Simple adjustments to processing parameters enable laser processing to accommodate a wide variety of production capacities, from trial runs and small batches to full on mass production. As a result, expectations of laser processing are on the rise.
Basic Knowledge of Lasers
What is a laser?
“Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation.”
A laser is a device that generates intense light by using coupled mirrors to reflect and amplify light that is emitted when energy is applied to a specific substance (medium for carrying energy waves).
What are the characteristics of laser light?
Characteristics of ordinary light, including natural light
- It diverges from its light source and shines in all directions (non-collimated)
- It is a mixture of different types of light of various wavelengths (polychromatic)
- Wavelength phases (peaks and valleys of wavelengths) of each type of light are not in sync (Incoherent)
On the other hand, artificially produced laser beams…
Characteristics of laser light
- It travels in a specific direction from the light source (directional/linear/collimated)
- It possesses a single wavelength (monochromatic)
- Phases (peaks and valleys of wavelengths) are in sync (coherent)
- It possesses a high energy density
Leveraging these features…
Laser beams are created using a condenser lens which collects and combines light, transforming it into light of an even higher energy density. This is then used in the irradiation of materials, enabling drilling, cutting and so on.
Laser processing is used in the machining of various materials, such as metals, ceramics, glass, wood, leather, and cloth. It is also used in the latest medical technology.
Employing laser characteristics to pursue new discoveries in microfabrication
Non-contact processing
When machining a rigid drill directly against a workpiece, cracks and distortions are likely to occur. However, the mechanical load on the workpiece is eliminated with non-contact laser processing, in which the light is set to a high energy level and applied to a small area of the workpiece. Therefore, it is also suitable for processing thin sheets, which tend to easily become misshapen.
Processing flexibility
The key to performing finer machining is in achieving a small machining point (spot diameter).
Laser processing uses a condenser lens to achieve a smaller machining point (focal spot diameter).
By selecting and adjusting the wavelength, the focal length of the lens, and other parameters, the size can be fine-tuned down to a few micrometers.
Laser processing, which allows the machining point to be drawn very small and moved around freely, enables a wide range of microfabrication, from large and small squares and rectangles to irregularly shaped holes with a mixture of straight and curved lines.Processing characteristics by wavelength type
Lasers have different wavelengths depending on the type. Wavelength selection options enable processing of various materials, such as resins, metals, ceramics, and glass. In addition, the shorter the wavelength, the smaller the obtained machining point (spot diameter) will be, which reduces the heat load and enables finer machining.
Dry process
A lubricant is required when applying a drill to a workpiece, however, it is not necessary in laser processing. This allows for a wider selection of workpiece materials than is possible with drill machining and eliminates the mechanical load on the workpiece. The absence of the need for waste oil treatment makes it an environmentally friendly process.
Thermal processing
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In laser processing, heat is used on the workpiece to instantly evaporate the material. This creates a tendency for dross and flying debris to stick to the workpiece. Furthermore, peripheral areas are exposed to heat, which makes them prone to becoming brittle and cracked.
Minimizing thermal effects
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In order to obtain clean results with high precision when using laser processing, which is a thermo-mechanical process, the material can be intermittently irradiated (pulsed) with laser light so as to avoid stress from the heat as much as possible.
When employing intermittent irradiation with a laser beam, although a shorter pulse width results in greater energy, conversely, the heat load on the material is lessened.
When carrying out our most finely detailed processing, we employ lasers set to an ultra-short pulse. This makes it possible to achieve microfabrication with minimal effects from heat.Peak energy is inversely proportional to pulse width
Occurrence of tapering
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Due to the nature of the light, it is unfortunately inevitable that laser processing will have a smaller processing diameter (taper) on the exit side than the processing diameter on the entrance side of the laser.
Taperless
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Although tapering in laser processing is inevitable, we have made taperless processing a reality by combining specialized optical systems.
Handling brittle material
Laser processing enables the processing of a variety of materials. By skillfully utilizing the combined characteristics of lasers, we are able to minimize the burden on the workpiece and achieve proper machining, even with fragile materials.
By harnessing the characteristics of lasers,
we are able to pursue even more possibilities in microfabrication.