Leave a message for inquiry
Leave your phone number, and we'll get in touch with you as soon as possible.
Structured Light
As a core method in the field of 3D imaging, structured-light technology achieves high-precision, non-contact 3D surface measurement by projecting encoded optical patterns onto an object's surface and analyzing their deformations.
1. The basic principle of structured light technology
The core idea of structured-light technology is to actively project specific optical patterns onto the surface of the object being measured. By leveraging the spatial modulation effect that the object's morphology has on these patterns, three-dimensional surface profiles can be reconstructed based on the principle of triangulation. When the projected structured-light pattern illuminates the object's surface, variations in the object's height cause the pattern to deform from the observer's perspective. This deformation carries crucial three-dimensional information about the object. By mathematically analyzing the differences between the original and deformed patterns, it is possible to precisely determine the spatial coordinates of each point on the object's surface. Laser light, with its high brightness, high collimation, and monochromaticity, has become the primary light source for structured-light systems.
Working Principle of Typical Structured Light
A structured-light system typically consists of three main components: a laser projection unit, an image acquisition unit, and a data processing unit. The projection unit projects encoded structured-light patterns—such as sinusoidal fringes, Gray codes, or speckle patterns—onto the object being measured. The image acquisition unit (usually a CCD or CMOS camera) captures deformed patterns modulated by the object’s surface from different viewing angles. The data processing unit then converts the two-dimensional image coordinates into a three-dimensional point cloud through phase calculation, decoding algorithms, or feature matching. Modern structured-light systems also integrate mechanical scanning devices or multi-camera arrays to achieve large field-of-view, high-resolution 3D reconstruction.
Compared to other 3D imaging methods (such as laser scanning and stereo vision), structured-light technology has significant technical advantages:
Technical Parameters | Structured Light | Laser scanning | Stereo Vision | TOF |
Measurement Principle | Active triangulation | Point-Scanning Triangulation | Passive Triangulation | Light Flight Time |
Measurement speed | Fast (全场) | Slow (point-by-point) | Fast (全场) | Fast (全场) |
Measurement accuracy | High (μm-mm) | High (μm-mm) | Medium (mm-cm) | Low (cm) |
Hardware Complexity | Middle | High | Low | Middle |
Anti-interference performance | Middle | High | Low | Middle |
Typical Applications | Industrial Inspection | Precision Measurement | Robot Navigation | Somatosensory Interaction |
2. Classification of Structured Light Encoding Methods and Systems
The performance and application effects of structured-light technology largely depend on the encoding strategy employed. Depending on differences in encoding dimensions and implementation methods, structured-light technology can be categorized into three major types: time-domain encoding, spatial-domain encoding, and direct encoding. Each method has its own unique characteristics in terms of measurement speed, accuracy, and applicable scenarios.
Time Encoding Method
Time encoding achieves object surface coding by projecting multiple patterns in temporal sequence, and it features simple decoding and high precision. This type of method requires the object to remain stationary during measurement, making it suitable for high-precision static measurements.
Spatial coding method
Spatial coding achieves 3D reconstruction with just a single projection of a specially designed pattern, making it suitable for measuring dynamic scenes. This type of method encodes information based on the local features of the pattern itself or its spatial arrangement relationships, sacrificing some precision in exchange for higher temporal resolution.
Direct coding method
Direct encoding embeds depth information directly into the projection pattern, allowing the acquisition of 3D coordinates without the need for complex decoding algorithms. These methods typically rely on special optical designs or devices for implementation.
Performance Comparison of Main Structured Light Encoding Methods
Encoding Type | Number of patterns required | Measurement speed | Measurement accuracy | Anti-interference performance | Typical Applications |
Gray code | log2N (usually 8-10) | Slow (static) | High (1/1000 field of view) | Strong | Industrial Inspection |
PMP | 3-12 | Slow (static) | Extremely high (1/100 pixel) | Middle | Precision Measurement |
FTP | 1 | Quick | Medium (1/50 pixel) | Weak | Dynamic Measurement |
Pseudo-random array | 1 | Extremely fast (real-time) | Low (1/100 field of view) | Middle | Somatosensory Interaction |
Laser speckle | 1 | Extremely fast (real-time) | Low (mm-level) | Middle | Consumer Electronics |
Polarization Encoding | 3-4 | Middle | High (normal) | Weak | Mirror objects |
Hybrid Coding Method
Hybrid coding combines the advantages of multiple methods to meet complex measurement requirements. The selection of a coding method should comprehensively consider the measurement object, environmental conditions, and performance requirements.
3. Application fields of structured light technology
Thanks to its high precision, non-contact nature, and flexibility, structured-light technology has been widely applied in various fields such as industrial manufacturing, biomedicine, and cultural heritage preservation. With improvements in hardware performance and algorithm optimization, the application scenarios for structured-light 3D measurement continue to expand, constantly driving technological innovation in related industries.
3.1 Industrial Inspection and Quality Control
Precision component inspection:
The core application of structured-light technology in the industrial sector enables high-precision, full-scale inspection of complex curved surfaces and is widely used for inspecting critical components such as aero-engine blades, automobile engine cylinder blocks, and turbine blades.
Online Monitoring of Welding Quality:
Structured-light technology identifies welding defects through real-time 3D morphology analysis.
Reverse Engineering:
Structured-light scanning has become a key tool in product digital design. In automotive styling design, large-scale structured-light scanning systems can complete the digitization of an entire vehicle’s exterior within just a few hours; the point cloud data is then used for aerodynamic analysis and aesthetic evaluation.
3.2 Biomedical and Health Monitoring
3D Human Body Measurement:
It is widely used in fields such as personalized medicine and orthopedic rehabilitation.
Three-dimensional dental imaging:
Dental age 3D imaging represents a successful application of structured-light technology in the medical field. It can directly acquire the 3D morphology of teeth and gums, replacing traditional silicone impressions with an accuracy of up to 10 μm and a scanning time of less than 2 minutes.
4. CNI Typical Structured Light Laser
CNI offers tunable lasers that support various structured light patterns, including single-line, multi-line, grid, and cross patterns. These lasers feature high stability and narrow linewidth, making them ideal for high-precision 3D imaging and measurement applications.
 |  |
Structured Light Output Mode | Typical Application Scenarios |
 |  |
OEM Structured Light Module | Low-noise research-grade structured-light module |
 |  |
High-power structured-light laser | Integrated Fiber-Output Structured Light Laser |
Changchun New Industries Optoelectronics Technology Co., Ltd.
Address: No. 888 Jinhu Road, High-Tech Zone, Changchun, 130103, P.R.China
International Tel:+86-431-85603799
Email: sales@cnilaser.com
Send a Message
Leave your phone number, and we'll get in touch with you as soon as possible.