The Newton s ring experiment was to prove something

Turn on the sodium light source, pre-warm for 5 minutes, and align the reading microscope objective with the ** part of Newton's ring.

Adjust the reading microscope to see clear light and dark fringes, and the fringes and forks have no parallax.

Adjust the Newton ring within the range of the range, then use the right hand to reverse the auxiliary gear, move the cross wire to the right 35 dark ring, and then use the right hand to rotate forward, so that the cross wire begins to advance to the left, until the longitudinal wire is pressed to the 30th dark ring ring**,..

Continue to rotate the auxiliary gear, so that the longitudinal wire passes through the center of the Newton ring to the other side, aligns with the 10th 30 ring, and notes the corresponding scale x10,, x15,, x20,, x25,, x3....

Calculate the corresponding dark ring diameter, then calculate R20-10, R25-15, R30-20, and finally calculate R.

The purpose of the Newtonian ring experiment is to observe and analyze the interference phenomenon of equal thickness with Newton ring. Newton's rings, also known as "Newton's circles".

Optically, Newton's rings are a thin-film interference phenomenon. An interference pattern of light, which is a number of concentric rings of light and dark. For example, when the convex surface of a convex lens with a large radius of curvature is in contact with a flat glass, in daylight or irradiation with white light, the contact point can be seen as a dark point, and it is surrounded by some light and dark colored rings; When illuminated with monochromatic light, it appears as some monochromatic circles with light and dark.

If a beam of light is irradiated to a thin film, the light wave will be reflected by the upper and lower interfaces of the film due to the different refractive indexes, and new light waves will be formed due to mutual interference, which is called thin film interference. The study of this phenomenon can reveal information about the surface of the film, including the thickness and refractive index of the film. There are a wide range of commercial uses for films, such as anti-reflection coatings, mirrors, optical filters, and more.

The experimental error analysis of Newton's ring is as follows:

In the formula we derive, the difference between the two orders is used to deal with it, but this can only avoid the problem of determining the dark ring order, and the influence of the size of the dark spot in the center can be completely eliminated on the result. Because the size of the dark spot in the center reflects the size of the lens deformation, under the pressure and gravity of the screw, not only the center is deformed, but the entire surface is deformed.

The farther away the deformation is, the smaller the δh, because the (m-n) on the denominator in this relation is not the same as when there is no deformation, but it becomes smaller, and it can be inferred that the measurement result is larger.

Experimental considerations.

1. When focusing, the position of g is about 1 cm away from the objective lens, do not operate blindly, so as not to crush the reflective glass piece.

2. Do not vibrate during measurement, do not shake the reading microscope, and do not count wrongly.

3. Do not touch the optical surface of the Newton ring instrument with your hands, if it is not clean, wipe it with a special mirror paper.

4. Do not overtighten the three screws on the Newton ring instrument, so as not to deform and damage the Newton ring instrument in serious cases.