JPH02173551A - Scattered light sensor - Google Patents

Abstract

PURPOSE:To measure a scattered light extending over a wide range with high accuracy by providing a photosensor array consisting of plural sensors having a concentric circular photodetecting surface, on the outside of a ring-like photosensor array. CONSTITUTION:A ring-like photosensor array 1 in which plural sensors 1a - 1n having photodetecting surfaces of different radiuses are arranged on one piece of wafer centering around a point 0, and which forms a semicircle or a 1/4 circle as a whole, and two pieces of photosensor arrays 2, 3 formed in a sector shape or a strip shape by arranging plural sensors 2a - 2e, 3a - 3e having photodetecting surfaces of each different radius centering around the point 0 on separate wafers, respectively are provided at an angle of 90 degrees mutually on the same plane of the outside of the sensor array 1. In such a way, the influence of a polarization of a laser light is eliminated and a ring-like photosensor array of an equivalently large size is obtained, and a sufficient particle size range can be covered by one range, and also, the device can be made low in cost and simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a scattered light sensor used, for example, to measure the intensity distribution of scattered light in a laser beam diffraction/scattering type particle size distribution measuring device.

<Conventional technology> Laser light diffraction/scattering type particle size distribution measurement equipment utilizes the phenomenon that laser light is irradiated onto a group of particles in a dispersed flying state, and the laser light is diffracted or scattered in correlation with the size of the particles. Scattered light or diffracted light (hereinafter referred to as
By measuring the intensity distribution of the scattered light (simply referred to as scattered light), that is, the relationship between the scattering angle and the light intensity, the particle size distribution of the particle group is determined.

The intensity distribution of scattered light is usually measured using a ring-shaped photosensor array (a so-called ring detector) in which sensors with light-receiving surfaces of different radii are arranged concentrically around one point on two wafers. This is done by forming a scattering image on the sensor surface.

FIG. 3 is a configuration diagram of a general optical system of a laser beam diffraction/scattering type particle size distribution measuring device.

The laser light from the laser light source 31 passes through the collimator lens 3
2, the particles flying within the flow cell 33 are irradiated with a parallel light beam. The light scattered by the particles is transmitted through the Fourier transform lens 34 to the ring detector 3 described above.
The light is focused on the light receiving surface of 5.

Note that the ring detector 35 is a full circle, two circles, or two circles in order to avoid the influence of the polarization of the laser beam.

<Problems to be Solved by the Invention> By the way, in such a particle size distribution measuring device, in order to expand the dynamic range of measurement, that is, the measurement range of particle size in lunges, it is necessary to maintain photometric accuracy at a small scattering angle. However, it is necessary to measure light with a large scattering angle, which requires a large ring detector.

In other words, the scattering angle θ becomes smaller as the particle size increases, but in order to measure even large particles, the focal length of the Fourier transform lens 34 should be increased so that the distance from the center on the light receiving surface of the ring detector 35 It is necessary to expand the overall light focusing position.

However, when the focal length is increased, the convergence position of the light with a large scattering angle due to particles with a small diameter is shifted to the ring detector 35.
In the end, the dynamic range is determined by the size of the ring detector 35.

Here, as mentioned above, the ring detector is manufactured on a common semiconductor wafer, and the size of the wafer is generally about 4 inches in diameter, so A that can obtain the largest size (radius). Even if you use a circular one,
A radius of approximately 71.8+u is the maximum that can normally be manufactured.

For this reason, in order to measure scattered light at a wide range of angles at once, conventionally, instead of using a ring detector, a so-called linear photosensor is used, which uses tiny sensors on the light-receiving surface arranged discretely in a one-dimensional manner. had to use.

However, scattered light with a large scattering angle is weak, and in order to improve its measurement accuracy, a sensor with a large light-receiving surface is required, but a linear photosensor cannot satisfy this requirement.

An object of the present invention is to provide a scattered light sensor that can accurately measure scattered light from a small scattering angle to a large scattering angle.

<Means for Solving the Problems> In order to achieve the above object, the present invention uses a plurality of sensors having light-receiving surfaces of mutually different radii around one point O, as shown in FIG. 1 corresponding to the embodiment. la, lb...1n
In addition to the ring-shaped photosensor array 1 which is arranged concentrically on two common wafers and forms two circles or two circles as a whole, a ring-shaped photosensor array 1 is arranged on the same plane as the ring-shaped photosensor array 1, and , on the outside thereof, a plurality of sensors 2a, 2b...(3a) each having a light-receiving surface with a different radius centered on the above-mentioned point O on an individual wafer.

3b...) are arrayed to form two photosensor arrays 2 and 3 that are fan-shaped or rectangular as a whole,
They are arranged at an angle of 90° to each other.

<Operation> Centering on the center 0 of the ring-shaped photosensor array 1,
a plurality of sensors 2a having concentric light-receiving surfaces on the outside;
2b..., 3a, 3b... are arranged, and by setting these at an angle of 906 to each other, the influence of polarization of the laser beam is removed, and the equivalently large 4
A ring-shaped photosensor array of J size is obtained.

<Example> FIG. 1 is a front view of an embodiment of the present invention.

Similar to a conventional ring detector, the ring-shaped photosensor array 1 includes a plurality of sensors la, lb, lb, etc., each having a light-receiving surface with a different radius, centered on a point O on a single wafer.
. . 1n are arranged in an array, and the sensor array has a quarter circular shape as a whole.

This ring-shaped photosensor array 1 has a flat support 4
On the surface of the same support 4, two fan-shaped photosensor arrays 2 and 3 are supported further outside the outermost sensor 1n of the ring-shaped photosensor array 1.

The fan-shaped photosensor arrays 2 and 3 have exactly the same shape and dimensions, and 1. A plurality of sensors 2a, 2b, etc., each formed on a separate wafer, each having a light-receiving surface having a mutually different radius with the center O of the ring-shaped photosensor array 1 as a common center, or 3
a, 3b, . . . are formed in an array. The light-receiving surfaces of the corresponding sensors 2a and 3a, 2b and 3b, . . . in the fan-shaped photosensor arrays 2 and 3 have the same radius and area, respectively.

The fan-shaped photosensor arrays 2 and 3 are arranged so that their center lines intersect at point 0 at 90'.

The second embodiment of the present invention is used, for example, in place of the ring detector 35 of the optical system shown in FIG.

At this time, the photometric data from the ring-shaped photosensor array 1 is input into a computer and used as data for particle size distribution calculation, just as in the case of using the conventional ring detector 35, but the outputs of the fan-shaped photosensor arrays 2 and 3 Let the sum of the outputs of the sensors 2a and 3a, 2b and 3b, . . . at corresponding angular positions be the photometric data of the scattered light at each angle. Then, the sum of the outputs of each two sensors is corrected so that it is equivalent to having a light-receiving surface for A circle at each scattering angle position, and then used as data for particle size distribution calculation. . As a result, the influence of the polarization of the irradiated laser beam is removed from the photometric data obtained by the fan-shaped photosensor arrays 2 and 3, and as a whole, the ring-shaped photosensor array 1 is divided into the respective fan-shaped photosensor arrays 2 and 3.
Photometric data equivalent to the case where the sensors 2e and 3e on the outermost periphery of No. 3 are present can be obtained.

Although the width (circumferential direction) of the fan-shaped photosensor arrays 2 and 3 is arbitrary, it is not preferable to make it too small because light with a large scattering angle becomes weak. Further, the width dimensions of the fan-shaped photosensor arrays 2 and 3 do not necessarily have to be the same, but if they are not the same, it is necessary to make a corresponding correction when calculating the sum of the outputs of the corresponding sensors. be.

Further, the external shape of the photosensor array placed outside the ring-shaped photosensor array 1 is not limited to the sector shape as in the above embodiment, but may be a rectangular shape as shown in FIG. In fact, the rectangular shape is more advantageous in terms of semiconductor wafer processing.

Further, a fan-shaped or rectangular photosensor array having a light-receiving surface centered at point O is provided further outside the fan-shaped photosensor arrays 2 and 3 in FIG. 1 to further expand the measurement range. You can.

Furthermore, it goes without saying that the ring-shaped photosensor array 1 can be of a 2-circular type in addition to a 1/4-circular type.

<Effects of the Invention> As described above, according to the present invention, a ring-shaped photosensor array includes a plurality of sensors having concentric light-receiving surfaces having a common center and different radii on the outside of a ring-shaped photosensor array. Since the 2WJ fan-shaped or strip-shaped photosensor arrays are arranged at an angle of 90' to each other,
It is not affected by the polarization of laser light (and can equivalently expand the measurement range of its scattered light. For example, a quarter-circle ring-shaped photosensor array (ring detector) is manufactured from a 4-inch wafer. In the case of It can be more than doubled.Also, 1
If four two-circular ring-shaped photosensor arrays are cut out from one wafer, the radius will be about 5e, but if eight fan-shaped or strip-shaped photosensor arrays are cut out from another wafer, By combining each of them, the scattered light sensor of the present invention can be obtained from two wafers for 4 cents. In this case, each set can obtain a detector equivalent to a ring detector with a maximum radius of about 130 cranes, and is inexpensive. A scattered light sensor with a wide dynamic range can be obtained.

For this reason, when the present invention is used as a detector for a laser beam diffraction/scattering particle size distribution analyzer, the particle size measurement range with a lunge becomes larger, and unlike conventional methods, a Fourier transform lens with a different focal length is selected. freely set up, and
The lunge can cover a sufficient particle size range without increasing the range by moving the detector according to its focal length, making it possible to greatly contribute to the cost reduction and simplification of the device.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of the present invention, Fig. 2 is a front view of a rectangular photosensor array used in another embodiment of the invention, and Fig. 3 is a front view of a laser beam diffraction/scattering particle size distribution measuring device. It is a structural diagram of a general optical system. 1... Ring-shaped photosensor array 2. 3... Sector-shaped photosensor array 4... Support body

Claims (1)

[Claims] A ring-shaped photosensor array in which a plurality of sensors having light-receiving surfaces with different radii around one point are arranged concentrically on a single wafer to form a 1/2 circle or a 1/4 circle as a whole; A plurality of light-receiving surfaces are arranged on the same plane as the ring-shaped photosensor array and at an angle of 90 degrees to each other on the outside thereof, and each has a light-receiving surface with a different radius from the above-mentioned point on a separate wafer. A scattered light sensor comprising two photosensor arrays in which the sensors are arranged concentrically to form a sector-like or rectangular shape as a whole.