MEMS Spatial Light Modulators With Helium Thermal Control
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Solution Overview
Problem
Existing MEMS based spatial light modulators (SLMs) fail to handle high power lasers due to the Soret effect, where reflective metal atoms migrate, reducing reflection efficiency and shortening device life.
Innovation Solution
Enclose MEMS based SLMs in a package filled with a low molar mass and high thermal conductivity gas, such as helium or hydrogen, to enhance thermal management and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If MEMS based SLMs are exposed to high power lasers, then the laser processing capability is improved, but the reflective metal atoms migrate due to the Soret effect, reducing reflection efficiency and shortening device life
Solution Approach 1:
The patent applies this principle by filling the sealed cavity with helium gas, which creates an inert thermal environment that conducts heat away from the reflective metal surfaces. This prevents the metal atoms from migrating due to the Soret effect by maintaining a controlled thermal environment, thereby extending device lifetime while allowing high power laser operation
Solution Approach 2:
The patent uses helium gas as an intermediary medium between the high power laser and the MEMS reflective surfaces. The helium acts as a thermal conductor that mediates heat transfer, preventing direct thermal damage to the metal atoms while still allowing the laser to function at high power levels
2Power
If MEMS based SLMs are exposed to high power lasers, then the laser processing capability is improved, but the reflection efficiency decreases due to metal atom migration
Solution Approach 1:
The sealed cavity filled with helium creates an inert thermal environment that prevents metal atom migration by conducting heat away from the reflective surfaces, eliminating the harmful Soret effect while maintaining high power laser operation
Solution Approach 2:
The patent changes the thermal parameter of the environment by introducing helium gas with high thermal conductivity, which fundamentally alters the thermal field distribution and prevents the temperature gradients that cause metal atom migration
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
Improves thermal conductivity and cooling, increasing power handling capability and extending the device's lifetime by 3.5 times compared to nitrogen-filled cavities.
Implementation Method 1
a low molar mass fill gas having an atomic number of two or less and a thermal conductivity of greater than 100 milliwatts per meter kelvin (mW/(m·K))
Implementation Method 2
alignment of the mirrors is altered by electronic signals generating electrostatic forces to displace at least some of the mirrors
Implementation Method 3
an array of one or more diffractors or modulators that can control or modulate an incident beam of light
Data Source
AI summary
Microelectromechanical systems (MEMS) based spatial light modulators (SLMs) enclosed in a package filled with a gas to enhance the reliability and lifetime of the SLM, and methods for operating the same in various applications are described. Generally, the SLM includes a number of MEMS modulators, each including a number of light reflective surfaces, at least one light reflective surface coupled to an electrostatically deflectable element suspended above a substrate, and each adapted to reflect and modulate a light beam incident thereon. The package enclosing the SLM includes an optically transparent cover through which the reflective surfaces are exposed to the light beam, and a cavity is filled a low molar mass fill gas having an atomic number of two or less and a thermal conductivity of greater than 100 mW/(m·K). The SLM can include electrostatically deflectable ribbons suspended over a substrate, or a linear array of two-dimensional MEMS modulators.