JPH0688790A - Laminography apparatus - Google Patents

Abstract

PURPOSE:To obtain a transmission image of an arbitrary predetermined cross section in a short time. CONSTITUTION:A transmission image of a predetermined cross section of an object 3 to be inspected is obtained by arithmetically averaging transmission signals of a plurality of specific points sequentially obtained upon movement of the object 3 to be inspected in a position on the radiation detecting area of radiation detecting means 7 at each sampling intervals determined according to distances from a radiation source 1 to the plurality of specific points in a predetermined cross section. Thus, the image of the arbitray cross section can be obtained by one inspection without any particular complicate process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nondestructive inspection apparatus for inside of an object using radiation, and more particularly to a laminography apparatus for obtaining a transmission image focused on one layer inside the object.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional example of a laminography device. This apparatus irradiates the subject 104 with X-rays while placing the subject 104 on the table 103 and moving the X-ray tube 101 in an arc shape around the rotation axis 117 above the table 103, and places the subject 104 on the lower portion of the subject 104. The exposed film 105 is also moved while moving in an arc shape at the same time to expose the object 104.
This is to obtain a transmission image in focus on the surface to be inspected. Generally, a so-called tomography apparatus is widely used for medical purposes.

FIG. 9 shows another conventional example of a laminography apparatus. This apparatus obtains a transmission image of the subject 104 by an X-ray surface sensor (two-dimensional array) 115, rotates the subject 104 by one rotation axis 117, and obtains transmission images at various rotation angles obtained at this time. By performing arithmetic processing, a transmission image in focus on one focus surface is obtained. In the arithmetic processing, expansion and contraction in one direction and shift processing are performed on each image, and then the entire image is averaged.

In the case of a normal transmission image, since all the layers of the subject are overlapped images, it may be difficult to see if one layer is desired to be inspected. An in-focus image can be obtained.

[0005]

By the way, although this type of device was often used for medical purposes, it has been applied to industrial purposes in recent years. For example, in particular, inspection of a multilayer substrate. The possibility is being tried for use.

However, when the laminography apparatus as described above is directly applied as an industrial nondestructive inspection apparatus, the following problems occur.

That is, the apparatus of FIG. 8 is as follows.

Only one face can be inspected at a time. Specifically, since the focus is aligned with the focus surface 106 including the rotation axis 117, it is necessary to replace the film and reset the subject each time.

Focus is only on a flat surface, not on a curved surface.

The inspection time is long.

Since an image is obtained on a film, it is good for visual inspection, but it is not suitable for automatic processing such as automatic judgment.

The apparatus shown in FIG. 9 is as follows.

Image processing is complicated and the processing time is long. (Image expansion / contraction processing, shift processing, and averaging processing are required.)
It is not suitable for online processing because the subject is set on the turntable for inspection.

The focus is only on a flat surface, not on a curved surface.

In particular, when inspecting a substrate online, it is important to increase the inspection speed, and since the substrate has a warp, it is desired that the focus surface can be aligned with the surface aligned with the warp. There is.

The present invention has been made in view of the above,
It is an object of the present invention to provide a laminography device capable of obtaining a transmission image on a desired tomographic plane in a short time.

[0017]

In order to achieve the above object, the present invention provides a radiation source, radiation detecting means having a two-dimensional radiation detection region arranged opposite to the radiation source, the radiation source and the radiation detection. Transport mechanism means for transporting and moving the subject in parallel with the radiation detection area of the radiation detecting means, and a transmission signal output from the radiation detecting means in time series with the transport movement of the subject. , The radiation source is sequentially obtained along with the movement of the subject at the position on the radiation detection area at each sampling pitch interval determined according to the distances from the radiation source to the multiple singular points in the required tomographic plane of the subject. The gist of the present invention is to have an averaging means for averaging the transmission signals of the respective singular points to form a transmission image of the required tomographic plane of the subject.

[0018]

In the laminography apparatus according to the present invention, the transmission image of the required tomographic plane of the subject is determined according to the respective distances from the radiation source to a plurality of singular points in the required tomographic plane. In particular, by obtaining the transmission averages of the transmission signals for the respective singular points sequentially obtained with the movement of the subject at the position on the radiation detection area in the radiation detection means for each sampling pitch interval, A transmission image of an arbitrary cross section can be obtained by a single inspection without performing complicated processing.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a laminography apparatus according to an embodiment of the present invention. In the figure, an X-ray tube 1 which is a transparent radiation source and a line sensor 7 which faces the X-ray tube 1 and detects radiation with a spatial resolution on a line are arranged at equal intervals in n channels. Between the X-ray tube 1 and the line sensor 7, there is a transport mechanism unit 5 that translates in a direction perpendicular to the line direction of each channel of the line sensor 7, and the subject 3 is placed thereon. Further, a signal collecting unit 10 that collects a transmission signal from each channel of the line sensor 7, and an averaging unit 12 that adds and averages transmission signals obtained by different line sensors for the collected transmission signals while shifting them in the parallel movement direction. And a CRT 14 for image display. In FIG. 1, 2
Reference numeral 0 is an X-ray control unit, and 22 is a mechanism control unit.

Next, the operation of this embodiment will be described.

First, the subject 3 is placed on the transport mechanism 5 and X
The X-ray irradiation from the ray tube 1 is started. The parallel movement speed of the transport mechanism unit 5 is controlled to a constant speed by the mechanism control unit 22, and its feed amount is P.

The sensor interval of n line sensors 7 arranged under the transport mechanism 5 is D, the distance from the focus of the X-ray tube 1 to the line sensor 7 is FDD, and the focus is from the focus surface of the subject 3. Assuming that the distance is 1, the sensor interval ΔS on the focus plane is as shown in FIG.

[Equation 1] It is represented by.

The data acquisition by each line sensor 7 is executed by the signal acquisition unit 10 at a constant sampling period. Assuming that the feed amount P in one sampling cycle, that is, the sampling pitch is ΔP and the channel pitch of the line sensor 7 is Δy, the object 3 is detected by the line sensor 7.
ΔP, Δ on the P, y plane after completely passing over
The transmission data collected at the y intervals are accumulated for the number of line sensors as shown in FIG.

The transmission data is represented by I _k (i, j), where i and j are sample points No in the P and y directions for the k (1 ≦ k ≦ n) th line sensor. This image data is shifted by .DELTA.S in the P direction each time the line sensor is shifted by 1 in the No direction of the line sensor, and the transmission data is averaged. Expressed as an expression,

[Equation 2] Becomes By the way, in general, ΔS · (k−1) /
Since ΔP is not an integer, in practice I _k (i + ΔS
・ (K-1) / ΔP, j) is interpolation calculation

[Equation 3] Ask in. Here, INT means rounded down integer, and FRAC means too much at the time of integerization. The arithmetic mean of the transmission data including the above interpolation is executed by the arithmetic mean unit 12.

Here, the addition by shifting by ΔS means addition of transmission data passing through one point on the focus surface of the subject 3, as is clear from FIG. The transmission path of the data to be added passes through the above-mentioned one point, but since the directions are different from each other, after the addition, the above-mentioned one point is in focus and the upper and lower areas become blurred data. In this way, it is possible to obtain an image in focus only on the target focus surface. If it is desired to change the focus plane, the averaging unit 12 may change the value of ΔS.

By the above procedure, an image in focus on the surface of the X-ray tube 1 at the distance l from the focus can be displayed on the CRT 14.

The above is the case where the focus surface is set parallel to the measurement surface of the line sensor 7. However, by setting the value of ΔS as a function of i and j, any surface such as an inclined flat surface, a curved surface or a cut surface can be set. You can get an in-focus image. That is, referring to FIG. 4, the focus surface can be expressed as a value l (P, y) of 1 when the first line sensor 7-1 passes. The focus plane is set by a two-dimensional array of numerical values taken at ΔP and Δy pitches of l (P, y).

[Equation 4] To calculate ΔS (i, j). Then, when the averaging is performed by the equations (2) and (3), by using this ΔS (i, j) instead of ΔS, an image in focus on an arbitrarily set focus surface can be created. Of.

Therefore, according to this embodiment, the following effects can be exhibited.

There is no need to move X-rays or sensors,
You can leave each fixed. Therefore, since it is only necessary to feed the transport mechanism section in a fixed direction, the mechanism section can be simplified.

The transfer mechanism is suitable for online inspection because it does not need to be continuously fed and stopped.

Unlike film photography, since digital data can be processed, an optimum image can be obtained by changing the contrast, window level, and window width, so that data acquisition only needs to be performed once.

Since it is digital data, it is suitable for automatic determination.

An image with the focus plane changed can be obtained from the collected data once.

Further, many images having different focus planes can be obtained from the collected data once. Therefore, the inspection time can be shortened.

An image in focus can be created on any surface such as an inclined plane, a curved surface, and a cut surface.

Although the line sensor is used as the X-ray sensor in the above-described embodiment, the present invention is not limited to this, and another X-ray sensor may be used. Specifically, for example, an image intensifier (II) 30 may be used as shown in FIG.

This is an I.D. I. If the coordinates on the surface are x, y (x is taken in the feeding direction), the feeding amount of the subject 3 is P, and the data sampling pitch is ΔP, I.
I. The sampling pitch ΔP 'on the surface is

[Equation 5] It is represented by. Then, as shown in FIG. 6, the data obtained in the period of ΔP is AD-converted, and Δ is obtained in the same manner as described in the operation of the embodiment of FIG.
P's are shifted and added (interpolation calculation is executed at this time),
Furthermore, by adding, an image on a certain focus plane can be obtained. In this case, ΔP ′ may be changed to change the focus surface.

FIG. 7 shows the I.V. of the embodiment of FIG. 5 described above. I. The X-ray fluorescent plate 31 and the television camera 32 are used instead of 30, and the operation is the same.

[0040]

As described above, according to the present invention,
The transmission image of the required tomographic plane in the object is located on the radiation detection area in the radiation detecting means at each sampling pitch interval determined according to the respective distances from the radiation source to a plurality of singular points in the required tomographic plane. By obtaining the transmission signals for each singular point sequentially obtained with the movement of the subject by averaging, the required tomographic slice can be obtained by a single inspection without any complicated processing. A transmission image of the surface can be obtained in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment.

FIG. 3 is a diagram for explaining the operation of the embodiment.

FIG. 4 is a diagram for explaining the operation of the one embodiment.

FIG. 5 is a configuration diagram of another embodiment of the present invention.

FIG. 6 is a diagram for explaining the operation of the other embodiment.

FIG. 7 is a configuration diagram of still another embodiment of the present invention.

FIG. 8 is a diagram showing a conventional example.

FIG. 9 is a diagram showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray tube 3 Subject 5 Transport mechanism section 7 Line sensor 10 Signal collecting section 12 Addition / averaging section 14 CRT 20 X-ray control section 22 Mechanism control section 30 Image intensifier 31 X-ray fluorescence plate 32 Television camera

Claims (1)

[Claims] 1. A radiation source, a radiation detecting means having a two-dimensional radiation detecting area arranged opposite to the radiation source, and a radiation detecting area of the radiation detecting means between the radiation source and the radiation detecting means. Conveyance mechanism means for conveying and moving the subject in parallel with each other, and transmission signals output in time series from the radiation detecting means in association with the conveying movement of the subject, The transmission signals for each singular point sequentially obtained with the movement of the subject at the position on the radiation detection area for each sampling pitch interval determined according to the distance to the singular point are added and averaged. And a averaging means for forming a transmission image of the required tomographic plane of the subject.