Overlapping Pattern Projector Using Diffractive Optical Element
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Solution Overview
Problem
Micro-miniature optical projectors face limitations in achieving high pattern density due to physical constraints of emitter distances and focal lengths, which restricts their ability to project dense light patterns effectively for applications like 3D mapping.
Innovation Solution
An integrated optical projector design featuring a semiconductor substrate with an array of optical emitters in a two-dimensional pattern, a projection lens, and a diffractive optical element (DOE) that generates multiple overlapping replicas of the pattern, allowing for a finer pitch and dynamic control of pattern density, and reducing ambiguity in depth estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the distance between optical emitters is reduced to increase pattern density, then the pattern density improves, but the manufacturing precision and reliability deteriorate due to physical constraints
Solution Approach 1:
The patent uses a diffractive optical element to create multiple copies (replicas) of the light pattern generated by the optical emitters. Instead of reducing emitter spacing, the system projects several replicated patterns that overlap to form a denser combined pattern, thereby achieving high pattern density without compromising emitter spacing precision
Solution Approach 2:
The invention transitions from increasing density by reducing spatial separation in the emitter array to achieving density through optical replication and superposition in the projection space. The diffractive element creates multiple angularly separated replicas that overlap on the target, effectively adding a dimensional approach to pattern density that bypasses physical emitter spacing constraints
2Quantity of substance
If the focal length of the projection lens is reduced to increase pattern density, then the pattern density improves, but the measurement precision of depth estimation deteriorates
Solution Approach 1:
Multiple replicated patterns are projected with different angular orientations. The overlap region of these replicas provides redundant depth information from multiple viewing angles, enhancing depth estimation precision while maintaining high pattern density without requiring a short focal length lens
Solution Approach 2:
The system changes the angular parameters of the projected patterns through the diffractive optical element, creating replicas at different angles. This parameter variation allows the system to achieve both high density and precise depth measurement by analyzing transverse shifts across multiple angularly separated pattern replicas
3Quantity of substance
If multiple overlapping replicas are projected to achieve high pattern density, then the pattern density improves, but the device complexity increases due to the diffractive optical element
Solution Approach 1:
A diffractive optical element serves as an intermediary component that efficiently generates multiple pattern replicas through diffraction. This single optical element performs the function of creating multiple angularly separated copies, achieving high pattern density without requiring multiple separate projection systems or complex mechanical arrangements
Solution Approach 2:
The patent replaces what would otherwise require a complex mechanical system with multiple movable mirrors or projection units with a static diffractive optical element. The diffraction-based replication achieves multiple pattern copies through optical interference rather than mechanical manipulation, significantly reducing device complexity while maintaining high pattern density
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 enables the production of high-density optical spot patterns with improved angular separation, overcoming physical constraints and enhancing depth estimation accuracy, suitable for applications like 3D mapping and user gesture recognition.
Implementation Method 1
a projection lens mounted on the semiconductor substrate and configured to collect and focus light emitted by the optical emitters so as to project optical beams containing a light pattern
Implementation Method 2
a diffractive optical element (DOE) mounted on the substrate and configured to produce and project multiple overlapping replicas of the pattern
Data Source
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AI summary
An optoelectronic device (30) includes a semiconductor substrate (132), an array (120) of optical emitters arranged on the substrate in a two-dimensional pattern, a projection lens (146) and a diffractive optical element (DOE - 144). The projection lens is mounted on the semiconductor substrate and is configured to collect and focus light emitted by the optical emitters so as to project optical beams containing a light pattern corresponding to the two- dimensional pattern of the optical emitters on the substrate. The DOE is mounted on the substrate and is configured to produce and project multiple overlapping replicas (152, 154, 156) of the pattern.