UV Optical Module Coating for Adhesive Heating Control
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Solution Overview
Problem
Existing optical assemblies in the ultraviolet wavelength range face issues with unwanted changes in optical properties due to heating from absorbed radiation, leading to wavefront deformation and imaging aberrations, particularly in UV lithography and inspection systems.
Innovation Solution
The implementation of a multilayered adhesive protection coating that is highly reflective and slightly absorbent at the operating wavelength, with specific layer materials and thicknesses to manage reflection, transmission, and absorption, and optionally incorporating anti-reflection or diffractive structures to minimize radiation impact on the optical element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer adhesive protection coating is used, then the structure is simple and manufacturing is easier, but it cannot simultaneously achieve high reflection at operating wavelength and sufficient transmission at curing wavelength
Solution Approach 1:
The adhesive protection coating is divided into multiple layers, each with specific optical properties. The multilayer structure includes at least a first layer and a second layer with different refractive indices and thicknesses, allowing each layer to contribute differently to the overall optical performance at various wavelengths
Solution Approach 2:
The patent optimizes specific parameters including layer thicknesses (d1, d2), refractive indices (n1, n2), and material compositions to achieve the desired wavelength-dependent optical performance. By adjusting these parameters, the coating achieves high reflection at operating wavelength while maintaining transmission at curing wavelength
2Reliability
If the adhesive protection coating has high absorption at operating wavelength, then radiation damage to adhesive is reduced, but unwanted heating of optical element occurs causing wavefront deformation
Solution Approach 1:
The coating structure is designed with spatially varying properties - the first and second layers have different thicknesses and refractive indices created locally. This local variation in optical properties allows the coating to reflect radiation away from the adhesive (protecting it) while minimizing heat absorption by the optical element
Solution Approach 2:
The patent converts the potentially harmful absorbed radiation into beneficial reflection. By designing the multilayer structure with specific optical interference properties, incoming radiation that could cause heating is instead reflected constructively, protecting both the adhesive from degradation and the optical element from thermal damage
3Reliability
If layer thicknesses are optimized for maximum reflection at operating wavelength, then adhesive protection is improved, but transmission at curing wavelength may be insufficient for proper adhesive curing
Solution Approach 1:
The patent carefully selects and optimizes the thickness parameters (d1, d2) of different layers to achieve the desired wavelength-dependent performance. The first layer thickness d1 and second layer thickness d2 are specifically chosen to create constructive interference for reflection at operating wavelength while maintaining adequate transmission at curing wavelength
Solution Approach 2:
Different layers are assigned different thicknesses and optical properties tailored to their specific functions. The first layer is optimized for one aspect of the optical performance while the second layer addresses another, allowing simultaneous satisfaction of both protection and curing requirements
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 solution effectively prevents unwanted heating and radiation damage to the optical elements, maintaining imaging quality by minimizing absorption and reflection at the operating wavelength while ensuring adequate transmission for adhesive curing, thus extending the adhesive's lifetime and maintaining optical performance.
Implementation Method 1
the adhesive protection coating is of a multilayered design and is highly reflective and slightly absorbent at the operating wavelength
Implementation Method 2
the adhesive protection coating is of a multilayered design and is highly reflective and slightly absorbent at the operating wavelength
Implementation Method 3
the optical element is adhesively bonded to the holder by adhesive that is curable by irradiation at a curing wavelength in the ultraviolet wavelength range
Data Source
AI summary
This disclosure relates to an optical module comprising an optical element for a working wavelength range in the ultraviolet wavelength range and a holder, wherein the optical element is bonded to the holder by irradiation of an adhesive curable at a curing wavelength range in the ultraviolet wavelength range, and wherein the module has a protective adhesive coating, wherein the protective adhesive coating is multi-layered and is highly reflective and slightly absorbent in the working wavelength range. Furthermore, an optical module is proposed in which the adhesive protective coating that absorbs at the working wavelength has an anti-reflective coating, as well as an optical module that has a diffractive structure in the region of the adhesive.