What is an Optical Drive?

M.R. Anglin

An optical drive is a piece of equipment that uses a laser to read or write information on a disc. Though this type of equipment is often associated with computers, it can stand alone as an appliance. For instance, a Digital Versatile Disc (DVD) player, Blu-ray disc (BD) player, and Compact Disc (CD) players are considered optical drives even though they may not be in a computer system. Many video games also use this type of device to read the game’s disc. Despite what type of disc they read or write, all these applications have the same basic workings.

Optical drives use lasers.
Optical drives use lasers.

The optical path makes an optical drive work. The optical path is composed of three components: a laser, a lens, and a photodiode. The laser writes and reads the data. The lens guides the laser across the surface of the disc. Lastly, the photodiode detects light reflected off the disc’s surface. The drive also uses two servomechanisms, or servos — one to maintain the proper distance between the disc and laser and the other to make sure the laser is moving in a continuous spiral path.

DVD player.
DVD player.

Lasers of different wavelengths are used to read different types of media. A CD player uses a laser with a wavelength of 780 nm. This is in the infrared light range. DVD players use wavelengths in the 650 nm range. This is why you will see a red light when the player is working. Blu-Ray® players use a much lower wavelength—450nm. This puts it in the violet range and explains the bluish light.

CDs and DVDs can only be read with an optical drive.
CDs and DVDs can only be read with an optical drive.

The discs an optical drive reads and writes vary. Read only media (ROM), such as in CD-ROMs or DVD-ROMs, do not write media, only read it. These are the type of discs that software is written on. The manufacturer will create the disc by embedding pits, called grooves, on the disc’s flat surface. Then, when a user inserts the disc into an optical drive, a reading laser shines on the disc. The light is reflected and detected by the photodiode which then translates the data into a form that the computer or player can understand and display.

An optical drive can also record media. This type of recording must be done on specific recordable (R) discs like CD-Rs, DVD-Rs, and BD-Rs. When writing, the recording laser melts organic dyes on the surface of the disc and embeds grooves into the surface. As with ROMs, the reading laser, which is at a much lower wavelength than the recording laser, shines on the disc and reflects light. The reflection is then detected by the photodiode and information is displayed.

Rewriteable media are able to be write media on rewriteable (RW or RE, in the case of Blu-Ray®) discs, such as CD-RWs, DVD-RWs, and BD-REs, again and again. The surface of these discs is made of a special crystalline alloy that enables data to be written on its surface over and over. Individual data is embedded onto the disc on grooves that reflect the laser differently. The photodiode is then able to distinguish between the different reflections and display the correct information.

Many new Macintosh computers, such as the iPad, feature no optical drive.
Many new Macintosh computers, such as the iPad, feature no optical drive.

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Discussion Comments


@ Singeasy- It would be impractical if not impossible to replace create a Blu-Ray optical drive from a DVD-RW drive. The biggest difference is the type of laser the two technologies use. This is why most first generation Blu-Ray players were not backward compatible. At the very least, you would need to change out the laser, lens...basically all of the internal components. It would be cheaper and more practical to spend the $150 on a new Blu-Ray player.


@ Comparables- You can easily have your disc drive replaced for about $100 to $150. The drive themselves start around $50, for a refurbished model, up to $300 plus. If you are somewhat mechanically inclined, or confident, you can find online tutorials on how to replace your broken drive on your own.

You may also want to consider buying a slot-loading optical DVD drive. If you can find one that fits your laptop, it may be a better solution for a person who is always on the go. Slot drives have no loose or exposed parts that can break off. You may spend an extra $50, but it is well worth it.


Does anyone know if it is worthwhile to replace the DVD optical drive on my laptop, or is it cheaper to just buy an external drive? The disc tray broke off so I cannot load discs onto my computer. I need something, but I do not want to spend more than a couple hundred dollars to find a solution. Someone please help!


Is it possible to convert a DVD audio player into a DVD Blu Ray player?

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