A backscattered electron scintillator detector device and detection method

Abstract

The present application relates to the technical field of electron-optical imaging, and particularly relates to a backscattered electron scintillator detector device and a detection method, which comprises a backscattered electron receiving sensor, an optical condensing group, an optical transmission group, a photoelectric conversion system and a detector protection mechanism. By using a scintillator as a sensor, a backscattered electron signal generated by an industrial electron gun electron beam is received, and then the electronic information carried by the backscattered electron is converted into an optical signal and transmitted to an area far away from the workpiece. Finally, a high signal-to-noise ratio voltage analog signal is formed by the photoelectric conversion system, avoiding the influence of spatial noise and other interference signals on weak signal transmission in the existing analog signal transmission process. For detailed topographic features, a backscattered electron image with high resolution can be displayed.

Description

Technical Field

[0001] This invention relates to the field of electron optical imaging technology, and in particular to a backscattered electron scintillator detector device and detection method. Background Technology

[0002] Vacuum electron beam processing technology, with its unique heat transfer mechanism and pure processing environment, has advantages over other special processing methods, such as high energy density, high workpiece purity, and strong process adaptability.

[0003] Currently, electron beam welding typically employs optical imaging systems to control the welding process and parameters. These systems consist of individually illuminated lens systems and movable prisms or plane mirrors. Light emitted from the light source is refracted through the prisms or plane mirrors onto the workpiece surface, then transmitted through another prism or plane mirror to the eyepiece and monitor via the optical system, enabling beam spot control and parameter adjustment. However, after a period of operation, the optical path becomes severely contaminated by metal vapor, reducing the observation effect. Furthermore, the metal vapor or splashed molten metal generated during electron beam welding can damage the optical lenses of the observation system, requiring regular cleaning and maintenance, significantly impacting production efficiency.

[0004] Electron optical imaging is a unique technique for monitoring electron beam processing. Electron optical imaging scans the processed sample with a focused electron beam, and then uses a small beam of electron beam to scan the surface of the electron beam processing area point by point. It collects the electrical signals of secondary electrons and backscattered electrons that carry morphological information during the interaction between electrons and the sample, and arranges them into a two-dimensional grayscale image according to the scanning point sequence. This image can reflect the morphological information of the scanned area.

[0005] However, most electron optical imaging detectors used in electron beam processing currently employ metal plate detectors. Since electron beam processing takes place in a complex environment with high-frequency power supplies, high-frequency voltages, and industrial noise, metal plate detectors will also synchronously acquire interference signals present in the environment during use. This will have a significant impact on signal changes caused by subtle morphological features, resulting in less than ideal electron optical image observation effects. Summary of the Invention

[0006] The purpose of this invention is to provide a backscattered electron scintillator detector device and method, which aims to provide a backscattered electron detector with good signal-to-noise ratio, fast response time and strong resistance to electronic interference, thereby improving the imaging effect of sample detection.

[0007] To achieve the above objectives, the present invention provides a backscattered electron scintillator detector device, comprising a backscattered electron receiving sensor, an optical focusing group, an optical transmission group, a photoelectric conversion system, and a detector protection mechanism. The detector protection mechanism includes a detector protection sleeve and a scintillator end-face light transmission protection sleeve. The scintillator end-face light transmission protection sleeve, the optical focusing group, and the optical transmission group are all disposed within the detector protection sleeve. The photoelectric conversion system is connected to one end of the optical transmission group and is independent of the detector protection mechanism.

[0008] The backscattered electron receiving sensor includes a scintillator and a scintillator frame, with the scintillator embedded in the central axis of the scintillator frame.

[0009] The optical focusing group includes a reflective lens, a reflector cup, and a focusing lens. The reflector cup is a smooth focusing cup. A single-sided slot is opened on the center line of the reflector cup. The scintillator is located on the central axis of the reflector cup and passes through the reflector cup. The reflective lens is disposed at one end of the scintillator. The focusing lens is connected to the outlet of the reflector cup.

[0010] The optical transmission assembly includes an optical fiber, an optical guide lens, and an optical fiber transmission base. The optical guide lens is connected to one end of the optical fiber and fixed on the optical fiber transmission base. The center of the optical fiber coincides with the center of the optical fiber transmission base, and the optical guide lens is located at the focal point of the condenser lens.

[0011] The scintillator is a scintillating crystal.

[0012] Both the scintillator and the reflector are cylindrical, and the size of the reflector is equal to the size of the end face of the scintillator.

[0013] The reflector cup is made of aluminum alloy.

[0014] The condenser lens is a biconvex lens.

[0015] The optical fiber is a quartz optical fiber with an insertion loss of less than 0.3 dB.

[0016] The photoelectric conversion system includes an I / V operational amplifier. The current signal generated by the avalanche diode is converted by the I / V operational amplifier to output a voltage signal. The response time of the avalanche diode is 0.5ns.

[0017] The photoelectric conversion system is connected to the end face of the optical fiber.

[0018] The detector protective sleeve is provided with a single-sided opening, which is located on the same side as the single-sided slot and their center lines coincide. The size of the single-sided opening is larger than the size of the single-sided slot.

[0019] The present invention also proposes a detection method using a backscattered electron scintillator detector device, specifically, the backscattered electron scintillator detector device is installed between the industrial electron gun barrel and the electron beam processing sample stage, and is parallel to the electron beam processing sample stage and perpendicular to the incident electron beam direction.

[0020] This invention provides a backscattered electron scintillator detector device and detection method. The device includes a backscattered electron receiving sensor, an optical focusing group, an optical transmission group, a photoelectric conversion system, and a detector protection mechanism. By using a scintillator as a sensor, it receives backscattered electron signals generated by the electron beam deflection of an industrial electron gun. The electronic information carried by the backscattered electrons is then converted into an optical signal and transmitted to an area far from the workpiece. Finally, the photoelectric conversion system generates a voltage analog signal that matches the acquisition data. This avoids the influence of spatial noise and other interference signals on weak signals during analog signal transmission in existing technologies. It can display a high-resolution backscattered electron image for detailed morphological features. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a backscattered electron scintillator detector device according to the present invention.

[0023] Figure 2 This is a schematic diagram of the incident end face of a backscattered electron scintillator detector device according to the present invention.

[0024] Figure 3 This is a schematic diagram of a practical application scenario of the present invention.

[0025] 1-Detector protective sleeve, 2-End face light transmission protective sleeve, 3-Scintillator, 4-Scintillator frame, 5-Reflecting lens, 6-Reflecting cup, 7-Condensing lens, 8-Fiber optic cable, 9-Optical guide lens, 10-Fiber optic transmission base, 11-I / V operational amplifier, 12-Industrial electron gun barrel, 13-Sample, 14-Incident electron beam, 15-Backscattered electronic signal, 21-Single-sided slot, 31-Single-sided opening. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Please see Figure 1 and Figure 2 This invention proposes a backscattered electron scintillator detector device, comprising a backscattered electron receiving sensor, an optical focusing group, an optical transmission group, a photoelectric conversion system, and a detector protection mechanism. The detector protection mechanism includes a detector protection sleeve 1 and an end-face light transmission protection sleeve 2. The end-face light transmission protection sleeve 2, the optical focusing group, and the optical transmission group are all disposed inside the detector protection sleeve 1. The photoelectric conversion system is connected to one end of the optical transmission group and is independent of the detector protection mechanism.

[0029] The backscattered electron receiving sensor includes a scintillator 3 and a scintillator frame 4, wherein the scintillator 3 is embedded in the central axis position of the scintillator frame 4;

[0030] The optical focusing group includes a reflective lens 5, a reflector cup 6, and a focusing lens 7. The reflector cup 6 is a smooth focusing cup. A single-sided slot 21 is opened on the center line of the reflector cup 6. The scintillator 3 is located on the central axis of the reflector cup 6 and passes through the reflector cup 6. The reflective lens 5 is disposed at one end of the scintillator 3. The focusing lens 7 is connected to the emission port of the reflector cup 6.

[0031] The optical transmission group includes an optical fiber 8, an optical guide lens 9, and an optical fiber transmission base 10. The optical guide lens 9 is connected to one end of the optical fiber 8 and fixed on the optical fiber transmission base 10. The center of the optical fiber 8 coincides with the center of the optical fiber transmission base 10, and the optical guide lens 9 is located at the focal point of the condenser lens 7.

[0032] Both the scintillator 3 and the reflector 5 are cylindrical, and the size of the reflector 5 is equal to the end face size of the scintillator 3.

[0033] The detector protective sleeve 1 is provided with a single-sided opening 31. The single-sided opening 31 and the single-sided slot 21 are located on the same side and their center lines coincide. The size of the single-sided opening 31 is larger than the size of the single-sided slot 21.

[0034] In this invention, preferably, a scintillator 3 is selected as an electronic signal receiving sensor. The size of the scintillator 3 is selected to conform to the actual spatial distribution of backscattered electrons. The scintillator 3 is arranged perpendicular to the incident electron beam to detect the backscattered electron signal that reflects the morphological information generated during the scanning process.

[0035] Preferably, the optical focusing group collects and focuses the weak light signal generated by the scintillator 3; the reflector 5 is placed on the end face of the scintillator 3 and transmits the light signal generated inside the scintillator 3 to the focusing lens at the other end; the reflector cup 6 has a 140° slot so that backscattered electrons can successfully strike the scintillator 3 to generate an optical signal, and the inner wall of the reflector cup 6 collects the optical signal emitted by the scintillator 3 and transmits it to the focusing lens.

[0036] Preferably, a focusing lens with a focal length of f=1 / 40 is used to focus the optical signals transmitted by the reflecting mirror 5 and the reflecting cup 6, and then transmit them to the light guide lens 9 located at the focal point of the focusing lens for output.

[0037] Further preferably, a quartz optical fiber 8 with insertion loss of less than 0.3dB and even lower optical loss is used to transmit the optical signal to a location far from the sample processing area for signal conversion.

[0038] Preferably, an avalanche photodiode with higher light sensitivity is used to convert the light signal into a current signal, and the voltage sampling signal below 5V is output after passing through the I / V operational amplifier 11, wherein the response time of the avalanche photodiode is 0.5ns.

[0039] Preferably, using 316L stainless steel with low thermal conductivity as the main material of the detector protection system can reduce the impact of high-temperature vapor deposition on the sensor.

[0040] The specific technical principles and implementation process are as follows:

[0041] The backscattered electron signal generated by the electron beam deflection of the industrial electron gun passes through the single-sided opening 31 of the detector protective sleeve 1 and the single-sided slot 21 of the reflector cup 6, and then strikes the scintillator 3. This causes the scintillator 3 to convert the electronic information carried by the backscattered electrons into an optical signal. The light signal generated inside the scintillator 3 propagates parallel to the condenser lens 7 via the reflector mirror 5. An end-face light transmission protective sleeve 2 protects the condenser lens 7 from the influence of metal vapor deposition on the propagation of the parallel light from the center of the scintillator 3. Irregular light signals emanating from the outer wall of the scintillator 3 are collected by the reflector cup 6 and refracted into parallel rays that propagate to the condenser lens 7. The condenser lens 7 focuses the light signals propagated by the reflector mirror 5 and the reflector cup 6 to the optical guide mirror 9 located at the focal point of the focusing lens. The optical guide mirror 9 then propagates the converged light signal to the quartz optical fiber 8. The quartz optical fiber 8 propagates the light signal to the photoelectric conversion system, where the I / V operational amplifier 11 generates a high signal-to-noise ratio voltage analog signal.

[0042] It should be noted that the backscattered electron scintillator 3 detector device should be used as follows: Figure 3 As shown, it needs to be installed between the industrial electron gun barrel 12 and the electron beam processing sample stage. The direction must be parallel to the electron beam processing sample stage and perpendicular to the inner wall of the vacuum chamber. The distance between the detector and the incident electron beam can be changed according to the detection needs, i.e., to detect the atomic number information or morphology information of the workpiece.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1) Backscattered electron detectors use scintillators as sensors. Compared to the metal plate detectors used in the electro-optical processes of industrial electron guns in existing technologies, scintillator sensors have less impact on signal resolution due to space charge effects during operation. Furthermore, scintillator detectors offer advantages such as a good signal-to-noise ratio, fast time response, high immunity to electron radiation, temperature resistance, and suitability for ultra-high voltage operation. These characteristics create conditions for obtaining higher quality backscattered electron images during industrial electron gun processing compared to existing methods.

[0045] 2) The optical signal generated by the scintillator excited by the backscattered electronic signal is transmitted to an area far away from the workpiece, which effectively avoids the influence of spatial noise and other interference signals on the weak signal in the analog signal transmission process in the prior art.

[0046] 3) The backscattered electron scintillator detector of the present invention has a simple structure and reliable performance. It can detect a variety of materials and can display high-resolution backscattered electron images for detailed morphological features, providing a reliable observation scheme for electron optical imaging of industrial electron gun processing.

[0047] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A backscattered electron scintillator detector device, characterized in that, The device includes a backscattered electron receiving sensor, an optical focusing group, an optical transmission group, a photoelectric conversion system, and a detector protection mechanism. The detector protection mechanism includes a detector protection sleeve and an end-face light transmission protection sleeve. The end-face light transmission protection sleeve, the optical focusing group, and the optical transmission group are all disposed inside the detector protection sleeve. The photoelectric conversion system is connected to one end of the optical transmission group and is independent of the detector protection mechanism. The backscattered electron receiving sensor includes a scintillator and a scintillator frame, with the scintillator embedded in the central axis of the scintillator frame. The optical focusing group includes a reflective lens, a reflector cup, and a focusing lens. The reflector cup is a smooth focusing cup. A single-sided slot is opened on the center line of the reflector cup. The scintillator is located on the central axis of the reflector cup and passes through the reflector cup. The reflective lens is disposed at one end of the scintillator. The focusing lens is connected to the outlet of the reflector cup. The optical transmission assembly includes an optical fiber, an optical guide lens, and an optical fiber transmission base. The optical guide lens is connected to one end of the optical fiber and fixed on the optical fiber transmission base. The center of the optical fiber coincides with the center of the optical fiber transmission base, and the optical guide lens is located at the focal point of the condenser lens.

2. The backscattered electron scintillator detector device as described in claim 1, characterized in that, The scintillator is a scintillating crystal. Both the scintillator and the reflector are cylindrical, and the size of the reflector is equal to the end face size of the scintillator.

3. The backscattered electron scintillator detector device as described in claim 2, characterized in that, The reflector is made of aluminum alloy.

4. The backscattered electron scintillator detector device as described in claim 3, characterized in that, The focusing lens is a biconvex lens.

5. The backscattered electron scintillator detector device as described in claim 4, characterized in that, The optical fiber is a quartz optical fiber with an insertion loss of less than 0.3 dB.

6. The backscattered electron scintillator detector device as described in claim 5, characterized in that, The photoelectric conversion system includes an I / V operational amplifier. A current signal generated by an avalanche diode is converted by the I / V operational amplifier to output a voltage signal. The response time of the avalanche diode is 0.5ns.

7. The backscattered electron scintillator detector device as described in claim 6, characterized in that, The photoelectric conversion system is connected to the end face of the optical fiber.

8. The backscattered electron scintillator detector device as described in claim 7, characterized in that, The detector protective sleeve is provided with a single-sided opening, the single-sided opening and the single-sided slot are located on the same side and their center lines coincide, and the size of the single-sided opening is larger than the size of the single-sided slot.

9. A detection method using a backscattered electron scintillator detector device, comprising the backscattered electron scintillator detector device as described in any one of claims 1 to 8, characterized in that, The backscattered electron scintillator detector is installed between the industrial electron gun barrel and the electron beam processing sample stage, and is parallel to the electron beam processing sample stage and perpendicular to the incident electron beam direction.

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