Light Restricting Elements for Glare Reduction in SEM
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Solution Overview
Problem
Charged particle beam apparatuses face issues with high-brightness portions on target surfaces due to the reflection of light beams, which obstruct observation, particularly in scanning electron microscopes where machining traces on sample holders cause glare.
Innovation Solution
A charged particle beam apparatus is designed with a light distribution adjustment member comprising light restricting elements placed between the target and light emitter devices, which attenuate the center intensity of each light beam, reducing glare and flattening the light distribution while maintaining overall illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a light emitter device that generates a narrowed light beam is used, then illumination efficiency is improved, but high-brightness portions (glare) are easily produced on the target surface
Solution Approach 1:
The patent applies local quality by making different parts of the light beam have different transmission characteristics. The light restricting element has a through-hole portion that transmits peripheral light and a light restricting portion that blocks center light, creating non-uniform light distribution to eliminate glare while maintaining illumination efficiency.
Solution Approach 2:
The light restricting element acts as an intermediary between the light emitter device and the target. It modifies the light beam by selectively transmitting and blocking different portions, thereby resolving the contradiction between maintaining narrow beam efficiency and preventing high-brightness glare on the target surface.
2Object-affected harmful factors
If the center part of each light beam is restricted to reduce glare, then high-brightness portions are prevented, but overall illumination of the target may be reduced
Solution Approach 1:
The light restricting element creates local quality differences in light transmission. The through-hole portion allows peripheral light to pass through maintaining illumination, while the light restricting portion blocks only the high-brightness center part, thus preventing glare without significantly reducing overall illumination.
Solution Approach 2:
Instead of blocking the entire light beam, the patent applies partial action by restricting only the center portion that causes glare. The peripheral light that contributes to overall illumination is preserved through the through-hole portion, achieving glare reduction while maintaining adequate illumination.
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 solution effectively reduces or prevents high-brightness portions on the target surface, improving image quality by ensuring even illumination and minimizing glare, thus enhancing the observation capabilities in charged particle beam apparatuses.
Implementation Method 1
Each of the light restricting elements restricts an intensity of the center part in each of the light beams
Data Source
AI summary
An imaging device images a sample holder held by a sample stage. At a front side (target side) of the imaging device, a light emitter device array and a mask array are provided. A plurality of light beams are generated by the light emitter device array. A plurality of center parts of the plurality of light beams are masked by the mask array. A plurality of shadows produced thereby are covered by a plurality of peripheral parts of the plurality of light beams.