Laser Beam Combining Prism and Birefringent Crystal
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Solution Overview
Problem
Current polarization combining methods for laser beams are inefficient in maintaining the input linear polarization of one beam while combining it with another beam, often resulting in unwanted polarization changes and directional shifts.
Innovation Solution
An apparatus comprising a prism with total internal reflection surfaces and a birefringent crystal, where the prism changes the polarization of one laser beam to orthogonal using total internal reflections, and the crystal combines the beams with orthogonal polarizations to produce a single orthogonally polarized output beam, maintaining the original polarization of the second beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an optical assembly with beam-splitter coating is used to combine laser beams, then two linearly polarized beams can be combined into one beam, but the input linear polarization of one beam cannot be maintained and unwanted polarization changes occur
Solution Approach 1:
The patent changes the polarization state parameter of one beam by 90 degrees using total internal reflection in the prism, while the other beam passes through with its original polarization maintained. This parameter change enables both beams to be combined orthogonally without interference, resolving the contradiction between combination efficiency and polarization maintenance.
Solution Approach 2:
The birefringent crystal acts as an intermediary element that receives both laser beams with different polarization states and combines them into a single orthogonally polarized beam. The crystal's birefringent properties enable it to manipulate the polarization states and facilitate efficient combination while maintaining the integrity of the input polarization of the second beam.
2Manufacturing precision
If total internal reflection is used to change polarization to orthogonal, then the polarization state can be effectively changed, but the beam direction may shift
Solution Approach 1:
The patent employs an asymmetric optical path design where the first beam undergoes total internal reflection at a specific angle (greater than critical angle) to change its polarization by 90 degrees, while the second beam passes through the birefringent crystal along a different path. This asymmetric arrangement allows precise polarization control for each beam independently while managing directional changes through the optical geometry.
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
Effectively combines laser beams with the same input linear polarization, ensuring the output beam is orthogonally polarized while maintaining the original polarization and direction of one beam, enhancing the precision and efficiency of laser beam combination.
Implementation Method 1
totally internally reflect the first laser beam off ones of the plurality of surfaces on which said first laser beam impinges at greater than or equal to a critical angle θc to change the linear polarization of the first beam to an orthogonal polarization
Implementation Method 2
the crystal having a transparent crystal body formed of a birefringent material, the crystal configured to: receive the first laser beam and the second laser beam from said prism; combine the first laser beam and the second laser beam to form an orthogonally polarized combined laser beam
Implementation Method 3
refract the second laser beam off ones of the plurality of surfaces on which said second beam impinges at less than said critical angle θc, thereby maintaining said input linear polarization
Data Source
AI summary
The specification is directed to an apparatus for combining laser beams having a same polarization. The apparatus includes a prism having a prism body and a plurality of surfaces, and a crystal coupled to the prism, the crystal having a crystal body and formed of a birefringent material. The prism is configured to receive two laser beams each having a same input linear polarization, totally internally reflect the first laser beam off one or more of the plurality of surfaces to change the linear polarization of the first beam to an orthogonal polarization, refract the second laser beam, and output the laser beams parallel to each other, and having orthogonal polarizations. The crystal is configured to receive the laser beams from the prism and combine them to form an orthogonally polarized combined laser beam.