Sponsored links

Dear readers, here is me with new topic regarding physic science about method of reducing spherical aberration as follow:

The spherical aberration as explained above cannot be eliminated completely for  a single lens with spherical surfaces. This is because it arises due to the 'spherical' shape of the lens and its amount is proportional to the square of the radius of the portion of lens surface through which the light rays pass. It can, however, he reduced appreciably by the following methods :

i) By use of stops.  Obviously spherical aberration can be reduced it either the marginal rays or the central rays are cut off by using suitable stops, the rest of the rays come practically to a point focus. The stop is usually circular and its center coincides with the pole of the lens.In camera lenses the marginal rays are cut off by placing a narrow circular aperture. In telescope objectives, which have large aperture, the central rays are cut off by covering the central portion of the lens. But use of stops reduces the intensity of light and the brightness of the image.

ii)  By combining suitable convex and concave lenses. We have already seen that the spherical aberration for a converging lens is positive and that for a diverging lens is negative. Therefore, by suitably combining a convex lens with a concave lens, spherical aberration may be minimized.