UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
What type of laser is in a Cd player, and what makes a laser?
Answer 1:

A very good web site to learn about laser is How stuff works:
http://science.howstuffworks.com/laser.htm
You will learn all you want to know about lasers.

In our ScienceLine database we have an answer to how CDs work. I have posted it here. Together both should help you understand lasers and CDs.

How do CDs work?Electronics are often times based in the "binary" language, meaning that everything is presented by 0's and 1's. It is the easiest scenario because you only need to find out of something is "on" or "off." CD's are composed of many concentric grooves, much like the old vinyl records. Each groove of a CD is like a long trench. However, the trench is not uniformly deep, but rather there are two different heights. Imagine the bottom of the trench being a race track with a set of irregularly spaced hurdles. Now, a laser shines into the trench, hits the bottom, reflects back out, and then hits a detector that records the event. Depending on if the laser hits the bottom of the trench or hits the top of a hurdle, a different signal is observed by the detector. Since we have only two levels, there are two different output signals. One signal is assigned a value of "0" and the other a value of "1" - this is how binary information is stored on a disc! The binary signal is then decoded by the CD player to be turned into the music that you hear.


Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2015 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use