Photocathode Electron Gun Alignment via Beam Blocking Feedback
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Solution Overview
Problem
There is no known method to verify misalignment of an electron beam emitted from a photocathode-equipped electron gun, which is crucial for ensuring proper alignment with the optical axis of electron optics in devices like electron microscopes and free electron laser accelerators.
Innovation Solution
The solution involves an electron gun configuration with an intermediate electrode, an electron beam shielding member, a measurement unit, and an electron beam emission direction deflector, which together allow for the verification of misalignment by measuring the intensity of the electron beam blocked by the shielding member and adjusting its emission direction to determine alignment with the designed emission center axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automated alignment methods are used for thermionic emission type electron guns, then alignment efficiency is improved, but these methods cannot be applied to photocathode-equipped electron guns
Solution Approach 1:
The patent introduces an intermediate electrode positioned between the photocathode and anode as a mediator to enable alignment verification. This intermediate electrode, combined with the electron beam shielding member and measurement unit, creates a detection system that adapts automated alignment methodology to work with photocathode-equipped electron guns, resolving the incompatibility between existing automated methods and photocathode technology.
2Ease of operation
If manual alignment operation is performed, then flexibility is maintained, but alignment time and labor intensity increase
Solution Approach 1:
The patent implements a feedback mechanism where the measurement unit detects the intensity of electron beams blocked by the shielding member, and this information is fed back to determine whether the electron beam emission axis is misaligned. This automated feedback system reduces alignment time while maintaining operational flexibility, allowing the system to automatically verify alignment status without requiring continuous manual intervention.
3Measurement precision
If alignment verification capability is added to photocathode electron guns, then alignment accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the electron gun into distinct functional components: the intermediate electrode, electron beam shielding member, and measurement unit. This segmentation allows each component to perform its specific function in the alignment verification process while maintaining modularity, thereby improving measurement precision without excessively increasing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables accurate verification and alignment of the electron beam emitted from a photocathode, ensuring optimal performance and alignment with the optical axis of electron optics in various devices.
Implementation Method 1
an electron gun equipped with a photocathode... can emit a bright, sharp electron beam by irradiating the photocathode with excitation light
Implementation Method 2
an electron beam shielding member that can block a part of an electron beam
Data Source
Figure 1~2
Figure 3A~4
Figure 5A~5C
AI summary
An object is to provide an electron gun that makes it possible to verify whether or not an electron beam emitted form a photocathode is misaligned from a designed emission center axis. The object can be achieved by an electron gun including: a light source; a photocathode configured to emit an electron beam in response to receiving light from the light source; and an anode. The electron gun includes an intermediate electrode arranged between the photocathode and the anode, an electron beam shielding member configured to block a part of an electron beam, a measurement unit configured to measure an intensity of an electron beam blocked by the electron beam shielding member, and an electron beam emission direction deflector arranged between the anode and the electron beam shielding member and configured to change a position where an electron beam that passed through the anode reaches the electron beam shielding member. The intermediate electrode has an electron beam passage hole through which an electron beam emitted from the photocathode passes through, and a drift space is formed in the electron beam passage hole such that, when an electric field is generated between the photocathode and the anode by application of a voltage, effect of the electric field can be disregarded.