Structured Light Projector Dynamic Focal Adjustment
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Solution Overview
Problem
Structured light projectors face reduced accuracy and energy loss due to the divergence of light beams, resulting in larger speckled patterns and incomplete illumination at greater distances from the object, which affects the accuracy of depth data collection.
Innovation Solution
The structured light projector incorporates a diffractive optical element and a voice coil motor to adjust the focal length of the camera, ensuring complete speckled patterns are projected onto the object, enhancing the utilization rate of light and improving accuracy by adjusting the distance between the camera and the object, using a lens with mirror surfaces to alter the light paths and a CMOS sensor for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between the structured light projector and the to-be-tested object is increased, then the measurement range is expanded, but the speckled pattern size increases and measurement accuracy deteriorates
Solution Approach 1:
The patent employs a voice coil motor to dynamically adjust the focal length of the camera lens in real-time based on the distance to the to-be-tested object. This dynamic focusing mechanism ensures that the speckled pattern remains sharp and well-defined regardless of the object distance, thereby maintaining measurement accuracy while expanding the measurement range.
Solution Approach 2:
The system changes the focal length parameter of the camera lens according to the object distance. By adjusting this optical parameter, the system compensates for the divergence of the light beam over distance, keeping the speckled pattern size appropriate for accurate depth measurement even when the object is far away.
2Area of stationary object
If the distance between the structured light projector and the to-be-tested object is increased, then the measurement range is expanded, but the light energy loss increases due to incomplete speckled pattern illumination
Solution Approach 1:
The voice coil motor dynamically adjusts the camera focal length to match the object distance, ensuring that the speckled pattern is properly focused and contained within the camera's field of view. This prevents light energy loss by ensuring complete illumination of the measurement area regardless of distance.
3Measurement precision
If the focal length of the camera is adjusted to maintain speckled pattern quality, then the measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent replaces manual or mechanical focusing mechanisms with a voice coil motor, which provides precise, electrically-controlled focal length adjustment. This substitution enables accurate focusing without complex mechanical structures, achieving high measurement precision while keeping the device relatively simple.
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 configuration ensures high utilization of light energy, reduces power consumption, and enhances the accuracy of three-dimensional data collection by maintaining complete speckled patterns and precise depth measurement across varying distances.
Implementation Method 1
a diffractive optical element (DOE)... The DOE converts the laser beam into a speckled pattern
Implementation Method 2
a voice coil motor to adjust the focal length of the camera
Implementation Method 3
a lens with mirror surfaces to alter the light paths
Implementation Method 4
a CMOS sensor for decoding... The camera collects the light reflected by the to-be-tested object to form data
Data Source
AI summary
A structured light projector outputting light which is adapt to variations in distance between an object under test and the structured light projector can efficiently obtain data as to three dimensions of the object. The structured light projector includes a lens, an infrared laser source, a voice coil motor, a first camera, and a second camera. The infrared laser source can emit infrared light towards the voice coil motor, the first camera is movably housed in the voice coil motor. The voice coil motor can adjust a focal length of the first camera. The first camera is disposed on a transmission path of the infrared light, so that the infrared light enters the to-be-tested object. The second camera is disposed on the second surface, to receive light reflected by the to-be-tested object.