Autocollimation the goniometer may also be measured from the refractive index of the collimator material. As shown in Figure 2 Figure 2 shows, the angle of incidence of light in front of the prism surface is i, if OC refraction of light perpendicular to the surface just after BD prism, the reflected light path of incident light path COS coincide with the SOC, called self-collimated light path. Known by the geometric relationship shown in Figure 2, then the light refraction angle f and the front surface of the prism angle θ is equal, according to the law of refraction n = sini / sinθ, measured i and θ, propylene glycol use, can be obtained n . On the goniometer to establish minimum deviation angle of the light path or from collimated light path, propylene glycol Jinan, not only through observation and adjustment problems, and there is a subjective error, over the years, China on the basis of digital goniometer developed on a fully automated refraction instrument on this instrument with the minimum deviation method or from quasi-linear method to measure the refractive index when homing automatically, the measurement results can be processed automatically. Measurement wavelength range can be extended to the ultraviolet and infrared (0.2 ~ 15μm). There are two types of negative refractive index material phenomenon. One class of materials is due to the localized resonance mechanisms leading permittivity and negative permeability simultaneously, both material has an effective negative refractive index. Slotted ring resonator arrays of such materials is also known as metamaterials (Metamaterials) .Smith et al belong to a specific material. However, seam-ring resonator array structure has a large loss and a narrower bandwidth of negative refraction, the application will be subject to many restrictions. Another class of materials are photonic crystals, Zibo propylene glycol, which itself does not have a valid negative refractive index, propylene glycol, Shandong, but the complexity of the dispersion relation in some special cases photonic band will lead to negative refraction. In photonic crystals, electromagnetic waves in periodic structures in Bragg scattering mechanisms play a major role. Although local and nonlocal resonance mechanism of Bragg scattering mechanism will produce negative refraction, but two mechanisms have their own characteristics. For Bragg mechanism, it has been understood more clearly by suitable photonic crystals and photonic band structure of selected design, you can obtain the desired negative refraction passband. But Bragg mechanism requires periodic structure of the lattice constant is comparable to the energy gap wavelength of electromagnetic waves on the microwave band structure is too large will cause the device to restrict the application of propylene glycol, Shandong, Xiang dry chemical (certified), propanediol from Jinan, Zibo Cheung dry chemical Limited. Jinan Cheung Dry Chemical Co. (www.xiangqianhuagong.com) (www.dilunyierchun.com) in this area alcohols devoted boundless enthusiasm and passion, Cheung dry chemical has been customer-centric, for customers to create the concept of value, quality, service to win market, and sincerely hope to cooperate with the community to create success, to create brilliant. Related businesses welcome inquiries, contact: Mr.