LED Pattern Projector for 3D Depth Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 3D camera technologies face challenges in deriving depth information due to the lack of suitable features in the scene, and laser-based pattern projection methods are hindered by high costs, speckle artifacts, and eye safety concerns, as well as drift issues from temperature fluctuations.
Innovation Solution
The implementation of an LED pattern projector with a projection lens, LED source, and pattern mask, which projects a light pattern onto the scene, utilizing a microlens array and amplitude or refractive masks to modulate light intensity and phase, enabling efficient depth information derivation without the drawbacks of laser-based systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser-based pattern projection is used, then depth information can be derived, but high costs, speckle artifacts, and eye safety concerns arise
Solution Approach 1:
The patent replaces expensive laser sources with inexpensive LED sources. LEDs are cost-effective, have no speckle artifacts, and are safe for eye exposure. The system uses a single LED source that can be rapidly modulated to create structured light patterns, eliminating the need for costly laser equipment while maintaining depth measurement capability.
Solution Approach 2:
The patent changes the fundamental parameter of light source type from laser to LED. This parameter change eliminates speckle artifacts (inherent to coherent laser light), reduces eye safety concerns (LEDs are incoherent and less intense), and lowers cost. The LED source is modulated in time to create structured light patterns, achieving depth measurement without the harmful effects of lasers.
2Measurement precision
If laser-based pattern projection is used, then depth information can be derived, but drift issues from temperature fluctuations occur
Solution Approach 1:
The patent changes the light source parameter from laser to LED, which fundamentally alters thermal behavior. LEDs generate less heat and have better thermal stability compared to lasers. The system achieves temperature-insensitive operation by using LED sources that maintain consistent emission characteristics across varying temperatures, eliminating the drift issues inherent in laser-based systems.
3Measurement precision
If structured light projection is implemented, then depth information is obtained, but device complexity increases
Solution Approach 1:
The patent segments the light emission in time, projecting different structured light patterns at different time intervals. A single LED source sequentially emits multiple patterns (e.g., horizontal lines, vertical lines, diagonal lines) rather than requiring multiple simultaneous light sources. This temporal segmentation simplifies the hardware while enabling complete scene illumination for depth measurement.
Solution Approach 2:
The patent uses periodic modulation of the LED source to project structured light patterns at regular time intervals. The LED is turned on and off in specific sequences to create different light patterns across the scene. This periodic action allows a single light source to perform the function of multiple sources, reducing device complexity while maintaining the ability to derive depth information from multiple directions.
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 solution provides a cost-effective, efficient, and safe method for deriving depth information, reducing the RMS error and maintaining performance across varying conditions, while offering a compact form factor and low power consumption.
Implementation Method 1
a light emitting diode (LED) source
Implementation Method 2
a mask to spatially modulate an intensity of emissions from the LED
Implementation Method 3
a projector lens to reimage the spatially modulated emission onto the portions of the scene
Data Source
AI summary
A light pattern projector with a pattern mask to spatially modulate an intensity of a wideband illumination source, such as an LED, and a projector lens to reimage the spatially modulated emission onto regions of a scene that is to be captured with an image sensor. The projector lens may comprise a microlens array (MLA) including a first lenslet to reimage the spatially modulated emission onto a first portion of a scene, and a second lenslet to reimage the spatially modulated emission onto a first portion of a scene. The MLA may have a fly's eye architecture with convex curvature over a diameter of the projector lens in addition to the lenslet curvature. The pattern mask may be an amplitude mask comprising a mask pattern of high and low amplitude transmittance regions. In the alternative, the pattern mask may be a phase mask, such as a refractive or diffractive mask.