Confocal Chromatic Sensor With Separate Beam Emitter And Detector
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Solution Overview
Problem
Confocal chromatic sensors with high numeric aperture requirements for lenses are not easily accommodated in many system environments due to the need for large diameter lenses and short focal distances, limiting their applicability in determining displacement and position with high precision.
Innovation Solution
A confocal chromatic sensor system that emits a multichromatic beam with different wavelengths having distinct focal lengths, allowing a separate beam detector to determine the prevalent wavelengths and calculate the relative position of a sample, thereby enabling precise distance measurement without the need for high numeric aperture lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high numeric aperture lenses are used to accept light reflected at angles, then measurement precision is improved, but device complexity and size increase due to large diameter lenses and short focal distances
Solution Approach 1:
The patent segments the optical path into two separate systems: a light source system that emits multichromatic light through a diffuser, and a detection system that collects reflected light at a different location. This segmentation eliminates the need for a single complex high-NA lens, allowing each subsystem to use simpler optics while maintaining measurement precision through the confocal chromatic arrangement.
Solution Approach 2:
The patent introduces a diffuser as an intermediary element between the light source and the sample. This diffuser spreads the multichromatic light into multiple wavelengths that travel along different paths, enabling the system to achieve high measurement precision without requiring the detector to be positioned at the exact focal point of a high-NA lens.
2Measurement precision
If large diameter lenses with short focal distances are used, then measurement precision is improved, but ease of operation deteriorates due to difficulty in accommodating such lenses in many system environments
Solution Approach 1:
The patent employs a confocal chromatic detection scheme where the system dynamically adapts to different sample distances by analyzing the spectral distribution of reflected light. Instead of requiring fixed-position high-NA lenses, the system uses a diffuser-based multichromatic light source combined with spectral analysis to achieve precise distance measurement, making the system more adaptable and easier to integrate into various environments.
Solution Approach 2:
The patent changes the operational parameters from relying on fixed geometric optics (high-NA lens focal lengths) to using spectral parameter analysis. By measuring the spectrum of reflected multichromatic light and identifying peak wavelengths, the system determines sample distance without requiring precise mechanical positioning of large lenses, thereby improving ease of operation and system integration.
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 allows for precise determination of sample position and distance with reduced lens size and focal length requirements, enhancing the system's versatility and applicability in various environments, including charged particle beam systems.
Implementation Method 1
the beam emitter is configured such that light of different wavelengths within the multichromatic beam have different corresponding focal lengths
Implementation Method 2
detects a portion of the multichromatic beam that is reflected by the surface
Data Source
AI summary
Confocal chromatic sensor systems for determining position of a sample include a beam emitter that emits a multichromatic beam incident on a surface of a sample, and a beam detector that is separate from the beam emitter and which detects a portion of the multichromatic beam reflected by the surface. The beam emitter is configured such that light of different wavelengths within the multichromatic beam have different corresponding focal lengths. The systems can include a memory storing computer readable instructions that cause a processing unit to determine which wavelength(s) are most prevalent in the detected portion of the multichromatic beam, and then determine the distance between the surface and the beam emitter based on the wavelength(s). When the surface is a sample within a charged particle beam system, a focus of the charged particle beam system or a sample position may be adjusted based on the position of the sample.