Laser cutters are intrinsically two-dimensional tools: a focused beam of infrared laser light (invisible to the human eye) moves on an XY gantry under computer control to trace out curves and lines. The beam is turned on and off to start and end lines during cutting. Laser cutters can also engrave images by sweeping quickly in a pattern and modulating the beam power to vary the depth of cut.
The fundamental cutting process is melting or burning a line using the heat from a material absorbing the energy of the light. An air jet blows into the cut area to help move melted material out of the cut before it resolidifies. The laser table can be moved up or down prior to cutting in order to locate the top plane of the material at the focal point of the laser.
The laser cuts flat materials such as cardboard, fabric, paper, MDF, plywood, and acrylic. The IDeATe facility limits laser cutting to a limited selection of materials known to be safe. A detailed listing of safe and prohibited materials may be found here.
The IDeATe fabrication facility in Hunt room A5B includes three Rabbit laser cutters. These are useful machines for cutting complex 2D forms. Their best feature is the speed with which you can test an idea: you can conceive a part, create a 2D drawing, output a DXF, and cut material to make a functional part within minutes.
Dave Touretzky’s lecture slides for the laser cutter from the 15-294 Rapid Prototyping mini-course are an excellent walk through the whole process.