Mass Spectrometer Laser Beam Shaping for Uniform Ionization
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Solution Overview
Problem
Conventional mass spectrometers face inefficiencies in analyzing substances due to non-uniform ionization and overlapping laser beam irradiation regions, leading to low sample use efficiency and potential substance omission in imaging mass spectrometry.
Innovation Solution
A mass spectrometer with a laser beam shaping unit that forms a rectangular laser beam irradiation region, allowing complete plane tiling without gaps or overlaps, and a position controller to adjust the sample stage movement for precise alignment, ensuring uniform ionization across the analysis target region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a circular or elliptical laser beam irradiation region is used, then the laser beam can be easily focused, but it cannot completely tile the plane, resulting in non-uniform ionization and sample waste
Solution Approach 1:
The circular or elliptical laser beam irradiation region is divided into multiple rectangular regions through the optical system. By segmenting the beam profile, the patent enables complete plane tiling with rectangular pixels, eliminating gaps and overlaps while maintaining easy laser focusing capability.
Solution Approach 2:
The patent changes the spatial distribution parameters of the laser beam by introducing an amplitude mask with a specific transmission function. This transforms the beam intensity profile from circular/elliptical to rectangular, allowing perfect tiling of the analysis region while preserving the original laser focusing advantages.
2Ease of operation
If the laser beam irradiation region does not match the pixel shape, then the association between irradiation region and pixel becomes complex, but changing the beam shape to rectangular simplifies this association
Solution Approach 1:
The patent modifies the intensity distribution parameter of the laser beam using an amplitude mask, transforming the beam profile from circular/elliptical to rectangular. This parameter change makes the irradiation region shape match the pixel shape, greatly simplifying the association between them while the optical system remains relatively simple.
3Reliability
If overlapping laser beam irradiation regions are used to ensure complete coverage, then no substance is omitted, but ion intensity becomes non-uniform and sample use efficiency decreases
Solution Approach 1:
The patent segments the analysis region into non-overlapping rectangular areas that perfectly tile the plane. Each rectangular region corresponds to one pixel, ensuring complete coverage without overlap, thus maintaining both substance detection completeness and high sample use efficiency.
Solution Approach 2:
The patent creates uniform irradiation conditions across all pixels by using rectangular beam regions that exactly match pixel boundaries. This equipotential approach ensures that each pixel receives the same amount of laser energy, producing uniform ion intensity throughout the analysis region.
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 enables high-sensitivity analysis with improved sample use efficiency, avoiding non-uniform ion intensity and substance omission, and simplifies the association between laser beam positions and mass spectrometry results.
Implementation Method 1
an ion source capable of irradiating a solid sample with a laser beam to desorb a substance in the sample
Implementation Method 2
ionize the substance or to simultaneously perform the desorption and the ionization of the substance in the sample
Data Source
AI summary
An aperture member including an opening having a predetermined shape and an image forming optical system having a short focal length are disposed at predetermined positions between a laser emitter and a sample, and a substantially square laser beam irradiation region is formed by reducing and forming an image of the opening shape on the sample. The aperture member and the image forming optical system are movable in an optical axis direction, and a size of substantially square laser beam irradiation region on the sample is variable. The size of the laser beam irradiation region is adjusted to a size of a unit attention region in an analysis target region on the sample, and a step width of scanning for moving the laser beam irradiation position is also adjusted to the size of the unit attention region.