In the last decades, motivated by application requirements, our researches have focused on the related theories, methods and techniques of laser radar (ladar or lidar), including laser scattering characteristics from objects, the evaluation and measurement of laser radar-cross-section (LRCS), the design and development of lidar system. We have already developed series of lidar principle prototypes. Now and in the near future, we will devote to the development of 3D imaging and muti/hyperspectral lidar systems in order to improve detecting ability and situation awareness for the topographical objects in recognition and classification.
1. LRCS of several types of target
Based on theoretical analysis of laser scattering properties, the measurement and evaluation of LRCS of specific targets are carried out using scaling model method and the automatic measurement system developed by our group.
(1) Evaluation of target LRCS
Figure 1. LRCS evaluation of specific targets
(2) Laser scattering characteristics of small UAV
The test method of three-dimensional target LRCS is studied, which provides reliable technological data of Lidar system used to detect the small UAV.
Figure 2. Target of UAV (left) and the measuring results of LRCS (right)
2. Principle prototype of Lidar system
We have developed several prototype of lidar systems with different operation modes, such as monostatic and bistatic systems, tracking Lidar system with small field of view (FOV), etc.
● Monostatic system and bistatic receiver (array aperture)
Figure 3. Monostatic lidar system (left) and bistatic receiver with array aperture (right).
● Tracking Lidar system with small FOV
Figure 4. Tracking Lidar system using high-speed scanning
3.New techniques of laser radar systems
Exploiting some emerging techniques of beam controlling and optical imaging technology, our group strives for exploring some new principle and technology of Lidar system. Advanced lidar detection technologies are researched, including phased array lidar, correlation imaging lidar, three-dimensional imaging lidar, and hyperspectral lidar.
(1) Optical waveguide phased array lidar
In order to overcome the limitations of traditional beam scanning system, a new type of optical waveguide phased array lidar prototype has been designed and tested with large angle and high speed optical scanning.
Figure 5. The scanning and receiving parts of optical waveguide phased array lidar
(2) Correlation imaging lidar
The theories and methods of correlation imaging lidar based on pseudo-thermal light source produced by fiber-type optical phased array are studied. The optical circuit of correlation imaging lidar was set up with experimental verification according to different applied background.
Figure 6. The schematic system of fiber array pseudo-thermal source.
(3) 3D imaging lidar
For the demand of long-range target and environment sensing, the two-dimensional super-resolution imaging technology are applied to develope a high-speed 3D imaging lidar with a low-resolution detector.
(4) Muti- / hyperspectral lidar
To bypass the limitations of single-wavelength laser radar and thus improve the detecting ability of topographical objects in recognition and classification, the active lidar detection combined with passive multi- or hyperspectral remote sensing has being explored in our team. Multi- or hyperspectral lidar has the ability of physical properties detection and simultaneously maintains the capability of three-dimensional space exploration with high spatial resolution.
