The surfaces of objects in the nature can be thought of as random rough surfaces at the laser wavelength scale. According to the correlation of the height distribution, they can be divided into one-dimensional (1D) and twodimensional (2D) random rough surfaces. They can modulate the fully polarized incident light, and the scattered light carries the information of material and microstructure. Understanding this modulation is helpful to extract the target features. The Mueller matrix can characterize this modulation, and the Stokes vector can represent the scattered light. In this paper, a large number of 1D and 2D random rough surfaces were generated to simulate the target surfaces by frequency domain filtering, and the statistical stability of Mueller matrix and Stokes vector of the rough surfaces was obtained by Monte Carlo method. The results showed that for 1D rough surfaces of metal and dielectric, m34 and m43 of the Mueller matrix had obvious difference. Due to coupling, the Mueller matrices of 1D and 2D rough surfaces were obviously different. Metal rough surface could make 45º polarized light into elliptically. However, the dielectric rough surface had no such conversion ability. This difference had nothing to do with the roughness, but only with the property of the material. We could effectively identify metal targets by the difference. This conclusion provided a new theoretical basis for the design of laser detection and target recognition system.
The laser has good coherence and its polarization is easy to modulate. It is an important light source. The surfaces of common objects can be regarded as random rough surfaces at the laser wavelength scale. Random rough surface modulates incident polarized light, and the scattered light contains the information of geometric profile and physical properties of the target surface. For the laser detection system, it is important to perceive the high dimensional information which was contained in the target echo signal. In this paper, the Stokes vector was used to describe the scattered light. The virtual instrument technology was adopted to develop a laser scattering measurement system. The Labview software that running on the computer issued control commands to microcontroller unit (MCU) by serial port communication. We made a high precision digital light detector. The MCU obtained the scattered light intensity from the photoelectric sensor via I2C bus. The incident light was modulated to two typical linearly polarized light using a polaroid and a half wave plate. The Stokes vector could describe the state of the scattered light completely, and which was measured by the polarization detection system. The Stokes vector of all angular hemispheric space backscattering light was measured. The results showed that the scattered light on the surface of metal object appeared circularly polarized component. However, the circular polarized component of the scattered light on the dielectric target surface was almost zero. The above conclusions could provide theoretical basis for the laser detection system to identify metal targets.
The surface of target is thought of as random rough surface at laser wavelength scale, which can modulate the incident light, and the information of material and texture of which is carried by the scattered light. Understanding this modulation is helpful to improve the accuracy of target recognition. In this paper, a large number of random rough surfaces were generated to simulate the surface of target by frequency domain filtering, and the statistical stability of Stokes vector of scattered light was obtained by Monte Carlo method. The results showed that the intensity and peak position of the scattered light had obviously difference under different polarized incident light. As the angle between the polarized direction of the incident light and the incident plane changed, the scattered light from the dielectric rough surface remained linearly polarized, however the scattered light from the metal rough surface turned elliptically polarized. We believed that the research could provide a new criterion for laser detection and measurement system to distinguish the materials and roughness of targets.