JPH071241B2 - Method for analyzing composition of object to be measured by X-ray - Google Patents

Description

The present invention relates to a method for analyzing the composition of an object to be measured by a nondestructive measuring means utilizing X-rays.

"Prior Art" Non-destructive measurement by X-ray is used in various fields.

X-rays include white X-rays and characteristic X-rays. For example, when a tomographic photograph is taken by an X-ray CT device in the medical field, white X-rays are radiated radially to the human body, and the transmitted rays are mainly
I am measuring with multiple detectors consisting of Xe ionization chamber,
It is said that it is difficult to accurately analyze the composition of the object to be measured by such a measuring method.

On the other hand, a method of measuring and analyzing the composition, concentration, etc. of an opaque object using a γ-ray source such as an isotope (Ga Ir Co) has been implemented, but this method has a high stability of the source. However, there are many restrictions such as half-life and restrictions on handling, which makes it difficult to industrialize.

"Problems to be Solved by the Invention" As an alternative to the above, a method has been proposed in which white X-rays are monochromaticized, and the object to be measured is irradiated, and the transmitted rays thereof are measured by an X-ray detector. This type of composition analysis method generally requires high analysis accuracy.

In order to secure high analysis accuracy, it is necessary to scan either the X-ray source or the object to be measured during X-ray irradiation, but in such a case, the measurement time becomes longer due to the need for scanning, The equipment for scanning also becomes large-scale.

Even if you try to perform composition analysis that does not require the above scanning,
For example, the Xe detector described above cannot perform this because its accuracy is low, and in the composition analysis of the non-measured object by the scanning method,
It becomes almost impossible to analyze the composition while manufacturing the measured object, that is, online.

In order to realize highly accurate measurement while shortening the measurement time, it is necessary to increase the amount of X-ray irradiation to the DUT. For that purpose, the X-ray beam width is 1 mm or less and the length is 5 mm.
Although the above setting is preferable, a single crystal capable of diffracting a vertically long X-ray beam into a single color and a measuring instrument therefor are difficult in terms of a space for arranging them.

For example, in the case of NaI scintillation counter, even the smallest size has 0.5 inch.

In particular, when analyzing the composition of a porous preform for optical fibers, which consists of two or more compositions, after branching the white X-rays, make this into two or more types of monochromatic X-rays and measure the respective transmission lines. Therefore, the number of single crystals and the number of X-ray detectors increase,
The difficulty of the above space factor increases.

In view of the above-mentioned problems, the present invention is to provide a composition analysis method capable of performing composition analysis of an object to be measured in a short time without scanning the object to be measured, an X-ray source, etc., and capable of online control. To do.

"Means for Solving Problems" In the composition analysis method of an object to be measured by X-ray according to the present invention, in order to achieve the intended purpose, white X-rays are irradiated over the entire area between the measurement parts of the object to be measured. And a multi-collimator for splitting a transmission line (transmission white X-ray) after passing through the object to be measured into a large number of X-ray beams, (5 × width) <(1 × length A number of longitudinal slits that are aligned in the width direction, and a large number of low-energy X rays for diffracting low-energy monochromatic X-rays in the longitudinal direction of the transmission slit branched by the multi-collimator. Single crystal for line diffraction, a large number of single crystals for strong energy X-ray diffraction for diffracting strong energy monochromatic X-rays in the width direction of a longitudinal slit in a transmission line branched by a multi-collimator, and low energy X-ray diffraction Incident through a single crystal for low An X-ray detector for measuring an energy transmission line, and an X-ray detector for measuring a strong energy transmission line incident through a single crystal for strong energy X-ray diffraction, and X An X-ray detector for measuring low-energy transmission lines and an X-ray detector for measuring high-energy transmission lines, which are arranged on the irradiation region side of white X-rays emitted from the radiation source, have a relative height difference. Face each of the X-ray sources, the object to be measured is placed at a fixed position between the X-ray source and each X-ray detector, and a multi-collimator is provided to the object to be measured and each X-ray detector. And a single crystal for low-energy X-ray diffraction, in order to make the low-energy transmission line in the transmission line branched by the multi-collimator incident on the X-ray detector therefor, X-ray detector for measuring DUT and low energy transmission line Are arranged in the width direction of the longitudinal slit and correspond to the multi-collimator and the X-ray detector for low-energy transmission line measurement, respectively. In order to make the energy transmission line incident on the X-ray detector for this purpose, each single crystal for strong energy X-ray diffraction is arranged between the object to be measured and the X-ray detector for measuring strong energy transmission line. When arranged along the width direction of the longitudinal slits and corresponding to these multi-collimators and X-ray detectors for measuring strong energy transmission lines, and when analyzing the composition of the object to be measured through the above means. The white X-ray emitted from the X-ray source is applied to the entire area between the measurement parts of the object to be measured, and the transmission line after passing through the object to be measured is branched by the multi-collimator, and (5 × width) <( 1 x length) Add a number of longitudinal beams to be added, diffract a low energy transmission line among the transmission lines branched by a multi-collimator into a single crystal for incidence, and make it incident on an X-ray detector for measuring low energy transmission lines. The high-energy transmission line in the transmission line branched by the collimator is diffracted by a single crystal for this and made incident on the X-ray detector for measuring the high-energy transmission line. The X-ray detector is used to analyze the composition of the object to be measured.

[Operation] In the case of the method of the present invention, since white X-rays are applied to the entire area between the measurement parts of the object to be measured, it is not necessary to scan the X-ray source or the object to be measured, and the transmission line thereof is (5 ×
Since the beam is branched into an X-ray beam of (width) <(1 × length), the measurement time can be shortened and the conditions for achieving highly accurate measurement can be satisfied. Since monochromatic X-rays are diffracted by a single crystal in the vertical direction (longitudinal direction of the longitudinal slit), and strong energy monochromatic X-rays in the transmission line are laterally diffracted by another single crystal (in the longitudinal direction of the longitudinal slit). The X detectors corresponding to this can also be arranged in a plurality of stages such as upper and lower two stages, and the space factor when arranging the X-ray detectors is relaxed.

In the above, the reason why the transmission line after passing through the object to be measured is branched into the X-ray beam of (5 × width) <(1 × length) is as follows.

When measuring and analyzing a transmission line of an object to be measured through an X-ray detector, the smaller the X-ray beam width and the larger the number of X-ray beams, the higher the resolution of the object to be measured.
When the line beam width becomes smaller, the amount of light received by the X-ray detector decreases, and the measurement accuracy of the X-ray detector decreases.

In the present invention, the shortage of the amount of received light that occurs when the X-ray beam width is reduced and the number of X-ray beams is increased is compensated by increasing the length of the X-ray beam.

The X-ray beam shape for satisfying the resolution and the amount of received light is expressed by the width: length relationship,
It is necessary to satisfy (5 × width) <(1 × length).

[Examples] Examples of the method of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is an X-ray source, 2 and 3 are multi-collimators, 4 and 5 are single crystals, and 6 and 7 are X-ray detectors.

One multi-collimator 2 has a large number of longitudinal slits 2a arranged in the width direction, and the other multi-collimator 3 also has a large number of longitudinal slits 3a arranged in the width direction.

8 is an opaque measured object.

When carrying out the method of the present invention in FIGS. 1 and 2, the object to be measured 7 is placed between the multi-collimators 2 and 3, and the white X-rays emitted from the X-ray source 1 are focused by the multi-collimator 2. The entire area of the measured object 8 in the width direction is irradiated.

The white X-rays pass through the object 7 to be measured, and the transmission lines are split into a number of vertically elongated beams by the multi-collimator 3.

Then, among the above-mentioned transmitted rays, the low-energy monochromatic X-rays are diffracted by the single crystal 4 in the vertical direction, for example, upward as shown in FIG. 1 or downward (not shown), and the X-ray detector arranged at a position corresponding thereto. 6, its energy intensity is measured.

On the other hand, the high-energy monochromatic X-rays in the transmission line are transmitted through the single crystal 4 and then laterally diffracted by another single crystal 5, and by the X-ray detector 7 arranged at a position corresponding thereto. Its energy intensity is measured.

In this way, the results measured by the X-ray detectors 6 and 7 are input to an electronic calculator (not shown), and the calculator analyzes the composition of the measured object 8.

As the X-ray detectors 6 and 7 described above, a scintillation counter in which NaI is laminated is used.

In the method of the present invention, a porous preform for an optical fiber made of SiO 2 —GeO 2 having a diameter of 60 mm was used as an object to be measured, and the composition thereof was analyzed under the following conditions.

[X-ray source 1] Max160kev, target = W Radiation angle = 30 degrees [Multi-collimator 2, 3] Spectra for spectroscopy with width x length = 0.5 x 10, spectrum number 30 [single crystal 4] Si, width X Length x Thickness = 1 x 20 x 1, 30 pieces [Single crystal 5] Si, width x length x thickness = 40 x 15 x 1.5, 30 pieces [X-ray detector 6] NaI, caliber 0.5 inch, 30 pieces [X-ray detector 7] NaI, 0.5 inch, 30 pieces X-ray detectors 6 and 7 used were integrated with a Photomul preamplifier.

When the method illustrated in FIGS. 1 and 2 is performed under the above conditions to analyze the composition of the porous preform for optical fibers, the single crystal 5 diffracts 80 kev of energy and the single crystal 6 of 200 kev. The energy was diffracted and these were measured with the X-ray detector.

The measurement time at this time was several minutes.

When analyzing the above-mentioned optical fiber porous base material having a compositional distribution that is axially symmetric, the analysis accuracy is improved by also measuring the base material composition between the X-rays dispersed by the collimator.

In such a case, each device after the X-ray source may be rotated and moved in the horizontal direction by a small amount around the X-ray source.

When rotating each device, the accuracy of NaI is not required because the diameter of NaI is 0.5 inch.

[Effects of the Invention] As described above, according to the method of the present invention, since it is not necessary to scan the X-ray source or the object to be measured, the object to be measured can be analyzed online, and the transmission line is a multi-collimator. Since the beam is branched into a predetermined X-ray beam, the measurement time can be shortened and highly accurate measurement can be realized.
Moreover, since the transmission line is diffracted in the lengthwise direction and the widthwise direction of the vertically elongated slit made of a single crystal, the X detectors corresponding thereto are also arranged in a plurality of stages, and the space factor when arranging the X-ray detectors is also increased. Can be relaxed.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an embodiment of the method of the present invention, and FIG.
The figure is a plan view of the above. 1 ... X-ray source 3 ... Multi-collimator 3a ... Vertical slits 4, 5 ... Single crystal 6, 7 ... X-ray detector 8 ... Object to be measured

Claims (4)

[Claims] 1. A white X over the entire area between the measurement parts of the object to be measured.
An X-ray source for irradiating X-rays, and a multi-collimator for branching a transmission line (transmission white X-rays) after passing through an object to be measured into a plurality of X-ray beams (5 × width) < A large number of longitudinal slits satisfying (1 x length) are arranged in the width direction, and a large number for diffracting low energy monochromatic X-rays in the longitudinal direction of the longitudinal slit among the transmission lines branched by the multi-collimator. Low-energy X-ray diffraction single crystal, and a large number of high-energy X-ray diffraction single crystals for diffracting high-energy monochromatic X-rays in the transmission line branched by the multi-collimator in the width direction of the longitudinal slit, X-ray detector for measuring low-energy transmission line incident through a single crystal for energy X-ray diffraction, and X for measuring high-energy transmission line incident through a single crystal for strong energy X-ray diffraction Equipped with line detector And an X-ray detector for measuring low-energy transmission lines and an X-ray detector for measuring high-energy transmission lines, which are arranged on the irradiation region side of white X-rays emitted from the X-ray source, The X-ray source and the X-ray source facing each other with a certain height difference, the object to be measured is placed at a fixed position between the X-ray source and each X-ray detector, and the multi-collimator is connected to the object to be measured. It is arranged between each X-ray detector, and in order to make the low-energy transmission line among the transmission lines branched by the multi-collimator incident on the X-ray detector for this, a low-energy X-ray diffraction Each single crystal is arranged between the DUT and the X-ray detector for measuring low-energy transmission lines and arranged along the width direction of the longitudinal slit, and these multi-collimators and X-ray detection for measuring low-energy transmission lines are also provided. That correspond to each In order to make the strong energy transmission line in the transmission line branched by the rutile collimator enter the X-ray detector for this purpose, each single crystal for strong energy X-ray diffraction is for measuring the object to be measured and the strong energy transmission line. It is arranged between the X-ray detector and arranged along the width direction of the longitudinal slit, and corresponds to the multi-collimator and the X-ray detector for measuring the strong energy transmission line, and the above means. When analyzing the composition of the object to be measured through, irradiate the white X-rays emitted from the X-ray source to the entire area between the measurement parts of the object to be measured, and the transmission line after passing through the object to be measured by the multi-collimator. Divide into a number of longitudinal beams satisfying (5 x width) <(1 x length), diffract the low energy transmission line in the transmission line branched by the multi-collimator with a single crystal for this Low energy transmission Incident on the measuring X-ray detector, diffracting the strong energy transmission line in the transmission line branched by the multi-collimator by the single crystal for incidence on the X-ray detector for measuring strong energy transmission line, A method for analyzing the composition of an object to be measured by X-rays, characterized in that the composition of the object to be measured is analyzed by measuring the low energy transmission line and the high energy transmission line by respective X-ray detectors. 2. The method for analyzing the composition of an object to be measured by X-ray according to claim 1, wherein the object to be measured comprises a binary component optical fiber porous preform having a substantially equal composition distribution in the vertical direction. 3. The method for analyzing the composition of an object to be measured by X-ray according to claim 1, wherein two types of monochromatic X-rays are measured by separate multi-layer X-ray detectors. 4. A multi-collimator, which rotates a small amount of each single crystal around the X-ray source, by irradiating the object to be measured with white X-rays radially emitted from the X-ray source. A method for analyzing the composition of an object to be measured by X-ray according to the item.