Which lasers produce light in the visible region?

The lasers that produce light in the visible region include the Ruby and Helium-Neon lasers. The Ruby laser emits a deep red light, which falls into the visible spectrum, specifically around ruby laser emits light at 694 nm, making it visible to the human eye. The Helium-Neon (HeNe) laser also produces visible light, particularly in the red region at around 632.8 nm. Both of these lasers are commonly used in various applications such as laser pointers, barcode scanners, and alignment tools, demonstrating their capacity to produce visibly tangible beams of light.

In contrast, the other lasers mentioned do not primarily produce light in the visible region. For instance, the CO2 laser emits in the infrared range and is therefore not visible to the naked eye. The Nd:YAG laser also typically emits in the infrared spectrum at wavelengths around 1064 nm, although it can be frequency-doubled to produce visible light; however, its primary output is infrared. The Argon laser predominantly emits in the blue-green region but is often considered a specialized source and is less commonly referenced compared to Ruby and He-Ne lasers for general visible light applications.