JP4818527B2 - Scattering particle size distribution measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention irradiates a sample with light from a light source, causes the scattered light generated at that time to enter an array detector through a condenser lens, and based on the scattered light intensity pattern obtained at this time, The present invention relates to a scattering type particle size distribution measuring apparatus for measuring a particle size distribution.
[0002]
[Prior art]
FIG. 5 shows a main part of a conventional scattering type particle size distribution measuring apparatus. In this figure, 1 is a light source that emits laser light 2, for example, 3 is a beam expander that appropriately expands the laser light 2, and 4 is For example, a flow cell for storing a sample, 5 is a condenser lens provided behind the flow cell 4, 6 is an array detector for detecting scattered light and transmitted light from the condenser lens 5, and 7 is from the array detector 6. A multiplexer for taking in the signal, a CPU 8 for receiving a signal from the multiplexer 7 and calculating the particle diameter distribution by performing an operation based on the scattered light intensity pattern, and a computer 9 for controlling the entire apparatus and displaying the operation result and the like. A display device 10 such as a color display is provided.
[0003]
In the scattering type particle size distribution measuring apparatus, when a sample is accommodated in the flow cell 4 and the laser beam 2 is irradiated onto the sample flow cell 4, a part of the laser beam 2 irradiates particles in the sample in the flow cell 4. Thus, the scattered light 11 is obtained, and the remaining light passes between the particles and becomes transmitted light 12. Then, both the scattered light 11 and the transmitted light 12 reach the array detector 6 through the condenser lens 5.
[0004]
[Problems to be solved by the invention]
Incidentally, as shown in FIG. 6, the array detector 6 is formed by concentrically arranging a plurality of arc-shaped scattered light receiving elements 6b around the transmitted light receiving element 6a. The diameter of the transmitted light receiving element 6a located at the center of the array detector 6 is about several μm to several tens of μm, and the beam diameter of the laser light 2 is about several μm to several tens of μm. In this kind of scattering type particle size distribution measuring apparatus, it is necessary that the optical axis of the laser beam 2 and the center of the array detector 6 (center position of the transmitted light receiving element 6a) exactly coincide.
[0005]
However, when the apparatus is delivered to the user for installation or when parts are replaced during periodic inspection, there is a discrepancy between the laser optical axis and the center of the array detector 6, and in some cases, the difference is large. It may shift. In this case, when the optical axis is on any one of the scattered light receiving elements 6b, the approximate positional relationship between the laser optical axis and the center of the array detector 6 is known. 6 can be estimated and the optical axis can be adjusted based on this.
[0006]
However, as can be seen from FIG. 6, since the array detector 6 has a region (insensitive region) 6c in which the light receiving elements 6a and 6b are not formed, the laser optical axis 2a is located in the insensitive region 6c. Therefore, it is impossible to estimate the adjustment direction and the amount of movement. In such a case, the array detector 6 is once moved greatly in one direction (in the illustrated example, the array detector 6 is moved downward) so that the laser beam 2 comes on one of the detection elements 6a and 6b. Then, it is sufficient to make the state where the position of the laser optical axis 2a is known and then perform a predetermined optical axis adjustment. However, as will be understood from the above description, there is a problem that the effort for adjusting the optical axis increases. .
[0007]
The present invention has been made in consideration of the above-described matters, and its purpose is to reliably detect even if the optical axis is located in the insensitive area of the array-shaped detector and to perform predetermined optical axis adjustment. It is an object of the present invention to provide a scattering type particle size distribution measuring apparatus that can be easily performed.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, light from a light source is irradiated onto a sample in a cell, and scattered light generated at that time is incident on an array detector through a condenser lens, and scattering obtained at this time is obtained. In a scattering type particle size distribution measuring apparatus for measuring a particle size distribution in a sample based on a light intensity pattern, a diffracted light generating means is provided on any one of optical paths connecting the light source and the array detector when adjusting the optical axis. Irradiation is performed by irradiating light from a light source in the provided state, generating a diffraction image on the array detector, and analyzing the intensity of 0th-order diffracted light received by a plurality of light receiving elements of the array detector. It is possible to determine how much the center of the light is deviated from the center of the array detector, and the plurality of light receiving elements that receive the 0th-order diffracted light are arranged concentrically around the transmitted light receiving element, A plurality of light receiving element groups each including a plurality of arc-shaped band scattered light receiving elements whose distances from the transmitted light receiving elements are different from each other and whose directions from the transmitted light receiving elements are substantially the same are provided adjacent to each other. The light receiving element groups are arranged so as to sandwich a dead area extending from the transmitted light receiving element, and the discrimination is performed based on position information of a plurality of scattered light receiving elements that detect zero-order diffracted light and the intensity of detection signals. An arithmetic unit for performing
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1 to 4 show one embodiment of the present invention. In addition, in the following figures, the same thing as the code | symbol shown in FIG. 5 and FIG. 6 has shown the same thing.
[0010]
First, FIG. 1 schematically shows the structure of the main part of the scattering type particle size distribution measuring apparatus of the present invention. This scattering type particle size distribution measuring apparatus is the scattering type particle size distribution measuring apparatus shown in FIG. A significant difference from the apparatus is that the diffracted light generating means 14 is provided so as to be freely inserted into and retracted from the optical path 13 at any position on the optical path 13 connecting the light source 1 and the array detector 6.
[0011]
As the diffracted light generating means 14, for example, as shown in FIG. 2, a plate hole 15 provided at the center of an appropriately sized plate material 15 made of a light blocking material can be suitably used. In this embodiment, the diffracted light generating means 14 is provided in the optical path 13 between the beam expander 3 and the flow cell 4 so that it can be moved in the direction of the arrow U or V by a drive mechanism such as a manual or motor. It has been.
[0012]
Next, the operation of the scattering particle size distribution measuring apparatus having the above configuration will be described with reference to FIGS. When performing the measurement, the diffracted light generating means 14 is moved in the direction of arrow U in FIG. Then, a sample is supplied to the flow cell 4, and the laser light 2 is irradiated from the light source 1 toward the flow cell 4 in that state. Thereby, the measurement similar to the conventional scattering type particle size distribution measuring apparatus can be performed.
[0013]
When adjusting the optical axis, the diffracted light generating means 14 is moved in the direction of the arrow V, inserted into the optical path 13 and positioned so as to be orthogonal to the optical path 13. The cell 4 is supplied with a dispersion medium.
[0014]
In this state, the laser light 2 is irradiated from the light source 1 toward the cell 4. This laser light 2 generates diffracted light when passing through the pinhole 16 of the diffracted light generating means 14, and this diffracted light generates a diffracted image on the array detector 6 through the cell 4 and the condenser lens 5. Let
[0015]
FIG. 3 schematically shows the state of the laser light 2 when the diffracted light generating means 14 is provided in the optical path 13 as described above. In FIG. 3, 17 is the diffracted light on the array detector 6. The intensity distribution is shown. The diffracted light has a concentric striped pattern, and a circle with a high intensity at the center contains most of the energy of the diffracted light, and is called zero-order diffracted light 18. Reference numeral 19 denotes a first-order diffracted light continuous with the 0th-order diffracted light 18.
[0016]
The size of the 0th-order diffracted light 18 is determined by the wavelength of the laser light 2, the optical characteristics of the condensing lens 5, and the diameter of the pinhole 16 in the diffracted light generating means 14. In particular, the pinhole diameter is selected. Thus, even when the light receiving elements 6a and 6b are not provided at the center of the optical axis of the irradiated laser beam 2, the magnitude of the zero-order diffracted light 18 is set to two or more as shown in FIG. The light receiving elements 6a and 6b can be set so as to be detected.
[0017]
As described above, the 0th-order diffracted light 18 is normally detected by the two or more scattered light receiving elements 6a and 6b. Therefore, the detected position information of each of the light receiving elements 6a and 6b and the intensity of the detection signal are determined. By performing arithmetic processing in the CPU 8, the center of the optical axis of the irradiated laser beam 2 can be obtained, and the adjustment direction and the adjustment amount can be obtained from the position of the obtained optical axis center. Can be displayed on the display screen 10a of the display device on the personal computer 9.
[0018]
Then, the optical axis adjustment can be reliably performed in a short time by moving the array detector 6 in a predetermined direction by an optical axis adjustment mechanism using a manual or motor-driven actuator based on the display. .
[0019]
In the above-described embodiment, the diffracted light generating means 14 is inserted into or retracted from the optical path 13 between the beam expander 3 and the flow cell 4, but the present invention is not limited to this. It is only necessary to be able to insert or retract in any one of the optical paths 13 connecting the detectors 6 and the array detector 6.
[0020]
And as the diffracted light generation means 14, you may use what formed the small diameter light-shielding part in the translucent member. That is, the plate material 15 shown in FIG. 2 may be made translucent, and instead of the pinhole 16, spherical or circular particles made of a light-shielding material may be formed in this portion.
[0021]
In the above-described embodiment, since the diffracted light generating means 14 is inserted with the cell 4 provided in the optical path 13, it is suitable for a scattering type particle size distribution measuring apparatus in which the cell 4 cannot be removed. However, instead of this method, the cell 4 may be removed from the optical path 13 and the diffracted light generating means 14 may be set at that position.
[0022]
Furthermore, it goes without saying that the present invention can also be applied to a scattering type particle size distribution measuring apparatus using light rays other than laser light. The cell 2 may be a so-called batch processing type cell other than the flow cell.
[0023]
【The invention's effect】
As described above, in the scattering type particle size distribution measuring apparatus of the present invention, even if the optical axis is located in the insensitive area of the array detector, this is reliably detected, and predetermined optical axis adjustment can be easily performed. Can be done.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of a scattering type particle size distribution measuring apparatus according to the present invention.
FIG. 2 is a diagram showing an example of diffracted light generating means.
FIG. 3 is a diagram illustrating a state in which optical axis adjustment is performed.
FIG. 4 is a diagram showing a state when diffracted light is collected on the surface of an array detector for optical axis adjustment.
FIG. 5 is a diagram schematically showing a configuration of a conventional scattering type particle size distribution measuring apparatus.
FIG. 6 is a diagram for explaining a problem of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Light, 4 ... Cell, 5 ... Condensing lens, 6 ... Array detector, 6a, 6b ... Light receiving element, 11 ... Scattered light, 13 ... Optical path, 14 ... Diffracted light generation means, 18 ... Zero order diffracted light.

Claims (1)

Light from the light source is applied to the sample in the cell, and the resulting scattered light is incident on the array detector via the condenser lens. The particle diameter in the sample is based on the scattered light intensity pattern obtained at this time. In the scattering type particle size distribution measuring apparatus for measuring the distribution, when adjusting the optical axis, light is irradiated from the light source in a state where a diffracted light generating means is provided anywhere on the optical path connecting the light source and the array detector. The center of the irradiated light is the center of the array detector by generating a diffraction image on the array detector and analyzing the intensity of the zero-order diffracted light received by the plurality of light receiving elements of the array detector. So that it can be discriminated from the
The plurality of light receiving elements that receive 0th-order diffracted light are arranged concentrically around the transmitted light receiving element, and the distances from the transmitted light receiving element are different from each other and the directions from the transmitted light receiving element are substantially the same. A plurality of light-receiving element groups composed of a plurality of arc-shaped band scattered light light-receiving elements, and the adjacent light-receiving element groups are arranged so as to sandwich a dead area extending from the transmitted light light-receiving element,
A scattering type particle size distribution measuring apparatus comprising: a calculation unit that performs the determination based on position information of a plurality of the scattered light receiving elements that have detected zero-order diffracted light and the intensity of detection signals.

Images