JPH04339577A - Beam converging position measuring instrument - Google Patents

Abstract

PURPOSE:To exactly determine the converging position of an energy beam, such as electron beam. CONSTITUTION:The electron beam 4 emitted from an electron gun 5 is so scanned as to intersect orthogonally with the slit of a measuring instrument body 1. The signal corresponding to the quantity of the beam transmitted through the slit is output from the measuring instrument body 1 and the signal waveform thereof is measured by a voltage waveform measuring instrument 3. This waveform signal is sent to a controller 11 and is displayed on a display device 12. The measuring instrument body 1 is intermittently moved along a direction A by a moving device 7. The signal waveforms in the respective positions are thus obtd. The converging position of the electron beam 4 is decided in accordance with these signal waveforms.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam convergence position measuring device for measuring the convergence position (focus position) of an electron beam in an electron beam welding device applied to welding pressure vessels and the like.

0002

2. Description of the Related Art Conventionally, there has been no suitable device for measuring the convergence position of an electron beam generated in an electron beam welding device.As shown in FIG. By scanning the electron beam 4 under the conditions to be measured over the test plate 16, the test plate 16 is melted, and the melted portion 17 is
The melting width of the electron beam 4 was measured, and the position where the width was the smallest was determined to be the convergence position of the electron beam 4.

0003

SUMMARY OF THE INVENTION The conventional electron beam convergence position measuring means described above has the following problems. That is, from the melting width of the test plate 16, the electron beam 4
The measurement result is unstable because it attempts to estimate the dimension (diameter) of In some cases, it was impossible to determine the convergence position. In addition to these problems with measurement accuracy, conventional measurement means use a test plate 16 formed into a comb shape, which requires a large amount of money to produce the test plate, and it is difficult to use for electron beam quality control, etc. Therefore, it was virtually impossible to frequently measure the convergence position of the electron beam.

In view of the above-mentioned prior art, the present invention provides a beam convergence position measuring device that can accurately detect the convergence position of an energy beam such as an electron beam.

[0005]

[Means for Solving the Problems] The present invention, which solves the above problems, scans an electron beam, transmits the electrons through a slit arranged to intersect with the electron beam, and converts the amount of electrons into a current value or voltage. The method is characterized by comprising a device for measuring the amount of electron beam by converting it into an electron beam, and further detecting the convergence position of the electron beam by moving this measuring device by a moving device using a pulse motor or the like that moves in the direction of irradiation of the electron beam. shall be.

[0006]

[Operation] When the electron beam is scanned across the slit, the measurement device that measures the amount of electron beam has a peak at the center of the slit as shown in Figure 4, and the voltage (electron Quantity) relationship diagram can be obtained. By further changing the position of the measuring device using a moving device at a gap in the irradiation direction of the electron beam, the degree of convergence of the beam is measured in accordance with the position of the measuring device as shown in FIG. As a result, it can be determined that the position where the voltage is at its peak or the position where the beam width is at its minimum (assuming that the measured voltage height V1 is constant) is the position where the beam is focused. If the measurement is repeated with the position where this peak is shown as the center and the movement pitch is reduced, the focal position can be specified even more accurately.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the invention. As shown in the figure, an electron beam 4 is output from an electron gun 5, and a measuring device main body 1 is disposed at a position where the electron beam 4 is irradiated. The measuring device main body 1 is placed on a table 8 of a moving device 7, and by driving the pulse motor 6, the measuring device main body 1 moves together with the table 8 in the direction A (this direction is referred to as the "beam irradiation direction"). do. The pulse motor 6 is driven via a pulse motor controller 9 in response to commands from a control device 11 .

The configuration and operation of the measuring device main body 1 will now be explained with reference to FIGS. 2 to 4. As shown in FIGS. 2 and 3, the measuring device main body 1 includes a slit plate 13 having a slit 15 and a beam receiver 14, and the beam receiver 14 is grounded via a resistor 2. The electron gun 5 is
The electron beam 4 is moved so as to scan orthogonally to the slit 15 (see FIG. 4(b)). That is, in FIGS. 1 to 3, the electron gun 5 is moved so that the electron beam 4 is scanned in the vertical direction on the slit plate 13. slit 1
The electron beam 4 transmitted through the electron beam 5 is received by a beam receiver 14. Since the electrons generated by the received electron beam 4 head from the beam receiver 14 to the ground, a current having a value corresponding to the amount of received light flows. This current is converted into voltage by resistor 2,
The waveform of this voltage (voltage value over time) is detected by the voltage waveform detector 3.

When the electron beam 4 scans the slit plate 13 once in a direction perpendicular to the slit 15, for example, as shown in FIG.
A voltage waveform as shown in a) is obtained. This voltage waveform changes depending on the distance between the electron gun 5 and the slit plate 13. Returning to FIG. 1 and continuing the explanation, the voltage waveform, which is an analog quantity detected by the voltage waveform measuring instrument 3, is converted into a digital quantity by the AD converter 10 and then sent to the control device 11. Note that when the voltage waveform measuring instrument 3 has a digital output function, the AD converter 10 is not necessary.

The control device 11 controls the scanning of the electron beam 4 by one
Once the voltage waveform at this time is captured, a command is issued to move the table 8 of the moving device 7 by a predetermined distance in the A direction. When the table 8 and the measuring device main body 1 reach the next position, a second scan of the electron beam 4 is performed to capture the voltage waveform at this time, and then the table 8 is further moved in the direction A by a predetermined distance. Thereafter, similarly, the position of the measuring device main body 8 is sequentially shifted along the A direction, and the voltage waveform at each position is captured. The voltage waveform captured each time is stored in the control device 11 and displayed on the display device 1.
It is shown on 2.

FIG. 5 shows how the measuring device body 1 is moved by the moving device 7.
FIG. 4 is an image diagram showing that by moving the electron beam 4, the degree of convergence of the electron beam 4 changes and the voltage waveform changes. In other words, the distance between the electron gun 5 and the measuring device main body 1 is H1, H
2, H3, and H4, each voltage waveform is shown together with the position state. From this figure, we can see that the voltage is high in the in-focus position, and low in the out-of-focus position, and that the voltage is in focus at the position where the voltage peaks (position H2 in this figure). I can distinguish things.

0012

According to the present invention, it is possible to obtain a voltage waveform according to the degree of convergence of the electron beam using the measuring device main body, the waveform measuring device, the control device, and the moving device, and as a result, the focal position of the electron beam can be can be measured accurately. As a result of the above, compared to conventional measurement methods, measurement accuracy is improved, measurement can be performed at low cost without the need for a comb-shaped test plate, and quality control of electron beams can be adequately controlled. It is extremely useful for industry.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a beam convergence position measuring device of the present invention.

FIG. 2 is a sectional view showing a measuring device main body used in the device of the present invention.

FIG. 3 is a front view showing a slit plate used in the device of the present invention.

FIG. 4 is an explanatory diagram showing the relationship between voltage waveform and beam scanning in the present invention.

FIG. 5 is an explanatory diagram showing the operation mode of the device of the present invention.

FIG. 6 is an explanatory diagram showing a prior art.

[Explanation of symbols]

1　Measuring device main body 2 Resistance 3 Voltage waveform measuring device 4　Electron beam 5 Electron gun 6 Pulse motor 7. Mobile device 8 Table 9 Pulse motor controller 10 AD converter 11 Control device 12 Display device 13 Slit plate 14 Beam receptor 15 Slit 16 Comb-shaped test plate 17 Melting part

Claims (1)

[Claims] Claim 1: A measuring device body, which has a slit formed therein, receives an energy beam scanned to intersect with the slit, and outputs a signal according to the amount of received light; A waveform measuring device that measures the waveform of the output signal, a moving device that moves the measuring device main body along the energy beam irradiation direction, and a measuring device sequentially positioning the measuring device main body at multiple measurement points along the energy beam irradiating direction. At the same time, when the measuring device body is located at each measurement point, the energy beam is scanned and the signal waveform at each position obtained by the waveform measuring device is received. A beam convergence position measuring device comprising: a control device that specifies a convergence position of an energy beam based on these signal waveforms.