Control light with heat and magnets (Magneto-optical Kerr effect)

TL;DR

The video demonstrates the magneto-optical effect on a computer storage disk, showcasing temporary and permanent effects created by a magnet and a laser.

Transcript

in my previous video I said that a magnetized object will actually affect the light that is reflected off its surface and I've spent a lot of time searching for a way that I can capture this on video and show it to you and so today I was finally successful here's the setup we've got a polarized light source shining down on this computer storage dis... Read More

Key Insights

• 🙂 The magneto-optical effect can be observed by placing a magnet underneath a magnetized surface, resulting in permanent and temporary effects on the light reflected off the surface.
• 💿 Magneto-optical storage disks have a different design compared to CDs and DVDs, using concentric individual tracks for random access.
• 💿 The magneto-optical effect is utilized in the read and write processes of these disks, with light polarization changes allowing for data reading and laser-induced magnetization changes enabling data writing.
• 💿 The material composition of magneto-optical storage disks is specialized to optimize for both readout and storage capabilities, using multiple layers to achieve the desired effects.
• 🍉 The magneto-optical storage method offered advantages over other storage formats in terms of robustness and reliability, although it had limitations in terms of density and rewrite ability.
• 💽 The magneto-optical technique was also used in other storage devices, such as the Sony mini disc, which allowed for random access and overwriting of data.

Questions & Answers

Q: How does a magnet affect the light reflected off a magnetized surface?

When a magnet is placed underneath a magnetized surface, it can affect the polarization of the reflected light, leading to temporary and permanent effects.

Q: Can the magneto-optical effect be observed without a magnet?

No, the magneto-optical effect is not observed without the presence of a magnet. Removing the magnet from the setup results in no permanent effect on the disk.

Q: Why was the magneto-optical storage method developed for computer storage disks?

The magneto-optical storage method was developed to achieve random access, high density, and robustness in computer storage disks, providing an alternative to hard drives and CDs/DVDs.

Q: How does the magneto-optical disk read and write data?

The magneto-optical disk reads data by shining a polarized light on the disk and detecting changes in reflected light based on the magnetization of the magnetic domains. To write data, a laser heats up the magneto-optical layer past its Curie point, allowing the magnetization to be altered in specific areas.

Summary & Key Takeaways

• The video showcases the setup of a polarized light source shining on a computer storage disk, with a camera capturing the reflected light through another polarizer.

• A magnet is placed underneath the disk, causing a temporary effect when a laser is shined on it and a permanent effect that leaves a track on the disk.

• The video explores the magneto-optical effect, compares the disk's design to CDs and DVDs, explains the read and write processes, and discusses the material composition.