| 摘要 |
PURPOSE:To perform an easy measurement of a group refractive index through a very simple means, by a method wherein an interference fringe due to a luminous flux of wavelengths lambda1, lambda2 is detected by a like detector, and based on the output of the detector, a group refractive index is found. CONSTITUTION:Laser lights from a laser light source 1 of a wavelength lambda1 and a laser light source 2 of a wavelength lambda2 are mixed by a beam mixing device 3. The lights are caused to enter an interference meter in a manner that the optical shafts are arranged in order. Each interference due to a luminous flux of wavelengths lambda1 and lambda2 is produced, and an interference fringe due to a luminous flux transmitting a vacuum cell 9 is reflected by a reflection mirror 11 to detect it by a detector 12. An interference fringe due to a flux not transmitting the cell 19 is detected by a detector 13. From a phase difference between the interference fringes, a group refraction index of air is found highly precisely. |
