What is the difference between Mach Zehnder interferometer and Michelson interferometer?

The text is not clear, but the optical paths of these two interferometers can be drawn. Every mirror of Mach-Zehnder interferometer will not return to the original optical path, so this effect is good, unlike Michelson interferometer, which will return to part of the original optical path.

Working principle:

Michelson interferometer is the most common optical interferometer, and its inventor is American physicist Albert Abrahan Michelson.

The principle of Michelson interferometer is that a beam of incident light is split into two beams by a beam splitter and then reflected by a corresponding plane mirror. Because the two beams of light have the same frequency, the same vibration direction and constant phase difference (that is, they meet the interference conditions), they can interfere.

By adjusting the length of the interference arm and changing the refractive index of the medium, different optical paths of two beams of light in interference can be realized, thus forming different interference patterns. Interference fringes are trajectories with equal optical path difference. Therefore, in order to analyze the patterns produced by some interference, it is necessary to find the function of the optical path difference position distribution of coherent light.

If the interference fringe moves, the optical path difference corresponding to the field point must change, which may be caused by the change of the optical length L, the refractive index N of the medium in the optical path or the thickness E of the film.

S is a point light source, M 1 (top) and M2 (right) are plane total reflectors, where M 1 is a fixed mirror; M2 is a moving mirror, which is connected by precision thread. Rotating the drum can make it move forward and backward. The minimum reading is 10 mm, which can be estimated as10mm ... m1and there are three small screws behind M2 to adjust its direction.

G 1 (left) is a beam splitter, and its right surface is coated with a semi-transparent and semi-reflective film, so that the incident light is divided into two beams (reflected light and transmitted light) with equal intensity. The reflected light and the transmitted light are vertically incident on the total reflection mirror M 1 and M2, respectively. They return to the semi-transparent and semi-reflective film (left) of G 1 after reflection, and reach the observation area E after transmission and reflection respectively.

G2 (right) is a compensation plate, which is made of the same material and thickness as G 1 and installed in parallel, in order to make the two interfering beams pass through the glass plate equally, and the glass medium will not introduce additional optical path difference when the two beams reach the observation area E. ..

When M2 and M 1' are strictly parallel, they appear as circular stripes with equal inclination interference. When M2 is moved, it will continuously "spit" or "swallow" the ring from the center of the disturbed ring. When the "air gap" distance between two flat mirrors increases, the center will "spit out" stripes; On the contrary, it is "swallowing".

When M2 and m 1' are not strictly parallel, they show equal thickness interference fringes. When M2 moves, the fringe moves at a certain mark position in the field of view. The relationship between M2 translation distance d and fringe movement number n satisfies: d=Nλ/2, where λ is the wavelength of incident light.