Optical Rotary Joint with Conical Surfaces
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Solution Overview
Problem
Existing rotary transmitters for optical signals suffer from high optical return loss due to strong reflections within the device, which is exacerbated by the dependence on the refractive index of the surrounding medium and the presence of vertical surfaces that cause significant light reflection back into the waveguides.
Innovation Solution
The design incorporates two collimator arrangements that can rotate relative to each other, featuring a derotating element like a Dove prism, with conical surfaces on the collimators and matching prism elements that are inversely angled to minimize reflections. These conical surfaces reduce reflections by ensuring light is not reflected back into the collimator, and the arrangement functions independently of the medium's refractive index, using materials like glass or plastic for the adjustment elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light enters the Dove prism perpendicularly to avoid refraction dependence, then the arrangement becomes independent of the refractive index of the surrounding medium, but strong reflections occur at the vertical transition surface causing low return loss
Solution Approach 1:
The patent applies curvature by replacing vertical surfaces with conical surfaces that have an angle of 15-45 degrees relative to the axis of rotation. This conical geometry ensures that light entering the prism does so at an angle that prevents total internal reflection at the interface, thereby reducing reflection loss while maintaining independence from the refractive index of the surrounding medium.
Solution Approach 2:
The patent changes the geometric parameter of the prism interface from vertical (90 degrees) to conical (15-45 degrees). This parameter change fundamentally alters the reflection characteristics by ensuring that the angle of incidence never reaches the critical angle for total internal reflection, thus reducing reflection loss across different media.
2Ease of manufacture
If vertical surfaces are used in the optical path, then the structure is simple and easy to manufacture, but strong reflections occur inside the rotary transmitter degrading signal transmission
Solution Approach 1:
The patent replaces vertical surfaces with conical surfaces having an angle of 15-45 degrees relative to the axis of rotation. This conical geometry is still relatively simple to manufacture using standard machining techniques while fundamentally eliminating the strong reflections that occur at vertical interfaces by ensuring light always enters at a non-critical angle.
3Object-generated harmful factors
If conical surfaces are used on collimators to reduce reflections, then optical return loss is improved, but the device complexity increases due to additional adjustment elements and precise angular requirements
Solution Approach 1:
The patent introduces asymmetric conical surfaces on the collimators with specific angular ranges (15-45 degrees), breaking the symmetry of traditional vertical surfaces. This asymmetric design is tailored specifically to the optical path requirements to prevent total internal reflection, and while it adds some complexity, the conical geometry itself is a standard form that can be manufactured efficiently.
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 significantly reduces optical return loss by eliminating vertical surfaces and ensuring that light is not reflected back into the waveguides, maintaining functionality regardless of the medium inside the rotary transmitter, such as oil or gas, thereby improving signal transmission efficiency.
Implementation Method 1
Light is refracted at the light entry surfaces of the Dove prism according to the refractive index of the glass of the Dove prism and the environment
Implementation Method 2
The light is refracted at the light entry surfaces of the Dove prism according to the refractive index of the glass of the Dove prism and the environment
Implementation Method 3
Because of this perpendicular light entry, there is no refraction at the interface. The disadvantage of this is the partial reflection of the light at the vertical transition surface
Data Source
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AI summary
The invention relates to an optical rotary joint comprising a first collimator arrangement for coupling first optical fibers and a second collimator arrangement for coupling second optical fibers, wherein the second collimator arrangement is mounted in such a way that it can rotate about a rotational axis relative to the first collimator arrangement. Between the collimator arrangements, a Dove prism is provided as a derotating element. Furthermore, the collimator arrangements have matching elements with rotationally symmetric conical surfaces. Prism-matching elements are applied to the end faces of the Dove prism and have prism-matching elements on the sides facing the collimator arrangements. Said matching elements likewise have rotationally symmetric conical surfaces which are oriented inversely with respect to the matching elements of the collimator arrangements.