Resolving Power of Microscopes and Astronomical Telescopes

Several optical instruments have been designed using the concept of reflection, refraction, lenses, prisms and many more. Microscopes and astronomical telescopes are two of the most useful instruments. Microscopes allow individuals to see items that are not visible to the naked eye. On the other hand, telescopes are meant to observe distant, faint objects and have larger lens diameters, greater focal lengths and interchangeable eyepieces. Although these devices utilise similar scientific concepts, their distinctions are critical to their capacity to achieve their goals. Now let’s delve into the study material notes on the Resolving power of Microscopes and Astronomical Telescopes.

Resolving power of microscopes

Celestial objects are often seen through telescopes. These bodies can be millions of miles away from each other, but the direction of the light coming from them can be almost the same. In comparison, microscopes are used to see nearby objects. The resolving power of a microscope is also determined by its resolving range (inversely proportional).

The resolution limit of a microscope is the shortest distance between two nearby objects when the images formed by the microscope are properly differentiated. The smaller this distance, the higher the resolving power of the microscope.

If two points of an object are so close that their diffraction discs overlap each other, we cannot see those points separately. The resolving power of a microscope tells us how far apart points can be seen separately.

Resolving range 

The resolution range of an optical instrument is equal to the minimum angular distance between two point objects at which their images can be seen separately by the optical instrument.

d = 0.61 λN.A

Here, λ is the wavelength of the light used, d is the diameter of the aperture of the objective lens, and N.A is the numerical aperture.

Resolving power

The resolving power of an optical instrument is the minimum distance between two objects at which the optical instrument can form images of both objects separately. It is represented by D, and its unit is a metre or centimetre.

1Δd = 2nsinϴ ƛ

Telescope

A telescope is an optical tool that uses curved mirrors to collect and focus light from the night sky to see distant objects that are not visible to the naked eye.

Because a concave mirror behaves like a convex lens, a telescope can use a concave mirror as its first component or objective. Flat mirrors are commonly used in optical instruments to make them more portable or transfer light to cameras and other sensor systems. 

There are numerous advantages to employing mirrors instead of lenses in telescopes. Mirrors can be built larger than lenses, allowing them to collect vast volumes of light required to observe distant objects. Telescopes, like microscopes, can also use frequencies of various ranges from the electromagnetic spectrum. Large and completely flat mirrors have very long focal lengths, allowing for considerable angular magnification.

Refractors and reflectors are the two primary types of telescopes. The type of telescope can be determined by the objective lens, which is the part of the telescope that collects light. The target of a refractor telescope is a glass lens. The front of the telescope has a glass lens that bends (refracts) light as it goes through it. The objective of a reflector telescope is a mirror. Light is reflected off (reflected) as it hits the mirror, which is close to the back of the telescope.

The magnifying power of the telescope

The ratio of the angle subtended at the eye by the image formed at the least distance of distinct vision to the angle subtended at the eye by the object lying at infinity is the magnifying power of a telescope.

M = (fo/fe)(e1 + f/D)

M = magnifying power

fo= the object’s focal length

fe = focal length of the eyepiece

D = least distance of the distinct vision

The resolving power of the telescope

1Δϴ = d1.22ƛ

Conclusion

An objective lens is used in both microscopes and telescopes. This lens collects light from the real object or scene the observer is looking at. It concentrates on light rays to help us view a crisp picture, usually things our naked eye cannot see. An astronomical telescope serves the basic purpose of displaying the magnified image of any distant object that might seem negligible in size to the naked eye.

Microscopes and astronomical telescopes are both experts in magnification. They allow us to get a closer look at something difficult to see with the naked eye. It gives the impression that the image is bigger and clearer. Under a microscope, the movement of cells can be observed, and via a telescope, one can watch the movement of shooting stars in the sky.

Microscopes and telescopes are powerful instruments that have greatly aided our current understanding of the microcosm and macrocosm. The development of these gadgets resulted in breakthroughs in fields like physics, astronomy and biology.