Interference fringes arising from multiple reflections can significantly alter the diffraction patterns of diffractive optical elements. One way to reduce interference effects is by timeintegrating the diffraction pattern while frequency sweeping the laser source. This method is especially useful when it is not possible to remove the cover glass from the observation camera. The use of charge coupled device (CCD) cameras in optical systems, together with a laser light source, is widely applied to a variety of measurements. But coherent imaging can introduce severe alterations of the detected signal due to the unwanted interference of multiple reflections of the beam. These reflections that arise from various optical surfaces in the system, including the cover glass of the CCD chip, ar
