Thermo-Optical Ground Plane for Low-Flow Laser Cooling
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Solution Overview
Problem
Conventional thermal management systems (TMS) for high energy laser systems are bulky and heavy, primarily due to the high flowrate and pressure drop requirements of coolant channels, making them impractical for mobile platforms.
Innovation Solution
A thermo-optical ground plane with an evaporation chamber and low-flowrate coolant channels that utilize a porous medium to spread heat over a larger surface area, reducing the need for high coolant flow and pressure, combined with a diode pump module that integrates optical elements for efficient heat dissipation and optical power combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional micro or mini-channel coolers are used to remove heat from diode laser devices, then heat removal efficiency is improved, but system size and weight increase significantly
Solution Approach 1:
The patent employs phase change material (paraffin wax) that undergoes phase transition from solid to liquid to absorb and store heat energy. This phase transition mechanism enables efficient heat removal without requiring high flowrate coolant pumps and complex micro-channel structures, thereby reducing system weight while maintaining heat removal effectiveness.
Solution Approach 2:
The patent extracts the heat removal function from the traditional coolant circulation system and implements it through a passive phase change heat storage system. By separating the heat absorption function (performed by phase change material) from the heat transport function, the system eliminates the need for heavy high-flowrate pumps and complex cooling channels, significantly reducing system weight.
2Temperature
If high flowrate coolant circulation is used to remove heat, then heat dissipation performance is improved, but pressure drop across coolant channel increases
Solution Approach 1:
The phase change material absorbs heat through melting, which is a phase transition process. This passive heat absorption mechanism eliminates the need for high flowrate coolant circulation, thereby avoiding the associated high pressure drops across coolant channels while maintaining effective heat dissipation performance.
3Temperature
If conventional TMS with high flowrate coolant pumps is used, then heat removal capability is improved, but system size increases
Solution Approach 1:
The patent uses phase change material to provide passive heat removal capability. This approach eliminates the need for large high-flowrate coolant pumps and extensive coolant channel networks, significantly reducing system size while maintaining adequate heat removal capability for the diode laser device.
Solution Approach 2:
The patent extracts the active pumping function from the thermal management system and replaces it with a passive phase change heat storage system. This extraction of the active cooling mechanism eliminates the need for large pump components and complex coolant circulation infrastructure, thereby reducing overall system 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
The system achieves efficient cooling with a significantly reduced size and weight, enabling high energy laser systems suitable for mobile platforms by minimizing coolant flowrate and pressure drop while maintaining optical performance.
Implementation Method 1
the evaporation chamber comprising a porous medium to hold the working fluid
Implementation Method 2
the evaporation chamber and the first plate are in thermal communication to transfer heat from the evaporation chamber to the first surface area of the first plate
Implementation Method 3
the channel is configured to receive and circulate a coolant at a predetermined flowrate... to transfer heat from the evaporation chamber to the circulating coolant
Implementation Method 4
the channel positioned adjacent to and in thermal communication with the evaporation chamber to transfer heat from the evaporation chamber to the circulating coolant
Data Source
AI summary
A thermo-optical ground plane includes a plate configured to mount a diode laser device defining a first surface area, an evaporation chamber in thermal communication with the plate, and a channel defined in thermal communication with the evaporation chamber. The channel is configured to receive and circulate a coolant fluid at a predetermined flowrate. The evaporation chamber is configured to receive a working fluid. The inner walls of the evaporation chamber define a second surface area that is greater than the first surface area of the diode laser device. The plate comprises beam shaping and folding optics for collimating and focusing the light from the diode laser device on an optical fiber. Light from a plurality of thermo-optical ground planes is combined on a single optical fiber. The structure enables cooling with exceptionally low coolant flowrate while also maintaining small specific volume and small specific weight.