Multipass Cell Using Spherical Mirrors for Dense Spot Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical multipass cell configurations face limitations in creating dense spot patterns without significant overlap, leading to inefficient use of mirror surface area and increased costs due to high precision requirements for astigmatic mirrors, while spherical mirror-based designs suffer from beam skew and scattering issues.
Innovation Solution
The use of direct ray tracing techniques with artificial intelligence-based optimization to simulate and create intricate, non-overlapping spot patterns on spherical mirrors, eliminating thin lens and paraxial approximations, allowing for the design of multipass cells with high spot density and efficient mirror utilization using simple plano-concave substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spherical mirrors are used to create dense spot patterns, then the number of spots increases and optical path length extends, but beam skew and scattering occur that degrade beam quality
Solution Approach 1:
The patent changes the geometric parameters of the spherical mirrors, specifically using mirrors with different radii of curvature rather than identical mirrors. This parameter modification allows the beam to maintain its quality while still achieving dense spot patterns and extended optical path length, resolving the contradiction between productivity and reliability.
2Manufacturing precision
If astigmatic mirrors are used to prevent spot overlap, then spot patterns remain separated, but manufacturing costs increase due to high precision requirements
Solution Approach 1:
The patent replaces expensive astigmatic mirrors with simpler spherical mirrors that have different radii of curvature. These spherical mirrors are easier and cheaper to manufacture while still achieving the desired spot pattern separation through their geometric configuration, eliminating the need for high-precision astigmatic mirror fabrication.
Solution Approach 2:
By changing from identical spherical mirrors to spherical mirrors with different radii of curvature, the patent achieves spot pattern separation without requiring the high manufacturing precision of astigmatic mirrors. This parameter modification allows use of standard spherical mirror fabrication processes, reducing costs significantly.
3Stability of the object's composition
If concave mirror surfaces are used to refocus the beam, then beam divergence is prevented, but spot overlap occurs that creates interference etalon fringe patterns
Solution Approach 1:
The patent modifies the geometric parameters of the concave spherical mirrors by using different radii of curvature for the two mirrors. This parameter change allows the beam to be refocused at each bounce while the asymmetric configuration prevents the spots from overlapping, thereby eliminating interference fringe patterns while maintaining beam focus stability.
4Measurement precision
If the number of mirror bounces is increased to extend optical path length, then detection sensitivity improves, but the physical size of the instrument increases
Solution Approach 1:
The patent uses spherical mirrors with different radii of curvature to create a three-dimensional spot pattern distribution on the mirror surfaces. This dimensional approach allows the beam to traverse a longer optical path through multiple bounces within a compact physical configuration, achieving high detection sensitivity without proportionally increasing instrument size.
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 approach results in dense, circular spot patterns that fill a significant portion of the mirror surface, increasing optical path length while reducing fabrication costs and minimizing beam skew, thereby enhancing the sensitivity and portability of gas detection instruments.
Implementation Method 1
an incoming light beam will reflect multiple times between the first mirror element and the second mirror element, creating a spot pattern of locations where the beam impinges the reflecting surface
Implementation Method 2
These multipass cells necessarily avoid having the mirror bounce spot locations overlap, since scattered light from each spot can reflect into the overlapped spot's beam direction, causing an interference etalon fringe pattern. These cells also generally use concave mirror surfaces to refocus the beam on each bounce, preventing the laser beam from diverging over the long optical path.
Data Source
AI summary
A technique for designing a multipass optical cell utilizes an iterative artificial intelligence-based optimization process based upon evaluation of direct ray tracing with mirrors simulated as having true spherical surfaces (i.e., defined as a “thick lens”) to identify particular cell configurations that result in creating spot patterns which fill a significant portion of the surface of each mirror without significant spot overlap. This technique allows the use of relatively simple, low-cost spherical mirrors while providing the desired dense spot patterns.