Annular Beam Shaping for Spectral Beam Combination
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Solution Overview
Problem
Conventional spectral beam combining systems face significant power losses due to central obscuration in beam-expanding telescopes, particularly when using Gaussian spatial beam profiles, which results in inefficient energy transmission to the target.
Innovation Solution
The system reshapes each fiber-laser source beam into an annular spatial power profile before combining, using refractive or diffractive optics to minimize losses by redistributing optical power around the central obscuration of the Cassegrain telescope, thereby enhancing energy transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Gaussian spatial beam profiles are used in spectral beam combining systems, then the beam structure is simple and easy to generate, but significant power losses occur due to central obscuration in beam-expanding telescopes
Solution Approach 1:
The patent transforms the beam spatial profile from a conventional Gaussian distribution to an annular distribution by modifying the intensity parameter distribution. This parameter change redirects optical power from the central region (which would be blocked by obscuration) to an annular region, thereby maintaining ease of generation through standard optical components while eliminating power losses from central obscuration.
Solution Approach 2:
The patent converts the harmful effect of central obscuration into a beneficial annular beam structure. By intentionally creating an annular profile that matches the obscured aperture, the previously harmful central blockage becomes the expected and optimized beam shape, transforming the problem into a solution that maximizes transmitted power through the telescope.
2Device complexity
If conventional beam profiles are used, then the optical system is simpler, but energy transmission efficiency to the target is reduced
Solution Approach 1:
The patent modifies the spatial intensity distribution parameter of the beam from Gaussian to annular profile. This parameter transformation is achieved using relatively simple optical components such as phase plates or refractive index modifications, thereby improving energy transmission efficiency without significantly increasing overall system complexity.
3Loss of energy
If optical power is redistributed around central obscuration, then power loss is reduced and energy transmission is enhanced, but the beam shaping process becomes more complex
Solution Approach 1:
The patent introduces an intermediary optical element (such as a phase plate or refractive index structure) that performs the beam shaping function. This intermediary component transforms the Gaussian beam into an annular beam through a well-defined optical mechanism, achieving power redistribution and loss reduction while keeping the added complexity localized and manageable through a single dedicated element.
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 approach significantly reduces power loss by redistributing optical power around the central obscuration, ensuring that more of the beam power is transmitted through the telescope and available for targeting, improving the efficiency of high-power beam directors.
Implementation Method 1
using refractive or diffractive optics to minimize losses by redistributing optical power
Implementation Method 2
using refractive or diffractive optics to minimize losses by redistributing optical power
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 2A~2B
AI summary
A method and apparatus for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination. This invention includes a plurality of laser sources that emit a plurality of beamlets, wherein each one of the plurality of beamlets has a different wavelength; a beam annularizer that includes a plurality of optical units arranged to receive the beamlets, and configured to convert each beamlet into a respective annular beam that has an annular cross-sectional power profile; a beam-intersection transform element configured to point each respective one of the plurality of annular beams in an angular intersection arrangement toward a first location; and a spectral beam combiner at the first location configured to combine the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam.