What is Optical Disc ? Types of Optical Discs

What is Optical Disc ? Types of Optical Discs

Welcome friends, previous posts mein Maine bataya tha kuch primary storage and secondary storage devices ke bare mein. Iss article mein Main basically Optical Disc ke bare mein complete information dunga.

What is Optical Discs ?

Jis tarah magnetic storage, secondary memory mein aate hain ushe tarah optical disc bhi secondary memory hain. Inhe bhot sare jagah optical disk bhi likha jata hain but yeah galat hain issko sahi se optical disc he kaha jata hain. Optical Disc ek electronic data storage medium hain jis mein laser beam ki help se data ko read aur write kiya jata hain. Optical Disc 3 types ke hote hain jo ke hain :-

• Compact Disc
• Disital Versital Disc
• Blu - Ray Disc

James T. Russell ne sabse pehle optical disc ko banaya tha. Russell ke system mein high power back-light ki jaroorat hote the. Yeah light transparent sheet se jakar dots ko decode karte the. Bad mein yeah technology improve hue aur back light ko Laser se replace kar diya gaya. Laser jab dots par padti hain toh data ko electrical signal mein convert kar dete hain. Iss ke bad data audio aur video mein convert hota hain. Philips aur Sony 1982 mein iss technology ko as a CD market mein laye aur phir kai formats like - DVD ka invent hua.

Aaj ke time mein internet ki help se most of the content online stream aur download ho jata hain aur flash memory ki high capacity, durability, portability ke karan USB flash drives ka jyada use hone laga. Isshe karan optical discs ki popularity kam ho gaye.

Physical Properties of Optical Discs :-

Optical Disc invention ke bad se ab tak same physical design ke sath he update hote rahi hain. Inke physical design mein koi change nahi kiya gaya. Sabhe standard optical disc ka diameter 120mm hota hain, 1.2mm patli aur center mein 15mm ka hole hota hain jo disc ko drive se attach karne mein help karta hain. Normal optical disc mein 4 layers hote hain :-

• Label
• Plastic
• Reflective Aluminum
• Protective Polycarbonate

Label layer par related data ki information ko mention kiya jata hain jaise - kise DVD par movie ka poster print hota hain. Plastic layer mein data binary code (0 aur 1) ke form mein save hota hain. Disc mein next layer hote hain Reflective aluminum. Laser pehle disc par padti hain aur phir reflective aluminum se reflect ho kar detector par padti hain. Laser bapas reflect hone par jab detector par padti hain toh CD / DVD reader data ko read kar leta hain. Next layer hain protective polycarbonate as par name yeah layer CD aur DVD ko choote particles like - dust etc... protect karte hain. Yeah layer disc ko scratches se nahi bacha sakte.

Types of Optical Discs :-

CD - ROM: CD - ROM ka pura name Compact disc read only memory hain. Yeah apne time par modern computers ke liye bhot he jyada useful rahi. Sabse popular CD ke capacity 700MB the jo us time ke computers ke liye sufficient the but time ke sath yeah storage kam use hone lage aur DVD ka use hone laga. Iss ka mostly use sifr audio player mein kiya jata hain. CD ko read karne ke liye jo drive hota hain woh sirf CD ko he read kar par hain.

DVD - ROM: DVD - ROM ka pura name digital versatile disc read only memory hain. CD ke bad DVD ka use bhot he jyada hone laga tha. CD aur DVD ki physical design same the but yeah aachi capacity aur performance provide karte the. Sabse popular DVD ki capacity 4.7 GB the. DVD ko read karne bala DVD drive DVD ke sath - sath CD ko bhi read kar sakta tha.

Blu - Ray Disc: Blu - ray disc, optical disc ka sabse latest version hain. Bly ray drive aur disc bhot jyada amount mein data ko process kar sakte hain. Dual - sided blu - ray disc 50 GB se jyada data ko bhi store kar sakte hain. Aur mini - discs, jo normal blu - ray disc se 4cm chooti hote hain data ka kam amount ko store kar sakte hain. Blu - Ray discs ko read karne bale drives Blu - Ray discs ke sath - sath CD aur DVD ko bhi read kar sakte hain.

Re-writable Drives: Yeah koi dedicated type nahi hain yeah optical discs ke woh variants hain jin ko re-write kiya ja sakta hain. Writable discs one time write (R) aur multiple time write (RW) variants mein aate hain. One time write disc ko use sirf ek bar data ko permanently store karne ke liye kiya jata hain. Multiple time wrtie disc ko user many times apne according data ko store kar sakta hain. Rewritable drives mein disc ko write karne ka function bhi hota hain. Write speed, read speed ke compare mein thodi slow hote hain aur iss process mein disc kabhe - kabhe corrupt bho ho sakte hain.

Other Posts :-

What is Computer Storage Devices ?

What is Magnetic Devices ? What is Hard Disk ?

Everything About RAM That Should Know

Everything About ROM That Should Know