JPS63140904A - Scattered light measuring instrument - Google Patents

Abstract

PURPOSE:To measure scattered light having a large angle of scattering by providing an optical system which converges light from a light source and makes it incident on a body to be measured and receiving the scattered light from the body to be measured by a cylinder body. CONSTITUTION:When a light source 2 is put in operation, the light emitted by the light source 2 is guided to a lens side by a beam splitter 5, converged by a condenser lens 4, and projected on the surface 1a of the body 1 to be measured 1. Consequently, the light is reflected by the surface 1a to generate regular reflected light and scattered light A corresponding to a pattern to be measured on the surface 1a. Then the regular reflected light is cut off by a stopper 7 and the scattered light A is reflected by the reflecting surface 6a of the cylinder body 6 and guided to the surface of an area array sensor 8 together with scattered light A passing through the peripheral part of the condenser lens 4. Consequently, the scattered light A not only from the condenser lens 4, but also having a large angle of scattering is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a scattered light measuring device that makes light incident on an object to be measured and measures the object from the scattered light generated at the time.

(Prior Art) There is a method for measuring particle size and measuring the surface pattern of an object to be measured using scattered light generated when light is incident on the object to be measured.

Scattered light measurement devices used for such measurements have conventionally
As shown in FIG. 6, a sphere C surrounding the object to be measured a is provided on the optical path that roughly divides the light to the object to be measured a such as a particle.
Scattered light d received on the inner surface of sphere C is measured by integration, and as shown in Figures 7 and 8, scattered light d from object a is detected through lens e. Furthermore, as shown in Fig. 9, in addition to providing a paraboloid IAa on the side of the optical path to receive the scattered light d... Set up the utensils,
A device that measures scattered light d... in combination with a photodetector f on the optical path is used.

(Problems to be Solved by the Invention) However, although the measurement technique using an integrating sphere can detect the total scattered light, it has the drawback that it cannot measure the angular distribution of the scattered light. Furthermore, the structure in which the scattered light d... is guided to the photodetector f using the optical system (lens e) is good when the scattering angle θ is small, but when trying to measure a large scattering angle θ,
Either a lens e with a very large numerical aperture must be used, or the lens e must be placed very close to the object to be measured a.
Very difficult. In addition, the structure using a reflecting mirror (parabolic mirror f) has the problem that the device itself becomes large-scale, and none of them are effective.

This invention was made with attention to these problems, and its purpose is to improve the scattering distribution of scattered light and the measurement of the scattering distribution of scattered light without using a large numerical aperture and without bringing the distance to the object to be measured too close. An object of the present invention is to provide a compact scattered light measuring device capable of measuring scattered light with a large scattering angle.

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention includes an optical system 3 that focuses light from a light source 2 and makes it enter the object to be measured 1, and an output side of the optical system 3. A cylindrical body 6 having a reflective surface 6a on the inner surface is provided so as to cover the surroundings to receive scattered light from the object to be measured 1, and the scattered light from the cylindrical body 6 is photoelectrically converted by a photoelectric conversion section 8. and process its output.

(Embodiment) The present invention will be described below based on a first embodiment shown in FIGS. 1 to 3. FIG. 1 shows a schematic configuration of a scattered light measuring device, in which 1 is an object to be measured with a flat upper surface, 2 is a light source placed above the object to be measured 1 with its emission part facing sideways, and 3 is an optical It is a system. The optical system 3 has a configuration in which a condenser lens 4 is disposed directly above the object to be measured 1, and a beam splitter 5 is provided between the condenser lens 4 and the output part of the light source 3. The light is focused so that it can be irradiated onto the surface 1a of the object to be measured 1.

Further, around the condenser lens 4, a substantially bowl-shaped cylindrical body 6 as shown in FIG. 3 is disposed. The cylindrical body 6 is arranged along the optical path with a small opening close to the surface 1a of the object to be measured 1, and is provided with a reflective surface 6a made of a mirror surface on its inner surface. Scattered light A scattered on the surface of the reflective surface 6a can be received by the reflective surface 6a through a small aperture. Further, a stopper 7 is provided at the back of the beam splitter 5 to block the specularly reflected light, so that only the scattered light A can be emitted from the large opening of the cylindrical body 6.

As shown in FIG. 2, a photoelectric conversion unit 1 such as an area array sensor 8 (multi-pixel image sensor; photodetector) is mounted on the output side (large aperture side) of the cylindrical body 6. It is provided along a direction perpendicular to the axis, so that the scattered light A can be detected from a concentric distribution. A processing circuit 9 (corresponding to a processing section) composed of a microcomputer is connected to this area array sensor 8, and from the obtained electrical signal of the scattered light distribution, the total scattered light necessary for pattern inspection, the scattering angle, etc. distribution, ii! ! It is possible to obtain the turbulent angle of turbulence.

Next, the operation of the thus configured scattered light measuring device will be explained.

When light source 2 is activated, light io! The light emitted from the device 2 is guided to the lens side by the beam splitter 5, and after being condensed by the condensing lens 4, it is irradiated onto the surface 1a of the object to be measured 1. As a result, reflection occurs on the surface 1a, and specularly reflected light and scattered light A are generated according to the (constant) pattern to be measured on the surface 1a.

Of the reflected light, the specularly reflected light is blocked from advancing by the stopper 7, and the scattered light A is reflected on the reflective surface 6a, and together with the scattered light A passing through the peripheral part of the condenser lens 4, the area array sensor 8 being guided to the surface of As a result, the scattered light A is irradiated onto the sensor surface in a concentric manner, and not only the scattered light A from the condenser lens 4 but also the scattered light A having a large scattering angle is detected.

However, when detecting the total scattered light A, the processing circuit 9 only needs to calculate the total light detection area on the sensor surface, and when detecting the distribution of scattering angles, the processing circuit 9 calculates the total light detection area on the sensor surface. To calculate the sum, or even the distribution of the solid angle of scattering, the processing circuit can calculate the sum of circular arcs at the same angle.

Thus, using a lens with a large numerical aperture.

Scattered light A having a large scattering angle can be measured without bringing the lens very close to the object to be measured 1. Moreover, it can be seen that the angular distribution of scattered light can be measured. In addition to providing the cylindrical body 6 around the optical system 3, it is sufficient to provide the area array sensor 8 on the open end side of the cylindrical body 6. The device does not need to be large-scale, and it is compact.

In the first embodiment, only the scattered light A is detected, but the stopper 7 may be removed so that the specularly reflected light is also detected together with the scattered light A.

Further, in the first embodiment, a certain pattern on the surface 1a of the object to be measured 1 is detected, but the present invention is not limited to this. Particle size measurement may be performed based on the distribution of particles (particle measurement).

Further, in the first embodiment, the area array sensor 8 is used, but as in the second embodiment shown in FIG. 4, a linear array sensor 1o is used to know only the scattering angle distribution of the scattered light. Alternatively, the distribution of the solid angle of the scattered light may be determined using a divided sensor 11 divided into four parts as in the third embodiment shown in FIG.

In addition, in the first embodiment, the bowl-shaped cylindrical body 6 was used;
The material is not limited to this, and may be a cylindrical body, such as a cylindrical shape or a conical shape. Of course, a split type cylindrical body may be used, and the structure is not limited to this.

[Effects of the Invention] As explained above, according to the present invention, it is possible to measure scattered light at a large scattering angle without using a large numerical aperture and without bringing the object to be measured very close. Moreover,
The angular distribution of scattered light can also be measured. Moreover,
There is also the advantage that the device is compact, and a scattered light measuring device with good performance can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a scattered light measuring device according to a first embodiment of the present invention, FIG. 2 is a plan view showing a photoelectric conversion section thereof, and FIG.
The figure is a perspective view showing the cylindrical body, and FIG.
FIG. 5 is a plan view showing a third embodiment of the present invention, and FIGS. 6 to 9 are side views of different conventional scattered light measuring devices. 1... Object to be measured, 2... Light source, 6... Cylindrical body, 8
...Area array sensor (photoelectric conversion unit), 9...Processing circuit (processing unit), A...Scattered light. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 5 Figure 89

Claims (3)

[Claims] (1) A light source, an optical system that focuses the light from the light source and makes it incident on the object to be measured, and a device for receiving scattered light from the object that is provided to cover the output side of the optical system. A scattering device comprising: a cylindrical body having a reflective surface on its inner surface; a photoelectric conversion section that photoelectrically converts scattered light from the cylindrical body; and a processing section that processes output from the photoelectric conversion section. Light measurement device. (2) The scattered light measuring device according to claim 1, wherein the photoelectric conversion section is composed of a split type sensor or a multi-pixel image sensor. (3) The scattered light measuring device according to claim 1, wherein the photoelectric conversion section receives scattered light together with specularly reflected light.