Optical instruments

powerpoint presentation

1. Optical Instruments

2. 2 Your eye is a very effective organ, but its ranged can be extended in a lot of ways by means of optical instruments such as: magnifying glasses, cameras, microscopes and telescopes. Stamp collectors use magnifying glasses to look closer into their collection. Photojournalist are able to “stop time” and capture a certain event using cameras . Biologist can see and study small entities such as microbes and bacteria using a microscope . Astronomers can probe the heavenly bodies using telescope . These and many others, are just some of the technologies that help your eyes to investigate everything around you .

3. 3 Magnifying Glass Magnifying glasses are simple instruments used to enlarge objects. They consist of a single, biconvex lens mounted in a frame with a handle. Camera The camera is used to capture images to a medium and store it over a period of time. A simple camera follows the same mechanism as the human eye. The major parts of the eye used in vision, the lens, iris, and the retina, correspond to the major parts of a camera: the lens, aperture, and the focal plane.

4. 4 Microscope A microscope is an optical instrument for viewing objects that are too small to be seen by the naked eye or unaided eye. The simplest microscope is the compound microscope that uses two converging lens used to magnify objects: the objective and the eyepiece lenses . The objective lens forms a real and enlarged image , while the eyepiece forms final and virtual image . The objective lens regulates and forms an enlarged real image which is viewed through the eyepiece.

5. 5 Telescope Is a device that gathers light or electromagnetic waves and focuses it to form an image. It is commonly used to make far away objects, like the planets of our solar system, seem closer. There are two main types of telescopes: refracting and reflecting telescopes . The difference depends on the components used to observe distant objects. The refracting telescope or refractor is a type of optical telescope that uses lens as its objective to form object. It uses refraction to make distant objects appear closer and more visible.

6. 6 These are usually made up of two lenses: the objective lens (larger lens) and the eyepiece lens (smaller lens ). This uses the same principle as the optical microscope. However, the object is effectively placed at infinity instead of putting the object near the object lens. The reflecting telescope, or reflector   has a concave mirror that gathers light from the object and focuses it into an adjustable eyepiece or combination of lenses through which the reflection of the object is enlarged and viewed.

7. 7 Myopia (Nearsightedness) – A myopic or nearsightedness person sees clearly but far objects appear blurred to him/her. Hyperopia(Farsightedness) – A hyperopic person sees distant objects clearly but see nearly objects appear blurred to him/her. Some Common Eye Defects

8. 8 Astigmatism – It is an eye defect in which the surface of the cornea is not spherical, but it is more sharply curved in one plane than another. Presbyopia – This eye condition is common among people who reach middle age. Unlike farsightedness, this condition produces blurred images of near objects because of a decrease in ability to focus on light and nearly objects due to weakening of the ciliary muscles and the hardening of the lens. Some Common Eye Defects

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