Combined Incident and Scattered Light Detection for Small Particles
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Solution Overview
Problem
Existing optical particle counters struggle to efficiently detect and characterize small particles due to high cost, complexity, and sensitivity to thermal expansion and optical misalignment, leading to poor signal-to-noise ratios and missed detections.
Innovation Solution
A particle detection system that combines incident and pump beams to enhance the signal-to-noise ratio by detecting unscattered and scattered light, using interferometric methods with orthogonal or oblique angles to improve detection sensitivity and volumetric sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scattered light optical particle counters are used to detect small particles, then detection capability for small particles is improved, but signal-to-noise ratio deteriorates due to overwhelming unscattered light
Solution Approach 1:
The patent extracts only the scattered light component from the total light detected by blocking the unscattered incident light with a beam block. This allows the detector to measure only the weak scattered light signal from small particles without being overwhelmed by the strong unscattered light, thereby improving signal-to-noise ratio while maintaining detection capability.
Solution Approach 2:
The detection process is segmented into two distinct components: unscattered light (blocked) and scattered light (detected). By spatially separating these components using a beam block positioned at the detector plane, the system can independently measure scattered light intensity, which corresponds to particle presence, without contamination from the dominant unscattered light background.
2Device complexity
If conventional optical particle counters are used, then device complexity is reduced, but detection sensitivity for nanometer scale particles deteriorates
Solution Approach 1:
The patent replaces complex mechanical or optical systems (such as condensation nuclei counters or interferometric systems with multiple beams and mirrors) with a simple beam block and detector arrangement. This substitution maintains low device complexity while achieving high detection sensitivity for nanometer-scale particles through the principle of blocked incident light and detected scattered light.
3Measurement precision
If laser power is increased to detect smaller particles, then detection capability is improved, but system cost and complexity increase
Solution Approach 1:
The beam block acts as an intermediary element that enables the use of lower laser powers by eliminating the need to detect scattered light against a bright unscattered light background. By blocking the incident light, the system can use modest laser powers while still achieving high detection capability for small particles, thereby reducing system cost and complexity.
4Measurement precision
If transmission/extinction particle counters are used, then detection of particles is improved, but sensitivity to optical misalignment and thermal expansion increases
Solution Approach 1:
The patent extracts the scattered light signal while eliminating dependence on precise optical alignment by using a beam block at the detector plane. This configuration measures scattered light intensity directly without requiring complex optical paths or interferometric alignment, thereby improving reliability by reducing sensitivity to optical misalignment and thermal expansion while maintaining particle detection capability.
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
Enhances detection sensitivity and signal-to-noise ratio, allowing for faster and more accurate detection of small particles, including those missed by conventional systems, with improved volumetric sampling rates and reduced noise sensitivity.
Implementation Method 1
interference may occur between three types of light: (i) unscattered light from the incident beam, (ii) forward scattered light from the incident beam, and (iii) scattered light from the second beam
Implementation Method 2
forward-scattered light resulting from incident beam/particle interactions may be essentially coincident with and parallel to the incident beam
Data Source
AI summary
Particle detection systems and methods are disclosed. In one embodiment, a particle detection system comprises an incident beam light source that emits an incident beam, a particle interrogation zone disposed in the path of the incident beam, a photodetector disposed to detect the incident beam after passing through the particle interrogation zone, a pump beam light source for emitting a pump beam, the pump beam being targeted at the particle interrogation zone, wherein the incident beam, the pump beam, and photodetector are arranged such that the photodetector is configured to detect a combination of light from the incident beam, scattered light due to incident beam scattering in the particle interrogation zone, and scattered light due to pump beam scattering in the particle interrogation zone.