Structured Light Projector Spectral Encoding
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Solution Overview
Problem
Existing structured light projectors for three-dimensional scanners face challenges in accurately projecting and measuring spectral reflectance, especially with complex surfaces and dynamic scenes, due to limitations in wavelength range and adaptability, leading to biased or incomplete depth maps and lack of material identification capabilities.
Innovation Solution
A structured light projector with a spectral encoding device using a light source that emits a continuous spectrum, a spectral decomposition optical system, an encoding device with a binary encoding matrix mask, and a spectral recombination optical system, allowing for real-time adjustment of wavelength channels to match ambient lighting and surface reflectance, enhancing depth map precision and material identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional light projector with fixed RGB channels is used, then the device structure is simple, but the wavelength range is limited and cannot adapt to different ambient lighting conditions and surface reflectance characteristics
Solution Approach 1:
The patent implements dynamic adaptability by enabling real-time adjustment of the projector's wavelength channels through a spectral encoding device. The system can dynamically select and tune specific wavelength ranges based on ambient lighting conditions and surface reflectance characteristics, transforming a static projector into an adaptive spectral instrument that optimizes its performance for different measurement scenarios
Solution Approach 2:
The patent changes the fundamental parameter of the projector from fixed wavelength channels (RGB) to continuously adjustable spectral channels. By incorporating a spectral encoding device with selectable wavelength ranges, the system can modify its spectral parameters in real-time to match the reflectance characteristics of different materials and lighting conditions, thereby achieving material identification capability
2Measurement precision
If structured light projection is performed without spectral encoding, then the depth map acquisition is straightforward, but the precision is reduced in scenes with strong relief gradients or occlusions
Solution Approach 1:
The patent segments the spectral information into multiple selectable wavelength channels through the spectral encoding device. By dividing the continuous spectrum into distinct可调 wavelength ranges, the system can project structured light patterns at specific wavelengths that are optimally reflected by different material surfaces, thereby improving depth map precision in complex scenes with varying reflectance properties
Solution Approach 2:
The spectral encoding device acts as an intermediary between the light source and the projection optics. It mediates the spectral composition of the projected light, allowing selective enhancement of specific wavelength components that are most effective for penetrating occlusions or reflecting off surfaces with strong relief gradients, thereby improving measurement precision without directly modifying the projection geometry
3Illumination intensity
If multiple monochromatic sources are used to achieve spectral projection, then the wavelength range can be covered, but the device becomes bulkier and more expensive
Solution Approach 1:
The patent implements a universal light source that can perform multiple spectral functions through the spectral encoding device. Instead of requiring separate monochromatic sources for different wavelengths, a single broadband source combined with the spectral encoding device can generate and tune across multiple wavelength channels, achieving spectral coverage equivalent to multiple sources while maintaining a compact and cost-effective single-source architecture
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical light sources with an optical/electronic spectral encoding device. This substitution allows dynamic spectral selection and tuning without the physical bulk and complexity of housing and aligning multiple separate monochromatic sources, thereby achieving spectral coverage with a more compact and integrated system
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 precise and adaptive structured light projection, improving depth map accuracy and allowing for the identification of surface materials, even in complex scenes with strong relief gradients or dynamic conditions.
Implementation Method 1
a spectral decomposition optical system configured to separate a spectrum of a light beam emitted by the light source into a plurality of wavelength channels spatially
Implementation Method 2
a spectral recombination optical system configured to recombine the separated wavelength channels into a single recombined light beam
Data Source
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AI summary
The present application relates to a structured light projector comprising successively a light source, a spectral decomposition optical system (3), an encoding device (5), a spectral recombination optical system (8) and a projection optical system; the encoding device (5) comprising a mask (51) which has a binary encoding matrix pattern formed of 2*n rows and m columns, a sub-pattern defined by rows "1" to "n" being illuminated by an image of the beam at the wavelength λmin and a sub-pattern defined by rows "n+1" to "2*n" being illuminated by an image of the beam at the wavelength λmax, the two sub-patterns being identical or complementary, and two adjacent columns each having a binary encoding different from the other.