Depth Scanning with Multiple Offset Emitters

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Solution Overview

Problem

Current depth mapping systems face limitations in scan resolution and frame rate, with mechanical constraints limiting the increase in scanning speed, and existing methods struggle to achieve high resolution without reducing the field of view or increasing the number of raster lines.

Innovation Solution

The system employs multiple pulsed beams with mutually offset axes, scanned in a raster pattern using a rotating mirror, allowing for increased scan resolution by generating multiple parallel scan lines without increasing the scanner speed, and utilizing emitters like edge-emitting laser stripes or VCSELs with microlenses to reduce angular separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If mechanical scanning speed is increased to improve frame rate, then productivity improves, but scan resolution deteriorates due to mechanical constraints

Engineering Contradiction:
Improveframe rateVSAvoidscan resolution
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent divides a single scanning beam into multiple parallel beams (e.g., three beams) that scan simultaneously across the field of view. This segmentation allows the system to achieve higher scan resolution by covering more spatial positions in parallel without increasing the mechanical scanning speed, thus resolving the contradiction between productivity and manufacturing precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an additional spatial dimension by arranging multiple beams parallel to each other in the transverse direction. Instead of increasing resolution along a single scanning path, the system adds resolution in the perpendicular dimension by using multiple offset beams, thereby achieving high scan resolution without requiring faster mechanical scanning.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the number of raster lines is increased to improve scan resolution, then manufacturing precision improves, but the field of view decreases

Engineering Contradiction:
Improvescan resolutionVSAvoidfield of view
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent segments the field of view into multiple parallel scanning regions, each covered by a separate beam. This allows the system to maintain a wide field of view while achieving high scan resolution in each segment, as the beams operate in parallel rather than sequentially increasing the total number of raster lines.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple parallel beams into a single scanning system that operates simultaneously. By merging the scanning functions of multiple beams, the system achieves high overall scan resolution across the entire field of view without requiring an increased number of sequential raster lines, thus preserving the field of view.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If multiple emitters are used to increase scan resolution, then manufacturing precision improves, but device complexity increases

Engineering Contradiction:
Improvescan resolutionVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent designs the multiple emitters to share common optical components and control systems, making each component serve multiple functions. For example, a single scanner controls multiple beams, and common optics are used for all beams, thereby reducing the overall device complexity despite the increased scan resolution achieved through multiple emitters.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the control and optical paths of multiple emitters into a unified system. By combining the scanning mechanism, optical components, and signal processing for all beams into a single integrated system, the patent reduces the complexity that would otherwise result from having completely separate systems for each emitter.

Inventive Principle:
Principle #5Merging (Combining)

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 doubles the scan resolution by multiplexing scanning spots, allowing for higher pixel density without increasing scanner speed, and enables dynamic zooming and shifting of the scanned region without requiring user beacons or markers.

Implementation Method 1

A receiver is configured to receive the light reflected from the scene and to generate an output indicative of a time of flight of the pulses to and from points in the scene

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

A scanner is configured to scan the two or more beams in the raster pattern over a scene

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2972081B1Depth scanning with multiple emitters
Publication Date: 2020.04.22 APPLE INC
  • EP2972081B1 patent drawingFigure 1
  • EP2972081B1 patent drawingFigure 2
  • EP2972081B1 patent drawingFigure 3A~3B

AI summary

Mapping apparatus includes a transmitter (44), which is configured to emit, in alternation, at least two beams comprising pulses of light along respective beam axes (87, 88) that are mutually offset transversely relative to a scan line direction of a raster pattern. A scanner (64) is configured to scan the two or more beams in the raster pattern over a scene. A receiver (48) is configured to receive the light reflected from the scene and to generate an output indicative of a time of flight of the pulses to and from points in the scene. A processor (24) is coupled to process the output of the receiver so as to generate a 3D map of the scene.