They have the advantages of having both a quite linear response and a reasonably good dynamic range. They also have three major disadvantages. First, the plasma created by the laser and the burning acrylic inhibits the entrance of the beam. This creates an artificial hole in the center of the beam pattern, as shown in Figure 1. Second, the fumes from the plasma are toxic.
Many operators tune a laser by maximizing the power or the energy.
But it can be very deceptive in terms of analyzing the actual performance from the beam. Often, the power or energy is maximized in a multimode beam. With multiple modes running in the laser cavity, much of the energy is in the wings or lobes of the beam, instead of the central core. Thus, this beam will not focus as well as a Gaussian beam and may not perform as well as a beam of lower energy but better mode pattern. While merely being able to see the laser beam's profile can solve many problems, quantitative measurements are necessary for precision operation.