Optical Chamber Curtain Flow for Stable Aerosol Contamination Control
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Solution Overview
Problem
Optical particle counters and condensation particle counters face contamination issues due to particles and vapors in the aerosol flow, leading to degraded optical signals and inaccurate measurements, with existing designs like sheath flow and orthogonal filtered air flow failing to effectively prevent contamination on sensitive optical components.
Innovation Solution
A curtain flow design is implemented, using a plenum chamber and curtain-flow concentrating nozzle to create a co-axial curtain flow that surrounds the aerosol flow, minimizing contamination by containing particles and vapors within the flow stream and reducing deposition on optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sheath flow or orthogonal filtered air flow is used to protect optical components, then contamination prevention is improved, but flow disturbances occur allowing particles and vapors to deviate and deposit on optical components
Solution Approach 1:
A curtain flow is introduced as an intermediary protective layer between the aerosol flow and optical components. This curtain flow acts as a mediator that blocks contaminants without causing flow disturbances, solving the contradiction between protection and stability
Solution Approach 2:
The harmful flow disturbances are extracted and eliminated from the system by replacing traditional sheath flow or orthogonal filtered air flow designs with a curtain flow configuration that maintains stable aerosol flow while providing protection
2Object-affected harmful factors
If filtered air flow is introduced orthogonally to aerosol flow, then working fluid vapors are prevented from reaching optical components, but the filtered air flow must turn 90 degrees before merging causing non-uniform surrounding of aerosol flow
Solution Approach 1:
Instead of introducing filtered air orthogonally and requiring it to turn 90 degrees, the curtain flow is introduced parallel to the aerosol flow direction, eliminating the sharp turn and achieving uniform surrounding from the beginning
3Measurement precision
If optical chamber is cleaned frequently to remove contamination, then measurement accuracy is maintained, but instrument downtime increases
Solution Approach 1:
The curtain flow is established in advance as a preventive measure to block contaminants before they reach optical components. This preliminary protective action eliminates the need for frequent cleaning operations
Solution Approach 2:
The potentially harmful aerosol flow containing particles and vapors is converted into a beneficial system where the curtain flow configuration allows the aerosol to be contained and directed without contamination, transforming a harmful situation into a protective arrangement
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 curtain flow design significantly reduces optical contamination, ensuring accurate particle counting and sizing over extended periods without the need for frequent cleaning, thereby maintaining instrument performance and reducing downtime.
Implementation Method 1
A curtain flow design is implemented, using a plenum chamber and curtain-flow concentrating nozzle to create a co-axial curtain flow that surrounds the aerosol flow, minimizing contamination by containing particles and vapors within the flow stream
Implementation Method 2
When a particle enters the viewing volume, the particle is illuminated by the focused light-beam and scatters the light. The scattered light is collected with one or more collector lenses/and/or mirrors and is then received by a photo detector.
Implementation Method 3
a focusing nozzle is used to narrow down the aerosol flow to a small-diameter flow stream
Implementation Method 4
An intense light source (e.g., a solid-state laser diode) is shaped and focused by one or more optical lenses to form a focused light-beam (e.g., perhaps less than about 100 μm in a minor axis to as small as being diffraction limited) so that the light intensity is substantially uniform in and focused on a small viewing-volume
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Various embodiments include systems and apparatuses for reducing contamination levels within optical chambers of particle -detection instruments. In one embodiment, an apparatus to reduce contamination within an optical chamber of a particle-detection instrument is described. The apparatus includes a plenum chamber to at least partially surround an aerosol -focusing nozzle of the p article- detection instrument and accept a filtered gas flow. A curtain-flow concentrating nozzle is coupled to the plenum chamber to produce a curtain flow into the optical chamber to substantially surround an aerosol flow. Other methods and systems are disclosed.