Optical Instruments
Optical instruments processes light waves to enhance an image for viewing or analyze light waves to determine number of characteristic properties. The very first optical instruments were telescopes and microscopes used for magnifications of images. Mirrors and lenses find their applications in very many walks of life. Since the days of Galileo, these optical instruments have been greatly improved and extended into other portions of the electromagnetic spectrum. These instruments employ calculations of positions of objects and images from ray diagrams that we have discussed in Spherical Mirrors and Lenses.
Some optical instruments that we see in everyday lives are:
The human eye – convex lens.
Corrections of defects of vision – combinations of concave and convex lenses.
Compound microscope – double convex lens.
Telescope – convex lenses.
Holography – combination of convex lens and mirrors.
Three dimensional viewing – combination of convex lenses.
Binoculars – Prisms, convex lenses and mirrors.
Camera – combination of convex lenses.
Periscope – Plane mirrors or prisms.
Human Eye
Light is the only thing we see with the most remarkable optical instrument known – the eye. Light enters the eye through the transparent cover called the cornea, which does about 70% of the necessary bending of the light before the light passes through the pupil (which is an aperture in the iris). The light then passes through the lens, which is used only to provide the extra bending power needed to focus images of nearby objects on the layer at the back of the eye, the retina…
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