JP2007078594A - Angle measuring device for minute plane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high precision angle measuring device for planes of several tens of micrometer (corresponding to a domain of micro Vickers test) by measuring angles of minute plane of samples using optical system installing two beam splitters in the middle of an ocular lens and an objective lens of an optical microscope. <P>SOLUTION: The angle measuring device for minute plane is characterized making incidence of reference light passing through the optical axis of optical systems and the measuring light reflected at minute planes of samples to an imaging element to measure the angle of minute plane of samples from difference between the positions of reference light and measuring light in the imaging element, in a measuring device for measuring the angle of minute planes of samples placed on a sample table. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an angle measuring apparatus for precisely measuring the angle of a microplane of about several tens of μm, and in particular, a square or triangular pyramid diamond indenter such as a Vickers hardness tester, a micro Vickers hardness tester, a nanoindentation device, etc. The present invention relates to a microplanar angle measuring apparatus used for verification of an indenter for a hardness tester using a slab.

Conventionally, a method for measuring the angle of a Vickers hardness indenter using an optical microscope and a rotary table has been announced (for example, see Non-Patent Document 1), and measuring machines based on this principle have been commercialized by companies. Yes. However, a plane of about several hundred μm is required for the measurement, and it cannot cope with a hardness test with a small indentation depth such as micro Vickers. Micro Vickers has the highest industrial needs among hardness tests.
In addition, a product that measures the angle of a Vickers hardness indenter using a microscopic interferometer has been introduced (for example, see Non-Patent Document 2). However, since the normal direction of the surface is detected using the interference fringes, the measurement accuracy decreases as the target plane becomes smaller.
Namada Hamada, Research on Accuracy Improvement of Vickers Hardness Standard, Report of Metrology Institute, 26, 4 (1977) A. Liguori, et al., Galindent: The Reference Metrological System for the Verification of the Geometrical Characteristics of Rockwell and Vickers Diamond Indenters, VDI-Berichte, 1685 (2002)

Hardness testing is a material testing method widely used in industry, but it is essential to use the testing machine in a correctly calibrated state in order to obtain correct measurement values. In particular, the shape of the indenter used is an important factor that directly affects the hardness value, but it is not easy to accurately measure and verify a minute three-dimensional shape. In recent years, the demand for micro Vickers tests and nano-indentation tests with small indenter penetration has increased with the miniaturization and thinning of objects to be measured, and indenter verification is also required to be performed in a very narrow area near the tip. ing.
However, most of the methods used today require a relatively large measurement surface of about several hundreds of μm, and the measurement accuracy at a sufficient angle cannot be obtained when the observation magnification is increased.

  In the present invention, the angle of a micro plane of a sample is measured by using an optical system in which two beam splitters are installed between an eyepiece and an objective lens of an optical microscope. It is an object of the present invention to provide an apparatus capable of measuring an angle with high accuracy with respect to a measurement surface. Further, by applying this technique, it is possible to calibrate a small angle gauge that can be used in AFM or the like.

In order to achieve the above object, a microplanar angle measuring device of the present invention is a device for measuring the microplanar angle of a sample placed on a sample table using an optical system, and a reference light passing through the optical axis of the optical system. And measurement light reflected by the minute plane of the sample are incident on the image sensor, and the angle of the minute plane of the sample is measured from the deviation of the position of the reference light and measurement light in the image sensor.
In addition, the microplanar angle measuring device of the present invention places the sample on the sample table constituted by a biaxial rotating stage so that the reference plane of the sample is orthogonal to the optical axis of the optical system, and sequentially from the sample table side. The objective lens, half mirror, objective lens side beam splitter, eyepiece side beam splitter, and eyepiece lens are provided on the optical axis to form an optical system, and light from the light source is incident on the objective lens side beam splitter. The image sensor for measurement passes through the eyepiece side beam splitter and irradiates the measurement surface of the sample through the objective lens with the light transmitted through the mirror, and reflects the measurement light reflected by the measurement surface and the reference light reflected by the half mirror. It is characterized in that it is made incident on.
In addition, the minute plane angle measuring apparatus of the present invention is characterized in that one side of the measurement surface of the sample is several tens of μm.
In addition, the microplanar angle measuring apparatus of the present invention is characterized in that the sample is an indenter for a hardness test.

The present invention has the following excellent effects.
(1) In recent years, traceability to national standards is required for various measurements used in industry. Concerning hardness, the traceability system is being developed within the framework of the Measurement Law Calibration Company Certification System (JCSS) .For example, for micro-Vickers testing, calibration technology for indenters with minute three-dimensional shapes is used. Since there was no maintenance, the maintenance is delayed and the present invention is expected to play a role of breakthrough. In the industry, Tokyo Diamond Tool Manufacturing Co., Ltd. has already produced an indenter, and the Japan Bearing Inspection Association has performed an indenter calibration business. It is considered possible to proceed.
(2) From the viewpoint of application to an AFM angle gauge, the angle is calibrated indirectly by calibrating the three axes of the AFM with the standard sample at present, but the uncertainty of the standard sample is large at present. Therefore (especially in the z direction), a satisfactory angle calibration cannot be performed. The size of several tens of μm can be observed with an optical microscope and is also included in the measurement range of the AFM. Therefore, a calibration value with higher accuracy can be given to an angle gauge of such a size. If possible, it is expected that the uncertainty of AFM angle calibration will be greatly reduced.

  The best mode for carrying out the microplanar angle measuring apparatus according to the present invention will be described below with reference to the drawings based on the embodiments.

1 to 4 are diagrams for explaining a microplanar angle measuring apparatus according to the present invention. FIG. 1 is a front view showing the outline of the apparatus, and FIG. 2 shows a path of reference light in the apparatus. FIG. 3 is a front view showing a path of measurement light (when there is an angle error) in this apparatus, and FIG. 4 is a view taken along line AA of FIG.
In FIG. 1, a sample to be measured is an indenter 1 for hardness test used in a micro Vickers test, and the tip of the indenter 1 has a shape of a regular quadrangular pyramid, and four surfaces 2 of the regular quadrangular pyramid, 2, 2 and 2 are surfaces to be measured sequentially. The length of one side of the surface 2 to be measured is several tens of μm.
The angle of the surface 2 of the regular quadrangular pyramid of the indenter 1 is determined by the standard as 68 ° with respect to the central axis of the indenter. In the present specification, a regular quadrangular pyramid surface having no error determined by the standard is referred to as a “reference surface” for convenience.
The sample is not limited to the indenter for hardness test used in the micro Vickers test, and any length of one side of the measurement surface may be several μm or more, and desirably the length of one side of the measurement surface is What is necessary is just 10 micrometers or more. Further, the angle of the indenter is 68 ° in the case of the Vickers test, but it goes without saying that it is a different angle in cases other than the Vickers test.

The indenter 1 is supported via a rotary encoder 6 on one surface 4 (vertical surface) of the dog-shaped sample table 3 having two orthogonal surfaces. The other surface 5 (horizontal plane) of the sample table 4 is fixed to a rotary encoder 7 that is rotatable about an x axis (an axis extending in the vertical direction parallel to the paper surface of FIG. 1), and the entire sample table 3 is rotatable about the x axis. It has become. As described above, the sample table 4 is composed of a biaxial rotating stage.
When an optical axis of an optical system to be described later is a Z-axis (in FIG. 1 to FIG. 3, an axis parallel and horizontal to the paper surface), the indenter 1 has a rotary encoder 6 so that the reference plane of the regular pyramid is orthogonal to the Z-axis. , 7 is controlled.

  In FIG. 4, an indenter without an angle error is indicated by a one-dot chain line, and an indenter 1 with an angle error is indicated by a solid line, and the central axis of the indenter 1 for micro Vickers test in FIGS. 1 to 3 is from left to right. It can be seen that the optical system is disposed in a state tilted by 22 ° toward the front side of the drawing with respect to the Z axis, which is the optical axis of the optical system. That is, the central axis of the indenter 1 is arranged at an angle of 22 ° with respect to the Z axis so that the reference plane is orthogonal to the Z axis, which is the optical axis of the optical system, and measurement is indicated by a solid line. When there is an angle error in the surface 2 of the regular quadrangular pyramid of the indenter 1, the surface 2 with the angle error is not orthogonal to the optical axis Z of the optical system, so that the light reflected by the surface 2 is relative to the optical axis Z. Have a certain angle.

An objective lens 8 of the optical microscope is arranged facing the indenter 1, and an eyepiece 9 of the optical microscope is arranged behind the objective lens 8.
Between the objective lens 8 and the eyepiece lens 9, a beam splitter 10 positioned on the objective lens 8 side and a beam splitter 11 positioned on the eyepiece lens 9 side are provided on the optical axis Z of the optical system. A half mirror 12 is provided adjacent to the objective lens 8 side of the beam splitter 10 located on the objective lens 8 side, and the laser beam 14 of the laser light source 13 is shown on the beam splitter 10 located on the objective lens 8 side as shown in the figure. It has been introduced. In addition, a measurement imaging device 15 is installed at a position where the reflected light reflected by the beam splitter 11 located on the eyepiece 9 side is introduced.
Further, an imaging device 16 for observation is arranged behind the eyepiece 9.

The laser light 14 emitted from the laser light source 13 enters the beam splitter 10, and half of the reflected light 17 passes through the half mirror 12 as shown in FIG. 3 and passes through the objective lens 8 and reaches the tip of the indenter 1. The measurement surface 2 of the regular quadrangular pyramid is irradiated.
On the other hand, the light 19 reflected by the half mirror 12 passes through the beam splitter 10 and enters the beam splitter 11 located on the eyepiece lens 9 side as shown in FIG. 15 is incident.
In the present specification, light reflected by the half mirror 12 and incident on the measurement image sensor 15 is referred to as reference light 20.

On the other hand, as shown in FIG. 3, the light 18 reflected by the measuring surface 2 of the regular quadrangular pyramid at the tip of the indenter 1 is incident on the beam splitter 11 through the objective lens 8, where it is divided into two directions and transmitted. The one light 21 is imaged by the eyepiece 9 and indicates the position of the laser light irradiated on the measurement surface 2 in the imaging device 16 for observation.
The other light 22 reflected by the beam splitter 11 enters the measurement image sensor 15 as a non-coupled optical system (infinity optical system).
In the present specification, the light reflected by the measurement surface 2 and incident on the measurement image sensor 15 is referred to as measurement light 22.
Since two spots 23 and 24 of the reference light 20 directly incident from the laser light source 13 and the measurement light 22 reflected by the measurement surface are observed in the measurement image pickup device 15, the method of the measurement surface is determined from the positional deviation. Detect line direction. That is, the direction of the indenter 1 is adjusted by the rotary encoder 7 so that the two spots 23 and 24 on the measurement image pickup device 15 coincide with each other, and the normal direction of the measurement surface 2 of the indenter 1 is detected from the adjustment angle at that time. can do.

  As described above, in order to measure the angle of the measurement surface using the apparatus shown in FIG. 1, it is sufficient that the measurement surface has a surface that can be irradiated with laser light. For example, since the length of one side of the measurement surface of the quadrangular pyramid of the indenter of the micro Vickers test is several tens of μm, it can be sufficiently measured by the apparatus shown in FIG.

Industrial applicability

The present invention can be used for calibration of a hardness tester (JCSS) and product inspection during indenter production.
The indenter calibration results are necessary for all offices that conduct hardness tests that require traceability, and indirectly affect all such companies.

It is a schematic front view for demonstrating the angle measuring apparatus of a micro plane which concerns on embodiment of this invention. It is a front view which shows the path | route of the reference light in the micro plane angle measuring apparatus which concerns on embodiment of this invention. It is a front view which shows the path | route of the measurement light in the micro plane angle measuring apparatus which concerns on embodiment of this invention. It is an AA view of FIG.

Explanation of symbols

1 Indenter 2 Four faces of regular square pyramid (measurement face)
3 Sample Table 4 Vertical Surface of Sample Table 5 Horizontal Surface of Sample Table 6 Rotary Encoder 7 Rotary Encoder 8 Objective Lens 9 Eyepiece 10 Beam Splitter 11 Beam Splitter 12 Half Mirror 13 Laser Light Source 14 Laser Light 15 Imaging Device 16 for Observation Imaging Element 17 Reflected light at beam splitter 10 18 Light reflected by measurement surface 2 19 Light reflected by half mirror 12 20 Reference light 21 Light incident on image sensor 16 for observation 22 Measurement light 23, 24 On image sensor for measurement Two spots

Claims (4)

  In an apparatus that measures the angle of a minute plane of a sample placed on a sample table using an optical system, reference light passing through the optical axis of the optical system and measurement light reflected by the minute plane of the sample are incident on an image sensor. An apparatus for measuring the angle of a micro-plane, wherein the angle of the micro-plane of the sample is measured from the difference between the positions of the reference light and the measurement light in the image sensor.   The sample is placed on a sample table composed of a biaxial rotating stage so that the reference plane of the sample is orthogonal to the optical axis of the optical system, and in order from the sample table side, an objective lens, a half mirror, an objective lens side beam splitter, An optical system is configured by providing an eyepiece-side beam splitter and an eyepiece on the optical axis. Light from the light source is incident on the objective-lens side beam splitter, and the light transmitted through the half mirror is passed through the objective lens. The measurement light irradiated on the measurement surface, and the reference light reflected by the half mirror and the reference light reflected by the half mirror are made incident on the measurement image sensor via the eyepiece side beam splitter. 1. A microplanar angle measuring apparatus according to 1.   3. The microplanar angle measuring device according to claim 1 or 2, wherein one side of the measurement surface of the sample is several tens of micrometers. The microplanar angle measuring apparatus according to any one of claims 1 to 3, wherein the sample is an indenter for a hardness test.

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