JP2874067B2 - Scattering plate for calibration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattering plate for calibration. More specifically, the present invention relates to a scattering plate for calibration capable of easily calibrating a particle size distribution measuring device with high accuracy.

[0002]

2. Description of the Related Art In recent years, ultrafine particles have been attracting attention in the process of manufacturing ceramic raw materials, superconducting materials, magnetic materials, etc. or in the process of manufacturing semiconductors. There is a growing need to measure the size of micron particles. Generally, an optical particle size distribution measuring device is used to measure the diameter or particle size distribution of these fine particles. The optical particle size distribution measuring device is configured such that scattered light generated by irradiating a laser beam to a group of particles to be measured is condensed by an optical lens, and is measured by a light receiving element for detection arranged on a lens focal plane. The scattered light intensity for each scattering angle is determined from the scattered light intensity distribution, and the particle size distribution is determined from the analysis. This particle size distribution is obtained by calculation based on Mie's scattering theory by measuring the intensity distribution of scattered light.

Usually, a particle size distribution measuring device is calibrated by measuring a particle size distribution of a reference powder having a certain particle size distribution (reference powder), and the powder has a particle size distribution that is always stable. Is required. However, the reference powder is consumed every time the particle size distribution measuring device is calibrated. In addition, it is industrially impossible to newly prepare a powder having exactly the same particle size distribution. Therefore, when a new reference powder is prepared, the particle size distribution of the reference powder must be measured, and the particle size distribution serving as a reference for calibrating the particle size distribution measurement device must be obtained. Is required, and there is a high risk of causing confusion in lot management. Furthermore, since the reference particle size distribution is determined using a particle size distribution measurement device that should be calibrated with the reference powder, it cannot be an absolute reference, and the relative size between the particle size distribution measurement device and the reference powder can be determined. It's just a relationship.

Further, as described above, the calibration of the particle size distribution measuring apparatus is performed on the assumption that the particle size distribution of the reference powder is stable and a constant particle size distribution is always measured. Therefore, careful storage of the reference powder is required so that the reference particle size distribution does not change due to deterioration of the reference powder. The present invention has been made based on the above circumstances. That is, the object of the present invention is:
An object of the present invention is to provide a scattering plate for calibration as an absolute standard, which does not require many facilities and processes and can always calibrate a particle size distribution measuring device with high accuracy.

[0005]

Means for Solving the Problems The present invention for attaining the above object comprises a transparent support and a metal film formed on the surface of the support, wherein the metal film has a fine pore diameter. A scattering plate for calibration, comprising a plurality of pores perforated with a constant number distribution.

[0006]

The particle size distribution serving as a reference for calibrating the particle size distribution measuring device can be determined by measuring the scattered light intensity when the reference powder is irradiated with laser light. In the present invention, after forming a metal coating on the surface of the transparent support, several μm
By disposing a calibration scattering plate having a plurality of pores of m to several tens of μm in the optical path output from the laser light irradiation means, scattered light equivalent to scattered light by particles having a certain particle size distribution is obtained. It is always possible to measure.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view of one embodiment of a particle size distribution measuring apparatus provided with a calibration scattering plate of the present invention, as viewed from above. The calibration scattering plate of the present invention is limited to the embodiment of FIG. Not something. As shown in FIG. 1, a particle size distribution measuring device 1
Is performed, a calibration scattering plate 4 is provided instead of the scattered light measurement cell in the traveling optical path of the laser light irradiated from the laser light irradiation means 2.

(1) Scattering Plate for Calibration The scattering plate for calibration 4 of the present invention basically comprises a transparent support 5
And a metal coating 6 having a plurality of pores formed on the surface of the support. The support 5 is not particularly limited as long as it is transparent and has a supporting ability, and examples thereof include glass. The metal for forming a coating on the surface of the support is not particularly limited, and various kinds of metals or alloys composed of two or more metals can be used.

The method of forming a metal film on the surface of the support may be a conventionally known method, for example, a metal deposition method, an electric deposition method, an anodic oxidation method, an electroless deposition method, a sputtering method, or the like.
A metal spraying method can be used. The thickness of the support is about 1 to 5 mm, preferably about 2 to 3 mm, and the thickness of the metal coating is about several μm to several tens μm. The metal coating formed on the surface of the support has a pore diameter of several microns.
By having a plurality of pores of m to several tens of μm and adjusting the number, size, etc. of the pores, it is possible to obtain scattered light equivalent to scattered light of particles having an arbitrary particle size distribution. . The method for perforating the metal film may be a conventionally known method, and examples thereof include photoetching.

(2) Laser Light Irradiating Means The laser light irradiating means 2 includes a laser light source (not shown), a laser light oscillating device (not shown), and a collimator lens 3 for collimating the output laser. The laser light source and the laser light oscillating device may be conventionally known ones. As the laser light that can be output by the laser light oscillating device, for example, 632.8 by a He—Ne gas laser
nm laser light, 680-780n by semiconductor laser
m laser light and the like. The collimator lens 3 includes a plurality of lens groups (not shown), and converts the laser light output from the laser light transmitting device into a parallel light beam.

(3) Scattered Light Measurement Cell A scattered light measurement cell (not shown) is provided at the position of the calibration scattering plate 4 of the present invention when measuring the particle size distribution of the particles after the completion of the calibration of the particle size distribution measuring device. Is done. The scattered light measurement cell is
The suspension is formed as a flow cell into which a suspension obtained by dispersing the particles to be measured in a medium can flow from a storage tank (not shown) through a pipe (not shown). As a material forming the scattered light measurement cell, conventionally known glass, Pyrex glass, quartz glass and the like can be mentioned.

(4) Light-receiving element for detection The light-receiving element 8 for detection is arranged on the opposite side of the converging lens 7 from the scattering plate 4 for calibration. The light receiving element for detection 8
Are formed from a group of photoelectric conversion elements (for example, photodiodes or the like) having a plurality of light receiving surfaces arranged in a direction orthogonal to the optical axis of the condenser lens 7 in the polarization plane of the laser light. .

The intensity of the scattered light generated by the particles to be measured in the calibration scattering plate 4 or the scattered light measurement cell is symmetric with respect to the optical axis center of the scattered light. Therefore, the detection light-receiving element 8 includes a central photoelectric conversion element that receives the central optical axis of the scattered light, and another group of photoelectric conversion elements that are arranged in a line in one direction from the central photoelectric conversion element. . Normally, after a light receiving element for detection is formed on a semiconductor wafer by division using a semiconductor technique, the semiconductor wafer is cut and used as a scattered light intensity measuring detector of a particle size distribution measuring device.

(5) Particle Size Distribution Analysis System The particle size distribution analysis system in the particle size distribution measuring device includes a multiplexer, an amplifier, an A / D converter, an arithmetic control unit, an output device, etc., all of which are not shown. The multiplexer is a switch for switching an electric signal output from each photoelectric conversion element group constituting the light receiving element for detection. The detection signal output from the multiplexer is amplified by an amplification amplifier, converted into a digital signal by an A / D converter, and output to an arithmetic and control unit. The arithmetic and control unit calculates the particle size distribution of the data indicating the measured scattered light intensity and scattering angle based on the well-known Fraunhofer diffraction theory and Mie scattering theory. The particle size distribution data calculated by the arithmetic and control unit is, for example, CRT,
Output to an output device such as an XY plotter.

(6) Calibration method of particle size distribution measuring device Particle size distribution measuring device 1 using the scattering plate for calibration 4 of the present invention.
The calibration method will be described. The calibration scattering plate 4 of the present invention is provided in the laser beam path output from the laser beam irradiation means 2. The laser light oscillated by the laser light irradiating means 2 is converted into a parallel light beam by the collimator lens 3 and is irradiated on the calibration scattering plate 4. The scattered light simulated by the calibration scattering plate 4 is converged by the condenser lens 7 and irradiated to the light receiving element 8 for detection. The electric signal output from each photoelectric conversion element of the detection light receiving element 8 indicates the scattered light intensity, and
The scattering angle is determined based on the position of the photoelectric conversion element. Further, the arithmetic control unit calculates the particle size distribution measured from the scattered light intensity and the scattering angle, and calibrates the particle size distribution measuring device based on the reference particle size distribution.

(7) Method of Measuring Particle Size Distribution Measurement of particle size distribution by a calibrated particle size distribution measuring device will be described. First, a sample liquid in which particles to be measured are suspended in water is filled in a scattered light measurement cell. Next, the laser light oscillated by the laser light irradiating means is converted into a parallel light flux by a collimator lens, and is irradiated on the scattered light measuring cell.

The laser beam applied to the scattered light measuring cell is scattered by the particles to be measured suspended in the scattered light measuring cell. The scattered light generated by being scattered by the particles to be measured is converged by the condenser lens and irradiated to the light receiving element for detection. In the light receiving element for detection, a plurality of photoelectric conversion elements are arranged in a line in a direction perpendicular to the optical axis of the condensing lens within the plane of polarization of the laser light. The electric signal indicates the scattered light intensity, and the scattering angle is determined based on the position of the photoelectric conversion element.

The electric signal output from each photoelectric conversion element in the light receiving element for detection is amplified by an amplification amplifier via a multiplexer, and then converted into a digital signal by an A / D converter. Further, the arithmetic control unit calculates the particle size distribution of the particles from the intensity and scattering angle of the scattered light, and the calculated particle size distribution is output from the output device.

[0019]

As described above, the present invention comprises a transparent support and a metal film formed on the surface of the support, wherein the metal film is formed by a plurality of fine holes perforated with a constant number distribution based on the pore diameter. According to the calibration scattering plate having holes, complicated steps are not required as compared with the case where the particle size distribution measuring device is calibrated using the reference powder, and it is consumed like the reference powder. Since a plurality of identical products can be manufactured industrially, the particle size distribution serving as a constant calibration standard can always be measured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a particle size distribution measuring device provided with a scattering plate for calibration of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particle size distribution measuring device 2 Laser beam irradiation means 3 Collimator lens 4 Calibration scattering plate 5 Support body 6 Metal film 7 Condensing lens 8 Light receiving element for detection

Claims (1)

(57) [Claims] 1. A method comprising: a transparent support; and a metal film formed on the surface of the support, wherein the metal film comprises a plurality of pores perforated with a constant number distribution based on the pore diameter. A scattering plate for calibration, which is provided.