What is the effect of the introduction of interferometers compared to the conventional grating method

Precision measurement of length, refractive index determination.

1, precision measurement of length. Interferometer, if the refractive index of the medium is uniform and constant, the movement of the interference fringes is caused by the difference between the two coherent light geometric distance caused by changes in the number of movements according to the fringes can be carried out for the length of the precise more or absolute measurement.

2, refractive index determination. Geometric distance of the two beams remains constant, the refractive index of the medium changes can also lead to changes in the optical distance difference, thus causing the stripes to move.