Flood Projector Microlens Array Irradiance Management
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Solution Overview
Problem
Compact structured light projectors in portable devices face the challenge of high irradiance on optical metasurfaces and subsequent layers, which can lead to damage, and existing solutions fail to effectively reduce this while maintaining a high signal-to-noise ratio for 3D mapping and imaging.
Innovation Solution
The use of semiconductor substrates with multiple arrays of emitters and optical metasurfaces comprising multiple optical apertures, along with microlenses that steer and collimate beams to spread optical power over a large surface area, reducing irradiance on the metasurfaces and allowing for efficient beam steering and pattern projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high optical power is concentrated on a small area of the metasurface to maintain high signal-to-noise ratio, then measurement precision is improved, but the metasurface and adjacent layers are damaged due to high irradiance
Solution Approach 1:
The patent divides the optical system into multiple emitter arrays (first array and second array) that emit optical beams through different optical apertures of the metasurface. This segmentation distributes the optical power across multiple paths, reducing the irradiance concentration on any single area of the metasurface while maintaining sufficient signal-to-noise ratio through the combined effect of multiple beams.
Solution Approach 2:
The patent introduces a spatial dimension by using multiple emitter arrays positioned at different locations and orientations. The first emitter array and second emitter array are arranged to illuminate the target from different angles and positions, effectively distributing the optical load across multiple spatial dimensions rather than concentrating it in a single plane.
2Object-affected harmful factors
If multiple emitter arrays and optical apertures are used to distribute optical power, then irradiance on metasurface is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple emitter arrays and optical apertures into an integrated system where the first emitter array, second emitter array, and metasurface with multiple optical apertures work together as a unified structure. This merging approach manages the complexity by creating a coordinated system where each component serves multiple functions simultaneously.
Solution Approach 2:
The metasurface with multiple optical apertures serves multiple functions: it acts as both a beam steering element and an irradiance distribution mechanism. The same optical apertures that guide the beams also serve to distribute the optical power across different areas, reducing the need for additional specialized components.
3Manufacturing precision
If emitters are disposed on back side of semiconductor die and microlenses on front side, then manufacturing precision is improved, but alignment between emitters and microlenses becomes more difficult
Solution Approach 1:
The patent introduces the semiconductor die thickness and the optical path through the die as an intermediary element that facilitates alignment. By positioning emitters on the back side and microlenses on the front side of the same semiconductor die, the die itself serves as the alignment reference, with its thickness and optical properties enabling precise positioning of both emitter and microlens without requiring external alignment mechanisms.
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 approach effectively reduces the risk of damage to optical metasurfaces and adjacent components while maintaining a high signal-to-noise ratio for accurate 3D mapping and imaging, enabling both spot and flood illumination with improved design flexibility and cost-effectiveness.
Implementation Method 1
Microlenses are disposed between the semiconductor substrate and the optical diffuser in respective alignment with the emitters and configured to steer the beams at different, respective angles
Implementation Method 2
An optical diffuser is mounted over the semiconductor substrate and configured to diffuse the beams
Implementation Method 3
the optical metasurface is configured to split the beams into respective groups of diverging sub-beams, and to direct the sub-beams to illuminate a target with flood illumination
Data Source
AI summary
An optoelectronic apparatus includes a semiconductor substrate and an array of emitters disposed on the semiconductor substrate and configured to emit beams of optical radiation having respective chief rays. An optical diffuser is mounted over the semiconductor substrate and configured to diffuse the beams. Microlenses are disposed between the semiconductor substrate and the optical diffuser in respective alignment with the emitters and configured to steer the beams at different, respective angles, which are selected so that at least some of the chief rays cross one another before passing through the diffuser.