Optical instruments

Introduction 

A number of optical instruments have been designed using the concept of reflection, refraction, lenses, prisms, and many more. Among these, microscopes and telescopes are two powerful instruments that have greatly aided our current understanding of the micro-and macrocosmic. In addition, the development of these gadgets resulted in breakthroughs in fields like physics, astronomy, and biology, to name a few. 

Microscopes and telescopes both work by allowing individuals to see items that aren’t visible to the naked eye. Telescopes are meant to observe distant, faint objects and have larger lens diameters, greater focal lengths, and interchangeable eyepieces. Aside from that, both tools magnify the object of interest using convex and concave lenses. Even though both devices utilise similar scientific concepts, their distinctions are critical to their capacity to achieve their goals.

Microscopes

Microscopes were invented by eyeglass makers in the Netherlands and Denmark in the early 1600s. 

The simplest compound microscope is made up of two convex lenses. The objective lens is the first lens, and it has magnification values ranging from 5 to 100. The lenses in ordinary microscopes are positioned so that the sample remains in focus when you change between objectives. Parfocal objectives are those that are organised in this manner. The eyepiece, also known as the ocular, comprises numerous lenses that move inside a cylindrical tube. The eyesight is provided by both the objective lens and the eyepiece moving. Both lenses lead to total magnification, which is used to magnify small objects. Since the eye cannot concentrate on objects or images that are too close, the final expanded image is created far from the viewer to be easily perceived.

Magnifying power of a compound microscope

The power of a microscope is the product of the powers of the ocular (eyepiece) and the objective lens and is given by

 m= (L/f0)(D/fe)

 where L is the length of the tube

           D is the least distance of clear vision.

           f0​ is the focal length of the objective

           fe​ is the focal length of the eyepiece

A simple microscope is a magnifying glass with a short focal length and a double convex lens. The hand and reading lenses are two examples of this type of equipment. When an object is kept close to the lens, the image created by its principal focus is upright and larger than the original thing. Because the produced image is virtual, it cannot be displayed on a screen in the same way that a real image can.

A biconvex lens is used to magnify the image of a specimen in simple microscopes. These lenses are now commonly made up of two glass parts with colour correcting capabilities. The magnified picture grows as the object gets closer to the lens.

Magnifying power Of Simple Microscope

Because a simple microscope has one objective lens, its magnification potential is severely limited. For example, the magnification capacity of most basic microscopes is only 10x.

The magnifying power of a simple microscope is given by:

M=1+D/F

• F = the focal length of the convex lens
• D = the least distance of the distinct vision

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. However, 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 for telescope objectives instead of lenses. Mirrors may be built far larger than lenses, allowing them to collect vast volumes of light, such as that required to observe distant objects. Telescopes, like microscopes, can also use frequencies of various ranges from the electromagnetic spectrum. Large and highly flat mirrors have long focal lengths, allowing considerable angular magnification.

Refractors and reflectors are the two primary types of telescopes. The kind of telescope is determined by the objective, 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.

Refractor telescopes

A lens gathers and focuses light in a refractor telescope. Refractors were the first telescopes to be made. Small telescopes offered in department stores, as well as those used in rifle scopes, are refractors.

Reflector telescopes

A mirror gathers and focuses light in a reflector telescope. Because all celestial bodies (including those in our solar system) are so far away that all of their light beams reach the Earth parallel. The reflector telescope’s mirror has a parabola form because the light beams are parallel. The parallel light rays are focused to a single point by the parabolic-shaped mirror. Because of the benefits of reflector telescopes over refractor telescopes, all current research telescopes and big amateur telescopes are of the reflector type.

Magnifying power of telescope:

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

M=fo/fe

fo= the object’s focal length

fe= focal length of the eyepiece

Microscope Vs Telescope

Uses of Microscopes

In science, microscopes have opened many doors. Microscopes allowed scientists, researchers, and students to uncover the presence of microbes, analyse cell structure, and view the tiniest components of plants, animals, and fungus.

Microscopes are significant in biology since they are primarily concerned with studying cells (and their contents), genes, and all organisms. For example, some creatures are so minute that they can only be seen with magnifications of 40x to 1000x, which can only be done using a microscope. Likewise, the smallest cells can’t be seen with the naked eye.

Microscopes are employed in a variety of businesses in addition to observing cells and their structure. Electron microscopes, for example, aid in the creation and observation of extremely small electrical circuits seen on Silicon microchips. Scanning microscopes are far more sophisticated than light-refracting microscopes, and they have far higher magnifications.

Conclusion

An objective lens is used in both microscopes and telescopes. This collects light from the real object or scene that the observer is looking at. 

They’re both experts in magnification. They allow us to get a closer look at something that is difficult to see with the naked eye. It gives the impression that the image is larger 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.