Structured Light Projection Using Diffractive Optical Elements
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Solution Overview
Problem
The high cost of manufacturing arrays of light emitting devices configured to produce irregular light patterns for 3D shape measurement, and the increased power consumption of alternative methods that toggle light emitting devices on and off to achieve irregular patterns.
Innovation Solution
A structured light projection system using an array of light emitting devices that emit a regular pattern, which is altered by a first optical element to create an irregular pattern, and then reproduced by a second optical element in a tiled pattern, eliminating the need for expensive irregular arrays and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an irregular array of light emitting devices is used to generate an irregular light pattern for 3D shape measurement, then the quality of structured light pattern is improved, but the manufacturing cost increases
Solution Approach 1:
The system segments the light generation function into two parts: a regular array of light emitting devices that is easy to manufacture, and optical elements (diffractive optical elements or refractive optical elements) that transform the regular pattern into an irregular projected pattern. This segmentation allows the expensive irregular array to be replaced with a combination of a regular array and transformation optics.
Solution Approach 2:
The patent introduces optical elements as intermediaries between the regular light emitting array and the target surface. These optical elements (DOE or ROE) act as mediators that transform the regular light pattern into an irregular projected pattern, eliminating the need for an irregular light emitting array while achieving the desired irregular light distribution for 3D measurement.
2Manufacturing precision
If light emitting devices are selectively toggled on and off to produce an irregular light pattern, then the structured light pattern quality is improved, but the power consumption increases
Solution Approach 1:
The system performs preliminary action by using optical elements to pre-transform the regular light pattern from all activated light emitting devices into the desired irregular projected pattern. This eliminates the need for selective toggling of light emitting devices, as all devices can remain active while the optical elements create the irregular distribution, thereby reducing power consumption.
Solution Approach 2:
The patent replaces the mechanical/electrical control system (selective toggling of light emitting devices) with an optical transformation system (DOE or ROE). Instead of controlling which devices are on or off, the system uses optical elements to transform the light from all active devices into the desired irregular pattern, reducing the complexity and power consumption of the control system.
3Ease of manufacture
If a regular array of light emitting devices is used, then the manufacturing cost is reduced, but the quality of irregular light pattern deteriorates
Solution Approach 1:
The patent moves the pattern transformation from the light emitting element dimension to the optical path dimension. Instead of creating an irregular pattern at the source (light emitting array), the system uses optical elements to transform the regular pattern in the propagation dimension, achieving the irregular projected pattern while maintaining a simple regular array.
Solution Approach 2:
The system changes the parameters of the light pattern through optical transformation. The optical elements (DOE or ROE) modify parameters such as light direction, intensity distribution, and spatial arrangement, transforming a regular light pattern from a regular array into an irregular projected pattern suitable for 3D measurement.
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 reduces manufacturing costs and power consumption while generating effective irregular light patterns for 3D shape measurement, achieving efficient and cost-effective structured light projection.
Implementation Method 1
DOEs are configured to diffract an incoming beam or pattern of light to generate an output pattern in a predetermined way
Implementation Method 2
or additional optical elements to project the emitted light pattern onto a surface, or alter and then project the emitted light pattern onto a surface
Implementation Method 3
US 2010/284082 A1 describes an optical apparatus having first and second DOEs arranged in series to diffract an input beam of radiation
Data Source
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Figure 3A
AI summary
Structured light projection system includes an array of light emitting devices, which is configured to emit a pattern of light. A projection lens is configured to receive and project the pattern of light from the array to a first optical element. The first optical element alters the pattern of light to generate a first emitted pattern of light that is irregular. The first emitted pattern of light is transmitted to a second optical element that is configured to receive the first pattern of light and reproduce the first emitted pattern along a second emitted pattern, which comprises multiple instances of the first emitted pattern arranged in a tiled pattern.