JP3258904B2 - Scattered light detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattered light detector for irradiating a sample with light from a light source and detecting the scattered light with a light receiving element array, for example, an apparatus for measuring a particle size distribution in the sample. Belongs to the technical field.

[0002]

2. Description of the Related Art A scattered light detector called a ring detector in which a plurality of light receiving elements E ₁ ... (See FIG. 3) such as photodiodes formed in an arc shape are arranged concentrically in a fan shape is known. .

In such a scattered light detector, four divided light-receiving elements a to a are located at a central position for condensing transmitted light (laser light).
d, the optical output of each light source was measured, and the optical axis of the light source light was adjusted so that they became equal.

[0004]

The above-mentioned light receiving elements a to d for receiving the transmitted light need to have a size corresponding to the area in which the transmitted light moves. Therefore, the radius of the laser light whose optical axis moves by 100 μm is required. A light receiving element of 100 μm is required.

However, in order to measure small-angle scattered light having information of a larger particle diameter, a light-receiving element must be provided at a position closer to the center of the optical axis. Since the light receiving elements a to d are arranged, the light receiving element for detecting scattered light cannot be installed at that position, and there is a problem that a wide particle size distribution cannot be measured.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a scattered light detector capable of measuring a particle size distribution in a wider range.

[0007]

According to the present invention, means for solving the above-mentioned problems are constituted as follows. That is, a sample is irradiated with light from a light source, and the scattered light is detected by a light-receiving element array comprising a plurality of arc-shaped light-receiving elements arranged on concentric circles. A light-receiving element for detecting at the center position, a light-receiving element for adjusting the center of the three or more arcs arranged on the same circle around the light-receiving element, and a light-receiving element for adjusting the axis at least An element substrate on which the light receiving element row including one of the elements is arranged on the same plane is arranged in an optical axis direction (Z direction) of the light source light.
It is characterized by being constituted so that it can be moved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the scattered light detector of the present invention will be described below with reference to the drawings. FIG. 3 shows a main configuration of a particle size distribution measuring apparatus using a scattered light detector. Reference numeral 1 denotes a laser tube that emits laser light 2, 3 denotes a beam expander that appropriately expands the laser light 2, and 4 denotes a sample 5. A cell containing
Reference numeral 6 denotes a condensing lens provided behind the cell 4, reference numeral 7 denotes a scattered light detector in which a plurality of light receiving elements including photodiodes for detecting scattered light from the condensing lens 6 are arranged, and reference numeral 8 denotes a scattered light detector. A multiplexer that takes in signals from 7, 9
Is a CP which receives a signal from the multiplexer 8 and performs a calculation based on the scattered light intensity pattern to obtain a particle size distribution.
U.

In such a particle size distribution measuring device,
When the sample 5 is accommodated in the cell 4 and the laser light 2 is irradiated on the sample cell 4, a part of the laser light 2 irradiates the particles in the sample 5 in the cell 4 to become scattered light 10, and the remaining The light passes between the particles and becomes transmitted light 11. And
Both the scattered light 10 and the transmitted light 11 reach the scattered light detector 7 via the condenser lens 6.

The arrangement of the light receiving elements of the above-mentioned scattered light detector 7 is shown in FIG. 1. In FIG. 1, reference numeral 21 denotes the condensed transmitted light 11 detected at the axial center position and the intensity of the laser light is detected. The light receiving element for monitoring is set to a size substantially equal to the diameter of the laser beam. Are light-receiving elements for detecting scattered light, G is an isolation gap set between the light-receiving elements, and 32a and 32b are for adjusting the axial center arranged at equal intervals on the same circle as the light-receiving element 32. These light receiving elements are arranged on the front surface of the element substrate 41 (see FIG. 2).

The element substrate 41 is, as shown in FIG.
It is provided on a movable stage 42 that can move in the X, Y, and Z directions. In the figure, 43A and 43B are a pair of Y stages which are relatively moved in the Y direction by a motor 44 via a gear box 45, and the above-mentioned element substrate 41 is attached to one X stage 43A. 46A, 46
B is a pair of X stages, which are relatively moved in the X direction by a motor 48 via a gear box 47;
B is a pair of Z stages which are relatively moved in the Z direction by a motor 50 via a gear box 51,
The stage 43B is connected to the X stage 46A,
B is fixed to each of the Z stages 49A. Although not shown, the moving stage 42 may use a piezo element as an actuator.

In the scattered light detector 7 configured as described above, first, the light receiving element 21 disposed at the center causes the Z
When the focal position in the axial direction is confirmed and the optical axis is adjusted, three light receiving elements 3 in addition to the light receiving element 21 are used.
The scattered light detector 7 is moved in the Z direction so that the laser beams are also irradiated to the laser beams 2, 32a and 32b, and the converged laser beam is enlarged. And the light receiving elements 32, 32, respectively
a, the position of the scattered light detector 7 is adjusted in the X-axis and Y-axis directions so that the light outputs detected by the
The position of the scattered light detector 7 is adjusted to the center of the laser light. After the adjustment is completed, the position in the Z-axis direction is returned to the original focal position as it is, so that the scattered light can be detected with the optical axis adjusted.

At the time of detecting the scattered light, the light receiving element 31 disposed at the innermost side can detect the small angle scattered light having a large particle diameter, and the light receiving element 32 used for adjusting the optical axis can also detect the scattered light. Is possible, the scattered light detection region can be expanded to a position close to the center, and the measurable range of the particle size distribution is greatly expanded. In the present embodiment, three light receiving elements 32, 32a, and 32b are used for adjusting the optical axis, but it goes without saying that four or more light receiving elements may be used.

Incidentally, regarding the optical axis adjustment, not only is the intensity of the diffraction light detected by the three light receiving elements 32, 32a, 32b equalized, but also the intensity of the laser light detected by the light receiving element 21 at the center. X, so that
Adjusting the optical axis in the Y and Z directions can also improve the optical axis position accuracy.

[0015]

As described above, according to the scattered light detector of the present invention, the light receiving element for detecting the condensed transmitted light at the position of the axis and the light receiving element on the same circle around the light receiving element. An element substrate in which three or more light receiving elements for adjusting the center of the same arc and the light receiving element array including at least one of the light receiving elements for adjusting the center of the axis is arranged on the same plane. Since it is configured to be movable in the optical axis direction (Z direction) of the light source light and in the X direction and the Y direction orthogonal to the optical axis direction,
The light receiving element for detecting scattered light can be arranged at a position near the center, and the measurement area of the particle size distribution can be expanded with a more compact device.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a light receiving element in one embodiment of a scattered light detector of the present invention.

FIG. 2 is a perspective view of the scattered light detector.

FIG. 3 is a configuration diagram of the particle size distribution measuring device.

FIG. 4 is a layout view of a light receiving element of a conventional scattered light detector.

[Explanation of symbols]

2: light source light, 5: sample, 10: scattered light, 11: transmitted light,
21, 31, 32, 33, 34, 35, 36, 37, 3
2a, 32b: light receiving element, 41: element substrate.

Claims (1)

(57) [Claims] A scattered light detector for irradiating a sample with light from a light source and detecting the scattered light with a light receiving element array comprising a plurality of arc-shaped light receiving elements arranged on concentric circles. A light-receiving element for detecting at the axial center position, a light-receiving element for adjusting the axial center having three or more same arcs arranged on the same circle around the light-receiving element, and at least for adjusting the axial center; A light-receiving element array including one of the light-receiving elements arranged on the same plane so as to be movable in an optical axis direction (Z-direction) of the light source light; vessel.