Line-scan phase-resolved synthetic wavelength LiDAR using an off-axis holographic approach

Unmet Need

High-resolution three-dimensional (3D) imaging techniques have seen widespread adoption as a means by which to develop a real-time map of the world around us, such as is needed by a variety of autonomous devices to operate effectively. To accomplish this, light detection and ranging (LiDAR) is a commonly used technique as it can easily achieve centimeter-scale resolution over great distances. However, there is a strong desire to reach higher imaging resolutions without requiring costly and complicated equipment.

Technology

Duke inventors have developed a technique for accurate rapid absolute distance measurement and mapping of 3D surfaces at ranges from centimeters to kilometers. To achieve this, researchers utilized a synthetic wavelength – variable by the wavenumber difference between two coherent light sources – to perform frequency-modulated continuous-wave interferometric measurements. By leveraging an off-axis holographic approach to phase retrieval within the LiDAR application image resolution can be further improved in an efficient manner for small depth images. These techniques have been demonstrated for such practical applications as the imaging of complex microprocessors with micron level depth accuracy and precision with the potential to image at much greater distances.

Advantages

• < 1 mm depth resolution
• Efficient 3D surface detection (2.5D) at a throughput rate of ~30 Mvox/sec (~1,000 px × 1,000 × 30 Hz)
• Utilizes tunable “single frequency” continuous-wave lasers instead of the costly picosecond pulsed lasers common to other time-of-flight LiDAR methods
• Tunable synthetic wavelengths allow the ambiguity length to be tailored to the application