Features of instruments: ● Using semiconductor laser (650nm, 4mW) as the light source and it’s power stability is better than 1%. ● Use a one-dimensional displacement rack + 12 steps light probe to measure data, it’s more objective and the precision can reach 0.02mm. ● The optical experiment guide is 1200mm. Complete set of equipment: ● Optical experiment guide, semiconductor laser, biprism, lens, laser power indicator, one-dimensional displacement rack+ 12 steps light probe and etc..