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There are many applications of lasers in which the beam profile is of critical importance. When
the beam profile is important, it is usually necessary to measure it to insure that the proper profile exists.
For some lasers and applications this may only be necessary during the design or fabrication phase of the laser. In other cases it is necessary to monitor the laser profile continuously during the laser operation. For example scientific applications of lasers often push the laser to its operational limits and continuous or periodic measurement of the beam profile is necessary to insure that the laser is still operating as expected. Some industrial laser applications require periodic beam profile monitoring to eliminate scrap produced when the laser degrades. In other applications, such as some medical uses of lasers, the practitioner has no capability to tune the laser, and the manufacturers measure the beam profile in design to ensure that the laser provides reliable performance at all times. However, there are medical uses of lasers, such as photo-refractive keratotomy, PRK, wherein periodic checking of the beam profile can considerably enhance the reliability of the operation. PRK is an example of laser beam shaping which is a process whereby the irradiance of the laser beam is changed along its cross section.
In order for this laser beam shaping to be effective, it is necessary to be able to measure the degree to which the irradiance pattern or beam profile has been modified by the shaping medium.
This paper describes the general state of the art of laser beam profile analysis. 1-14 It introduces the general need for beam profile analysis, methods for measuring the laser beam profile, a description of instrumentation that is used in beam profile measurement, a discussion of the information that can be obtained simply by viewing the beam profile, and finally, how quantitative measurements are made on laser beam profiles, and the significance of those quantitative measurements.
