IMPORTANT LASER MATERIAL PROCESSING CONSIDERATIONS
L A S E R Light Amplification by Stimulated Emission of Radiation. An intense coherent beam of light radiant energy stimulated by the amplification of high-energy atoms from a laze medium, e.g., CO2 gas, nd:YAG, and other engineered crystals and gases. Power Supply Stimulation of the laze medium is accomplished by electromagnetic energy, or from fiber optic transmission of diode light energy. Direct diode semiconductor laser is a new technology that provides unique material processing capabilities for industrial manufacturers.
LASER WAVE LENGTH The Wave-length absorption spectra of the material or part is a Primary Factor for laser material processing
- CO2 @ 9.2 – 10.64 m
- IR (nd:YAG) @ 808-1064 nm
- Green @ 532 nm,
- UV @ 266 – 355 nm.
Shorter wavelength UV lasers offer two primary advantages in materials processing applications:
- Materials are processed by a relatively cold ablation “atomization” process – high energy photons break atomic/molecular bonds to remove material, versus a localized intense heating and boiling process of longer wave length lasers.
- Shorter wavelength lasers can be focused to smaller spot sizes which, when configured with advanced Q-switched designs, can be tuned to provide short pulse width (as short as 6 – 8 ns), and high repetition rates (up to 200 kHz) to maximize materials absorption, maximizing processing speed for increased production.
M2 is a laser beam profile rating Most laser material processes depend on energy density, measured in Joules/cm2. Laser beam energy profiles can affect processes differently. A beam profile analysis includes; spot size, beam divergence, power, and energy propagation properties of a laser beam. A collimated intrinsic stigmatic beam with all propagation properties identical in x and y transverse directions is theoretically ideal.
Reduced Laser Beam Spot Size increases power density by the square (X2) of laser power.
IRRADIANCE Power Density of a Continuous Wave Laser from Emission of rays of light.
FLUENCE Specific Energy Density of a Pulsed Laser Peak pulse power can be 100 times or more than a lasers power rating. High Repetition Rate (kHz) generally improves laser-processing speeds. Pulse width stability is vital to many material-processing parameters.