Optical instrument

• Hi guys
•  we all know that optics deal with light we can take common example of optical instrument isour eye.
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• Eye is a  very sensitive optical device.
• due to optical instrument eye  we can see anything in the universe.
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•  optical instruments are very important for everybody so we have to discuss about term and conditions formation rule and regulations construction and which used by optical instrument to make visible things
• There are large no of optical device in present time.
•                   Eye.
• Eye is a optical instrument. This is very sensitive.If any this goes in our eye .Eye itself close.This represent awareness of eye.
• Due to eye we can see anything 
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• Construction
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• The eye is not shaped like a perfect sphere,it like a pressured 🍊.
• The eye is not shaped like a perfect sphere, rather it is a fused two-piece unit, composed of the anterior segment and the posterior segment. The anterior segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 11.5 mm (0.3 in) in diameter, and 1/2 mm (500 μm) in thickness near its center. The posterior chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm. The cornea and sclera are connected by an area termed the limbus. The iris is the pigmented circular structure concentrically surrounding the center of the eye, the pupil, which appears to be black. 
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• Working function of eye.
• Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle. Photons of light falling on the light-sensitive cells of the retina  are converted into electrical signals that are transmitted to the brain by the optic nerve and interpreted as sight and vision.                                By R.m