https://www.selleckchem.com/products/tbopp.html We verified the DSS method using a 152 mm diameter optical flat mirror and determined the root-mean-square (rms) measurement error to be only 0.2 nm, which was comparable to the error of the full-aperture interferometric measurement. In addition, we tested a 1.2 m diameter flat mirror with a reference sphere with an aperture of 0.8 m and measured its SFE to be 11.9±0.5nm rms.In this paper, by considering wave phase analysis, the density of modes, group velocity, and lateral shift in one-dimensional multilayer are theoretically computed by using the transfer matrix method in the terahertz domain. The proposed structure is based on the Fibonacci sequence constituted of uniaxial indefinite medium and SiO2 layers. It is found that for both TE and TM beams, around an angle of 90º, the lateral shift is highly negative, while it is positive at the rest of the angles. Also, for non-vertical angles, a positive peak is observed about an angle of 60º (near the Brewster angle). Our numerical analysis shows that at angles less than about 10º, the lateral shift is negative for the TM mode. It is shown that for both polarizations the density of states (the group velocity) has maximum (minimum) value near the band gap edges, while inside the band gap it becomes minimum (maximum). Superluminal and subluminal cases can be defined here.We have proposed a polarization-independent directional coupler (DC) by using sections with optimal coupling strength designs on the lithium-niobate-on-insulator platform. With this design, arbitrary polarization-independent coupling ratio ranging from 0% to 100% can be achieved by tuning the length of the identical coupling region. The DC exhibits ultralow excess losses ( less then 0.1dB) and polarization-dependent losses ( less then 0.05dB for the complete coupling) over a bandwidth of 100 nm. Moreover, the proposed DC is compact in size, simple in structure, and easy to fabricate.In this work, the influ