The vibration isolator equipped with a negative stiffness corrector (NSC) excels at vibration isolation, but its stiffness often presents complex nonlinearity which needs to be approximated in calculation. To avoid the harmful effects of approximate stiffness, the NSC formed by the cam-roller mechanism with a quadratic polynomial trajectory (QCRM) is proposed to construct the vibration isolation system. From the inherent geometrical relationship in the structure, the generation mechanism of high-static-low-dynamic stiffness is analyzed, and the quasi-zero stiffness (QZS) condition of the system is derived. Based on the dynamic model of the QZS vibration isolator, the functions of response characteristics are solved by the harmonic balance method. Then, the absolute displacement transmissibility with different parameter values, and the vibration isolation performance under sinusoidal, multi-frequency wave, and random excitations are discussed. The simulated results show that the stiffness expression of the proposed QZS vibration isolator is directly a quadratic function, which removes the calculation error caused by approximate stiffness at large displacement and broadens the available isolation displacement range. Introducing the QCRM-NSC can significantly suppress the low-frequency vibration and resonance response without changing the load-bearing capacity of the vibration isolator. Under various excitations, the vibration isolation performance of the QZS vibration isolator all outperforms the linear counterpart.

Light-medium interaction produces polarized reflected light, where the polarization state of the reflected light is closely related to multi-dimensional information such as object shape, roughness, and material.^{1 – 3} A polarized bidirectional reflectance distribution function (PBRDF) can be built by simulating the polarization of light reflection, which is of important theoretical significance for surface target detection and measurement.^{4 – 6} However, for a coating surface, the coating and the substrate form a bilayer structure, and the measurement of its interaction with light involves various propagation modes such as diffuse/specular reflection, absorption, transmission, refraction, and single/multiple scattering, making the scattered light field of the coating surface more complex. This causes difficulties in the building of the PBRDF model.^7,8