JP2876253B2 - 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.

[Prior art] In a particle size distribution measuring apparatus utilizing diffraction or scattering of light by particles, the intensity distribution of diffracted light or scattered light,
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. 5 is a perspective view showing a conventional example of this type of particle size distribution measuring device.

In FIG. 5, 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 by the measurement with the laser light L, and a relatively small particle size distribution is measured by the measurement with the single wavelength light M. The whole apparatus has an advantage that a particle size distribution ranging from a small particle diameter to a large particle diameter can be measured.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional particle size distribution measuring apparatus, when the concentration of the sample particles flowing into the flow cell 1 is different, the light intensity measured by the ring-shaped photosensor array 5 and the plurality of photosensors 6a, 6b. Is also different.

That is, as the concentration of the sample particles increases, the light diffracted or scattered by the sample particles is strongly affected by the multiple scattering, and is received by the ring-shaped photosensor array 5 and the photosensors 6a, 6b,. The light intensity tends to decrease accordingly.

In particular, when the particle diameter is in the order of submicron, the degree of multiple scattering differs depending on the wavelength of the light to be irradiated. Therefore, the influence of multiple scattering on the light intensity of the laser light measured by the ring-shaped photosensor array 5 and Is different from the degree of multiple scattering affecting the light intensity of the single-wavelength light measured by the plurality of photosensors 6a, 6b.

However, in the case of a conventional particle size distribution measuring device,
Since the influence of the concentration of the sample particles on the measurement results is not taken into account, the measurement results differ depending on the concentration when flowing through the flow cell 1 even for sample particles having the same particle size distribution,
There is a problem that an accurate particle size distribution cannot be obtained.

In view of the above-mentioned conventional disadvantages, an object of the present invention is to provide a particle size distribution measuring apparatus capable of accurately measuring a particle size distribution without being affected by the concentration of sample particles.

[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 each scattering device 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 irradiation stage for irradiating the sample container with a 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 at each scattering angle diffracted or scattered by particles, and transmitted through the sample container without being diffracted or scattered by the sample particles A first transmitted light photosensor that measures the light intensity of the laser light to be transmitted, and transmits through the sample container without being diffracted or scattered by the sample particles. A second transmitted light photosensor that measures the light intensity of the single wavelength light that the first and second
Based on the measurement data of the transmitted light photosensor, the transmittance of the laser light and the single-wavelength light to the sample container is calculated, respectively, the amount corresponding to those transmittance, the ring-shaped detector and photosensor group of It is characterized by comprising a correcting means for correcting the measurement data and a particle size distribution calculating means for calculating the particle size distribution of the sample particles from the corrected measurement data based on the Fraunhofer diffraction or Mie scattering theory.

[Action]

According to the above configuration, the measurement data of the ring 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, The particle size distribution of the sample particles is calculated by the particle size distribution calculating means based on the corrected measurement data by an amount corresponding to the concentration of the sample particles. Therefore, the required particle size distribution is accurate.

Embodiment An embodiment of the present invention will be described below 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 laser beam L diffracted or scattered by the sample particles and a laser beam L transmitted through the sample cell 21 without being diffracted or scattered are placed on the optical axis of the laser beam irradiation means 22 in front of the sample cell 21. A condensing lens 24 for condensing light on the shape detector 25 is arranged.

The ring-shaped detector 25 receives laser light at each scattering angle diffracted or scattered by the sample particles, and measures the light intensity distribution thereof.The ring-shaped detector 25 is disposed in front of the condenser lens 24. I have.

FIG. 2 is a perspective view showing the configuration of the ring-shaped detector 25. The ring detector 25 includes a plurality of scattered light photosensors 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 of the laser beam irradiation means 22. Further, at the center position of the ring-shaped detector 25, one transmitted light photosensor 35 for detecting the laser light L transmitted through the sample cell 21 without being diffracted or scattered is arranged.

Each photo sensor 25a, 25b of the ring detector 25
, 35 are connected to a multiplexer 37 via amplifiers 36, which are individually 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.

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

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.

FIG. 3 is a plan view showing the configuration of the interference filter 33. The interference filter 33 is configured by vertically arranging a plurality of quarter-wave plates 33a, 33b,... Having different wavelengths to be transmitted, and by changing the position of the interference filter 33 up and down, The wavelength of the single-wavelength light M to be extracted can be switched over a plurality of stages.

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.

A single-wavelength light irradiating means behind the sample cell 21
On the optical axis 23, a transmitted light photosensor 38 that detects single-wavelength light M that is transmitted through the sample cell 21 as it is without being diffracted or scattered by the sample particles is arranged. The amplifier 37 is connected to the multiplexer 37 described above.

Further, around the sample cell 21, a plurality of photosensors 26a, 26b constituting a photosensor group 26 for individually detecting single wavelength light M diffracted or scattered by sample particles at each scattering angle. Are arranged separately for each scattering angle position. In particular, here, the sample cell
Photosensors 26a, 26b on the front side of the sample cell 21 as well as on the rear side of the sample cell 21, that is, on the
And the single-wavelength light M scattered in front of the sample cell 21
Is also configured to measure the light intensity.

Each of the photosensors 26a, 26b,... Receives the diffracted light or the scattered light collected by the corresponding condenser lens 39a, 39b,. These photo sensors 26a, 26b...
Connected to 37.

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.

The multiplexer 37 includes the photosensors 25a, 25b,..., 35 of the ring detector 25 and the other photosensors 26.
The measurement data of the light intensity detected by a, 26b..., 38 is taken in a predetermined order, the taken measurement data is converted into a serial signal according to the taking order, and sent to the A / D converter 39 of the next stage. This is a circuit that has the function of performing

The A / D converter 39 is a circuit that converts the transmitted measurement data, that is, analog data, into digital data, and the digital data is transmitted to the arithmetic processing device 40 at the next stage.

The arithmetic processing device 40 is a device that performs arithmetic processing for obtaining the particle size distribution of the sample particles in the sample cell 21 based on the transmitted digital data on the light intensity, and is configured by a computer or the like. Its arithmetic function 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.

That is, the correction processing in this case is to convert the diffracted light or the scattered light into the transmitted light data received by the transmitted light photosensors 35 and 38 when each of the photosensors 25a, 25b ..., 26a, 26b ... receives the light. Based on the photo sensors 25a, 25b ..., 26a, 26b
Are used to correct the light intensity data by the photosensors 25a, 25b, which receive the diffracted light or the scattered light of the laser light L.
For the measurement data of 25b… Photo sensor for transmitted light 35
Based on the transmitted light measurement data detected by the photo sensor 26a, which receives the diffracted light or the scattered light of the single wavelength light M,
For the measurement data of 26b…
Are respectively corrected based on the transmitted light measurement data detected by.

FIG. 4 is a flowchart showing an outline of the arithmetic processing performed in the arithmetic processing device 40.

Next, the procedure of 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 light irradiation means 22, the laser beam L from the laser light source 27 is expanded by a beam expander 28 to irradiate the sample cell 21.

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.

In the ring detector 25, the transmitted light photosensor 35 located at the center of the ring detector 25 measures the light intensity of the laser light L transmitted through the sample cell 21 without being diffracted or scattered by the sample particles. Further, the other photosensors 25a, 25b,... Arranged on the outer periphery measure 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,
The light intensity detected by the photosensor on the inner peripheral side reflects the amount of sample particles having a smaller particle diameter. The light intensity detected by each of these photosensors 25a, 25b,..., 35 is converted into an analog electric signal, and further input to a multiplexer 37 via an amplifier 36.

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 irradiated on the sample cell 21 after the light beam is narrowed down by the aperture 34.

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 condenser lenses.
Photo sensors 26a, 26b corresponding to 39a, 39b, respectively.
, And the light intensity distribution is measured by the photosensor group 26.

In each of the photosensor groups 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. Receives the single-wavelength light M having a smaller scattering angle. 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. The light intensity detected by each of these photosensors 26a, 26b..., 38 is converted into an analog electric signal, and further passed through an amplifier 36 to a multiplexer 37.
Is input to

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 37, each of the photo sensors 25a, 25b.
Measurement data input from 5, 26a, 26b,..., 37, 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 size to the photosensors 25a, 25b.

In the single-wavelength light irradiation means 23, the wavelength of the single-wavelength light M irradiated on the sample cell 21 is switched by changing the position of the interference filter 33 up and down.
By this switching operation, data in a range of particle diameters in several stages can be obtained as measurement data by the small-diameter particle detection optical system 20.

The analog electric signal captured by the multiplexer 37 is converted into a serial signal, sequentially converted into a digital signal by an A / D converter 39 at the next stage, and further input to an arithmetic processing unit 40 at the next stage.

As shown in FIG. 4, prior to performing the substantial particle size distribution calculation process, the arithmetic processing device 40 includes a sample liquid containing no sample particles in the sample cell 21 (hereinafter referred to as a blank if necessary). Under the state where the sample liquid is stored, data of each transmitted light measured by the transmitted light photosensors 35 and 38 is stored in advance (step S1). Among the data, the transmitted light data of the single wavelength light M is
Each single wavelength light of each wavelength switched by the interference filter 33 is separately measured and stored.

In the subsequent calculation process of the substantial particle size distribution, the transmitted light photosensor 38 that receives the single transmitted light M that has passed through the sample liquid containing the sample particles in the sample cell 21 and the laser beam L that is received The ratio between the transmitted light data measured by the transmitted light photosensor 35 and the transmitted light data for the previously stored blank sample liquid is calculated (step S2).

That is, the transmittance of the single-wavelength light M is calculated from the ratio of the transmitted light data measured by the transmitted light photosensor 35 and the transmitted light data corresponding to the blank sample liquid,
Similarly, the transmittance of the laser light L is calculated from the ratio between the transmitted light data measured by the transmitted light photosensor 38 and the transmitted light data corresponding to the blank sample liquid.

Next, the photo sensors 25a and 25b of the ring-shaped detector 25
Are corrected to increase by an amount corresponding to the transmittance obtained from the measurement data of the transmitted light photosensor 35, and similarly, the measurement data obtained by the photosensors 26a, 26b,. The increase is corrected by an amount corresponding to the transmittance obtained from the 38 measurement data (step S3).

Thereafter, the particle size distribution of the sample particles is obtained based on the measurement data of each light intensity corrected as described above (step S4). The calculation procedure is performed based on the Fraunhofer diffraction or Mie scattering theory.

[Effects of the Invention] The present invention has the above-described configuration, and has a ring-shaped detector for measuring light intensity of laser light diffracted or scattered by sample particles, and a photosensor for measuring light intensity of single-wavelength light. Since the measurement data of the group is corrected by the correction means by an amount corresponding to the concentration of the sample particles at that time, the particle size distribution of the sample particles is calculated by the particle size distribution calculation means based on the corrected measurement data. In addition, there is an effect that an accurate particle size distribution that is not affected by multiple scattering can be measured.

[Brief description of the drawings]

1 to 4 show an 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;
2 is a perspective view showing a ring-shaped detector in the particle size distribution measuring device, FIG. 3 is a plan view showing an interference filter in the particle size distribution measuring device, and FIG. 4 is a flowchart showing a measuring operation of the particle size distribution measuring device. It is. FIG. 5 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
... Photosensor group, 35... First transmitted light photosensor, 38... Second transmitted light photosensor, 40... Correction means and particle size distribution calculation means, L. 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 method for measuring the intensity of laser light transmitted through the sample container without being diffracted or scattered by the sample particles;
A second transmitted light photosensor for measuring the light intensity of a single wavelength light transmitted through the sample container without being diffracted or scattered by the sample particles; and the first and second transmitted light photosensors. Based on the measurement data of the transmitted light photosensor, the transmittance of the laser light and the single-wavelength light to the sample container is calculated, respectively, the amount corresponding to those transmittance, the ring-shaped detector and photosensor group of A particle size distribution measuring device, comprising: a correction unit that corrects measurement data; and a particle size distribution calculation unit that calculates a particle size distribution of the sample particles from the corrected measurement data based on Fraunhofer diffraction or Mie scattering theory.