Elastic Intermediate Layer Reduces Thermal Distortion in Plastic Beam Shaping Elements
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Solution Overview
Problem
Micro optical beam shaping elements made of plastic, when bonded to substrates with lower thermal expansion coefficients, experience significant dimensional distortions due to thermal expansion, leading to optical function degradation at elevated temperatures.
Innovation Solution
Incorporating an elastic intermediate layer with specific Young's Modulus, Poisson's ratio, and coefficient of thermal expansion between the beam shaping element and the substrate, or using a base layer with a larger footprint, to reduce mechanical constraint and thermally induced distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the beam shaping element is bonded directly to the substrate, then the manufacturing cost is reduced and the structure is simplified, but the lens experiences significant dimensional distortions and shear stresses at elevated temperatures due to CTE mismatch
Solution Approach 1:
An elastic intermediate layer is introduced between the plastic lens and the substrate. This intermediate layer has a higher CTE than the substrate and lower CTE than the lens, acting as a buffer that absorbs thermal expansion differences. The layer reduces shear stresses at the lens-substrate interface while allowing direct bonding manufacturing, thus resolving the contradiction between manufacturing simplicity and optical precision.
2Ease of manufacture
If the beam shaping element is made of plastic material, then the manufacturing cost is significantly reduced compared to glass, but the lens becomes more susceptible to thermal distortion due to higher CTE
Solution Approach 1:
The elastic intermediate layer protects the plastic lens from thermal stresses caused by CTE mismatch with the substrate. This allows the use of cost-effective plastic materials while maintaining optical reliability at elevated temperatures through stress reduction rather than material substitution.
Solution Approach 2:
The patent changes the mechanical parameters of the lens-substrate system by introducing an intermediate layer with specific elastic properties (Young's modulus 2-600 MPa, Poisson's ratio 0.2-0.5). These parameter changes allow the plastic lens to accommodate thermal expansion without exceeding stress thresholds that would cause optical degradation.
3Stability of the object's composition
If the lens is mechanically constrained at the substrate interface, then the structural stability is improved, but shear stresses increase at elevated temperatures causing dimensional distortion
Solution Approach 1:
The elastic intermediate layer acts as a flexible film between the rigid substrate and lens. This flexible layer allows for thermal expansion accommodation through elastic deformation, reducing shear stresses while maintaining structural stability through continuous mechanical contact.
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 elastic intermediate layer or base layer minimizes shear stress and deformation, maintaining optical integrity by reducing thermal distortions and maintaining the focal length stability of the beam shaping elements.
Implementation Method 1
the difference in CTE between the two materials can give rise to deleterious shear stresses in the higher-CTE plastic lens
Implementation Method 2
The elastic intermediate layer has a Young's Modulus in a range of 2-600 MPa and a Poisson's ratio in a range of 0.2-0.5
Implementation Method 3
These shear stresses engender significant dimensional distortions in the plastic lens
Data Source
AI summary
According to embodiments of the present invention, an apparatus comprising a beam shaping element (lens) is provided. The apparatus comprises a substrate; a beam shaping element; and an elastic intermediate layer disposed between, and in contact with, the substrate and the beam shaping element, wherein the elastic intermediate layer has a Young's Modulus in a range of 2-600 MPa and a Poisson's ratio in a range of 0.2-0.5. Techniques for reducing thermal distortion of lens are described.