1. Field of the Invention
The present invention relates to an X-ray analyzer that performs measurement by irradiating a sample with X-rays emitted by an X-ray source, and detecting X-rays released by the sample in response to the X-ray irradiation using an X-ray detector. The present invention also relates to an optical axis adjustment method used with the X-ray analyzer.
2. Description of the Related Art
The X-ray source of the X-ray analyzer is an X-ray focus constituted by a region in which electrons emitted by a cathode such as a filament collide with an anticathode. The X-ray detector is a zero-dimensional X-ray detector not possessing a function of detecting X-ray intensity according to position (i.e., X-ray intensity positional resolution), a one-dimensional X-ray detector capable of positional resolution within a linear region, a two-dimensional X-ray detector capable of positional resolution in a planar region, or the like.
A zero-dimensional X-ray detector is, for example, an X-ray detector using a proportional counter (PC), an X-ray detector using a scintillation counter (SC), or the like. A one-dimensional X-ray detector is, for example, an X-ray detector using a position-sensitive proportional counter (PSPC) or one-dimensional charge-coupled device (CCD) sensor, or an X-ray detector using a plurality of one-dimensionally arrayed photon-counting pixels, or the like. A two-dimensional X-ray detector is, for example, an X-ray detector using a two-dimensional charge-coupled device (CCD) sensor, an X-ray detector using a plurality of two-dimensionally arrayed photon-counting pixels, or the like.
When performing measurement using the X-ray analyzer described above, the centerline of the X-rays reaching the X-ray detector from the X-ray source (i.e., the optical axis of the X-rays) must be set at fixed suitable conditions. The process of setting the optical axis of the X-rays to fixed conditions is generally referred to as adjusting the optical axis.
The optical axis is adjusted by, for example, sequentially performing adjustments such as 2θ-adjustment and θ-adjustment. These various types of adjustment will be described hereafter using a fixed-sample X-ray analyzer as an example.
First, the fixed-sample X-ray analyzer will be described. In
The X-ray focus F and the incident-side slit 54 are supported by an incident-side arm 55. The incident-side arm 55 rotates around a sample axis X0 extending through the surface of the sample S in the drawing surface-penetrating direction, as shown by arrow θs. This rotational movement may be referred to as θs-rotation, and an operating system for effecting such θs-rotation may be referred to as a θs-axis. θs-rotation is effected using an actuating system comprising a motor of controllable rotational speed, such as a pulse motor, as a power source.
A receiving-side slit 56 is provided between the sample stage 52 and the zero-dimensional X-ray detector 53. The slit groove of the receiving-side slit 56 extends in the drawing surface-penetrating direction in
When using the X-ray analyzer 51 to perform X-ray diffractional measurement upon, for example, a powder sample S, the X-ray focus F and the incident-side slit 54 are θs rotated by the incident-side arm 55 continuously or stepwise at a predetermined angular velocity, while, simultaneously, the receiving-side slit 56 and the X-ray detector 53 are θd rotated by the receiving-side arm 57 continuously or stepwise at the same angular velocity in the opposite direction, as shown in
The angle formed by a centerline R1 of X-rays incident upon the sample S from the θs-rotating X-ray focus F with respect to the surface of the sample S is represented by “θ”. In other words, the angle of incidence of the X-rays incident upon the sample S is represented by “θ”. The centerline of the X-rays is labeled R1, but, in the following description, the X-rays incident upon the sample S may be referred to as incident X-rays R1. The θs-rotation of the X-ray focus F may be referred to as “θ rotation.”
When the X-rays incident upon the sample S meets certain diffraction conditions with respect to the crystal lattice plane of the sample S, the X-rays are diffracted by the sample S (i.e., diffracted X-rays is given off by the sample S). The angle formed by the centerline R2 of the diffracted X-rays with respect to the surface of the sample S is always equal to the X-ray angle of incidence θ. Accordingly, the angle formed by the diffracted X-rays with respect to the incident X-rays R1 is twice the X-ray angle of incidence θ. The angle formed by the diffracted X-rays R2 with respect to the incident X-rays R1 is represented by “2θ”.
Meanwhile, the θd-rotation of the X-ray detector 53 is performed at the same angular velocity as the θs-rotation of the X-ray source F, with the result that diffracted X-rays R2 emitted from the sample S at angle θ are received by the zero-dimensional X-ray detector 53, which forms angle θ with respect to the surface of the sample S. The X-ray detector 53 forms angle θ with respect to the surface of the sample S, but always forms an angle equal to twice θ with respect to the incident X-rays R1. For this reason, the θd-rotation of the X-ray detector 53 may be referred to as “28-rotation.”
Next, 2θ-adjustment will be described. 2θ-adjustment refers to adjustment performed so as to correctly align the angle 2θ=0° detected by the X-ray detector 53 and the centerline of the X-rays from the X-ray source F reaching the X-ray detector 53. When performing such adjustment, the incident-side arm 55 is first set at an angular position of θs=0°, and the receiving-side arm 57 at an angular position of θd=0°, as shown in
Next, the sample S is removed from the sample stage 52 to allow X-rays to pass freely through the position of the sample, a incident-side slit 54 of roughly 0.1 mm is set, a receiving-side slit 56 of roughly 0.15 mm is set, the X-ray detector 53 and the receiving-side slit 56 are positioned at 2θ=0°, the X-ray detector 53 and the receiving-side slit 56 are intermittently θd rotated at, for example, steps of 0.002°, and diffracted X-rays are detected by the X-ray detector 53 at each step position. A diffracted X-ray peak waveform such as that shown in
If the amount of deviation of the 2θ-angular position of the center P0 of the full width at half maximum intensity (i.e., FWHM) D0 of the peak waveform with respect to the angular position 2θ=0° of the X-ray detector 53 is within a predetermined tolerance, such as ( 2/1,000)°, 2θ-adjustment is considered to have been accurately performed. On the other hand, if the amount of deviation of the 2θ-angular position of the center P0 of the full width at half maximum intensity D0 with respect to the 2θ=0° of the X-ray detector 53 is outside of tolerance, the position, for example, of the receiving-side arm 57 in
2θ-adjustment can also be performed by correcting data obtained as the result of actual X-ray diffraction measurement according to the amount of deviation calculated, rather than by moving the position of the X-ray focus F or the X-ray detector 53.
Next, θ-adjustment will be described. In
Next, an optical axis adjustment jig 58 such as that shown in
Techniques for performing conventional X-rays adjustment as described above are disclosed, for example, in patent document 1 (Japanese Patent Laid-Open Publication H01-156644), patent document 2 (Japanese Patent Laid-Open Publication H01-156643), patent document 3 (Japanese Utility Model Laid-Open Publication H01-158952), patent document 4 (Japanese Patent Laid-Open Publication H03-291554), and patent document 5 (Japanese Patent Laid-Open Publication 2007-017216).
In the X-ray analyzer described above, a zero-dimensional X-ray detector was used as the X-ray detector. In recent years, X-ray analyzer using one-dimensional X-ray detectors instead of zero-dimensional X-ray detectors are known. Conventionally, when performing optical axis adjustment with an X-ray analyzer using a one-dimensional X-ray detector, the one-dimensional X-ray detector is replaced with a zero-dimensional X-ray detector to perform optical axis adjustment, after which the zero-dimensional X-ray detector is replaced with the one-dimensional X-ray detector to perform X-ray diffraction measurement. Another method known in the prior art is to abstract the positional resolution from the one-dimensional X-ray detector and use the same as a zero-dimensional X-ray detector in order to perform the optical axis adjustment described above.
A conventional apparatus in which a one-dimensional X-ray detector is replaced with a zero-dimensional X-ray detector to perform optical axis adjustment requires that the detectors be changed out, and that the zero-dimensional X-ray detector be oscillated in order to obtain an X-ray peak profile, leading to the problem that the optical axis cannot be quickly adjusted.
In addition, a conventional apparatus in which the positional resolution of a one-dimensional X-ray detector is abstracted and the detector is used as a zero-dimensional X-ray detector requires that the one-dimensional X-ray detector be switched to function as a zero-dimensional X-ray detector when adjusting the optical axis, for which software is required. In addition, the one-dimensional X-ray detector functioning as a zero-dimensional X-ray detector must be oscillated in order to obtain an X-ray peak profile, creating the problem that the optical axis cannot be quickly adjusted.
The present invention was conceived in view of the above-mentioned problems inherent in conventional apparatus, and has an object of enabling optical axis adjustment to be performed quickly and simply in an X-ray analyzer employing an X-ray detector having X-ray intensity positional resolution within a linear region.
An X-ray analyzer optical axis adjustment method according to the present invention is:
(A) an optical axis adjustment method for an X-ray analyzer comprising an incident-side arm that rotates around a sample axis passing through a sample position constituting a position at which a sample is placed, a receiving-side arm that rotates around the sample axis and extends toward a side opposite the incident-side arm, an X-ray source provided on the incident-side arm, an incident-side slit provided on the incident-side arm between the sample position and the X-ray source, and an X-ray detector that is provided on the receiving-side arm and possesses X-ray intensity positional resolution, which is a function of detecting X-ray intensity within predetermined regions on a straight line, wherein:
(B) the angle of incidence of X-rays incident upon the sample from the X-ray source is an angle of incidence θ;
(C) the angle formed by the centerline of X-rays diffracted by the sample and the centerline of X-rays incident upon the sample is an angle of diffraction 2θ;
(D) the method comprises a 2θ-adjustment step in which a 0° position of the rotation of the receiving-side arm and a 0° position of the angle of diffraction 2θ are aligned, a Zs-axis adjustment step in which the position of the incident-side slit along a direction orthogonal to the centerline of the X-rays incident upon the sample from the X-ray source is adjusted, and a θ-adjustment step in which the centerline of the X-rays incident upon the sample from the X-ray source and the surface of the sample are adjusted so as to be parallel; and
(E) in the 2θ-adjustment step, the Zs-axis adjustment step, and the θ-adjustment step, the capability for X-ray intensity position resolution upon a straight line possessed by the X-ray detector is used to perform 2θ-adjustment, Zs-axis adjustment, and θ-adjustment, respectively.
As schematically shown in
As shown schematically in
In the X-ray analyzer optical axis adjustment method according to the present invention, it is preferable to find X-ray intensities for a plurality of different 2θ angle values in an X-ray receiving region of the X-ray detector are found simultaneously using the X-ray detector, and to find the amount of angle deviation in 2θ-adjustment, the amount of incident-side slit positional deviation in Zs-axis adjustment, and the amount of deviation in parallelism in θ-adjustment on the basis of the measured X-ray intensities. Since the X-ray detector in the above configuration can detect each X-ray intensity at different 2θ-angles simultaneously, the optical axis adjustment may be performed extremely quickly.
During the 2θ-adjustment step of the X-ray analyzer optical axis adjustment method according to the present invention,
(A) a center slit may be disposed at the sample position, the incident-side arm may be placed at a position at which the angle of incidence θ is 0°, the receiving-side arm may be placed at a position at which the angle of diffraction 2θ is 0°, the incident-side slit may be set to an open state, and X-rays emitted by the X-ray source may be caused to pass through the incident-side slit and the center slit and be incident upon the X-ray detector;
(B) the amount of deviation between the position at which the X-rays are incident in the X-ray detector and the position at which the angle of diffraction 2θ is 0° may be obtained; and
(C) the optical axis of the X-rays may be adjusted either by moving the position of the receiving-side arm by the amount of deviation, or by correcting data obtained for the angle of diffraction 2θ by the X-ray detector by the amount of deviation.
In the X-ray analyzer optical axis adjustment method according to the present invention,
(A) the Zs-axis adjustment step may be performed after the optical axis of the X-rays is corrected by the amount of deviation in the 2θ-adjustment step; and
(B) in the Zs-axis adjustment step,
In the θ-adjustment step of the X-ray analyzer optical axis adjustment method according to the present invention:
(A) an optical axis adjustment jig or a sample may be disposed on the sample position;
(B) the incident-side arm may be placed at a position at which the angle of incidence θ is 0°;
(C) the receiving-side arm may be placed at a position at which the angle of diffraction 2θ is 0°;
(D) X-rays may be made to become incident upon the surface of the sample at a plurality of different angles of incidence θ, and X-ray intensity may be measured at each of the angles using the X-ray detector, and the value for the angle of incidence θ at which the X-rays are parallel with the surface of the sample may be calculated on the basis of the values for the angle of incidence θ and the results detected by the X-ray detector; and
(E) the position of the incident-side arm may be corrected according to the calculated angle of incidence θ.
Next, an X-ray analyzer according to the present invention is:
(A) an X-ray analyzer comprising an incident-side arm that rotates around a sample axis passing through a sample position constituting a position at which a sample is placed, a receiving-side arm that rotates around the sample axis and extends toward a side opposite the incident-side arm, an X-ray source provided on the incident-side arm, an incident-side slit provided on the incident-side arm between the sample position and the X-ray source, and an X-ray detector that is provided on the receiving-side arm and possesses X-ray intensity positional resolution, which is a function of detecting X-ray intensity in each predetermined region on a straight line, wherein:
(B) the angle of incidence of X-rays incident upon the sample from the X-ray source is angle of incidence θ;
(C) the angle formed by the centerline of X-rays diffracted by the sample and the centerline of X-rays incident upon the sample is angle of diffraction 2θ;
(D) the analyzer comprises 2θ-adjustment means for performing adjustment so that a 0° position of the rotation of the receiving-side arm and a 0° position of the angle of diffraction 2θ are aligned, Zs-axis adjustment means for adjusting the position of the incident-side slit along a direction orthogonal to the centerline of X-rays incident upon the sample from the X-ray source, and θ-adjustment means for adjusting the centerline of X-rays incident upon the sample from the X-ray source and the surface of the sample so as to be parallel; and
(E) the 2θ-adjustment means, the Zs-axis adjustment means, and the θ-adjustment means perform 2θ-adjustment, Zs-axis adjustment, and θ-adjustment, respectively, using the capability for positional resolution on a straight line possessed by the X-ray detector.
In the arrangement described above, the “2θ-adjustment means” is constituted, for example, by the combination of a control device, the incident-side arm, the receiving-side arm, the incident-side slit, an opening/closing drive device, the center slit, the X-ray source, and the X-ray detector. The “Zs-axis adjustment means” is constituted, for example, by the combination of the control device, the incident-side arm, the receiving-side arm, the incident-side slit, the opening/closing drive device, a Zs-movement device, the X-ray source, and the X-ray detector. The “θ-adjustment means” is constituted, for example, by the combination of the control device, the incident-side arm, the receiving-side arm, the X-ray source, and the X-ray detector.
In the X-ray analyzer according to the present invention, it is preferable that:
(A) the 2θ-adjustment means simultaneously finds X-ray intensity for a plurality of different 2θ angle values in an X-ray receiving region of the X-ray detector by using the X-ray detector, and finds the amount of angle deviation for 2θ-adjustment on the basis of the found X-ray intensities;
(B) the Zs-axis adjustment means simultaneously finds X-ray intensities for a plurality of different 2θ angle values in an X-ray receiving region of the X-ray detector by using the X-ray detector, and finds the amount of incident-side slit positional deviation for Zs-axis adjustment on the basis of the found X-ray intensities;
(C) the θ-adjustment means simultaneous finds X-ray intensity for a plurality of different 2θ angle values in an X-ray receiving region of the X-ray detector by using the X-ray detector, and finds the amount of deviation in parallelism for θ-adjustment on the basis of the found X-ray intensities.
In accordance with the present invention, as described above, the amount of deviation between the angle of incidence θ of the X-rays with respect to the sample and the θs angle of the incident-side arm, and the amount of deviation between the X-ray angle of diffraction 2θ and the θd angle of the receiving-side arm are found by using the capability for X-ray intensity positional resolution within a linear region possessed by the X-ray detector, thereby allowing the process of finding these amounts of deviation and the process of performing optical axis adjustment on the basis of the amounts of deviation to be performed quickly and simply.
An embodiment of the X-ray analyzer according to the present invention will now be described. As shall be apparent, the present invention is not limited to this embodiment. Constituent elements may be shown at other than their actual proportions in the drawings attached to the present specification so as to facilitate comprehension of characteristic portions.
A sample S is in place on the sample stage 2 in
The incident-side arm 3 supports an X-ray tube 7 and an incident-side slit 8. An X-ray source F is provided within the X-ray tube 7. A filament (not shown) is provided within the X-ray tube 7 as a cathode, and a target (not shown) as an anticathode. The region in which thermoelectrons released from the filament are capable of colliding with the surface of the target is the X-ray focus, from which X-rays are emitted. The X-ray focus constitutes the X-ray source F. In the present embodiment, the X-ray source F is an X-ray focus for a line focus extending in the drawing surface-penetrating direction. A slit groove of the incident-side slit 8 extends in the drawing surface-penetrating direction.
The receiving-side arm 4 comprises a one-dimensional X-ray detector 11, which is the X-ray detector having X-ray intensity positional resolution within a linear area. The one-dimensional X-ray detector 11 is constituted, for example, by a position-sensitive proportional counter (PSPC), a one-dimensional charge-coupled device (CCD) array, or a one-dimensional photon-counting pixel array. As schematically shown, for example, in
The incident-side arm 3 is driven by a θs-rotation drive device 12 so as to engage in θs-rotation around the sample axis X0. The θs-rotation drive device 12 rotates the incident-side arm 3 at a predetermined timing and predetermined angular conditions according to commands from a control device 13. The control device 13 is constituted by a computer comprising a central processing unit (CPU) and memory (a storage medium). Software for executing the 2θ-adjustment, Zs-axis adjustment, and θ-adjustment described hereafter is stored in the memory.
The receiving-side arm 4 is driven by a θd-rotation drive device 14 to engage in θd-rotation around the sample axis X0. The θd-rotation drive device 14 rotates the receiving-side arm 4 at a predetermined timing and predetermined angular conditions according to commands from the control device 13. The θs-rotation drive device 12 and θd-rotation drive device 14 are formed by a suitable power transmission mechanism, such as a power transmission mechanism using a worm and a worm wheel.
The slit width of the incident-side slit 8 can be adjusted using a slit opening/closing drive device 17. The slit opening/closing drive device 17 operates according to commands from the control device 13. The incident-side slit 8 is capable of moving in a direction orthogonal to the centerline R0 of the incident X-rays (i.e., vertical direction A-A′ in
Upon starting up, the control device 13 sets the various devices shown in
If instructions to set the optical axis have not been made in step S2, the process continues to step S4, it is checked whether instructions to perform measurement have been given, and, if so, the process continues to step S5 and X-ray measurement is executed. After X-ray determination is complete, it is checked in step S6 whether instructions to analyze the measured data have been given, and, if so, an analytical process is executed in step S7. Subsequently, it is checked in step S8 whether instructions to finish using the device have been given, and, if so, control is ended.
(1) X-Ray Measurement
Next, an example of the X-ray measurement performed in step S5 of
If the X-ray measurement consists of X-ray diffractional measurement being performed upon a powder sample, a powder sample S is placed upon the sample stage 2 in
Specifically, in
The X-ray diffractional measurement described here is one example of X-ray measurement, and another suitable type of measurement other than X-ray diffractional measurement can actually be performed as necessary.
(2) Optical Axis Adjustment
Next, the optical axis adjustment performed in step S3 of
(2-1) 2θ-Adjustment
2θ-adjustment is adjustment for aligning the 2θ=0° angle position in the optical system of the X-ray analyzer 1 (
2θ-adjustment involves determining a θd-correction value for correcting the angle of the X-ray detector 11 with the incident-side slit 8 set to an open state at a predetermined aperture. Specifically, in
In 2θ-adjustment, as shown in
With the one-dimensional X-ray detector 11 fixed in the state shown in
Assuming that the peak position of the profile P1 deviates δ0 from 2θ=0°, the amount of deviation δ0 indicates the sum of the amount of deviation of the θd-axis and the amount of deviation of the X-ray detector 11. This being the case, optical axis adjustment for the 2θ-direction can be performed by setting the amount of deviation δ0 as the correction value for the θd-axis for the X-ray measurement results data shown in
In the example shown in
(2-2) Zs-Axis Adjustment
Next, Zs-axis adjustment will be described. Zs-axis adjustment involves setting the incident-side slit 8 shown in
Next, the Zs-axis (i.e., the incident-side slit 8) is moved by the Zs-movement device 19 shown in
Next, the Zs-axis (i.e., the incident-side slit 8) is moved by the Zs-movement device 19 shown in
The positional information for Q1 on the Zs-axis shown in
Accordingly, it is possible to measure at least two measurement positions Q1, Q2 on the Zs-axis to draw profiles of measurement results on a diffraction-profile graph such as those shown in
For example, assuming that Q1=−0.5 mm, Q2=−0.2 mm, pp3=−0.06°, and pp4=0.11°, the position Zs on the Zs-axis corresponding to the X-ray angle 2θ=0° can be found using the formula
Zs=−0.5 mm+(b/a)×0.3 mm (1)
For confirmation, the incident-side slit 8 was replaced at the position Zs=0.4 mm in
For further confirmation, the position of the incident-side slit 8 on the Zs-axis was adjusted according to the calculated results, after which X-ray diffractional measurement was performed according to the following three sets of conditions.
(A) An incident-side slit 8 having an divergence angle of (⅔)° was disposed at the position of the incident-side slit 8 in
(B) An incident-side slit having a slit width of 0.2 mm was disposed at the position of the incident-side slit 8 in
(C) An incident-side slit 8 having a slit width of 0.2 mm was disposed at the position of the incident-side slit 8 in
When the measurement results for the various conditions described above were plotted on the X-ray diffraction diagram shown in
(2-3) θ-Adjustment
Next, the θ-adjustment variety of optical axis adjustment will be described. θ-adjustment involves aligning the surface of the sample S in
In a conventional X-ray analyzer, as described using
In the present embodiment, the sample S was placed on the sample stage 2 of the X-ray analyzer 1 shown in
Plotting the projected measurement results on a graph yielded the X-ray profile shown on
P11 is a profile corresponding to θ=−1.00°,
P12 is a profile corresponding to θ=−0.5°,
P13 is a profile corresponding to θ=+0.5°, and
P14 is a profile corresponding to θ=+1.00°.
Because the one-dimensional X-ray detector 11 possesses linear positional resolution, these profiles were each measured via a single round of X-ray irradiation.
P11 (θ=−1.00°): 2θ=approx. 0.104°
P12 (θ=−0.5°): 2θ=approx. 0.036°
P13 (θ=+0.5°): 2θ=approx. 0.082°
P14 (θ=+1.00°): 2θ=approx. 0.134°
Once the three types of adjustment described above (i.e., 2θ-adjustment, Zs-axis adjustment, and θ-adjustment) have been performed, the optical axis adjustment of step S3 in
In accordance with the present embodiment, as described above, the amount of deviation between the X-ray incidence angle θ with respect to the sample and the θs angle of the incident-side arm 3, and the amount of deviation between the X-ray diffraction angle 2θ and the θd angle of the receiving-side arm 4 are found respectively by using the capability for X-ray intensity positional resolution possessed by the one-dimensional X-ray detector 11, thereby allowing the process of finding these amounts of deviation and the process of performing optical axis adjustment on the basis of the amounts of deviation to be performed quickly and simply.
The foregoing has been a description of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made within the scope of the invention as set forth in the claims.
For example, although a dedicated one-dimensional X-ray detector such as that shown in
Number | Date | Country | Kind |
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2013-242712 | Nov 2013 | JP | national |
2014-185352 | Sep 2014 | JP | national |