Compared to a Gaussian beam, a flat-top beam profile lacks wings but has a steeper edge transition, resulting in more efficient energy transfer and a smaller heat-affected zone.
The energy of a flat-top beam is more cleanly contained in a given area than a Gaussian beam. Any feature etched, welded, or cut using a flat-top beam will be more accurate and will cause less damage to surrounding areas. The main advantages of flat-top beams make them beneficial to a wide variety of applications. In laser-induced damage threshold (LIDT) testing and other metrology systems, a well-defined and consistent flat-top beam irradiance profile minimizes measurement uncertainty and statistical variation. Flat-top beams also have application advantages in many fluorescence microscopy, holography, and interferometry systems.
How do you assess how close an actual laser beam is to an ideal flat-top profile? One way is to analyze the flatness factor (Fn) of an actual laser beam. As described in ISO 13694, this factor is calculated by dividing the average irradiance value by the maximum irradiance value of the beam.
