JP2626010B2 - Scattered light sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattered light sensor used for measuring the intensity distribution of scattered light in, for example, a laser beam diffraction / scattering type particle size distribution analyzer.

<Prior art> In a laser beam diffraction / scattering type particle size distribution analyzer,
By irradiating the dispersed group of particles with laser light, and utilizing the phenomenon that the laser light is diffracted or scattered in correlation with the particle size, the scattered light or diffracted light (hereinafter simply referred to as scattered light) ), That is, the relationship between the scattering angle and the light intensity is measured to determine the particle size distribution of the particle group.

In general, the intensity distribution of scattered light is measured by focusing one point on one wafer and forming concentrically arranged ring-shaped photosensor arrays (so-called ring detectors) with sensors having light receiving surfaces having different radii. To form a scattered 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 apparatus.

The laser light from the laser light source 31 is applied to a collimator lens 32.
As a result, the particles fly in the flow cell 33 in a state of a parallel light beam. The light scattered by the particles is collected by the Fourier transform lens 34 on the light receiving surface of the ring detector 35 described above.

As the ring detector 35, a full circle, 1/2 circle or 1/4 circle is used 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 measurement dynamic range, that is, the range of particle size measurement in one range, it is necessary to measure light with a large scattering angle while maintaining the photometric accuracy of a small scattering angle. Ring detector is required.

In other words, the scattering angle θ decreases as the particle size increases, but in order to measure particles having a large particle size, the focal length of the Fourier transform lens 34 is increased and the scattering angle θ is measured from the center on the light receiving surface of the ring detector 35. It is necessary to enlarge the light condensing position as a whole. However, when the focal length is increased, the light condensing position of light having a large scattering angle due to particles having a small particle size is separated from the center of the ring detector 35, and the dynamic range is ultimately determined by the size of the ring detector 35.

Here, as described above, the ring detector is manufactured on a common semiconductor wafer, and the size of the wafer is generally about 4 inches in diameter, and therefore, the size (radius) from which the largest size (radius) can be obtained. Even if a 4 yen one is used, a radius of about 71.8 mm is the largest that can be manufactured normally.

For this reason, to measure scattered light at a wide range of angles at one time, a so-called linear photo sensor in which sensors with a minute light receiving surface are arranged discretely in a temporary original shape without using a ring detector conventionally Had to use.

However, scattered light having a large scattering angle is weak, and a sensor having a large light receiving surface is required to improve the measurement accuracy. However, 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, according to the present invention, as shown in FIG. 1 corresponding to the embodiment, a plurality of sensors having light receiving surfaces of different radii centered on one point O are provided. In addition to the ring-shaped photosensor array 1a, 1b... 1n are concentrically arranged on one common wafer to form a 1/2 or 1/4 circle as a whole. A plurality of sensors 2a, 2b... (3a, 3b...) Each having a light receiving surface having a radius different from each other centering on the above-mentioned point O are arranged on the same plane as the array 1 and outside the respective wafers. Two photosensor arrays 2 and 3 which are formed and have a fan shape or a strip shape as a whole are arranged at an angle of 90 ° to each other.

<Operation> A plurality of sensors 2 having a concentric light receiving surface on the outside of the center O of the ring-shaped photosensor array 1
a, 2b…, 3a, 3b… will be disposed, and by placing them at an angle of 90 ° to each other, the influence of the polarization of the laser light will be eliminated, and equivalently large size Is obtained.

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

The ring-shaped photosensor array 1 includes a plurality of sensors 1a, 1b,..., 1n having light receiving surfaces having different radii from each other around a point O on one wafer, similarly to a conventional ring detector.
Are arrayed, and the sensor array has a 1/4 circular shape as a whole.

The ring-shaped photosensor array 1 is supported on the surface of a flat 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 are sensors formed on individual wafers, respectively. A plurality of sensors 2a, 2b ... or 3a, 3b ... having light receiving surfaces of different radii are arranged and formed. Each fan-shaped photosensor array 2
The light receiving surfaces of the corresponding sensors 2a and 3a, 2b and 3b in... Have the same radius and area, respectively.

The fan-shaped photosensor arrays 2 and 3 are arranged such that their center lines cross each other at a point O at 90 °.

The above embodiment of the present invention is used, for example, instead of the ring detector 35 of the optical system shown in FIG. At this time, the photometric data obtained by the ring-shaped photosensor array 1 is taken into a computer and used as data for calculating the particle size distribution in exactly the same way as when the conventional ring detector 35 is used. Are the sums of the outputs of the sensors 2a and 3a, 2b, 3b,. Then, the sum of the outputs of each of the two sensors is corrected so as to be equivalent to the case where each scattering angle position has a light receiving surface of 1/4 circle, and then provided to data for calculating particle size distribution. You. Thereby, the fan-shaped photosensor arrays 2 and 3
Is equivalent to the case where the ring-shaped photosensor array 1 is present up to the position of the outermost sensors 2e, 3e of the fan-shaped photosensor arrays 2, 3 as a whole. The photometry data will 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 having a large scattering angle becomes weak. Also,
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,
When obtaining the sum of the outputs of the corresponding sensors, it is necessary to make the corresponding correction.

Further, the outer shape of the photosensor array placed outside the ring-shaped photosensor array 1 is not limited to the sector shape as in the above-described embodiment, and may be a strip shape as shown in FIG. Rather, the strip shape is more advantageous in terms of processing the semiconductor wafer.

Further, a fan-shaped or strip-shaped photosensor array having a light receiving surface centered on the point O is provided outside the fan-shaped photosensor arrays 2 and 3 in FIG.
Further, the measurement range may be expanded.

Furthermore, it is a matter of course that the ring-shaped photosensor array 1 can use not only a 1/4 circular shape but also a 1/2 circular shape.

<Effects of the Invention> As described above, according to the present invention, a plurality of sensors having concentric light receiving surfaces having different radii from each other with the center as a common center are provided outside the ring-shaped photo sensor array, Since two fan-shaped or strip-shaped photosensor arrays are arranged at an angle of 90 ° to each other, the measurement range of the scattered light can be expanded equivalently without being affected by the polarization of the laser light. it can. For example, when manufacturing a 1/4 circular ring-shaped photosensor array (ing detector) from a 4-inch wafer, the maximum radius is That is, it is about 71.8 mm, but by arranging the fan-shaped or strip-shaped photosensor array outside the ring-shaped photosensor array, the measurement range can be doubled or more. Also, if four 1/4 circular ring-shaped photosensor arrays are cut out from one wafer, the radius will be about 50 mm, but eight fan-shaped or strip-shaped photosensor arrays will be cut from another wafer. And combining them, four sets of scattered light sensors of the present invention are obtained from two wafers. In this case, each set can obtain a detector equivalent to a ring detector having a maximum radius of about 130 mm. Thus, an inexpensive scattered light sensor having a wide dynamic range can be obtained.

For this reason, when the present invention is used as a detector of a laser beam diffraction / scattering type distribution measuring device, the particle size measuring range in one range becomes large, and a Fourier transform lens having a different focal length is selected as in the prior art. Freely provided, and
One range can cover a sufficient particle size range without moving the detector in accordance with its focal length, for example, without increasing the number of ranges, which can greatly contribute to a reduction in cost and simplification of the apparatus.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a front view of a strip-shaped photo senna array used in another embodiment of the present invention, and FIG. It is a structural diagram of a general optical system. 1 ... Ring-shaped photo sensor array 2,3 ... Fan-shaped photo sensor array 4 ... Support

Claims (1)

(57) [Claims] A plurality of sensors having light receiving surfaces having different radii from each other with one point as a center are concentrically arranged on one wafer and form a ring shape of a 1/2 circle or a 1/4 circle as a whole. The photosensor array and the ring-shaped photosensor array are mutually flush with and 90 ° apart from each other.
A plurality of sensors arranged at an angle of ゜, each having a light receiving surface having a different radius from each other centering on the above-mentioned one point on each individual wafer are formed concentrically and arranged in a fan shape or a strip shape as a whole. A scattered light sensor comprising the photosensor array of the above.