JPS63167250A - X-ray analyzer - Google Patents

Abstract

PURPOSE:To execute X-ray spectroscopy with high accuracy without spending considerably long time in adjustment by independently rotating a spectral crystal and X-ray detector and correcting an error quantity by computation. CONSTITUTION:The fluorescent X-ray K which is excited by an X-ray E from an X-ray tube 1 and is released from a sample S is spectrally split by the spectral crystal 2 and the characteristic x-ray T thereof is detected by a detector 4 which is provided with a mechanism rotatable around the center O of an X-ray spectroscope. A spectral crystal base 3 is rotated by a driving device 5 so as to bring the arbitrary spectral crystal to a use position. The entire part of the base 3 and the driving device thereof can be rotated around the center O of the X-ray spectroscope as shown by an arrow. Wavelength scanning by the spectral crystal positioned to the use position, i.e., the center of the X-ray spectroscope is thus executed. A CPU 7 controls the crystal driving device 5 and a detector driving device 6 by using the driving signal from a driving signal generator 9 and reads the rotating angle thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an X-ray analyzer equipped with a mechanism that allows a plurality of spectroscopic crystals to be exchanged and used. In a fluorescent X-ray analyzer equipped with 8 spectroscopic crystals, a rotating drum-type crystal exchange mechanism is usually used. As shown in Fig. 2, this mechanism has six to eight spectroscopic crystals 2 mounted on a rotating drum-shaped spectroscopic crystal stand 3.
The spectroscopic crystal stand 3 is rotated to position any one spectroscopic crystal at a use position. And spectroscopic crystal stand 3
and the entire switching drive device (not shown) that rotates it.

It is rotatable along the surface of the spectroscopic crystal in the use position, about the spectrometer center line passing through the center of the surface, and by this rotation, the spectrometer performs wavelength scanning by the spectrometer in the use position. At this time, the XvA detector 4 is set at 2θ, which is twice the rotation angle θ of the spectroscopic crystal, with the spectrometer center O as the center.
However, conventionally, the rotation of the spectroscopic crystal and the rotation of the detector are connected by a double angle transmission mechanism, driven by - wavelength scanning drive motors, and the wavelength is detected by the amount of rotation of these motors. I was supposed to.

C. Problems to be solved by the invention In order to maintain spectral accuracy, it is necessary to keep the machining accuracy of the drum and the accuracy of the rotation stop position of the drum to within 1/100 degrees, respectively. . This required a great deal of effort in processing, adjusting, and inspecting. By arranging the rotational axis of the drum parallel to the plane containing the optical axis of the spectrometer, the influence of the accuracy of the rotational stop position of the drum on the 711 degree spectrum of X-rays can be significantly reduced. but,
Regarding the machining accuracy of the drum and the accuracy of mounting the spectroscopic crystal on the base, there is no easy way to eliminate the effects on the spectroscopic accuracy. In any case, it is necessary to adjust the position of the spectroscopic crystal when a deviation in the setting position of the spectroscopic crystal is discovered by spectroscopy of X-rays of known wavelengths, so fine adjustments must be made between the spectroscopic crystal base and the spectroscopic crystal stand. It takes a lot of time and effort to set up a mechanism and make adjustments, and
Because it is extremely difficult to perfectly adjust the equipment,
Crystal exchange type X-ray analyzers did not have good spectral accuracy.

The present invention uses equipment that does not have particularly high processing precision of the drum, precision of the rotation stop position of the crystal exchange mechanism, etc. The precision of attaching the 7-minute spectroscopic crystal to the base, etc. is not particularly high, and the labor and time for adjustment are significantly reduced. 21 Means for Solving Problems Aiming to Obtain X-ray Spectroscopy Accuracy In an X-ray analyzer, a crystal exchange mechanism in which a plurality of spectroscopic crystals are alternately installed at the center position of the X-ray spectrometer. a means for rotating a spectroscopic crystal located at the center of the spectrometer around the center of the X-ray spectrometer, and a mechanism for rotating the X-ray detector around the center of the X-ray spectrometer, independently of each other;
A means for detecting the rotation angle of the spectroscopic crystal and the rotational position of the X-ray detector is provided, and the position of the spectroscopic crystal and X-ray detector where the detection output of characteristic X-rays of known elements is maximized, A means is provided for storing the difference between the position corresponding to the X-ray wavelength on the mechanism of the detector, and an offset corresponding to the above difference is applied to the spectroscopic crystal during wavelength scanning to drive the spectroscopic crystal. According to the above, since the rotation of the spectroscopic crystal and the detector can be controlled independently during wavelength scanning, it is possible to perform calibration measurements to find the optimum position where the X-ray detection intensity is the maximum at a predetermined wavelength position on the mechanism of each spectroscopic crystal and X-ray detector. If you measure the difference from the position, this deviation angle represents the error in the position of the spectroscopic crystal, which takes into account the accuracy of the installation of the spectroscopic crystal, the accuracy of the crystal exchange mechanism, etc., so the CPU takes this deviation angle into account. By driving the spectroscopic crystal at the optimal setting position, the spectroscopic crystal can be precisely set at the optimal setting position without having to make fine adjustments to the installation of the spectroscopic crystal. X-ray spectroscopic measurements are now possible.

To, Example An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

In Figure 2, S is the sample, E i,t X-ray, K is X
Fluorescent X-rays excited by the ray E and emitted from the sample S, 1 is an X-ray tube, 2 is a spectroscopic crystal for dispersing the fluorescent X-rays K, and 3 is a rotatable spectrometer in which a plurality of spectroscopic crystals 2 are installed. A crystal stand 4 is a detector for detecting the characteristic X-rays T separated by the spectroscopic crystal 2, and is equipped with a mechanism capable of rotating around the X-ray spectrometer center 0. The spectroscopic crystal stand 3 is rotated by a drive device (not shown), and the entire 0-spectroscopic crystal stand 3 and its drive device are rotated by a drive device (not shown) to position any spectrometer crystal at the use position. It can be rotated in the direction of the arrow in the center, and by this rotation, the use position, that is,
Wavelength scanning is performed by a spectroscopic crystal located at the center of the line spectrometer. In FIG. 1, reference numeral 5 denotes the above-mentioned spectroscopic crystal rotation drive device for wavelength scanning. A detector driving device 6 rotates the detector 4 around the zero point. Reference numeral 7 uses a drive signal generated by a drive signal generator in the CPU to control the crystal drive device 5 and the detector drive device 6 and read their rotation angles. 8 is an angle display device that displays the rotation angles of the spectroscopic crystal and the detector 4 read by the CPU 7, and the X-ray wavelength converted from these rotation angles.

With the above configuration, the spectroscopic crystal 2 installed on the spectroscopic crystal stand 3, for example LiF (200> plane, is located at the use position, and the CPU
The angular position θ is determined by θ=22.515°−0.3°
The detector driving device 6 is driven to emit the characteristic X-ray spectrum of Cu, 2θ = 45.03°, which is approximately in the middle of the wavelength range used for this crystal, in the angular range of 2θ ± 0.3°. Detector 6 that detects and maximizes the X-ray intensity
The corner position of is stored in the CPU 7. Next, the spectroscopic crystal 2 is tilted 0.05° from the above position and the same measurement as above is performed.In the same way, the inclination θ of the spectroscopic crystal 2 is θ=22.515°+0
．． Repeat the measurement until the angle reaches 3°. Based on the measurement results, a curve that connects the maximum values of the detection output in each measurement is created as shown in FIG. 3. From this curve, the angular position of the spectroscopic crystal and the angular position of the detector at which the X-ray detection output is maximized are determined.

This can be done by a human by drawing, or by setting an appropriate algorithm and having the CPU do it.In this way, the set angle of the spectroscopic crystal and the set angle of the detector 4 are determined, and each mechanical Theoretical position of θ=22.515°, 2θ
=45.03'), and calculate the deviation from CP
This deviation, which is stored in U7, represents an error in the position of the spectroscopic crystal. Therefore, when setting the spectroscopic crystal 2, the correct position is set by correcting the deviation from the mechanical wavelength position. Similarly, calibration measurements are performed on other spectroscopic crystals 2 as well.

G. Effects According to the present invention, the rotation of the spectroscopic crystal and the rotation of the X-ray detector are performed independently, and instead of correcting structural errors by structural adjustment, the amount of error is memorized and calculated. Since the correction is now made with , it is possible to reduce the price of the X-ray analyzer and improve the spectral accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the embodiment, and FIG. 3 is a graph showing the results of calibration measurements. DESCRIPTION OF SYMBOLS 1... X-ray tube, 2... Spectroscopic crystal, 3... Spectroscopic crystal stand, 4... Detector, 5... Spectroscopic crystal drive device, 6...
...Detector drive device, 7...CPU, 8...Angle display device, 9...Drive signal generator, E...X-ray, S...
...Sample, K...Fluorescent X-ray, T...Characteristic X-ray.

Claims (1)

[Claims] It is equipped with a crystal exchange mechanism that alternately places a plurality of spectroscopic crystals at the center of the X-ray spectrometer, a means for rotating the spectrometer crystal positioned at the center of the spectrometer around the center of the X-ray spectrometer, and an X-ray detector. A mechanism for rotating the X-ray spectrometer around the center is provided independently from each other, and a means for detecting the rotation angle of the spectroscopic crystal and the rotation position of the X-ray detector is provided to maximize the detection output of characteristic X-rays of known elements. A means for storing the difference between the position of the spectroscopic crystal and the X-ray detector and the position corresponding to the X-ray wavelength on the mechanism of the spectroscopic crystal and the X-ray detector is provided, and when scanning the wavelength, the spectroscopic crystal is An X-ray analysis device characterized in that a spectroscopic crystal is driven by applying an offset.