Movable Diffraction Grating Thermal Isolation for Laser Modules
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Solution Overview
Problem
Movable diffraction gratings used in external resonator type laser modules face challenges in maintaining optical characteristics due to thermal deformation when the movable portion is thinned for high-speed operation with large deflection angles, as heat generated by the driving portion can cause deformation of the metal film used for diffraction.
Innovation Solution
Incorporating a coil buried within the movable portion, an insulation layer, a resin layer with a diffraction grating pattern, and a metal reflection layer on the resin layer, which helps in reducing heat transfer and promoting heat radiation, thereby minimizing thermal deformation and maintaining optical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the movable portion thickness is decreased to enable high-speed operation with large deflection angle, then the operation speed and deflection angle are improved, but the heat generated by the driving portion is easily transferred to the metal film causing thermal deformation
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the coil (driving portion) and the metal film (diffraction grating). This resin layer acts as a thermal barrier that blocks heat transfer from the coil to the metal film, while allowing the mechanical driving function to remain effective. The intermediary layer thus resolves the contradiction by protecting the temperature-sensitive metal film from thermal deformation caused by the heat-generating coil.
Solution Approach 2:
The patent employs a composite structure consisting of multiple materials with different thermal properties: the resin layer (low thermal conductivity) is combined with the metal film (high thermal conductivity) and the movable portion material. This composite construction allows the system to achieve both high-speed operation (through the mechanical properties of the metals) and thermal isolation (through the resin layer's low thermal conductivity), thereby resolving the contradiction between speed and temperature control.
2Speed
If the movable portion thickness is decreased to enable high-speed operation with large deflection angle, then the operation speed and deflection angle are improved, but the structural integrity and heat resistance are degraded
Solution Approach 1:
The resin layer serves as a protective intermediary between the driving coil and the metal film, isolating the metal film from direct thermal exposure. This protection maintains the optical characteristics of the diffraction grating even when the movable portion is thinned for high-speed operation, thereby preserving reliability while achieving improved speed performance.
Solution Approach 2:
The patent applies local quality by introducing the resin layer specifically in the region where heat transfer occurs (between the coil and metal film), while maintaining the thin overall structure of the movable portion where mechanical performance is critical. This localized modification allows the structure to have different properties in different regions: thin and flexible where needed for speed, and thermally protected where needed for reliability.
3Loss of energy
If the coil thickness is ensured to decrease resistance, then the heating of the coil is suppressed, but the overall device complexity increases
Solution Approach 1:
The patent merges the coil structure with the movable portion by burying the coil within the movable portion structure. This integration allows the coil to have sufficient thickness for low resistance and minimal heating, while the overall assembly remains a unified component rather than separate stacked elements, thus reducing device complexity.
Solution Approach 2:
The coil is nested within the movable portion structure, with the resin layer and metal film arranged in concentric or layered fashion around the coil. This nesting arrangement allows multiple functional layers to occupy overlapping spatial volumes, maximizing the use of available space and reducing the overall device footprint and complexity.
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 configuration allows for high-speed operation with large deflection angles while suppressing thermal deformation, ensuring stable optical performance and enabling efficient wavelength change for applications like gas concentration measurement.
Implementation Method 1
a coil (14) buried in the movable portion (13); a magnetic field generator (15) applying a magnetic field to the coil (14)
Implementation Method 2
an insulation layer (16) provided on a surface of the movable portion (13); a resin layer (17) provided on the insulation layer (16)
Implementation Method 3
the movable portion (13) is swung at a high speed at a resonance frequency level
Implementation Method 4
a resin layer (17) provided on the insulation layer (16) and provided with a diffraction grating pattern (35)
Data Source
AI summary
A movable diffraction grating includes: a support portion; a movable portion swingably connected to the support portion; a coil buried in the movable portion; a magnetic field generator configured to apply a magnetic field to the coil; an insulation layer provided on a surface of the movable portion; a resin layer provided on the insulation layer and provided with a diffraction grating pattern; and a reflection layer formed of a metal and provided on the resin layer to follow the diffraction grating pattern.