Off-Axis Diffractive Optical Element for Zero-Order Beam Removal
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Solution Overview
Problem
In structured light systems, the normal incidence of light on diffractive optical elements leads to limitations in power performance due to the presence of a zero-order beam within the field of view, posing safety compliance issues and causing instability and interference effects.
Innovation Solution
Arranging the diffractive optical element to receive light at a substantially non-normal angle of incidence, which causes the zero-order beam to be transmitted outside the field of view, allowing other diffracted orders to be directed within the view for generating structured light patterns while maximizing power and reducing back-reflection and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light is incident on the diffractive optical element at normal incidence, then the diffracted orders can be symmetrically distributed, but the zero-order beam falls within the field of view causing safety compliance issues and interference effects
Solution Approach 1:
The patent applies asymmetry by deliberately designing the diffractive optical element with asymmetric microstructure patterns that cause the zero-order beam to be directed outside the field of view. This asymmetric design resolves the contradiction by eliminating the harmful zero-order beam from the detection region while maintaining functional diffraction orders within the field of view, thereby solving both the safety compliance issue and the interference problem.
2Productivity
If the diffractive optical element transmits multiple diffracted orders to generate structured light patterns, then the power distribution is spread thin, but the presence of the zero-order beam within the field of view reduces power performance
Solution Approach 1:
The patent applies the extraction principle by removing the zero-order beam from the field of view through asymmetric microstructure design. This allows the diffractive optical element to concentrate more power into the useful diffracted orders that form the structured light pattern, thereby improving power performance without sacrificing the ability to generate structured light patterns.
3Reliability
If the diffractive optical element is designed to direct the zero-order beam outside the field of view, then safety compliance and power performance are improved, but the microstructure design becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the microstructure parameters (such as pitch, depth, and shape) to achieve asymmetric diffraction that directs the zero-order beam outside the field of view. By carefully selecting and optimizing these parameters, the design achieves improved reliability and safety compliance while managing the complexity through systematic parameter optimization rather than fundamentally changing the device architecture.
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 configuration enhances system performance by maximizing power within the field of view while maintaining safety compliance and reducing instability and interference effects.
Implementation Method 1
a diffractive optical element to diffract the light such that one or more diffracted orders of the light, associated with forming a structured light pattern, are transmitted by the diffractive optical element
Data Source
AI summary
A structured light system may include a semiconductor laser to emit light and a diffractive optical element to diffract the light such that one or more diffracted orders of the light, associated with forming a structured light pattern, are transmitted by the diffractive optical element. The diffractive optical element may be arranged such that the light is to be incident on the diffractive optical element at a substantially non-normal angle of incidence. The substantially non-normal angle of incidence may be designed to cause the diffractive optical element to transmit a zero-order beam of the light outside of a field of view associated with the diffractive optical element.