Reflective Optics Cooling Layout for Uniform Mirror Heat Removal
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Solution Overview
Problem
Existing cooling systems for reflective optics in high average power lasers suffer from inadequate cooling efficiency, leading to optical aberrations and degradation due to thermal effects, particularly in vacuum environments and high power applications.
Innovation Solution
A two-stage cooling system comprising an intermediate chamber filled with thermally conductive fluid and a heat sink with integrated channels for a heat-transfer fluid, ensuring uniform heat distribution and minimizing thermal gradients, applicable to both fixed and deformable mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling channels are integrated within the mirror thickness or against the rear surface, then cooling efficiency is improved, but optical quality deteriorates due to thermal footprint and manufacturing complexity increases
Solution Approach 1:
The cooling system is segmented into separate functional components: a cooling plate with channels positioned away from the optical surface, and a mirror substrate. This segmentation allows the cooling function to be performed effectively without compromising the optical quality of the mirror surface, as the thermal footprint is isolated to the cooling plate rather than the optical path.
Solution Approach 2:
A thermally conductive intermediate layer or mounting structure is introduced between the cooling channels and the mirror. This intermediary allows heat to be conducted away from the mirror while preventing direct thermal interference with the optical surface, thus maintaining both cooling efficiency and optical precision.
2Loss of energy
If cooling liquid is pumped through channels on the rear side of the mirror, then heat removal is improved, but dynamic optical defects appear due to pumping pulsations
Solution Approach 1:
The pumping mechanism and associated pulsations are extracted from the immediate vicinity of the mirror. The cooling plate is designed with channels that can be fed by a steady-flow reservoir or damping chamber, separating the mirror from the dynamic pumping action. This eliminates the transmission of mechanical pulsations to the mirror while maintaining effective heat removal through the cooling fluid.
3Device complexity
If natural convection cooling with ambient air is used, then system complexity is reduced, but cooling effectiveness becomes insufficient for high average power lasers
Solution Approach 1:
The system transitions from air convection to liquid hydraulic cooling. A cooling plate with channels is positioned adjacent to or in contact with the mirror rear surface, allowing efficient heat removal through liquid circulation. This hydraulic approach provides superior cooling effectiveness for high power applications while maintaining relatively simple system architecture.
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 system effectively maintains optical quality by uniformly distributing heat across the mirror surface, reducing deformations and optical aberrations, while being adaptable to various mirror shapes and powers, and avoiding pressure fluctuations that affect the mirror's geometry.
Implementation Method 1
an intermediate chamber (6) filled with a thermally conductive fluid (7)
Implementation Method 2
a heat sink (3) made of a material with good thermal conductivity
Implementation Method 3
The system effectively maintains optical quality by uniformly distributing heat across the mirror surface, reducing deformations and optical aberrations
Data Source
AI summary
Reflective optics for transporting, transforming or correcting a light beam in particular of the laser type, including a mirror receiving the light beam, a primary cooling circuit formed by an intermediate chamber of thermally conductive fluid arranged against the mirror at the rear thereof, and a secondary cooling circuit formed by a thermal heat sink arranged against the intermediate chamber of thermally conductive fluid, the heat sink being either in the form of a cold mass cooled by convection or conduction, or in the form of a plate made from a material with good thermal conductivity, the heat sink having a size and a shape equivalent to those of the reflective optics.