function of a correction process for correcting input data used for the calculation prior to the calculation of the particle size distribution is also added.

In other words, the correction processing in this case means that the laser light L and the laser light L measured by the monitor photosensors 38 and 41 at the time when each of the photosensors 25a, 25b..., 26a, 26b. Based on the light intensity data of the single wavelength light M, the light intensity data by the photo sensors 25a, 26b,..., 26a, 26b. The measurement data of the photosensors 25a, 25b... Which receive the diffracted light or the scattered light of the laser light L is based on the measurement data detected by the monitor photosensor 38, and receives the diffracted light or the scattered light of the single wavelength light M. Are corrected based on the measurement data detected by the monitoring photosensor 41.

FIG. 3 is a flowchart showing an outline of the arithmetic processing performed in the arithmetic processing unit 43.

Next, the procedure for measuring the particle size distribution by the particle size distribution measuring device will be described with reference to the flowchart of FIG.

In the optical system constituting the laser beam irradiating means 22, the laser beam L from the laser light source 27 is expanded in beam by the beam expander 28, and a part of the beam is transmitted through the first beam splitter 37 to irradiate the sample cell 21. Is done.

The laser light L is diffracted or scattered by the sample particles in the sample cell 21, and the diffracted or scattered light is imaged on the ring detector 25 by the condenser lens 24.

Each of the photosensors 25a, 25b,... Arranged on the ring-shaped detector 25 measures the light intensity of the laser light L diffracted or scattered by the sample particles. Of the photosensors 25a, 25b,..., The outer photosensor receives scattered light having a larger scattering angle, and the inner photosensor receives scattered light having a smaller scattering angle. Therefore, the light intensity detected by the photosensor on the outer peripheral side reflects the amount of sample particles having a larger particle diameter, and the light intensity detected by the photosensor on the inner peripheral side indicates the amount of sample particles having a smaller particle diameter. It will be reflected.

Further, the beam expander of the laser beam irradiation means 22 is used.
Part of the laser light L exiting from the light source and separated by the first beam splitter 37 is received by the first monitoring photosensor.

The light intensity detected by each of these photosensors 25a, 25b,..., 38 is converted into an analog electric signal, and further input to a multiplexer 36 via an amplifier 35.

On the other hand, in the optical system constituting the single-wavelength light irradiating means 23, the lamp light from the lamp light source 29 passes through the aperture 31 and is collimated by the collimator lens 32. Light M is applied. Further, the single-wavelength light M is condensed by the aperture 34 and a part of the light is transmitted through the second beam splitter 40 and irradiated on the sample cell 21.

The single-wavelength light M is diffracted or scattered by the sample particles in the sample cell 21, and the scattered light is converted into individual condensing lenses.
Photo sensors 26a, 26b corresponding to 39a, 39b, respectively.
, And the light intensity distribution is measured by the photosensor group 26.

In the photosensor group 26, the photosensor disposed near the rear of the sample cell 21 receives the single-wavelength light M having a larger scattering angle, and the photosensor disposed near the front of the sample cell 21 , A single wavelength light M having a smaller scattering angle is received. Therefore, the light intensity detected by the photosensor disposed at the rear reflects the amount of sample particles having a smaller particle diameter, and the light intensity detected by the photosensor disposed at the front is larger than the particle diameter. This reflects the amount of sample particles.

A part of the single-wavelength light M that exits the aperture 34 of the single-wavelength light irradiation means 23 and is separated by the second beam splitter 40 is received by the second monitoring photosensor 41.

The light intensity detected by each of these photosensors 26a, 26b,..., 41 is converted into an analog electric signal, and further input to a multiplexer 36 via an amplifier 35.

As described above, the lamp light source 29 whose wavelength range is shorter than the wavelength of the laser beam L is selected in advance, so that the diffracted light or the scattered light of the single wavelength light M is used for sample particles having a small particle diameter. This is effective for obtaining the particle size distribution of. On the other hand, the diffracted light or the scattered light of the laser light L is effective for obtaining a particle size distribution for a sample particle having a large particle diameter.

In the multiplexer 36, each of the photo sensors 25a, 25b.
The measurement data input from 8, 26a, 26b,..., 41, that is, analog electric signals are taken in a certain order. That is, for example, the measurement data is taken from the photosensors 26a, 26b... Corresponding to the sample particles having a small particle diameter to the photosensors 25a, 25b.

The analog electric signal captured by the multiplexer 36 is converted into a serial signal, sequentially converted into a digital signal by an A / D converter 42 at the next stage, and further input to an arithmetic processing unit 43 at the next stage.

In the arithmetic processing unit 43, as shown in the flowchart of FIG. 3, prior to performing the substantial particle size distribution calculation processing, the measurement data obtained by the ring-shaped detector 25 is converted to the first monitor photo at the same measurement time. A process of correcting based on the measurement data by the sensor 38 (step S1);
A process (step S2) of correcting the measurement data by the photosensor group 26 based on the measurement data by the second monitoring photosensor 41 at the same measurement time point is performed.
That is, the measurement data of the ring-shaped photosensor 25 is corrected to increase or decrease according to the increase or decrease in the amount of light received by the first monitor photosensor 38, that is, the change in the amount of light of the laser light L. Increase or decrease, ie, single wavelength light M
The measurement data of the photosensor group 26 is corrected to increase or decrease in accordance with the fluctuation in the light amount.

Next, the particle size distribution of the sample particles is determined based on the measurement data of each light intensity corrected as described above (Step S).
3). The calculation procedure is performed based on the Fraunhofer diffraction or Mie scattering theory.

〔The invention's effect〕

The present invention has the above-described configuration, and includes measurement data obtained by a ring-shaped detector that measures light illuminance of laser light that is diffracted or scattered by sample particles, and measurement data of a photosensor group that measures light intensity of single-wavelength light. At the same measurement time point, the correction means corrects the laser light and the single-wavelength light measured by the first and second monitoring photosensors by an amount corresponding to the light intensity, and calculates the particle size distribution based on the corrected measurement data. Since the particle size distribution of the sample particles is calculated by the means, there is an effect that an accurate particle size distribution which is not affected by the fluctuation of the light amount of the light source can be measured.

In addition, both the data measured by the optical system for detecting large-diameter particles and the data measured by the optical system for detecting small-diameter particles are fetched by the data input unit and used as data of the particle size distribution calculating unit. There is also an effect that a wide range of particle size distribution over a large particle size can be easily measured.

[Brief description of the drawings]

1 to 3 show one embodiment of the present invention, and FIG. 1 is a diagram schematically showing an outline of a particle size distribution measuring apparatus of the present invention;
FIG. 2 is a perspective view showing a ring-shaped detector in the particle size distribution measuring device, and FIG. 3 is a flowchart showing a measuring operation of the particle size distribution measuring device. FIG. 4 is a perspective view showing a configuration of a conventional particle size distribution measuring device. 19 optical system for detecting large-diameter particles, 20 optical system for detecting small-diameter particles, 21 sample container, 22 laser irradiation means, 23
... Single wavelength light irradiation means, 25 ... Ring detector, 26
... Photo sensor group, 36 data input means 37 first beam splitter 38 first monitor photo sensor 40 second beam splitter 41 second monitor Photosensor 43... Correction means and particle size distribution calculation means L... Laser light M... Single wavelength light.

Claims (1)

(57) [Claims] 1. A laser beam irradiation means for irradiating a sample container containing a medium in which sample particles are dispersed with laser light, and measuring the light intensity of the laser beam at each scattering angle diffracted or scattered by the sample particles. A large diameter particle detection optical system including a ring-shaped detector, a single wavelength light irradiating means for irradiating the sample container with a single wavelength light obtained from lamp light, and each scattering diffracted or scattered by the sample particles. An optical system for detecting small-diameter particles including a photosensor group for measuring the light intensity of single-wavelength light for each angle,
A first beam splitter for separating a part of the laser light before being irradiated on the sample container, a first monitor photosensor for measuring the light intensity of the laser light separated by the beam splitter, and the sample A second beam splitter for separating a part of the single-wavelength light before being irradiated to the container, a second monitor photosensor for measuring the light intensity of the single-wavelength light separated by the beam splitter, Data input means for taking in the measurement data of the ring-shaped detector, the photo sensor group and the photo sensor for each monitor together, and measuring the measurement data of the ring-shaped detector and the photo sensor group taken in by the data input means to measure the measurement data Correction means for correcting each according to the measurement data of each of the monitor photosensors at a point in time, and Fraunhof Diffraction or particle size distribution measuring apparatus characterized by comprising a particle size distribution calculation means for calculating a particle size distribution of the sample particles from the corrected measurement data based on the Mie scattering theory.