JPH0212043A - Method for continuously radiographing x-ray diffraction image - Google Patents

Abstract

PURPOSE:To continuously radiographing X-ray diffracted images by setting plural measuring areas on the photosensitive surface of an imaging plate and successively exposing, reading, and erasing the X-ray diffracted images at each area while the imaging plate is rotated. CONSTITUTION:X-rays 4 radiated from an X-ray source 1 are made incident on a sample 6 after the rays are passed through a filter 3 and collimated into a parallel beam by means of a collimator 5. The X-rays 4 transmitted by the sample 6 form a diffracted image in a measuring area on an imaging plate 10 limited by a mask 9 for exposure and a beam stopper 12. The image plate 10 is stopped at every 60 deg. and exposure, reading, and erasing are performed once at each stoppage of the plate 10. Therefore, the diffracted images can be radiographed continuously in an on-line state and, as a result, the measuring time can be reduced and the efficiency of the measurement can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an imaging method for analyzing the structure of metals and non-metals using X-ray diffraction.

(Conventional technology) Initially, radiographic methods were used in this field.

Since X-ray photography is a two-dimensional detector that can obtain surface information, it has the characteristic of providing knowledge about crystal structures. For example, important information can be obtained about grain size and shape, internal structures such as subdalein, and strain distribution inside a single crystal. Also, taking advantage of its characteristics as a two-dimensional detector, it is possible to perform photographic positive pole mapping. According to this method, a small number of grains (100
Since it is possible to obtain positive pole figures of 0 or less, it is an essential method for understanding coarse grain structures and crystal orientation distributions in minute regions.

However, the general X-ray photography method using X-ray film is inferior in terms of quantitative performance and efficiency, so the counter method, which is superior in these respects, has been developed and is currently the mainstream method. However, the counting tube method has the drawbacks of extremely insufficient information on the crystal structure and the inability to obtain knowledge about the coarse grain structure and crystal orientation distribution in minute regions, and it is a second method that is superior in terms of quantitative performance and efficiency. The development of a dimensional detector was awaited.

In summary, the following points are listed as problems with the photographic method using an X-ray film, which is a common method of X-ray photography.

1) Lack of quantitativeness. That is, the linearity after conversion to intensity data is poor.

2) Detection intensity range is narrow.

3) The detection limit is high and long exposure is required.

Therefore, it takes a particularly long time in a small area.

4) It is inefficient. That is, it takes a long time to develop the film in an aqueous solution and convert it into strength data.

The challenge is to develop a radiographic method that overcomes these drawbacks.

The imaging plate is an integral two-dimensional detector with a minimum pixel of 0.1 aiXo and 1 m, which was recently invented in Japan. The imaging plate will be explained below.

The imaging plate is an organic film coated with a special fluorescent material containing Eu (Eurobium). When exposed to X-rays, a number of Eu atoms corresponding to the exposure amount are excited, and an X-ray image is stored. The exposed surface is then scanned with a narrow laser beam of a specific wavelength. This laser beam causes the excited Eu to emit light, and the intensity of this emitted light is read and recorded for each pixel. After reading, the imaging plate i- is irradiated with visible light to return the excited Eu atoms to the ground state and erase the X-ray image information. The erased imaging plate is also subjected to exposure. In this way, the imaging plate can be used repeatedly.

This imaging plate has the excellent feature of solving all of the above-mentioned four problems of photography using X-ray film. Nuclear Inst-rum
ents and Methods in Physi
cs Research A246 (1986) 57
As shown at the top of 2-578, excellent quantitative performance was obtained in a wide detection sensitivity range of 106. In addition, the lower limit of detection is low, and detection is possible even with a minimum of 10 counts per pixel. This value is approximately 1710 times that of an X-ray film, and therefore, the exposure time of an imaging plate can be reduced to approximately 1/10 compared to an X-ray film. Furthermore, high-speed reading using laser beams and high-speed erasing using visible light are possible, making them extremely efficient. Furthermore, since it is an integral type detector, there is no dead time (time ρ during which the detector does not perform detection) like in a counter tube, and high-speed phenomena can be measured.

(Problems to be Solved by the Invention) However, conventional methods of using imaging plates have been extremely unsatisfactory. For example, during exposure, the imaging plate remains fixed.

Moreover, the entire imaging plate surface is used as one piece. In addition, the reading/erasing device is a separate device from the exposure device, and each imaging plate must be manually set from the exposure device to the reading/erasing device, which is an offline method of use. However, this method is complicated and extremely inefficient for use in X-ray photography positive pole figure measurements that require a large number of images, and cannot be used in practice.

The present invention has been made in view of the above-mentioned problems, and provides a photography method for continuously photographing X-ray diffraction images online.

(Means for Solving the Problem) The present invention sets a plurality of measurement areas on the photosensitive surface of an imaging plate, and sequentially exposes, reads, and erases an X-ray diffraction image in each area while rotating the imaging plate. This is a method of continuously projecting X-ray diffraction images.

In the present invention, (1) During exposure, only the relevant measurement area is exposed to X-rays, and other measurement areas are shielded from exposure to X-rays.

(2) During reading, only the relevant measurement area should be scanned with a laser beam, and other measurement areas should be shielded from being irradiated with the laser beam.

(3) During reading, in order to prevent a decrease in measurement accuracy due to oblique incidence, the laser beam is made perpendicular to the imaging plate.

(4) In reading, the scanning of the laser beam should be completed in a short time in order to shorten the reading time.

(5) During erasing, visible light is irradiated only to the read and unexposed area, and other areas are shielded so that visible light is not irradiated.

(6) In (1) to (5) above, perform without damaging the surface of the imaging plate.

Taking these factors into consideration, the imaging plate is divided into parts and rotated, making it possible to continuously take X-ray diffraction images online.

(for production) Next, the present invention will be explained in detail along with its operation.

Multiple measurement areas are set on the photosensitive surface of the imaging plate. The larger the number of measurement regions, the more measurements can be made in a given period of time, which is better in terms of efficiency, but the smaller the area of the measurement regions, the less information can be obtained in one measurement.

The number of measurement areas is determined according to the purpose, taking into account the amount of information required and measurement efficiency.

Sequentially expose and read the X-ray diffraction images in each region.

Rotation is required in order to continuously take X-ray diffraction images by erasing. It is practically difficult to fix the imaging plate and rotate each large and heavy processing device. Therefore, it is desirable that the exposure, reading, and erasing processing devices are fixed and the imaging plate is rotated so that the measurement area is sequentially subjected to the three processes of exposure, reading, and erasing. To do this, it is necessary to determine in advance the positions for exposure, reading, and erasing, and to install an X-ray irradiation device, a reading device, and an erasing device at each location and operate them in synchronization. Furthermore, when performing the above processing, it is advantageous in terms of efficiency to stop the rotation of the imaging plate and perform the three processing at once. After completing the three processes, the imaging plate is rotated by a certain angle and the subsequent measurement area is processed. By repeating the rotation and stopping of the imaging plate in this manner, X-ray diffraction images are continuously taken.

Since the three processes are performed simultaneously in this way, the number of measurement areas is at least three. However, a wide space is required between the measurement areas. There is no particular upper limit, but for practical purposes it is 1.
It is about 20.

X-rays and visible light must be completely shielded from each other between each measurement area, and for this reason, if a lead plate is used for shielding, an interval of tau or more must be provided between the measurement areas. If a copper plate is used for shielding, it is desirable to provide a spacing of 3II111 or more. The shape of the measurement area can be any shape such as a circle, a rectangle, or a polygon.

Exposure 2 In order to perform each reading and erasing process in the measurement area of the desired shape and size, the exposure device must be
The exposure mask 9 shown in the figure and the reading mask 15 shown in FIG. 2 are attached to the reading device. A similar mask is also attached to the erasing device. The mask is a metal frame with the measurement area blank, and each device is attached to the mask. After the imaging plate has stopped, three masks are pressed against the imaging plate to prevent leakage of X-rays and light rays. A block that does not transmit X-rays or light rays is placed on the back side of the imaging plate to prevent distortion of the imaging plate due to pressing and leakage of X-rays or light rays due to transmission. In addition, the material of the mask and mask mounting tools is preferably a lead plate or a metal such as a seed plate suitable for shielding. An organic coating is applied to the surface of the mask that contacts the imaging plate to prevent damage to the imaging plate surface. For example, Teflon coating is desirable.

Furthermore, the imaging plate, reading device, and erasing device are installed in a measurement box that does not transmit visible light.

When performing reading processing, a method is used in which the rotation of the imaging plate is stopped and a laser beam reflecting mirror (hereinafter referred to as mirror) is scanned. A method that does not stop the rotation of the imaging plate is conceivable, but it would be inefficient in terms of efficiency as it would not be possible to process the exposure and erasing images at the same time.

The entire measurement area is read by scanning the mirror. A scanning mirror may be positioned at the center of curvature of the imaging plate to prevent a decrease in measurement accuracy due to oblique incidence. Further, the read data is stored in the storage device of the electronic computer in association with the symbol of the sample and measurement conditions (tilt angle, one position in the tilt direction, temperature, atmosphere, etc.).

As mentioned above, the rotation operation of the imaging plate is controlled by rotating and stopping the rotation motor, X-ray shutter, reading device, and erasing device through a control device to maintain appropriate rotation angle and rotation time interval. This is done using an electronic computer. Therefore, measurement regions of two shapes and spaces required for various experiments can be realized on one imaging plate. Exposure, reading, and erasing cannot be performed during rotation, so a faster rotation speed is desirable.

For the measurement of ultrahigh-speed phenomena, the entire circumference of the donut-shaped imaging plate can be used as one measurement area. In this case, exposure, reading, and erasing are performed sequentially for the entire circumference.

(Example) The following measurements were carried out using the method of the present invention.

■) Positive pole figure measurement 2) Stress measurement 3) Dynamic measurement of phase transformation, recrystallization and precipitation phenomena 4) Mapping of the crystal structure on the sample position side 5) Debye image measurement 6) Laue image measurement 1) Positive pole figure measurement implementation Example 1: As shown in FIG. 1, six regular hexagonal measurement areas were set on a circular imaging plate 10.

When the exposure process is performed in the measurement area A, the measurement areas B and C correspond to the reading and erasing processes, respectively.

FIG. 2 is a plan view of the device. The right half is o-a in Figure 1.
The left half of the exposure device installed in the cross section is 0-b in Figure 1.
The reader is shown installed in the cross section. Note that o in Figure 1
An eraser was installed on the -c cross section, and a parallel beam of diameter Inn was made incident on the steel plate sample 6 using a collimator 5. The X-rays transmitted through the sample 6 pass through the imaging plate 1, which is restricted by a fog light mask 9 and a beam stopper 12.
A diffraction image is generated in the measurement area above 0. Details of the fog light mask 9 are shown in FIG. 3, and the imaging plate 10 stops every 60 degrees. It takes 2 seconds to rotate 60 degrees. Exposure, reading, and erasing are performed all at once when stopped. The opening time of the steel plate shutter 2 during exposure was required to be 120 seconds. Reading took 30 seconds. Erasing was performed in 10 seconds. Therefore, the stopping time was 120 seconds. Changing the inclination angle of the steel plate sample 6 and stopping the imaging plate 10 (in this case, changing the inclination angle of the steel plate sample 6
Exposures were carried out one after another while synchronizing each other (every 0 degrees). After one measurement with the sample 6 perpendicular to the incident X-ray beam, tilt the sample in four directions parallel to the plate surface and orthogonal to each other.5.10.1
It was tilted at 5, 20, 25, and 30 degrees, and a total of 25 measurement data were obtained.

Example 2: When synchrotron radiation (2.5 GeV, 200+sA) was converted into a monochromatic light source and used as a light source, the exposure time was 10 seconds and +- minutes. The stop time was 30 seconds, which was necessary for reading, and efficiency was determined by the reading time.

Conventional method 1; The X-ray film method required a long time of 10 minutes x 25 times for exposure, 120 minutes for development (until drying), and 20 minutes x 25 times for reading with a microphotometer.

Conventional method 2: In the imaging plate method, it took 2 minutes for exposure, 5 minutes for reading and erasing, and 10 minutes for one measurement, including manual labor such as removing and attaching the imaging plate 10.

The above implementation results are summarized in Table 1.

Table 1 Effects of positive pole figure measurement In the case of a coarse grain structure, by scanning the sample in two directions parallel to the plate surface and perpendicular to each other, a sufficient number of crystal grains can be measured and analyzable data can be obtained. be able to.

2) Stress measurement example 1: As shown in FIG. 4, a circular imaging plate 10
Twelve rectangular measurement areas with a width of 20 mm are set on the top. A
B when performing exposure processing in the measurement area.

The measurement areas C correspond to reading and erasing processes, respectively. Cr tubes (4
After passing through a filter 3, characteristic X-rays 4 generated from a source (0 kV, 30 mA) were made incident on a steel plate sample 6 by a collimator 5 as a parallel beam with a diameter of 1 square. The X-rays reflected from the sample produce a diffraction image in the measurement head area limited by the exposure mask 9. Imaging plate 10 stops every 30 degrees. It takes 1 second to rotate 30 degrees. Exposure, reading, and erasing are performed all at once when stopped. Imaging plate 10
The opening time of the steel plate shutter 2 during exposure was required to be 120 seconds. It took 6 seconds to read. Erasing was performed in 2 seconds. Therefore, the stopping time was 120 seconds. Exposure was performed one after another while changing the inclination angle of the steel plate sample and stopping the imaging plate 10 in synchronization. After making the sample perpendicular to the incident X-ray beam for triaxial stress measurement, the sample is tilted in two directions parallel to the plate surface and orthogonal to each other, and
0.5.10.15.20.2 in the direction that bisects the direction
It was tilted at 5, 30, 35, 40, and 45 degrees, and a total of 30 measurement data were obtained.

Example 2: Synchrotron radiation (2.5 GeV, 200 m^) was made monochromatic using a monochromator and then used as a light source; the exposure time was 9 seconds, the reading time was 6 seconds, and the stop time was 9 seconds, which is the time required for exposure. Efficiency was determined by exposure time.

Conventional methods 1 and 2 were carried out in the same manner as in the case of l) positive pole figure measurement, and the results of 0 or more are shown in Table 2.

Table 2 Effects of stress measurement In the case of uniaxial stress measurement, it is sufficient to tilt the sample in one direction.

3) Dynamic measurement of phase transformation, recrystallization, and precipitation phenomena Using the same method as in section 1), 120 rectangular measurement areas with a width of 2 squares were set on the imaging plate NO, and the anticathode Mo was rotated 79 times.
A characteristic X-ray source (60 kv, 300 mA) was used. Dynamic measurements were performed every 3 seconds using an exposure time of 2.5 seconds and a reading time of 1 second.

Furthermore, in this method, the entire circumference of the donut-shaped imaging plate 10 was used as one measurement area for the measurement of ultrahigh-speed phenomena. The imaging plate 10 was rotated at one revolution per second, the shutter 2 was opened for one second, and the imaging plate 10 was exposed to light, and then the entire surface of the imaging plate 10 was read and erased. Using this method, we were able to measure ultrafast phenomena.

4) Mapping of crystal structure by sample position In the same method as in section 2), without tilting the sample,
This was carried out by step scanning in two directions parallel to the plate surface and perpendicular to each other.

5) Debye image measurement In the same method as in section 1), without tilting the sample, measurements were performed at multiple target positions using a mechanism that scans in two directions parallel to the plate surface and orthogonal to each other.

6) Lawe image measurement In the same method as in section ■), using a white XvA source and without tilting the measurement sample, two images parallel to the plate surface and perpendicular to each other are
Using a mechanism that scans in various directions, measurements were taken at multiple target positions.

(Effects of the Invention) Compared to the conventional method, the method of the present invention not only has a shorter measurement time and is superior in terms of efficiency, but also is superior in terms of labor saving as it does not require manual labor. In addition, the quantitative intensity range of the counted values is wide, and the quantitativeness is excellent. Furthermore, information on crystal structure can also be obtained.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the measurement area setting situation on the imaging plate during positive pole figure measurement, Figure 2 is an explanatory diagram of the X-ray diffraction image measurement method, and Figure 3 is the front view of the exposure mask during positive pole figure measurement. FIG. 4 is an explanatory diagram of the measurement area setting situation on the imaging plate during stress measurement. 1... X-ray source, 2... Shutter 3... Filter 4... X-ray, 5... Collimator, 6... Sample, 7... Measurement box, 8... Exposure 9... Exposure mask, 10... Imaging plate, 11... Imaging plate support block,
12... Beam stopper, 13... Pulse motor, 14... Imaging bracket support block (
for reading), 15...mask for reading, 16...
・To attach the reading mask, use the tool, 17...Mirror, 1
8... Light beam detector for reading, 19... Control device,
20...Electronic Computer Agent Patent Attorney Masaaki Akisawa 1 Name Piece 2 Figure 1 Figure 3 Figure 7i4

Claims (1)

[Claims] A continuous X-ray diffraction imaging method characterized by setting a plurality of measurement regions on the photosensitive surface of an imaging plate, and sequentially exposing, reading, and erasing X-ray diffraction images in each region while rotating the imaging plate.