Interferometer application profile

An interferometer is an instrument that measures the wavelength and fine structure of a spectral line. Its principle is based on the principle of interference and can accurately determine the wavelength and fine structure of a spectral line.

Interferometer applications mainly include the following aspects:

Precise measurement of length

In a two-beam interferometer, if the refractive index of the medium is uniform and constant, the movement of the interference fringe is caused by a change in the difference in the geometric path of the two-phase coherent light, and an exact or absolute measurement of the length can be performed according to the number of movements of the fringes. The Michelson interferometer and the Fabry-Perot interferometer were used to represent the international meters at the wavelength of the cadmium red line.

Determination of refractive index

The geometrical distance of the two beams remains unchanged, and the change of the refractive index of the medium can also lead to a change of the optical path difference, thereby causing the stripe to move. The Rayleigh interferometer is a typical interferometer that measures relative refractive index by moving stripes. The Mach-Qinter interferometer applied to the wind tunnel was used to observe the change in refractive index of the gas stream in real time.

Wavelength measurement

Any method of measuring the standard meter in units of wavelength is a method of measuring the wavelength in units of a standard meter. With the international standard, the interferometer can be used to accurately determine the wavelength of light waves. Fabry-Perot interferometers (etalons) have been used to determine the primary standard of wavelength (cadmium red line wavelength) and several secondary wavelength standards to determine the wavelength of other spectral lines by comparison.

Check the quality of optical components

The Twyman interferometer is commonly used to verify the quality of optical components such as plates, prisms, and lenses. Placing the plate or prism to be inspected in one of the optical paths of the Twyman interferometer, any inhomogeneities in the refractive index or geometry of the plate or prism must be reflected on the interference pattern. If a lens is placed in the optical path, the wavefront distortion caused by the lens can be known from the interference pattern to evaluate the wave aberration of the lens.