What Is a Green Laser?
Green laser is a term for lasers that emit light with a wavelength of 532 nm, visible as green. These lasers generate light at a fundamental wavelength, which, when passed through a nonlinear crystal, is converted to 532 nm. Despite energy reduction during this process, green lasers offer excellent focusing capabilities, making them suitable for microfabrication, marking, and other applications. Commonly, they employ Nd:YAG, Nd:YVO4, Yb:YAG crystals, or semiconductor lasers.
Uses of Green Lasers
Green lasers are instrumental in construction for projecting reference lines and in laser pointers at conferences. Scientifically, they support Raman spectroscopy, fluorescence analysis, interferometry, and holography. Industrially, machines equipped with green lasers are used for microfabrication tasks like dicing, drilling, scribing, wafer marking, PCB cutting, and marking.
Principle of Green Lasers
The 532 nm wavelength, or second harmonic, arises from a nonlinear optics effect. When light of a specific frequency passes through a nonlinear crystal, it emits light at an integer multiple of the original frequency. A fundamental wavelength of 1,064 nm, when passed through an LBO crystal, is halved to 532 nm. This conversion, though not 100% efficient, is preferred in microfabrication and semiconductor applications for its material processing advantages and beam-narrowing capabilities.
Other Information on Green Lasers
1. LBO Crystal
LBO crystals, consisting of lithium tetraborate, transmit light in a wide wavelength range from 160 nm to 2,600 nm. As nonlinear crystals, they double the energy of incident light while maintaining their phase, crucial for producing intense light. Thus, they are pivotal in generating green light from fundamental wavelengths.
2. Copper Processing Characteristics
Green lasers excel in processing copper, achieving more consistent spot diameters than other wavelengths. This precision is attributed to copper’s lower reflectance at the green laser wavelength compared to its near-total reflectance at fundamental wavelengths, enabling more uniform processing.