JP4310374B2 - Method for measuring annual ring width or density of wood or wooden cultural assets - Google Patents

Description

The present invention relates to a method for measuring the annual ring width or density of timber or wooden cultural properties, and more specifically, an annual ring chronology method that is a method for determining the age of logging or the death of wood, and a method for analyzing past climatic conditions, environmental conditions, etc. The present invention relates to a method for nondestructively measuring annual ring width and density as an aid.

1. There is an annual ring age method as a method of examining the cutting age and the dead age of timber forming the woody ancient cultural property. As a means of analyzing past climatic and environmental conditions, there is a method of measuring annual ring width and density.

The annual ring dating method is as follows. Since the annual ring width of trees varies depending on the weather and environmental conditions of each year, trees grown in the same age in a certain region where the growth environment is close have a unique growth pattern for each tree species. By measuring the characteristics of this growth pattern, which varies from one era to another, and finding the timber of older rings that match the current pattern of fluctuations in the width of the timber with a certain age, connecting the data in order A calendar standard pattern that represents the characteristics of the annual rings is created in advance. The annual ring pattern of the wood sample or wooden cultural property is matched with the annual pattern of the wood sample or wooden cultural property whose age is to be measured, and the calendar year standard pattern.

In addition, the density of timber varies depending on the annual climatic and environmental conditions. Therefore, in order to restore past climatic and environmental conditions, the density of each age is measured. Specifically, the density is obtained from the density of the X-ray image or the like of the investigation object.

2. Thus, it is important to measure the ring width in the annual ring dating method, and to measure the density of an image or the like representing the density in the density measuring method, and there are the following measuring methods.

(1) While observing the sample surface, measure the light and shade representing the annual ring width and density. Alternatively, an image of the sample surface is acquired and measured.

However, in this method, measurement may not be possible because the sample surface is colored or lacquered, or a gold foil is applied, or the sample surface is deteriorated or uneven.

(2) Take a rod-shaped core sample from the sample, or cut the sample and measure the annual ring width and lightness and shade.

  However, this method is not suitable for research on cultural assets based on non-destructive principles.

(3) The density of the image representing the annual ring width or density is measured from the X-ray transmission image.

However, the sample that can be measured by this method is a plate material or a thin piece, and it is necessary that the direction of the annual ring is a complete grid or a complete lip, and the objects that can be measured are limited.

(4) Using an X-ray computed tomography (hereinafter abbreviated as X-ray CT), the shade of the image representing the annual ring width and density is measured.

However, the conventional mini-focus class X-ray CT has a problem that the spatial resolution is low and a narrow annual ring layer (about 0.5 mm or less) important in the annual ring dating method cannot be resolved.

(5) As a technique for solving the problems of the above methods (1) to (4), there is a method of measuring the density of an image representing an annual ring width and density using a microfocus X-ray CT apparatus.

Here, the microfocus X-ray CT apparatus is an electron beam which is emitted from a microfocus X-ray tube having a micro focus to a sample placed on a rotary elevating stage, and X-rays generated there are received by an image intensifier as a light receiving unit. The non-destructive image of the internal structure of the sample is taken.

Since the microfocus X-ray CT is equipped with an X-ray tube having a focal point of several microns, the resolution is high and even a narrow annual ring layer can be resolved.

However, the microfocus X-ray CT apparatus is mainly used for inspection of relatively small industrial parts and the like, and it is not considered to handle objects of various sizes and shapes like a cultural property sample. In addition, the imaging field of view (FOV) is narrow and it is difficult to cover the number of annual rings (usually 100 layers or more) necessary for annual ring dating.

3. As described above, although a method and an apparatus for photographing an annual ring width or density of wood or a wooden cultural property with a wide range and high resolution without being destructed have been anxious, they have not been realized before the present invention.

4. Further, there is an invention described in Japanese Patent Application Laid-Open No. 11-232427 as a patent document relating to the annual ring number measuring method. Here, the invention described in the publication discloses that the surface of the mouth is picked up by an image pickup means, and the number of annual rings is measured based on the luminance change of the image.
JP-A-11-232427

The present invention relates to an improvement in the measurement method using the above-described microfocus X-ray CT apparatus, and more specifically, even if the imaging field of view (FOV) is narrow, the number of annual rings necessary for annual ring dating of wood or wooden cultural properties (usually 100). An object of the present invention is to provide a measurement method capable of acquiring a wide range of images necessary for a measurement method based on an image and density over a layer or more) with high resolution.

1. An annual ring width or density measuring device for wood or wooden cultural property constituting the present invention is used by being attached to a rotary lifting stage in a microfocus X-ray CT apparatus. Ingredients
Physically, it consists of the following members.

The X axis described below refers to any axis in the X-ray beam. The Y axis is an axis other than the X axis in the X-ray bundle. The Z axis is a lifting axis that is orthogonal to the XY plane.

Moving means for moving the sample in the X-axis direction.

  Moving means for moving the sample in the Y-axis direction.

  A moving means for moving the sample in the Z-axis direction.

  Inclination means for inclining the tomographic plane of the sample.

  Fixing means for fixing the sample.

And the annual ring width or density measuring method of the timber or the wooden cultural property according to the present invention is the measurement described above.
By using a microfocus X-ray CT apparatus, center set full scan (Claims 1 to 4), offset full scan (Claims 5 to 8), or center set half scan (Claims 9 to 12) It is something to shoot.

At that time, in order to photograph the annual rings over a wide area, a method of integrating a plurality of images photographed by center set full scan, offset full scan, or center set half scan was adopted.

  2. The following describes how the present invention configured as described above solves the problems.

In order to obtain a clear tomographic image for the annual ring dating method or the density measurement method, it is necessary to take images by a method suitable for the object. FIG. 1 shows a basic configuration diagram of an X-ray CT including a microfocus X-ray CT.

Of particular importance is the setting of geometric imaging conditions (geometry) such as the distance between source objects (SOD) and the distance between source images (SID). That is, in order to obtain a tomographic image, it is necessary to convert the coordinates of the three-dimensional model placed in space into screen coordinates. A process for performing this conversion is a geometry process. Specifically, first, a modeling coordinate system, which is coordinate data of polygons constituting an object, is converted into a viewpoint coordinate system with the viewpoint as the origin. Then, the projection conversion is performed by calculating the effects such as perspective and the part hidden behind the front object. Finally, convert to a screen coordinate system that matches the displayed screen. Thus, the distance from the viewpoint is important for geometry processing. In the case of the microfocus X-ray CT apparatus, the distance (SOD) from the X-ray tube as the X-ray source 1 to the rotational axis center position of the rotary elevating stage 4 and the distance (SID) from the X-ray tube to the image intensifier 3 are set. It becomes important.

If the annual ring width or density measuring device described in the present invention is used, fine adjustment of the imaging range and continuous shooting can be performed with the SOD and SID fixed, and various imaging methods shown below are applied to the SOD and SI.
This is possible while D is fixed.

That is, if the annual ring width or density measuring device according to the present invention is fixed on the rotary lift stage, the sample is moved in the X-axis direction, Y-axis direction, and Z-axis direction while the rotary shaft center position of the rotary lift stage is fixed. Alternatively, the sample can be tilted or the sample can be rotated. Ie S
This makes it possible to perform various shootings while fixing the OD and SID.

3. The photographing method and geometry in the present invention will be described below.
(A) When obtaining a tomographic image of the XY plane A-1) Center set Full scan The imaging field 5 is set at the center of the X-ray bundle 7, and the sample 2 is rotated once about the imaging field center 6 as an axis. This is the most basic imaging method for X-ray CT tomography including microfocus X-ray CT. In order to increase the magnification by shortening the SID in order to rotate the sample 2 once,
The sample 2 may interfere with the X-ray source 1 in some cases. The imaging visual field center 6 and the rotational axis center position of the rotary elevating stage 4 coincide with each other. The geometry is shown in FIG.
A-2) The center of the offset full-scan imaging field of view 5 is set at the end of the X-ray bundle 7, and the sample 2 is rotated once about the imaging field center 6 as an axis. Since the SOD can be shortened compared with the center set full scan to obtain the same imaging field of view 5, the enlargement magnification is increased, and a high-resolution tomographic image can be obtained. On the other hand, since the SID is shortened, the sample 2 is likely to interfere with the X-ray source 1, so that it is not very suitable for photographing a large sample having a large turning radius or a sample end. The imaging visual field center 6 and the rotational axis center position of the rotary elevating stage 4 coincide with each other. The geometry is shown in FIG.
A-3) Center set The center of the half-scan imaging field of view 5 is set at the center of the X-ray bundle 7, and the sample 2 is rotated halfway around the center of the imaging field 6 as an axis. Since the information density is halved, the image quality is inferior to that of the center set full scan, but the sample 2 does not interfere with the X-ray source 1. Ideal for photographing large samples and sample edges. The imaging visual field center 6 and the rotational axis center position of the rotary elevating stage 4 coincide with each other. The geometry is shown in FIG.

Then, by integrating a plurality of images taken by each of the above photographing methods, even a microfocus X-ray CT apparatus with a narrow imaging field of view, a measurement method based on tomographic images and density over the number of annual rings necessary for annual ring dating Therefore, it is possible to acquire a tomographic image having a width necessary for the above.

For example, a tomographic image is taken by an offset full scan. Next, the annual ring width or density measuring apparatus according to the present invention is shifted by about 2 cm in the X-axis direction and imaged again by the offset full scan.
Such shooting is performed a plurality of times while keeping the same distance. By connecting the tomographic images obtained in each imaging, it is possible to obtain a tomographic image over the number of annual rings necessary for annual ring dating of various samples and a tomographic image having a width necessary for a measurement method based on density. In addition, since the shifting distance is 2 cm if the distance is the same distance, the images can be easily integrated.

Similarly, taking a picture by shifting the same distance in the Y-axis direction or the Z-axis direction, or combining any or all of the shifting methods in the X-axis direction, Y-axis direction, and Z-axis direction, the annual ring dating of various samples. Therefore, it is possible to obtain a tomographic image over the number of annual rings necessary for the measurement and a tomographic image having a width necessary for a measurement method based on density.

Furthermore, by tilting the sample at the same angle or rotating it by the same angle, the width required for the measurement method based on the tomographic images and density over the number of annual rings required for the annual ring dating of various samples as in the above method. It is possible to acquire a tomographic image.

  Table 1 shows a tomographic image of the annual rings over a wide range taken in this way.

As described above, according to the present invention, the measurement method using the microfocus X-ray CT apparatus can be improved. In other words, it is possible to perform fine adjustment of the imaging range or continuous imaging while fixing the rotation axis center position of the rotary elevating stage, and to integrate tomographic images even if the imaging field of view is narrow, which is necessary for annual ring dating of various samples Thus, it is possible to acquire a tomographic image over a large number of annual rings and a tomographic image having a width necessary for a measurement method based on density.

In other words, even when the imaging field of view (FOV) is narrow, a measuring apparatus capable of acquiring an image over the number of annual rings (usually 100 layers or more) necessary for annual ring dating, and a wide range of images necessary for a density-based measuring method, A measurement method can be provided. As a result, the annual ring age can be measured by measuring the annual ring width or density of the timber or wooden cultural property.

  Hereinafter, one preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 5 is a perspective view schematically showing an annual ring width or density measuring apparatus according to the present invention.

The annual ring width or density measuring apparatus according to the present invention is used by being attached to a rotary elevating stage in a microfocus X-ray CT apparatus. The main components are a moving means 10 movable in the X-axis direction, a moving means 20 movable in the Y-axis direction, and a moving means 3 movable in the Z-axis direction.
0, a fixing means 40 for fixing the sample, a rotating means for rotating the sample around the axis in the Z-axis direction, and a tilting means (not shown) for tilting the sample with the sample fixed. is there.

The moving means 10 that can move in the X-axis direction is formed by a rail member 11 and a sliding member 12 that slides along the rail member 11.

The moving means 20 movable in the Y-axis direction is formed by a rail member 21 and a sliding member 22 that slides along the rail member 21.

The moving means 30 that can move in the Z-axis direction is formed by a cylindrical guide member 31 and a sliding member 32 that slides inside the guide member 31.

The fixing means 40 includes a clamping member 41 that can clamp the sample and can change the clamping width. The fixing means 40 is provided so as to be rotatable with respect to the sliding member 32 about a rotating shaft 50 as a rotating means around an axis in the Z-axis direction.

Of course, these moving means 10, 20, 30 and fixing means 40, and rotating means are schematically shown, and in actuality, it is necessary to provide a precise movement manually or electrically using a feed screw or a rack opinion and a precise rotation mechanism. There is.

  A gonio stage can be used as the tilting means.

When taking a tomographic image over the number of annual rings necessary for annual ring dating and a tomographic image having a width necessary for a density-based measuring method using the measuring device according to the present invention, the following method is used. .
1-1) When a desired annual ring measurement and density measurement can be performed in the XY plane, an XY plane tomographic image is acquired. If the sample is small or if the sample does not interfere with the X-ray source even with a large sample, the image is taken with an offset full scan with high resolution.
1-2) When the turning radius becomes large and interferes with the X-ray source, such as when photographing a large sample or the end of the sample, the image is taken by center set half scan with no risk of interference.

The basic block diagram of X-ray CT. The block diagram which shows the geometry in a center set full scan. The block diagram which shows the geometry in an offset full scan. The block diagram which shows the geometry in a center set half scan. The perspective view which shows typically the annual ring width or density measuring apparatus which concerns on this invention.

Explanation of symbols

1 .. X-ray source 2 .. Sample 3 .. Image intensifier 4 .. Rotating lift stage 5 .. Imaging field 6 .. Imaging field center 7 .. X-ray bundle 10, 20, 30.・ Fixing means

Claims (12)

  An apparatus for measuring an annual ring width or density of a wood or wooden cultural property, which has a moving means for moving the sample in the X-axis direction and a fixing means for fixing the sample, and is attached to a rotary elevating stage in a microfocus X-ray CT apparatus. Each time the sample is attached to the fixing means, and the sample is moved by the moving means, the microfocus X-ray CT apparatus is used for center set full scan, and the taken images are integrated for the purpose of annual ring dating. A method for measuring the annual ring width or density of wood or wooden cultural property, which makes it possible to acquire tomographic images of a wide range of high-resolution wood or wooden cultural property. The method for measuring an annual ring width or density of a wood or wooden cultural property according to claim 1, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is also movable in the Y-axis direction. The method for measuring an annual ring width or density of a wood or wooden cultural property according to claim 1 or 2, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is also movable in the Z-axis direction. The annual ring width or density of the wood or wooden cultural property according to any one of claims 1 to 3, wherein an inclination means for inclining the fault plane of the sample is added to the annual ring width or density measuring device of the wood or wooden cultural property. Measuring method.   An apparatus for measuring an annual ring width or density of a wood or wooden cultural property, which has a moving means for moving the sample in the X-axis direction and a fixing means for fixing the sample, and is attached to a rotary elevating stage in a microfocus X-ray CT apparatus. Each time a sample is attached to the fixing means and the sample is moved by the moving means, the microfocus X-ray CT apparatus is used to take an image with an offset full scan, and the taken images are integrated for the purpose of annual ring dating. A method for measuring the annual ring width or density of wood or wooden cultural property, which makes it possible to obtain a wide range of high-resolution tomographic images of wood or wooden cultural property. The method for measuring the annual ring width or density of a wood or wooden cultural property according to claim 5, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is movable in the Y-axis direction. The method for measuring an annual ring width or density of a wood or wooden cultural property according to claim 5 or 6, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is also movable in the Z-axis direction. The annual ring width or density of the wood or wooden cultural property according to any one of claims 5 to 7, wherein an inclination means for inclining the fault plane of the sample is added to the annual ring width or density measuring device of the wood or wooden cultural property. Measuring method.   An apparatus for measuring an annual ring width or density of a wood or wooden cultural property, which has a moving means for moving the sample in the X-axis direction and a fixing means for fixing the sample, and is attached to a rotary elevating stage in a microfocus X-ray CT apparatus. Each time a sample is attached to the fixing means, and the sample is moved by the moving means, the micro-focus X-ray CT apparatus is used for center set half scan, and the taken images are integrated for the purpose of annual ring dating. A method for measuring the annual ring width or density of wood or wooden cultural property, which makes it possible to acquire tomographic images of a wide range of high-resolution wood or wooden cultural property. The method for measuring the annual ring width or density of a wood or wooden cultural property according to claim 9, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is also movable in the Y-axis direction. The method for measuring the annual ring width or density of a wood or wooden cultural property according to claim 9 or 10, wherein the moving means of the annual ring width or density measuring device of the wood or wooden cultural property is also movable in the Z-axis direction. The annual ring width or density of the wood or wooden cultural property according to any one of claims 9 to 11, wherein an inclination means for inclining the fault plane of the sample is added to the annual ring width or density measuring device of the wood or wooden cultural property. Measuring method.