Laser Safety and Laser Classification

Laser safety is the safe design, use, and implementation of lasers to minimize the risk
of laser accidents, especially those involving eye injuries, as even relatively small amounts of laser
light can lead to permanent eye injuries. Additionally, risks to the eyes is not limited to the beam of the laser. The AP Lazer system also includes and utilizes a red dot diode laser for visual aid. The Red Dot Diode is a Class II laser product with a power of 1mW and wavelength of 650nm.
Thermal effects are the predominant cause of laser radiation injury. Even moderately powered
lasers can cause injury to the eye. High power lasers can also burn the skin. Some lasers are so
powerful that even the diffuse reflection from a surface can be hazardous to the eye.
Damage to the eyes results from direct contact with the beam of the laser or with the red dot diode. While this is not a likely scenario, it is important to always be mindful of the operations and the path of the laser beam. The path of the laser beam begins in the rear cabinet from the end of the laser tube. From the laser tube, it reflects off mirror one on the left rear side (viewing from the front) of the AP Lazer. From mirror one, the laser moves through the left side of the AP Lazer and reflects off mirror two. From mirror two, the laser beam travels from left to right across the workspace to mirror three on top of the vertical extension tube. The laser moves from mirror three, through the extension tube to the focal lens. The focal lens concentrates
the beam to its proper focal point and onto the workpiece. If there is nothing beneath the vertical extension tube, the laser will continue until it reaches a material to absorb the energy from the laser. Figure 1-1 is an illustration of the path of the laser beam.

Direct exposure to the laser beam will result in instant third-degree burns. The primary safety
the concern is contact with the skin and eyes; however, the risks are not limited to personal contact. The laser beam will react with most materials it contacts. Caution should also be taken with flammable and combustible materials. Due to the risk of fire, it is highly recommended to have an appropriate fire extinguisher readily available. Due to the wide range of materials that can be used with the AP Lazer, the proper fire extinguisher for the purposes of this context is an ABC fire extinguisher. Respiratory damage can be caused by lasering materials that create toxic or noxious fumes. While proper ventilation is required whenever lasering materials that create smoke or fume, there are certain materials that should simply be avoided.
Standard cast acrylic plastic, acrylic plastic sheet, and other cast resins generally laser very well. A commonly engraved material is a cast acrylic shape award designed to be lasered from the backside. Styrene (as in compact disc cases) and many of the thermoforming plastics tend to melt around the edge of the engraving spot. The end lasered result is usually "soft" and has no "etch" contrast. The surface may deform or "ripple" at the lip areas. In some applications this is acceptable; for example, date markings on 2-liter soda bottles do not need to be sharp.
For signage and faceplates, etc., special laser-marked plastics were developed. These
incorporate silicate or other materials that conduct excess heat away from the material before it
can deform. Outer laminates of this material vaporize easily to expose different colored material
below. Other plastics may be successfully engraved, but orderly experimentation on a sample piece is recommended. Bakelite is said to be easily laser-engraved; some hard engineering plastics work well. Expanded plastics, foams, and vinyl, however, are generally candidates for routing rather than laser engraving. Plastics with a chlorine content (such as vinyl and PVC) produce corrosive chlorine gas when lasered, which combines with hydrogen in the air to produce vaporized hydrochloric acid which can damage a laser engraving system. Urethane and silicone plastics usually don't laser well, unless it is a formulation filled with cellulose, stone or some other stable insulator material. Many light switch plates from companies such as Leviton or Lutron can be laser engraved. Again, experimentation may be necessary to develop the correct laser settings to result in engraving the surface rather than melting it. Often the laser engraving is followed by backfilling with paint on the engraved surface to produce more contrast between the engraved surface and the surrounding surface.
Kevlar can be laser-engraved and laser-cut. However, Kevlar releases extremely hazardous fumes
(hydrogen cyanide gas) when it is vaporized and therefore is not safe to use.

Laser Classification and Additional Safety Requirements