What kind of physical phenomenon is happening on the disc

Specular reflection: The laser tube hits the beam onto the disc and reflects it back. The focusing servo system divides the focused beam into three: two beams for tracking and focusing adjustment, and one main beam for extracting or writing data.

Disc burning data is to use a laser to burn traces of data coding rules on the disc (just like taking a needle to make a mark on the surface of an object), which is too thin for human eyes to distinguish, and the read data is reflected to the laser receiver with a laser, and then processed to form a data file.

A CD-ROM is an item that uses optical information as a storage carrier and is used to store data. Non-rewritable discs, such as CD-ROM, ***-ROM, etc.; and rewritable discs, such as CD-RW, ***-RAM, etc. So what are the physical characteristics of optical discs?

1. In terms of the main structure, the structure of CD and CD is the same, but their thickness and materials are different. In the introduction above, we mentioned that the thickness of the CD disc is, can this thickness be changed? No.

2. In practical applications, the lasers for reading and burning CDs, CDs, and Blu-ray discs are different. As we all know, the capacity of a CD is only about 700MB, while *** can reach it, and the Blu-ray disc can reach 25GB. The difference in capacity between them is closely related to the wavelength of the laser beam to which they are related.

3. Generally speaking, the recording density of the disc is limited by the size of the readout spot, that is, the diffraction limit of the optics, including the laser wavelength and the numerical aperture NA of the objective lens. Therefore, in order to increase the recording density of traditional optical disc technology, a short-wavelength laser or an increase in the numerical aperture of the objective lens can be used to reduce the optical spot, such as CD (780nm, Na: to ***(650nm, Na:

to Blu-ray Disc (405 nm, Na:.

1. This depends on how to throw it down.

2. If it is put down freely, the possibility of smashing people vertically is relatively low, and the harm is there, but the degree is not very large. Frightened or slightly injured, if placed horizontally, do not need to be considered. (Of course, this has to do with the part where the person was smashed).

3. If it is aimed at the eye (that is, the person downstairs just looks up, and the disc is smashed vertically), the eye is very damaged. After all, the eyes are fragile.

You can do a comparative experiment: throw the disc from the fifth floor to the sand or soft mud on the first floor; Look at the degree of depression. Then take a pebble on the first floor and smash it into a hole of the same depth. The damage caused by the disc is similar to the damage of the stone.

To be on the safe side, don't throw the disc down!!