Spectrometer Normal Viewing with Reflective Optical Element
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Solution Overview
Problem
Current surface analysis spectrometers face challenges in achieving high-quality optical imaging and sensitive spectral observations due to suboptimal sample viewing geometries, which result in poor image quality and reduced analysis sensitivity, especially when trying to balance the configuration of instrument ports in a multitechnique system.
Innovation Solution
A spectrometer design where the secondary charged particle lens arrangement focuses particles normal to the sample surface, and a light-reflecting optical element with a hole allows for simultaneous optical viewing and spectroscopic analysis without obstructing the secondary charged particles, ensuring high-quality images and sensitive particle collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the charged particle collection lens arrangement is mounted at normal to the sample surface, then the particle collection efficiency is improved, but the optical image quality deteriorates due to shadowing and focus issues
Solution Approach 1:
The patent introduces a fourth dimension (depth along the optical axis) by positioning the optical element at a distance downstream from the sample, rather than confining all components to a single plane. This allows the optical element to receive light without blocking the particle path, resolving the contradiction between particle collection and optical imaging
2Manufacturing precision
If the optical microscope is mounted at an angle to the normal to view the sample, then the optical image quality is improved, but the correspondence between optical and spectroscopic analysis areas deteriorates
Solution Approach 1:
The patent makes the optical axis and particle collection axis coincident (both normal to the sample), allowing a single geometric configuration to serve both optical imaging and particle collection functions simultaneously, eliminating the misalignment between analysis areas
3Ease of operation
If a light source is mounted at an angle to illuminate the sample, then the optical viewing is enabled, but shadows are formed that degrade image quality
Solution Approach 1:
The patent changes the illumination parameter from oblique to normal incidence, matching the optical axis direction. This parameter change eliminates shadow formation while maintaining optical viewing capability, improving image quality
4Measurement precision
If the sample height is changed to optimize particle collection, then the particle analysis sensitivity is improved, but the optical viewing position appears to move
Solution Approach 1:
The patent introduces a fixed optical element (mirror or beam splitter) as an intermediary that redirects light at a fixed position downstream. This intermediary decouples the sample height adjustment for particle collection from the optical viewing position, allowing independent optimization of both functions
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 design enables high-quality optical imaging and sensitive spectral observations, maintaining high collection efficiency while allowing normal sample viewing, thus improving the correspondence between optical and spectroscopic analysis areas and increasing the instrument's sensitivity.
Implementation Method 1
a secondary charged particle lens arrangement arranged to focus at least a proportion of the emitted secondary charged particles in a downstream direction along the first axis
Implementation Method 2
a light-reflecting optical element positioned downstream of the secondary charged particle lens arrangement and having a second axis in use substantially normal to the sample surface, the optical element being arranged to receive image light from the sample surface and to reflect that light away from the second axis
Data Source
AI summary
A spectrometer (10) for sample surface analysis by irradiation of the surface by primary particles and a corresponding method of surface analysis spectroscopy. The spectrometer (10) provides sample viewing and secondary charged particle collection substantially normal to the sample surface. A collection chamber (22) comprises a secondary charged particle lens arrangement (20) to focus the emitted particles in a downstream direction along a first normal axis (24) and thereby to define a charged particle optical crossover location (25); and a light-reflecting optical element (50) downstream of the lens arrangement and arranged to receive image light (41) and reflect it away from a second normal axis (42) for providing a viewable image of the surface. The optical element (50) is positioned at, or near to, the crossover location (25) and comprises an opening (52) therethrough, such that the focused particles pass through the opening for downstream spectroscopic analysis substantially without obstruction by the optical element.