Rotating Detector Assembly Maintains Laser Focus for LIBS Analysis
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Solution Overview
Problem
In portable analyzer devices using laser-induced breakdown spectroscopy (LIBS), the laser beam focus is not maintained consistently during analysis cycles due to movement of optical components, leading to inefficient plasma formation and reduced analysis accuracy.
Innovation Solution
A detector assembly with a rotatable element and a laser source positioned off-axis from the rotation axis, ensuring the laser beam remains focused at a predefined distance from the sample surface throughout the analysis cycle, allowing for consistent detection signal recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If optical components are moved to scan the laser beam across the sample surface, then the analysis area is increased and compositional variations are averaged, but the laser beam focus distance changes and focus is lost
Solution Approach 1:
The patent transitions from linear movement of optical components to rotational movement of the sample stage. By rotating the sample in a circular path around the stationary laser beam, the analysis area is increased while the focus distance remains constant. This dimensional change from linear to rotational motion resolves the contradiction between expanding analysis area and maintaining focus accuracy.
Solution Approach 2:
Instead of moving the laser beam across the sample surface by displacing optical components, the patent inverts the approach by keeping the laser beam stationary and rotating the sample underneath it. This inversion maintains the focus distance while still achieving coverage of a larger sample area, thereby resolving the focus loss problem.
2Reliability
If the laser beam is moved to cover an area of the sample surface, then compositional variations are averaged for more reliable analysis, but the distance between laser source and sample surface changes during the analysis cycle
Solution Approach 1:
The patent changes the motion paradigm from linear displacement to rotational movement. The sample rotates in a circular path around the stationary laser beam, ensuring that the radial distance (focus distance) remains constant while the tangential position varies to cover different sample areas. This maintains both focus distance stability and analysis reliability.
Solution Approach 2:
The patent introduces a stationary beam focusing arrangement as an intermediary element that decouples the laser beam generation from the sample positioning. The focusing arrangement remains fixed while the sample rotates, allowing independent optimization of focus stability and area coverage without compromising either analysis reliability or focus distance stability.
3Area of stationary object
If optical components are moved during analysis, then the laser beam can cover a larger sample area, but the plasma formation becomes inefficient due to out-of-focus conditions
Solution Approach 1:
The patent inverts the conventional approach by keeping the optical components stationary and rotating the sample instead. This ensures that the laser beam remains continuously in focus at the optimal distance from the sample surface, maintaining efficient plasma formation while still achieving coverage of a larger sample area through rotational movement.
Solution Approach 2:
By transitioning from linear to rotational motion, the patent enables area coverage expansion without compromising focus conditions. The rotational movement allows the sample to present different areas to the stationary focused beam, maintaining optimal plasma formation efficiency throughout the analysis cycle.
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 arrangement maintains correct laser beam focus, enhancing the accuracy and reliability of elemental composition analysis by ensuring consistent plasma formation and detection across the sample surface.
Implementation Method 1
laser-induced breakdown spectroscopy (LIBS) is widely used technique for optical emission spectroscopy
Implementation Method 2
The laser pulse is focused to the sample under study to form a plasma plume on a surface of the sample in order to cause atomization and excitation on the surface
Implementation Method 3
optical emission spectroscopy is widely employed in portable analyzer devices to determine elemental composition of the sample under study
Data Source
AI summary
According to an example embodiment, a detector assembly for use in analysis of elemental composition of a sample by using optical emission spectroscopy is provided, the detector assembly comprising a rotatable element that is rotatable about an axis and that has attached thereto a laser source for generating laser pulses for invoking optical emission on a surface of the sample, which laser source is arranged to generate laser pulses focused at a predefined distance from said axis at a predefined distance from a front end of the detector assembly, and an optical receiver for capturing optical emission invoked by said laser pulses.