Atom Interferometer Optics With Beam Combining and Grating Chips
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Solution Overview
Problem
Existing atom interferometry-based navigation sensors are large and complex, requiring numerous laser beams for operation, which complicates alignment and makes them unsuitable for practical use in dynamic environments.
Innovation Solution
The optical system is simplified by combining laser beams using reflective grating chips and time-multiplexing techniques, reducing the number of required input beams and aligning them efficiently for compact, robust operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical systems with multiple laser beams are used, then measurement precision is maintained, but device complexity and alignment difficulty increase significantly
Solution Approach 1:
The patent combines multiple laser beams into a single beam using beam combining optics. The system uses polarizing beam splitters and wave plates to merge several laser beams (cooling beams, Raman beams, detection beams) into one combined beam that enters the vacuum chamber through a single optical port, thereby reducing the number of required optical components and alignment points while maintaining all necessary functions
Solution Approach 2:
The patent implements multi-functionality by designing optical components that serve multiple purposes. For example, the same optical fiber delivers multiple different laser beams (cooling, Raman, detection) at different times through time-multiplexing. The beam combining optics universally handle different beam types and polarizations, reducing the need for separate dedicated optics for each function
2Measurement precision
If multiple laser beams are used for atom interferometry, then sensing accuracy is achieved, but ease of operation deteriorates due to alignment complexity
Solution Approach 1:
The patent merges multiple laser beams into a single combined beam that passes through a single optical port into the vacuum chamber. This is achieved using polarizing beam splitters, wave plates, and beam combining optics that integrate cooling beams, Raman beams, and detection beams into one unified optical path, dramatically simplifying alignment procedures
Solution Approach 2:
The patent introduces beam combining optics as an intermediary system between the laser sources and the atom interferometry chamber. This intermediary combines multiple beams spatially and temporally, providing a single simplified interface (one optical port) that maintains all necessary beam functions while eliminating the need for multiple separate alignment points
3Weight of moving object
If compact sensor design is implemented, then weight and power consumption are reduced, but the number of required laser beams must be minimized
Solution Approach 1:
The patent combines multiple laser beams into a single beam using polarizing beam splitters and wave plates, reducing the number of optical fibers and optical ports required. This merging approach allows compact sensor design by eliminating redundant optical components and reducing the overall optical system footprint
Solution Approach 2:
The patent uses time-multiplexing to deliver different laser beams (cooling, Raman, detection) through the same optical fiber at different time intervals. This periodic action allows a single optical fiber to serve multiple functions sequentially, reducing the number of permanent optical connections and enabling more compact sensor design
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 simplification results in a compact, lightweight, and power-efficient navigation sensor capable of operating in dynamic environments, with reduced alignment complexity and improved sensitivity.
Implementation Method 1
the laser cooling beam optics including at least one reflective grating chip, the laser cooling beam optics directing each laser cooling sub-beam toward a corresponding reflective grating chip, each reflective grating chip diffracting a corresponding laser cooling sub-beam into a corresponding plurality of diffracted laser cooling beams
Implementation Method 2
two counter-propagating, Doppler-sensitive Raman laser beams that coherently address the transition between two ground states of the atom and provides the state-dependent momentum kicks, i.e., photon recoils, on a ground state of the atoms
Implementation Method 3
The three light-pulse sequence (π/2→π→π/2) of the Raman laser beams in the AI process splits, redirects, and combines two matterwave packets to create atomic interference effects for measuring acceleration (in time and one-dimensional (1D) space) or angular velocity (in time and two-dimensional (2D) space)
Data Source
AI summary
Various optical systems for use in a light pulse atomic interferometer (LPAI)-based one-, two-, or three-axis accelerometer or gyroscope are disclosed. As an LPAI accelerometer or gyroscope may employ many different laser beams to implement the LPAI functionality, ways of combining these different laser beams to thereby simplify the optical systems are desired. The cooling laser beam portion of the optical system may be simplified using one or more reflective grating chips. The Raman laser beam optics may be simplified using combiners and separators. For LPAI systems sensing along three axes, various optical switching schemes may be employed, including ones that generate variable data-rates with a primary sensing axis having a higher data-rate than the secondary sensing axes. Further, by combining various laser beams in a time-multiplexed manner, the number of optical fiber tethers to a sensor head may be reduced.