Optical Multipass Cell Using Tilted Convex Lens
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Solution Overview
Problem
Conventional optical multipass cells that deform concave mirrors to increase reflection require cooling mechanisms, leading to size and cost issues, and are prone to dew condensation and frost formation, which attenuate laser beams and degrade performance.
Innovation Solution
A compact and cost-effective optical multipass cell design that uses a convex lens tilted relative to the concave mirrors to increase the number of laser reflections without a cooling mechanism, forming a Lissajous spot pattern and enhancing the optical path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If concave mirrors are cooled to deform the reflection surface and increase the number of reflections, then the optical path length is increased, but the device size increases and cost increases due to the cooling mechanism
Solution Approach 1:
The patent changes the physical state of the concave mirrors from cold to warm temperature, eliminating the need for cooling mechanisms. By controlling the temperature parameter (maintaining mirrors at temperatures above dew point), the system achieves mirror deformation for increased reflections without requiring complex cooling infrastructure, thus resolving the contradiction between optical path length and device complexity
Solution Approach 2:
The patent extracts and removes the cooling mechanism from the optical multipass cell system. By taking out the cooling component entirely and replacing it with a heating or temperature control approach, the system achieves the desired mirror deformation while significantly reducing device complexity and eliminating components that cause dew condensation and frost formation
2Length of stationary object
If concave mirrors are cooled to increase the number of reflections, then the optical path length is increased, but dew condensation and frost formation occur on the mirror surfaces causing laser beam attenuation
Solution Approach 1:
The patent applies preliminary anti-action by pre-heating or maintaining the concave mirrors at temperatures above the dew point before introducing the laser beam. This preventive measure counteracts the tendency for dew condensation and frost formation, ensuring that the mirror surfaces remain clear and free from harmful condensates that would attenuate the laser beam, thus resolving the contradiction between optical path length and harmful environmental factors
3Productivity
If the size of the container is increased to accommodate cooling mechanisms, then the number of reflections can be increased, but the device becomes large and expensive
Solution Approach 1:
The patent changes the temperature parameter of the concave mirrors from cold to warm, which eliminates the need for large cooling mechanisms. This parameter change allows the system to achieve high numbers of reflections (200-1000 times) within a compact container volume, resolving the contradiction between productivity (number of reflections) and container size by using thermal parameter control instead of mechanical cooling infrastructure
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 a significant increase in the number of laser reflections, reducing costs and eliminating the need for cooling, while maintaining performance by preventing dew and frost formation, thus improving the photoreaction rate and optical path length.
Implementation Method 1
a convex lens 9 is arranged on the optical path of the laser beam L to be multiply reflected between the concave mirrors 5 and 7, and the center of the convex lens 9 is positioned at a position inclined by a predetermined angle with respect to the central axis C1 of the concave mirrors 5 and 7
Implementation Method 2
laser light is introduced between the spherical mirrors, and incident light is multiply reflected between the opposing spherical mirrors
Data Source
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AI summary
An object of the present invention is to provide an optical multipass cell that is compact and low cost, does not require the installation of a cooling mechanism around the mirror, and can increase the number of reflections of laser light, and the present invention provides an optical multipass cell comprising a container (3) to which a sample gas is supplied and a pair of concave mirrors (5 and 7) arranged so as to face each other inside the container (3), a laser beam is incident into the container (3), and the laser beam is multiply reflected between the concave mirrors (5 and 7), wherein at least one convex lens (9) is arranged on the optical path of the laser beam that is multiply reflected between the pair of concave mirrors (5 and 7) so that the central axis (C2) thereof is inclined with respect to the central axis (Ci) of the concave mirrors (5 and 7), and an acute angle formed by the central axis (C2) of the convex lens (9) and the central axis (Ci) of the concave mirrors (5 and 7) is equal to or less than a critical angle when the laser beam is emitted from the convex lens (9).