JPS60212954A - Electron microscope - Google Patents

Abstract

PURPOSE:To improve the operation efficiency of an electron microscope and achieve its stable condition in a short time by automatically operating a means for producing and accelerating electron rays, a means for deflecting them and a lens system for converging electron rays and forming an image after a hard vacuum is produced by detecting the vacuum degree of the mirror tube. CONSTITUTION:Within the mirror tube 27 of an electron microscope, electron rays 28 are converged and deflected before being irradiated upon a sample 5 and then electron rays passing through the sample 5 are magnified by an image formation lens system 6 to project an image upon a fluorescent plate 7. The vacuum degree of the mirror tube 27 is detected with a detector 8 and a vacuum meter 20 and a signal produced when a given vacuum degree is achieved is sent into a micro processor 23. The signal from the processor 23 and data read from (ROM24) and (RAM25) are passed through read-out DA converters 17, 18 and 19 respectively before being used to apply acceleration voltage and to excite a lens coil and a deflection coil. In addition, data for cancelling the starting drift are used to achieve a shift to a stable condition. Therefore, the electron microscope can be automatically used only by turning on an operation switch for the exhaust system, thereby facilitating handling of the electron microscope.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electron microscope, and particularly to one in which accelerating voltage is automatically applied from exhaust gas.

[Background of the Invention] When operating a conventional electron microscope, the exhaust system is first operated, and after about 30 minutes, including warming up of the oil diffusion pump, the operator manually applies accelerating voltage, and at the same time the lens system, Operate the deflection system power supply. The high voltage system and lens system use a detection resistor for stabilization, and startup drift occurs due to temperature rise. Since it takes 1 to 2 hours to stabilize, it takes a long time to stabilize, especially when performing high-resolution photography. In this way, the total process from operating the exhaust system to the state of use is 2~
It takes 3 hours. Continuous energization can shorten the warming-up time, but increases the cost of electricity and cooling water.

[Purpose of the invention]

The present invention eliminates the drawbacks of the prior art, achieves a stable state in a short time, improves operability, improves performance, and reduces usage costs.

[Summary of the invention]

As a solution, recently the exhaust system and electrical system have been computerized, and if the vacuum level signal is sent to the CPU,
This generates a high voltage application signal, and the high voltage value is also DA
It is also possible to gradually step up the high voltage using a converter. In addition, startup drift occurs due to the temperature rise of the detection resistor at high voltages, but since the characteristics are constant, it is only necessary to output data that cancels the amount of drift in advance, convert it to analog with a DA converter, and change the reference voltage.
The same applies to the lens system and deflection system.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG. Electron microscope mirror body 2
7, the filament 1 is heated and an accelerating voltage is applied to the Wehnelt 2 to generate an electron beam 28.

The converging lens system 3 converges the electron beam, and the deflecting lens 4 adjusts the deflecting lens so that it is centered on the sample 5. The electron beam 28 transmitted through the sample 5 is magnified by the imaging lens system 6 and projected onto the fluorescent screen 7 as an image. Accelerating voltage is applied from the operation panel 22. A manual/automatic selector switch is provided in the panel. Signals generated from the operation panel are sent to the microprocessor 23, ROM 24 . RAM25
'h) is read out, converted into analog data by the DA converter 17, passed through the feedback amplifier 12, and then sent to the high voltage transformer 1.
0, and a high voltage is applied to Wehnelt 2. In order to stabilize the accelerating voltage, it is fed back to a feedback amplifier 12 using a detection resistor 11.

Similarly, the data linked to the acceleration voltage for the lens power supply is RO.
M24. Read from RAM 25 and converted to DA converter 18
The voltage is converted into an analog value and sent as a reference voltage to the feedback amplifier 15, which excites the lens coil 3. In order to stabilize the lens current, a detection resistor 13 is used, and a feedback amplifier 1 is used.
5 will be fed back.

The deflection power supply also has a DA converter 19, a feedback increaser [11 devices 16,
It passes through the deflection coil 4 and the detection resistor 14 and is made constant.

A detector 8 for measuring the degree of vacuum measures the degree of vacuum of the mirror body 27. The signal from the detector 8 passes through a vacuum gauge 20 and sends a signal to the microprocessor 23 when a certain degree of vacuum is reached. Set the vacuum degree generation signal to a degree of vacuum sufficient to apply the acceleration voltage.

Set the acceleration voltage on the operation panel to automatic. Turn on the operation switch of the exhaust system of the electron microscope. When the detector 8 reaches a value sufficient for applying an accelerating voltage and a signal is sent to the microprocessor 23, data is read from the ROM 24 and RAM 25 and passed through the DA converter 17, where the accelerating voltage is applied. At the same time, DA converter 18, 1 for lens and deflection
Data is also sent to 9 to excite the lens coil and deflection coil.

The accelerating voltage detector 11, the lens detection resistor 13, and the deflection coil detection resistor 14 have a startup drift before reaching temperature equilibrium, and it takes a long time to stabilize them.

In the present invention, once the operation switch of the exhaust system is turned on, the accelerating voltage, lens power source, and deflection power source can be automatically applied. CR that displays data such as magnification and acceleration voltage
The energization time after applying the accelerating voltage can also be displayed at T. This means that if you know in advance how stable the startup drift is, you can find out how stable it is currently by simply monitoring that time.

Also, the detection resistor 11. ]3.14 The startup drift is almost determined by the type of resistor used, so the microprocessor 23, ROM 24 and RA
If data that cancels the characteristics is written in M25, it is possible to take photographs in a stable state from the time when the accelerating voltage is applied.

〔Effect of the invention〕

Conventionally, the operator turned on the exhaust system operation switch and waited until the vacuum became good before turning on the accelerating voltage, lens power, and deflection power, but with the present invention, by turning the exhaust system operation switch on The remaining operations are performed automatically, improving operability and eliminating unnecessary time. Acceleration voltage, lens power supply, deflection power supply l! The power-on time after turning on is also displayed, so if you know the relationship between start-up drift and time in advance, you can know how stable the device is currently.

The data for canceling the start-up drift of the detection resistor +1, 13, and 14 is stored in the microprocessor 23° ROM 24. R
If you store it in AM25, the acceleration voltage, lens power supply,
It can be used in a stable state when the deflection power is turned on, and high-resolution observation is also possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an electron microscope according to an embodiment of the present invention. 3 Converging lens, 4... Deflection lens, 6... Image lens, 8... Vacuum degree detector, 11... Accelerating voltage detection resistor, 1
3... Lens detection resistor, 14... Deflection lens detection resistor, 22... Operation panel, 23... Micro Processera 1st
figure

Claims (1)

[Claims] 1. A means for generating and accelerating an electron beam, a means for converging an electron beam, a means for enlarging and imaging a sample, a means for observing and photographing,
In an apparatus having a means for evacuating a place through which an electron beam passes, after reaching a high vacuum by a means for detecting the degree of vacuum, a means for generating and accelerating an electron beam, and a means for converging the electron beam,
An electron microscope characterized in that a lens system for forming an image and a means for deflecting an electron beam are automatically operated. 2. In claim 1, the system automatically operates and displays the accumulated time. An electron microscope featuring 3. An electron microscope according to claim 1, comprising means for generating and accelerating an electron beam, and means for canceling startup drift of a lens system for converging and forming an image, and a deflection lens system.