Raman Microscope Uniform Illumination via Dynamic Scanning
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Solution Overview
Problem
Conventional Raman microscopes face challenges in achieving high-accuracy measurements due to non-uniform illumination and speckle noise, making it difficult to perform both fast and accurate measurements.
Innovation Solution
An optical microscope design that includes a laser light source, scanners for directional scanning, a beam splitter for wavelength separation, a spectroscope with an entrance slit, and a two-dimensional array photodetector, along with a diaphragm for uniform illumination and a dichroic mirror for stray light absorption, enables high-accuracy spectral measurement in a short period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser light is changed into linear light by a cylindrical lens to shorten measurement period, then productivity is improved, but measurement precision deteriorates due to non-uniform illumination and speckle noise
Solution Approach 1:
The patent divides the illumination approach into two independent scanning directions (first direction and second direction) rather than using a single cylindrical lens for line illumination. This segmentation allows uniform point-by-point scanning while maintaining fast measurement through efficient path coverage.
Solution Approach 2:
The patent employs dynamic scanning control where the light beam is actively scanned across the sample in a predetermined path using scanners. This dynamic approach replaces static line illumination with adaptive point scanning, enabling uniform illumination while maintaining measurement speed through optimized scanning trajectories.
2Productivity
If highly coherent laser light is used to illuminate the sample, then productivity is improved through efficient light delivery, but measurement precision deteriorates due to speckle noise from scattered light interference
Solution Approach 1:
The patent uses dynamic scanning to move the laser beam across the sample in a predetermined path rather than illuminating the entire sample area statically. This dynamic approach maintains the efficiency of coherent laser light while reducing speckle noise effects by distributing the illumination over time and space, preventing localized interference patterns from dominating the measurement.
Solution Approach 2:
The patent introduces scanners as intermediary components that mediate between the laser light source and the sample. These scanners control the light beam's position and movement, enabling precise delivery of coherent light while managing the spatial distribution to minimize speckle noise interference in the detected signal.
3Device complexity
If the sample is illuminated non-uniformly with Gaussian intensity distribution, then device complexity is reduced by using simple laser sources, but measurement precision deteriorates due to illumination unevenness
Solution Approach 1:
The patent employs dynamic scanning to achieve uniform effective illumination without modifying the laser source itself. By scanning the Gaussian beam across the sample in a predetermined path with appropriate timing and overlap, the system creates uniform time-averaged illumination while maintaining the simplicity of using a standard laser source.
Solution Approach 2:
The patent uses periodic scanning motion where the light beam repeatedly traverses the sample area in a controlled manner. This periodic action, with proper scan parameters and overlap, distributes the Gaussian intensity profile uniformly across the illuminated region over time, achieving uniform illumination without complex optical elements.
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
The design allows for high-accuracy spectral measurement in a short period by ensuring uniform illumination and minimizing stray light interference, thereby overcoming the limitations of conventional Raman microscopes.
Implementation Method 1
a beam splitter provided in an optical path between the first scanner and the sample and separating an outgoing light from the incident light beam incident on the sample, the outgoing light exits from the sample toward the objective lens with a wavelength different from a wavelength of the incident light beam incident on the sample from the laser light source
Implementation Method 2
a spectroscope having an entrance slit extending along an direction corresponding to the first direction on an incident side of the spectroscope where the outgoing light separated by the beam splitter is focused and incident; and a two-dimensional array photodetector detecting the outgoing light dispersed by the spectroscope
Implementation Method 3
an objective lens condensing the light beam deflected by the first scanner on the sample
Data Source
AI summary
An optical microscope according to a first embodiment of the present invention includes: a laser light source; a Y-directional scanning unit moving the light beam in a Y direction; an objective lens; a X-directional scanning unit moving the light beam in a X direction; a beam splitter provided in an optical path from the Y-directional scanning unit to the sample, and separating outgoing light out of the light beam incident on the sample, which exits from the sample toward the objective lens from the light beam incident on the sample from the laser light source; a spectroscope having an entrance slit extending along the Y direction and spatially dispersing the outgoing light passed through the entrance slit in accordance with a wavelength of the light; and a detector detecting the outgoing light dispersed by the spectroscope.