Optical Rotary Joint Intermediate Layer for Return Loss Reduction
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Solution Overview
Problem
Conventional optical rotary joints and micro-optical systems suffer from high optical return loss due to reflections at collimators and parallel light-entry/exit faces, which are not adaptable to different surrounding media.
Innovation Solution
Incorporating an intermediate layer with a refractive index between the optical material and the surrounding medium, featuring a nano-structure or refractive index gradient, to reduce reflections and enable operation with various media without modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If parallel light-entry and light exit faces are used in optical rotary joints, then the structure is simple and manufacturing is easier, but optical return loss increases due to reflections at the interfaces
Solution Approach 1:
An intermediate layer with refractive index between that of the optical component and the surrounding medium is introduced at the interface. This intermediary layer reduces the refractive index mismatch, thereby minimizing reflections and optical return loss while maintaining the simple parallel face structure
Solution Approach 2:
The refractive index parameter is gradually changed across the intermediate layer, creating a gradient that transitions from the optical component's refractive index to the surrounding medium's refractive index. This gradual parameter change reduces abrupt reflections at the interface
2Loss of energy
If vapor-coated intermediate layers are applied to reduce reflections, then optical return loss decreases, but the system becomes less adaptable to different surrounding media
Solution Approach 1:
The intermediate layer is designed with a refractive index gradient rather than a fixed vapor coating. This dynamic structure allows the layer to adapt to different surrounding media by maintaining optimal reflection reduction across various refractive index environments
Solution Approach 2:
The gradient intermediate layer serves multiple functions: it reduces reflections for different surrounding media (air, oil, etc.), maintains optical signal integrity, and works with various optical components. This universal solution eliminates the need for medium-specific adaptations
3Adaptability or versatility
If perpendicular light entry is implemented to make the arrangement independent from refractive index, then adaptability to different media is improved, but optical return loss increases due to partial reflection at the transition face
Solution Approach 1:
The gradient intermediate layer acts as an intermediary between the optical component and the surrounding medium, enabling perpendicular light entry to work effectively across different media while minimizing reflections through its refractive index gradient
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 solution significantly reduces optical return loss, achieving reflectance levels below 0.0003% and allowing the systems to function effectively with different surrounding media, such as gases or liquids, while maintaining signal integrity.
Implementation Method 1
an intermediate layer on a boundary to the medium and the intermediate layer has a refractive index in a range between a refractive index of an optical material of the at least one optical constituent part which is distinct from the intermediate layer and a refractive index of the medium
Data Source
AI summary
An optical rotary joint comprises a first collimator arrangement for coupling-on first light-waveguides and a second collimator arrangement for coupling-on second light-waveguides, with the second collimator arrangement being supported to be rotatable relative to the first collimator arrangement about a rotation axis. A Dove prism is provided between the collimator arrangements as a derotating element. An intermediate layer is provided on at least one boundary face of an optical constituent part to a surrounding medium, which the intermediate layer comprises a nano-structure having a mean refractive index lying between a refractive index of a material of the optical constituent part and a refractive index of the medium of the surroundings.