Laser Micromachining is a process that uses a laser to cut, drill, scribe or machine a certain type of material. The first fully functioning laser was invented in the 1960s. The improvement of lasers in the 1970’s allowed for lasers to play a major role in manufacturing from the 70s onwards.
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How Lasers work
Lasers function by producing a beam as a result of excited particles, normally in a tube. The laser beam is normally produced from a liquid, gas, solid or semiconductor. When the particles of the material are excited they produce photons. Photons are the particle version of light. A partial mirror is used to reflect these photons and at the same time allows a certain amount of photons to pass through. The partial mirror transfers energy throughout the tube and eventually produces a beam on the other side of the mirror. The energy inside of the tube is required to reach a certain threshold before a beam is produced outside of the tube. Once this threshold is met the beam leaves the tube, hits a lens, and is then focused at the laser cutting tool. Lasers work kind of like a magnifying glass being used to create a campfire.
Lasers and pulse timing
Laser Light Technologies manufactures lasers used for micromachining. Normally they produce a beam pulse every nanosecond, picosecond or femtosecond. A nanosecond is one-billionth of a second, a picosecond is one-trillionth of a second, and a femtosecond is one quadrillionth of a second. The beam pulse duration along with pulse rate(the number of beam pulses per second) will change how a laser can be utilized.
-Nanosecond lasers
Nanosecond lasers have the longest pulse duration. The longer pulse duration of nanosecond lasers allows enough time for heat to be transferred to surrounding material around the cutting zone. Nanosecond lasers may not be useful for projects that require precision or for materials that will be tempered by the excess heat. Nanosecond lasers evaporate most of the cut material but some of the melted material (called recast) will land back on the project. The recast may have to be removed in a second operation.
-Picosecond lasers
Picosecond lasers have a shorter duration than the nanosecond lasers.
Picosecond lasers have a high pulse rate, they allow for more accuracy than nanosecond laser and immediately turn cut material into plasma. Picosecond lasers require no second operation to remove recast material. Picosecond lasers are efficient for cutting materials like aluminum, copper, steel, diamonds and even glass.
-Femtosecond lasers
Femtosecond lasers have the shortest pulse duration. Femtosecond laser produces no recast, femtosecond lasers are accurate and produce a slow pulse rate. The slow pulse rate of Femtosecond lasers makes them unsuitable for industrial use.
Nanosecond lasers are more affordable than Picosecond lasers, picosecond laser can be used to create more precise machining, and Femtosecond lasers are still being perfected. Picosecond lasers are being used to advance technology. One way picosecond lasers are being used to advance technology in the car industry. picosecond lasers are being used for more efficient car machining which prevents the deposit of oil or fuel in blemishes created during machining.
Most commonly used lasers for micromachining
A wide variety of laser types can be designed and produced but only a few of these options are affordable or practical. The wavelength a laser produces dedicates which material it can cut through. The type of laser you will want to use will depend on factors such as the material, price range, and your required timeframe.
Co2 lasers are one of the more common lasers used for industrial purposes. Co2 lasers are affordable but best suited for use with organic material and coated metals only.
Excimer lasers use noble gases and reactive gases to produce a laser. Excimer lasers can produce a laser beam in the ultraviolet range. Excimer lasers can cut through basically any material and are normally used in the scientific, industrial and medical industries.
Yttrium aluminum garnet lasers (Nd:YAG lasers) are solid-state lasers. Nd:YAG lasers last longer than Co2 or Excimer lasers. Nd: Yag lasers are good for cutting metal materials and are normally used for laser marking, welding, cutting and deep cutting.
