JPH1092368A - Image pickup device for scanning electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a correcting method in such a manner that the distortion of an image on an image pickup CRT for a scanning electron microscope can be partially corrected in a circuit. SOLUTION: X, Y deflection signals 3 generated by a deflection circuit 2 set up in a scanning electron microscope 1 are input to a correction circuit 4 set UP in a photographing unit 9 to be independently corrected and output only to respective areas selected out of areas split into four domains, so that a photographing CRT 8 can be deflected with a photographing CRT deflecting coil 4 in accordance with the deflection signals to partially correct image signals 7 fed from an image amplification circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for adjusting a photographing device of a scanning electron microscope.

[0002]

2. Description of the Related Art Conventionally, correction of image distortion for photographing in a photographing apparatus of a scanning electron microscope has been performed by adding an electric correction circuit to a deflection circuit. It is configured to perform symmetric correction for
Partial asymmetric distortion such as upper right and lower right cannot be corrected. Therefore, when distortion occurs at one or several places, a permanent magnet is attached to the CRT deflection coil to symmetrically correct the distortion. In this case, there is a problem that the operation requires skill and the operation time is long.

[0003]

The prior art does not consider the case where distortion occurs partially in the upper right, lower right, etc. in the correction of image distortion in a photographing apparatus. In this case, the correction cannot be performed only with the electrical correction circuit.
Since the method is such that the worker attaches and adjusts the permanent magnet to the CRT deflection coil for photographing, there is a problem that the operation such as the amount of the magnet and the attachment position requires skill and time is required.

It is an object of the present invention to divide an area into four quadrants on a CRT screen for imaging by correcting image distortion of the imaging apparatus, and to independently adjust the X and Y directions in the divided quadrant areas. Image distortion correction by adding four sets of correction circuits and eliminating the method of attaching and adjusting a permanent magnet to a CRT deflection coil with asymmetrical distortion correction and enabling correction of image distortion of a photographing device using only an electric circuit. An object of the present invention is to simplify the operation and shorten the operation time.

[0005]

In order to achieve the above object, the present invention provides a method for dividing an area on a CRT screen for photographing into four quadrants. In other words, a zero cross detector whose output is inverted at the center of the CRT screen for both X and Y directions is used to detect a minus area and a plus area in both the X and Y directions. A method is used in which a logical product of the detected signals in the minus region and the plus region is taken to form four quadrants. As the image distortion correction method, there is used a method that utilizes the fact that the image distortion of the photographing device can be approximated by multiplying a cube curve by a coefficient. By doing so, it is possible to perform image distortion correction independently in both the X and Y directions only in the region selected from the region divided into four quadrants, and this has occurred partially in the upper right, lower right, etc. Image distortion can also be adjusted only by the electric correction circuit, and the adjustment can be made only by turning the variable resistor, so that the image distortion correction operation can be simplified and the operation time can be shortened.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIGS. In FIG. 1, 1 is a scanning electron microscope, 2 is a deflection circuit, 3 is an X and Y deflection signal,
4 is a correction circuit, 5 is a CRT deflection coil for photography, 6 is an image amplification circuit, 7 is an image signal, 8 is a CRT for photography, and 9 is a photography unit. FIG. 2 shows a block diagram of the correction circuit 4. FIG. 3 shows a selection circuit diagram in the correction circuit 4, and FIG.
Shows the correction area. In FIG. 1, X and Y deflection signals 3 generated by a deflection circuit 2 installed inside a scanning electron microscope 1 are input to a correction circuit 4 installed inside an imaging unit 9, and a screen of an imaging CRT is displayed. The upper part is divided into four quadrants, each is divided into quadrants, and the X and Y directions are subjected to a correction operation for image distortion and output only after being limited to the divided quadrant regions. Image signal 7
The imaging CRT deflection coil 4 deflects the imaging CRT 8 with the deflection signal for performing the partial correction of the above. The operation of the correction circuit 4 at this time will be described with reference to FIG. In the case of X-deflection, the input X-deflection signal is subjected to a cube operation by a squarer and a multiplier.

[0007]

X ³ ... (Equation 1) Next, the X-deflection correction coefficient is selected by the selection switch of the correction area selected by the selection circuit, and the value is used to calculate the correction coefficient for the quadrant. Make it. In this case, the selection circuit includes a zero-cross detector and a logical product as shown in the selection circuit of FIG. The operation is X, Y
Both ± 10V deflection signals are input to the zero cross detector,
Inversion from the negative voltage to the positive voltage OV is detected, and a positive region and a negative region are detected for both X and Y deflections. An AND operation is performed on the detected signals of the positive region and the negative region, and the signal is divided into four quadrants to determine a correction region. Here, the correction area corresponds to −XY of the output of the selection circuit corresponding to the correction area A in FIG. 4, + XY corresponds to the B part, −X + Y corresponds to the C part, and + X + Y corresponds to the D part.
Has been split. As a result, independent correction can be performed in each area divided into four in both the X and Y directions. Here, the above-mentioned correction coefficient for X deflection is calculated by a coefficient unit to generate a correction signal, and the correction coefficients for the four quadrants are αA and α, respectively.
B, αC, αD and collectively αi, the correction signal is

[0008]

(2) αiX ³ (2) This is added to the input X deflection signal using an adder, and the corrected X deflection signal is

[0009]

X + αiX ³ (Equation ³ ) is output, and the photographing CR is used by the photographing CRT deflection coil 5.
In T8, only the electric correction circuit can perform X deflection in which the image signal 7 is partially corrected. Similarly, in the case of Y deflection, the input Y deflection is subjected to a cubic operation by a squarer and a multiplier.

[0010]

Y ³ (Equation 4) Next, the Y-deflection correction coefficient is selected by the selection switch of the correction area selected by the selection circuit, and the correction signal for the quadrant is calculated by using the value to calculate the Y-deflection correction coefficient. To produce At this time, the correction coefficients are set to αE, αF, αG, α
H and collectively αn, the correction signal is

[0011]

[Formula 5] αnY ³ (Formula 5) This is added to the input Y deflection signal using an adder, and the corrected Y deflection signal is added.

[0012]

Y + αnY ³ (Equation 6) is output, and the photographing CRT deflection coil 5 uses the photographing CR.
In T8, only the electrical correction circuit can perform Y deflection in which the image signal 7 is partially corrected.

[0013]

According to the present invention, in a photographing apparatus for a scanning electron microscope, the correction circuit of the present invention is added to a photographing unit to correct the image distortion for photographing, thereby correcting the image distortion for photographing on a CRT screen. The image can be divided into quadrants and adjusted independently only in the selected area in both the X and Y directions, and the adjustment is made by turning a variable resistor. Since a skillful operation of attaching a permanent magnet to the deflection coil to make the distortion symmetrical for the correction is not required, the simplification of the photographic image distortion correction operation and the operation time are shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a photographing device in a scanning electron microscope of the present invention.

FIG. 2 is an explanatory diagram of a correction circuit in an imaging device in the scanning electron microscope of the present invention.

FIG. 3 is an explanatory diagram of a correction circuit correction area selection unit in the imaging device in the scanning electron microscope of the present invention.

FIG. 4 is an explanatory diagram of a correction area on a photographing CRT in a photographing device in the scanning electron microscope of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scanning electron microscope, 2 ... Deflection circuit, 3 ... X and Y deflection signals, 4 ... Correction circuit, 5 ... CRT deflection coil for photography, 6 ...
Image amplification circuit, 7: image signal, 8: CRT for photographing, 9: unit for photographing.

Claims (2)

[Claims] 1. An apparatus for photographing an image signal obtained from a detector of a scanning electron microscope, wherein a screen of a photographing CRT is divided into four quadrants, each of which is limited to an area of each divided quadrant. An imaging device for a scanning electron microscope, comprising: an image distortion correction device configured by four sets of electric circuits so that image distortion can be corrected independently in both the X and Y directions. 2. An image distortion correction method in the X direction,
X = X + αiX ³ , and in the Y direction, Y = Y + αnY ³
2. The photographing apparatus in a scanning electron microscope according to claim 1, wherein αi and αn can be set independently in each quadrant of the CRT.