Self-Referencing Interferometer Compact Spatial Phase Shifter
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Solution Overview
Problem
Conventional interferometers are large, complex, and heavy, limiting their implementation in directed energy and laser communications due to non-common path aberrations, optical throughput issues, and polarization sensitivity, which complicates their design and increases cost.
Innovation Solution
A compact spatial phase shifting interferometer design that reduces non-common path aberrations by ensuring the signal and reference beams travel similar paths, using fewer optical components, and incorporating a single mode fiber shunt to filter the reference beam, along with adaptive optics to correct aberrations, allowing for improved beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional interferometers use numerous wave plates and prisms to split and recombine beams, then beam splitting and recombination functionality is achieved, but device complexity and weight increase significantly
Solution Approach 1:
The patent combines multiple optical components (wave plates and prisms) into a single integrated beam splitting and recombination system. The interferometer uses a simplified optical path where beams are split and recombined with fewer discrete elements, reducing the total number of optical surfaces from 60 or more to a minimal set, thereby improving optical throughput while maintaining the required functionality.
2Measurement precision
If signal and reference beams travel different paths in the interferometer, then beam splitting functionality is achieved, but non-common path aberrations increase
Solution Approach 1:
The patent implements an optical path design where the signal beam and reference beam travel through equivalent optical paths with matching components and lengths. By ensuring both beams experience the same optical conditions (same number of surfaces, same path length, same environmental exposure), the system eliminates non-common path aberrations while still enabling accurate phase difference measurement through interferometric recombination.
3Adaptability or versatility
If the interferometer includes many optical surfaces from multiple prisms and wave plates, then beam manipulation capability is improved, but optical throughput decreases
Solution Approach 1:
The patent extracts and removes unnecessary optical components from the conventional interferometer design. By eliminating redundant wave plates and prisms that do not contribute to the core interferometric measurement, the system reduces the total number of optical surfaces, thereby minimizing light loss and improving optical throughput while retaining the essential beam splitting and recombination functionality.
4Measurement precision
If conventional interferometers use long single mode reference fibers for spatial filtering, then reference beam quality is improved, but mechanical and thermal disturbances increase
Solution Approach 1:
The patent changes the parameter of reference fiber length from conventional long lengths to a optimized shorter length that maintains sufficient spatial filtering capability. By adjusting this physical parameter, the system achieves the required reference beam quality while reducing the fiber's susceptibility to mechanical vibrations and thermal expansions, thereby eliminating measurement errors caused by environmental disturbances.
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 results in a smaller, less complex, and more cost-effective interferometer that effectively corrects aberrations, enhancing optical throughput and reducing mechanical and thermal disturbances, thereby improving beam quality and measurement accuracy.
Implementation Method 1
The reference beam is spatially filtered
Implementation Method 2
spatially filtered, and then the beams are recombined in such a way that the wave front of the signal beam can be determined
Implementation Method 3
The recombined beams produce an optical interference pattern for each of the phase shifts between the reference beam and the signal beam
Implementation Method 4
Phase shifting interferometry can be used to accurately determine the phase differences between the two beams
Data Source
AI summary
Systems and methods are described herein for a self-referencing interferometer. The interferometer can comprise an improved spatial phase shifter that reduces the number of components, size and complexity of the spatial phase shifter and maintains a common path for a combined reference beam and signal beam. The self-referencing interferometer further comprises a single mode fiber shunt for filtering the reference beam and further reducing the size of the interferometer. The angle of the reference beam can be tilted before being recombined with the single beam which further simplifies the spatial phase shifting component of the interferometer.