Coaxial Aspheric Mirror LIBS Optical Assembly
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Solution Overview
Problem
Current laser-induced breakdown spectroscopy (LIBS) systems face limitations in efficiently collecting and analyzing plasma emitted light due to the complexity of optical pathways and the need for precise alignment of laser and plasma light beams, which affects the detection of elemental composition and impurities.
Innovation Solution
The system employs an optical assembly with aspheric mirrors and a dichroic mirror to redirect plasma emitted light coaxially with the laser beam path, allowing for efficient collection and redirection of plasma light to a spectrometer for analysis, utilizing a Nd:YAG laser and optical fibers to maximize wavelength range detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical assemblies are used to collect plasma emitted light, then the system can detect elemental composition, but the optical pathway complexity and alignment precision requirements increase
Solution Approach 1:
The patent combines the laser beam delivery path and the plasma light collection path into a single coaxial optical pathway. The laser beam passes through the objective lens to focus on the sample, and the plasma emitted light collected by the same objective lens travels back along the same path. This merging of paths eliminates the need for separate collection optics and complex alignment mechanisms, reducing device complexity while maintaining detection sensitivity.
Solution Approach 2:
The objective lens serves multiple functions: it focuses the laser beam onto the sample during the excitation phase, and it collects the plasma emitted light during the analysis phase. This multi-functionality reduces the number of optical components needed and simplifies the overall optical assembly, addressing the contradiction between measurement precision and device complexity.
2Device complexity
If the laser beam axis is perpendicular to the plasma light collection axis, then the optical assembly is simpler, but the beam alignment precision and detection accuracy decrease
Solution Approach 1:
Instead of having the laser beam and plasma light travel along perpendicular axes as in traditional designs, the patent inverts the approach by making them travel along the same coaxial axis. The laser beam enters the objective lens, focuses on the sample, and the plasma light returns through the same lens along the same path. This inversion of the traditional perpendicular arrangement creates a coaxial system that maintains simplicity while improving alignment precision.
3Adaptability or versatility
If multiple mirrors and optical components are used to redirect plasma light, then the wavelength range detection can be extended, but the light collection efficiency and system reliability decrease
Solution Approach 1:
The patent extracts and removes the multiple mirror redirection components from the optical pathway. By using a coaxial design where the plasma light travels back through the same objective lens that focused the laser beam, the system eliminates the need for additional mirrors and redirection optics. This extraction of unnecessary components improves light collection efficiency and system reliability while maintaining broad wavelength range detection capabilities through the objective lens's inherent optical properties.
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 configuration enhances the detection of elemental composition by ensuring efficient plasma light collection and analysis, improving the sensitivity and accuracy of LIBS systems by allowing for broader wavelength range analysis from near-infrared to deep ultraviolet.
Implementation Method 1
The first aspheric mirror is configured to receive a laser beam at non-normal incidence along a first axis. The optical assembly is configured such that the first aspheric mirror directs the beam to the object for plasma spectrum analysis along a second axis
Implementation Method 2
The dichroic mirror may be configured to receive the laser beam from the second mirror
Implementation Method 3
When the laser beam is discharged it ablates a very small amount of material, in the range of nanograms to picograms, which generates a plasma plume with temperatures in excess of 100,000 K
Implementation Method 4
The laser is focused to form a plasma, which atomizes and excites samples
Implementation Method 5
LIBS makes use of optical emission spectrometry and is to this extent very similar to arc/spark emission spectroscopy
Data Source
AI summary
A device for analyzing the material composition of an object via plasma spectrum analysis includes an optical assembly having a first aspheric mirror and a second aspheric mirror. The first and second aspheric mirrors have an aspheric surface profile. The first aspheric mirror is configured to receive a laser beam at non-normal incidence along a first axis. The optical assembly is configured such that the first aspheric mirror directs the beam to the object for plasma spectrum analysis along a second axis, the second axis being different from the first axis. The plasma emitted light emitted is collected coaxially along the second axis and redirected along the first axis in the opposite direction by the first aspheric mirror. The second aspheric mirror is configured to redirect a portion of the plasma emitted light along a third axis to a spectrometer for analysis.