The Gataca Systems classical TIRF systems suffer from non uniform illumination and interference patterns the image. When a laser beam is focussed at the back of an objective and spins to describe a circle, each point of that circle creates a parallel beam which has the same incidence angle onto the coverslip. Thus, in TIRF and for a given wavelength, the evanescent wave resulting from each spot has the same penetration depth. However,
interference patterns depend on the azimuth of the beam. Being able to spin the Laser beam very rapidly during the exposure time of the camera will removes fringes or rings patterns.