Sample Holder for Atmospheric Pressure Secondary Electron Detection
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Solution Overview
Problem
Current charged particle observation systems, such as electron microscopes, cannot simultaneously detect transmission and secondary electrons when the sample environment is at atmospheric pressure, as diaphragms block secondary electrons, preventing their detection.
Innovation Solution
A sample holder with a minute orifice for secondary electron passage and a coil heater, along with a gas introduction nozzle and vacuum gauge, maintains atmospheric pressure around the sample while allowing secondary electron detection without adversely affecting the electron gun, using a diaphragm below the sample and positioning the charged particle passage hole to avoid direct exhaust to the electron gun.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a diaphragm is used to maintain atmospheric pressure around the sample, then the sample can be observed in atmospheric pressure environment, but secondary electrons are blocked and cannot be detected
Solution Approach 1:
The sample holder is divided into two pressure zones: the sample chamber maintained at atmospheric pressure for environmental observation, and the electron optical path maintained at high vacuum for electron transmission. This segmentation allows both atmospheric pressure sampling and electron detection to coexist without interference
Solution Approach 2:
A thin film membrane serves as an intermediary between the atmospheric pressure sample chamber and the vacuum electron optical path. This membrane allows secondary electrons generated at atmospheric pressure to pass through to the detector while maintaining the pressure differential, solving the contradiction between atmospheric pressure maintenance and secondary electron detection
2Adaptability or versatility
If gas is introduced to the sample to simulate operational environment, then dynamic change observation is enabled, but the electron gun is adversely affected
Solution Approach 1:
The system is segmented into a gas-introduced sample chamber and a vacuum-maintained electron optical path. Gas can be freely introduced into the sample chamber to simulate operational environments without affecting the electron gun, as the two regions are pressure-separated
Solution Approach 2:
The thin film membrane acts as a barrier that prevents gas molecules from reaching the electron gun while allowing secondary electrons to pass through. This intermediary structure enables gas introduction for operational environment simulation without exposing the electron gun to harmful gas exposure
3Measurement precision
If a minute orifice is used for secondary electron passage, then secondary electron detection is enabled, but the structure becomes more complex
Solution Approach 1:
The thin film membrane serves multiple functions simultaneously: it maintains the pressure differential between sample chamber and electron optical path, allows passage of secondary electrons, and acts as a physical barrier preventing gas contamination of the electron gun. This multi-functionality reduces the need for additional separate components, thereby reducing overall structural complexity despite the precision requirements
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
Enables efficient detection of secondary electrons and observation of dynamic sample changes, facilitating research in fuel cell degradation and supporting various sample types, including powders and microsamples, by controlling pressure and heating the sample.
Implementation Method 1
a coil heater for heating the sample via the orifice on a charged particle passage
Implementation Method 2
a minute orifice as a secondary electron passage
Implementation Method 3
a minute vacuum gauge for control of the pressure in the vicinity of the sample
Implementation Method 4
a structure to isolate only the surrounding of the sample, using a thin film which charged particles pass through such as a diaphragm
Data Source
AI summary
The objective of the present invention is to maintain the surrounding of a sample at atmospheric pressure and efficiently detect secondary electrons. In a sample chamber of a charged particle device, a sample holder (4) has: a gas introduction pipe and a gas evacuation pipe for controlling the vicinity of a sample (20) to be an atmospheric pressure environment; a charged particle passage hole (18) and a micro-orifice (18) enabling detection of secondary electrons (15) emitted from the sample (20), co-located above the sample (20); and a charged particle passage hole (19) with a hole diameter larger than the micro-orifice (18) above the sample (20) so as to be capable of actively evacuating gas during gas introduction.