JPH0429363Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to an apparatus that automatically measures parallel minute dimensions of a sample to be measured using image processing technology while optically enlarging them.

BACKGROUND OF THE INVENTION The sample to be measured, such as the size of a gap in a magnetic head, is usually measured by optically magnifying it with a magnifying glass and visually reading a scale on a screen. However, with these measurement methods, it is necessary to position the sample to the measurement position, and it is also necessary to read the scale on a screen, making the measurement work complicated and limiting the time processing capacity. be.

On the other hand, with the spread of image processing technology, image processing devices are being used to measure minute dimensions. However, when the dimensions of the object to be measured approach the dimensions of dots (pixels) in the image memory, it becomes difficult to measure with accurate accuracy. For example, if the dot size is 17.2 [μm] square, the dimension of the object to be measured is smaller than that.
If it is around 0.3 [μm], the resolution of the image memory will be larger than the dimension of the measurement target.
Measurement using image processing becomes impossible.

Purpose of the invention Therefore, the purpose of the present invention is to enable the field of image processing technology to measure parallel minute dimensions close to the resolution of image processing technology with high accuracy.

Therefore, in the present invention, by rotating the parallel minute dimensions of the sample to be measured by a minute angle with respect to the scanning direction of the imaging camera, the scanning line of the imaging camera is crossed at the position of the parallel minute dimensions. Then, using trigonometric functions from the length of the scanning line within that infinitesimal dimension,
It is possible to calculate minute dimensions.

Configuration of the invention FIG. 1 shows a minute dimension measuring device 1 of the invention. This minute dimension measuring device 1 includes a microscope 2,
It is assembled by an imaging camera 3, an image memory 4, a rotation indexing means 5, and an image processing device 6.

The microscope 2 optically examines the sample 7 to be measured on the stage 2a at a magnification K of about 250 times.
to optically magnify the image. And the above-mentioned imaging camera 3
scans a real image of the sample 7 through the microscope 2, performs amplification and clamping operations, and then converts it into a digital image signal. The image memory 4 also temporarily stores the digital image signal from the imaging camera 3 as one frame, and sends an image of the sample 7 to be measured to the image processing device 6 through the interface 8.

On the other hand, the rotation indexing means 5 uses a driving source 5a attached to the stage 2a of the microscope 2 to move the stage 2a, which is perpendicular to the optical axis of the microscope 2, into a predetermined minute position about the optical axis. Rotate by an angle θ, and rotate the small angle θ
Information corresponding to is sent to the image processing device 6 through the interface 8.

The image processing device 6 is composed of a computer, is connected to a display 9, a keyboard 10, and a printer 11, and stores an image processing program in its built-in memory. , performs necessary image processing operations and calculation operations.

Effect of the invention During the measurement operation, the sample 7 to be measured is placed under the microscope 2.
It is supplied onto the stage 2a in a predetermined position using a stopper or the like. In this way, the sample 7 is positioned by the rotary indexing means 5 while being rotated about the optical axis of the microscope 2 by a predetermined minute angle θ with respect to the scanning direction of the imaging camera 3. As a result, the scanning line 12 of the imaging camera 3 intersects the parallel line of the minute dimension D of the measurement object at a minute angle θ, as shown in FIG.

In this state, the microscope 2 optically magnifies the sample 7 at a magnification K. Therefore, the imaging camera 3
scans the real image, converts it into an analog image signal, further amplifies this, superimposes an appropriate DC component through a clamp circuit, and then converts it into an analog image signal.
It is converted into a digital image signal by a D converter and sent to the image memory 4 as one frame.

Therefore, when the image processing device 6 receives a command to start measurement, it first reads out one frame of image signals from the image memory 4 through the interface 8, and also reads out the minute angle θ from the rotation indexing means 5 through the interface 8. is read at the same time and stored in internal memory. Thereafter, the image processing program of the image processing device 6 determines the range of the parallel minute dimension D of the sample 7 from the image signal of one frame, and from the change in the signal level V of the image signal,
By determining the length L of the scanning line 12 in the portion corresponding to the minute dimension D and counting the number of dots in the portion corresponding to the length L, the dimension of the length L is quantitatively calculated. In this calculation process, multiple scanning lines 1
By calculating the average value for 2, the accuracy of the length measurement can be further improved.

Thereafter, the image processing program calculates the minute dimension D by performing the following calculation based on the magnification K, the length L of the scanning line, and the minute angle θ.

D=(L·sinθ)/K In this way, the minute dimension D of the object to be measured is automatically determined by image processing and calculation. Note that this minute dimension D is stored on the recording paper by the printer 11 as necessary, and is displayed on the display 9 together with the image signal as necessary.

Effects of the invention In this invention, the parallel minute dimensions of the sample to be measured are positioned at a slight angle with respect to the scanning direction of the imaging camera, and the measurement length in the field of image processing is expanded. Regardless of the resolution limit of , smaller dimensions can be measured with sufficient accuracy for practical use. In addition, sample positioning, measurement operations, and image processing operations are performed automatically, and measurement operations are completed in a short time, making it effective for continuous measurement of minute dimensions and quality control in mass production processes. .

In particular, the length to be measured using image processing by the rotation indexing means is set to match the direction of the scanning line, and there is no theoretical limit to the minute angle for setting the inclination. The minute dimensions of the object can be appropriately enlarged on the scanning line. Moreover, as a result of the enlargement, the length L is measured as more dots than in direct measurement of minute dimensions, so the accuracy of dimension measurement is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the minute dimension measuring device of the present invention, and FIG. 2 is an explanatory diagram showing the positional relationship between the minute dimension and the scanning line and the level of the image signal. 1...Minimum dimension measuring device, 2...Microscope, 3...
...imaging camera, 4...image memory, 5...rotation indexing means, 6...image processing device, 7...sample,
8...Interface, 9...Display,
10...Keyboard, 11...Printer, 12...
...scan line.

Claims (1)

[Scope of utility model registration request] A microscope that optically magnifies the sample to be measured at a predetermined magnification K, an imaging camera that scans the image of the sample taken by the microscope and converts it into a digital image signal, and an image that stores the image signal as one frame. a memory; rotation indexing means for rotating the sample around the optical axis of the microscope by a minute angle θ with respect to the scanning direction of the imaging camera; and reading out image signals from the image memory and determining the image memory from a signal level fluctuation range. Determine the upper length L, read out the minute angle θ from the rotation indexing means, input the magnification K of the microscope, and calculate the parallel minute dimension D=(L・sinθ)/K of the sample. and an image processing device for calculating the parallel minute dimension D of the sample.