Diffractive Optical Element Phase Design for Zeroth Order Leakage
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Solution Overview
Problem
Conventional diffractive optical elements are susceptible to surface errors during manufacture, leading to high intensity zeroth order leakage, which limits the operating power of light sources and compromises the desired output intensity distribution.
Innovation Solution
A diffractive optical element is designed with independent phase profiles for collimation and beam shaping functions, combined using phase angle addition and wrapped between 0 and 2π radians, to create a single diffractive surface that impedes high intensity zeroth order leakage and enhances manufacturing error tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional diffractive optical element is used to shape the beam, then the output intensity distribution is achieved, but high intensity zeroth order leakage occurs due to surface errors during manufacture
Solution Approach 1:
The patent divides the single diffractive surface into two separate optical elements: a collimating diffractive optical element and a beam shaping diffractive optical element. This segmentation isolates the collimation function from the beam shaping function, preventing surface errors from causing zeroth order leakage while maintaining the desired output intensity distribution.
Solution Approach 2:
The patent introduces a collimating lens as an intermediary element between the light source and the beam shaping diffractive optical element. This intermediary component creates a virtual source that allows the beam shaping DOE to operate without being directly exposed to the high intensity collimated beam, thereby eliminating the zeroth order leakage pathway.
2Object-affected harmful factors
If the light source power is reduced to prevent zeroth order leakage, then safety is improved, but the operating power level is limited
Solution Approach 1:
By segmenting the optical system into separate collimating and beam shaping elements, the patent enables the light source to operate at higher power levels. The collimating element handles the high intensity collimated beam safely, while the beam shaping element processes the beam at the appropriate intensity level, thus maintaining both safety and high operating power.
3Manufacturing precision
If manufacturing errors occur in the diffractive surface, then the desired output intensity distribution is degraded, but the zeroth order leakage becomes more dominant
Solution Approach 1:
The patent separates the collimation and beam shaping functions into distinct elements, which improves tolerance to manufacturing errors. Each element can be optimized independently for its specific function, reducing the impact of depth errors on overall system performance and preventing the dominance of zeroth order leakage even when manufacturing variations occur.
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 significantly reduces the sensitivity to manufacturing errors, allowing for higher power operation of light sources while maintaining the desired output intensity distribution, even with significant depth errors, and prevents the passage of undesirable high intensity collimated beams.
Implementation Method 1
a diffractive optical element (DOE) and a method for designing a DOE to reduce or eliminate the risk of high intensity zeroth order leakage
Data Source
AI summary
A diffractive optical element (DOE) is designed to implement both a collimation function with respect to an input divergent beam and a beam shaping function with respect to an output divergent beam. The phase designs of the collimation function and the beam shaping function are independently produced in the phase domain. These phase designs are then combined using a phase angle addition of the individual functions and wrapped between 0 and 2π radians. The diffractive surface of the DOE is then defined from the wrapped phase angle addition of the individual functions.