Diffractive Beam Splitter with Immersed Continuous Surface
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Solution Overview
Problem
Current diffractive beam splitters have limited diffraction efficiency and accuracy due to their discrete stepped structures, which are challenging to manufacture with high precision, especially for sub-micron surface processing, and suffer from manufacturing-related shape and position tolerance issues.
Innovation Solution
A diffractive beam splitter with an immersed continuous surface is developed, featuring a single-period structure with different refractive index optical media and anti-reflection films, where the surface sagittal height is optimized to enhance processing accuracy and efficiency, and a preparation method involving master masks and optical media imprinting is used to create a smooth, high-efficiency beam splitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a discrete stepped structure is used for the beam splitter, then the manufacturing process is simplified, but the diffraction efficiency is limited and manufacturing precision is reduced due to shape and position tolerances
Solution Approach 1:
The invention changes the surface profile parameter from a discrete stepped function to a continuous function. The continuous surface is defined by a sagittal height formula that varies continuously across the periodic structure, eliminating the discrete steps while maintaining the diffraction grating functionality. This parameter change enables higher diffraction efficiency (>95%) and better beam splitting uniformity (error <5%) by avoiding the theoretical efficiency limits and tolerance sensitivities of stepped structures.
2Manufacturing precision
If sub-micron surface processing accuracy is required for high precision beam splitting, then the manufacturing difficulty and cost increase significantly
Solution Approach 1:
The invention transforms the surface profile from sub-micron precision stepped structures to a continuous surface with larger, more manufacturable sagittal heights. The continuous surface formula produces profiles that can be manufactured with conventional precision techniques, eliminating the need for ultra-precision sub-micron processing while achieving equal or superior optical performance.
Solution Approach 2:
The continuous surface profile employs curved transitions between periods instead of sharp angular steps. The sagittal height varies continuously according to a mathematical function, creating smooth curved surfaces that are significantly easier to manufacture with conventional polishing and finishing techniques compared to the sharp sub-micron steps required by discrete structures.
3Manufacturing precision
If a continuous surface structure is implemented, then diffraction efficiency exceeds 95% and beam splitting uniformity improves, but the manufacturing complexity increases
Solution Approach 1:
The invention segments the continuous surface into repeating periodic units, each following the same mathematical sagittal height formula. This periodic segmentation allows the complex continuous profile to be manufactured using replication techniques such as master mold fabrication followed by multiple copies, reducing the actual manufacturing complexity despite the sophisticated surface profile.
Solution Approach 2:
The continuous surface profile can be created by copying a master template or mold that defines the sagittal height variation. Once the master continuous surface is fabricated (possibly using ultra-precision techniques or direct laser writing), subsequent beam splitter elements can be replicated using molding, casting, or replication bonding techniques, significantly reducing the complexity of mass production.
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 immersed continuous surface diffractive beam splitter achieves an overall diffraction efficiency of more than 95% with uniformity error less than 5%, significantly reducing processing difficulties and improving beam splitting uniformity.
Implementation Method 1
A beam splitter may be placed in an optical path for modulating light to achieve the function of proportionally dividing a single beam into multiple target beams. The beam splitter is a periodic structure, the period of which is affected by parameters such as the angle between adjacent orders and the operating wavelength, and determined by the diffraction equation: d sin θ=mλ
Implementation Method 2
The single-period structure sequentially includes, from bottom to top, a base structure layer, a first optical medium, and a second optical medium. The first optical medium and the second optical medium have different refractive indexes. The surface sagittal height h between the first optical medium and the second optical medium satisfies the following formula: h=1⁄4*λ*（1-cosφ）/(n2-n1), where λ represents the wavelength; φ represents the phase; n1 represents the refractive index of the first optical medium; and n2 represents the refractive index of the second optical medium
Data Source
AI summary
The present disclosure provides a diffractive beam splitter with immersed continuous surface and a preparation method thereof. The diffractive beam splitter includes a single-period structure in array. The single-period structure sequentially includes, from bottom to top, a base structure layer, a first optical medium, and a second optical medium. The refractive indexes of the first optical medium and the second optical medium are different. The surface sagittal height h between the first optical medium and the second optical medium meets the following formula:h=1/2*λ*Φ*<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>n1-n2<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>/π.