Optical Axis Alignment Using Iris Diaphragm and QPD
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Solution Overview
Problem
Existing optical wireless communication systems face challenges in achieving efficient long-distance transmission due to misaligned optical axes, particularly in bidirectional communication, leading to reduced reception efficiency and difficulty in maintaining alignment over long distances without additional alignment equipment.
Innovation Solution
The use of a quadrant photodiode (QPD) and an iris diaphragm to align optical axes of optical components, such as optical fibers and lenses, by adjusting the beam size to ensure it centers on the QPD, facilitating collinear alignment without the need for additional alignment equipment, and allowing for real-time tracking and data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical axes of multiple lenses are aligned using additional parallel light sources and alignment equipment, then optical axis alignment precision is improved, but device complexity and cost increase
Solution Approach 1:
The optical fiber end surface itself serves as the light source for alignment, eliminating the need for separate alignment light sources. The system uses its own transmission components (optical fiber, lenses) to perform alignment, making the alignment process self-contained and reducing external equipment requirements
Solution Approach 2:
The optical fiber end surface serves dual purposes: as the actual light transmission medium for communication and as the alignment reference source. This multi-functionality eliminates the need for dedicated alignment equipment, reducing system complexity while maintaining alignment precision
2Measurement precision
If beam size is reduced to fit within QPD light-receiving area, then measurement precision is improved, but light intensity decreases
Solution Approach 1:
The iris diaphragm is adjusted to create a beam size that is slightly smaller than the QPD light-receiving area, ensuring the beam fits within the detection area while maximizing the captured light intensity. This partial restriction optimizes both measurement precision and energy utilization
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 method enhances the efficiency of optical wireless communication by ensuring collinear optical axes, maximizing reception efficiency, and enabling easy alignment and tracking between optical transmitters and receivers, even over long distances, without requiring additional alignment equipment.
Implementation Method 1
a QPD configured to receive the light output from the light output device
Implementation Method 2
an iris diaphragm placed between the light output device and the QPD and configured to adjust a beam size of the light received by the QPD
Data Source
AI summary
Provided are an apparatus and method for adjusting an optical axis. In the apparatus, an iris diaphragm and a quadrant photodiode (QPD) are used to align optical axes of an optical system of the apparatus so that optical transmission efficiency between an optical transmitter and an optical receiver can be increased. Since a hole of the iris diaphragm can be adjusted to be small, a beam larger than a light-receiving area of the QPD can be included in the light-receiving area, and optical axis alignment is facilitated accordingly. When the QPD and the iris diaphragm are applied to the apparatus, it is possible to simultaneously perform data transmission, tracking, and optical axis alignment. An optical fiber end surface and optical axes of lenses arranged in parallel are aligned in the apparatus so that alignment between two terminals can be easy and reception efficiency can be increased.