Photoelectron Emission Microscope Pulsed Beam Charging Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
When observing insulator samples with a photoelectron emission microscope, charging issues lead to variable contrast in photoelectron images, making it difficult to maintain a desired charged state for high-contrast imaging.
Innovation Solution
A photoelectron emission microscope system that includes an excitation optical system for irradiating the sample with excitation light, a camera for capturing photoelectrons, an image formation electron optical system with an objective lens, and an irradiation electron optical system that uses a pulsed electron beam, controlled by a unit to overlap the electron beam with the excitation light after a predetermined time, ensuring optimal charging and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sample is irradiated with excitation light to generate photoelectrons, then photoelectron image can be obtained, but charging of the insulator sample progresses causing contrast degradation
Solution Approach 1:
The patent applies periodic action by using pulsed electron beam irradiation instead of continuous irradiation. The electron beam is irradiated in periodic pulses with controlled duty cycle, allowing the sample to be recharged between pulses while maintaining the desired charged state during photoelectron emission. This periodic approach prevents excessive charging accumulation that would degrade image contrast.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting electron beam irradiation parameters including pulse width, pulse interval, and duty cycle based on the sample's charging state. The control unit modifies these parameters in real-time to maintain optimal charged state stability, thereby preserving photoelectron image contrast throughout the measurement period.
2Stability of the object's composition
If electron beam irradiation is used to neutralize charge, then charging is prevented, but photoelectron image contrast does not necessarily improve
Solution Approach 1:
The patent implements feedback control by continuously monitoring the sample's charged state and adjusting the electron beam irradiation parameters accordingly. The control unit receives information about the charging state and dynamically modifies pulse width, pulse interval, and duty cycle to maintain the desired charged state, ensuring both charging prevention and high image contrast.
Solution Approach 2:
The patent applies dynamics by making the electron beam irradiation conditions variable rather than fixed. The system dynamically adjusts irradiation parameters based on real-time charging state measurements, allowing optimal balance between charge neutralization and photoelectron emission efficiency, thereby achieving high contrast images.
3Stability of the object's composition
If continuous electron beam irradiation is applied, then charging is continuously neutralized, but secondary electron emission and sample damage increase
Solution Approach 1:
The patent uses periodic pulsed irradiation instead of continuous irradiation to reduce harmful effects. By interrupting the electron beam between pulses, the total electron dose to the sample is reduced, minimizing secondary electron emission and sample damage while still maintaining effective charge neutralization during the pulse periods.
Solution Approach 2:
The patent applies partial action by using pulsed electron beam irradiation with controlled duty cycle rather than continuous irradiation. This partial irradiation approach provides sufficient charge neutralization during pulse periods while reducing overall electron exposure, thereby minimizing harmful effects like secondary electron emission and sample damage.
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
Facilitates the acquisition of high-contrast photoelectron images by controlling the pulsed electron beam to maintain the sample's charged state, thereby stabilizing the contrast and improving image quality.
Implementation Method 1
a photoelectron emission microscope (PEEM) is an apparatus that forms an image by using photoelectrons generated by irradiating a surface of a sample with ultraviolet light or X-rays (excitation light)
Implementation Method 2
an image formation electron optical system including an objective lens configured to focus the photoelectron on a detection surface of the camera
Implementation Method 3
an irradiation electron optical system configured to irradiate the sample with a pulsed electron beam
Data Source
AI summary
Provided is a photoelectron emission microscope that facilitates acquisition of a high-contrast photoelectron image. A photoelectron emission microscope starts irradiation of a pulsed electron beam 13 performed by an irradiation electron optical system 10 in a manner of overlapping excitation light after predetermined time has elapsed since start of irradiation of a sample 4 with excitation light 2 performed by an excitation optical system 1, and starts capturing a photoelectron image performed by a camera 6 at the time of the start of the irradiation of the pulsed electron beam performed by the irradiation electron optical system or thereafter.