A laser is used to make a CD or DVD by _____.
cutting patterns of pits into a blank plastic disc
burning grooves into a blank plastic disc
creating a holographic surface on a plastic disc
reflecting coherent light off grooves in a disc
cutting patterns of pits into a blank plastic disc
What does “stimulated emission of radiation” mean?
Gas particles in a laser emit coherent light when bombarded with X-rays.
Radioactive particles in a laser emit gamma rays of the same wavelength.
Gas particles in a laser emit photons of light when exposed to an electric current.
Electromagnetic currents are produced by neon particles when they bump into helium particles.
Gas particles in a laser emit photons of light when exposed to an electric current.
How is laser light different from the light produced by a flashlight?
Flashlights use reflecting mirrors and lasers do not.
The crests of laser light waves align with one another.
Lasers produce multiple wavelengths of light.
Lasers produce light that is incoherent.
The crests of laser light waves align with one another.
How is light amplified in a laser?
Photons “leak” through a partially reflecting mirror, causing them to travel in step.
Photons collide with gas particles, multiply, and reflect back and forth in a tube.
Integrated circuits in a laser amplify the sound produced by photon emission.
Electric current is amplified and directed into gas particles, which emit photons.
Photons collide with gas particles, multiply, and reflect back and forth in a tube.
What is an advantage of using a laser over a scalpel for surgery?
A laser can cut through tissue.
A laser also seals blood vessels.
A laser can cut through bones.
Laser surgery is much faster.
A laser also seals blood vessels.
A laser is used to make a CD or DVD by cutting patterns of pits into a blank plastic disc. To understand how this works, let's break it down step by step:
1. CD/DVD Production: Initially, a blank plastic disc is used as the starting material. This disc is typically made of a polycarbonate substrate.
2. Laser Technology: The laser used in CD/DVD production is highly focused and emits a concentrated beam of coherent light. Coherence refers to the light waves being in phase and having a consistent waveform.
3. Pits and Lands: The laser beam is precisely controlled to create microscopic indentations on the surface of the disc. These indentations are called pits. The areas between the pits are called lands. Pits and lands together form a continuous spiral track that starts from the center and moves towards the outer edge of the disc.
4. Reflectivity: The plastic disc has a reflective layer on top of it, typically made of aluminum or silver. When the laser beam hits the surface of the disc, it interacts with the pit or land differently. Pits appear as non-reflective areas, while lands reflect light back.
5. Reading Data: During playback, a laser beam is redirected onto the CD/DVD surface. The reflective layer reflects the beam differently depending on whether it is hitting a pit or land. Photodetectors in the player pick up the changes in reflected light and convert them into electrical signals.
6. Digital Information: The electrical signals are then processed, interpreted, and converted back into digital information such as audio, video, or data stored on the disc.
So, in summary, a laser is used to make a CD or DVD by cutting patterns of pits into a blank plastic disc. These pits and lands represent the actual information encoded on the disc, which is then read back by a laser during playback.