Use of Moire fringes in digital holography for optical alignment

Moire fringes may be encountered in digital holography when the local fringe period is comparable to the pixel separation of the recording CCD array. In this work, we demonstrate the relation between the transverse misalignment of a lens used in an inline digital holographic system using CW illumination with the position of Moire pattern on the recording CCD plane. A test object such as a one-dimensional opaque block is used along with a single lens imaging system, and the CCD plane is assumed to be in the far-field of the image plane. Our preliminary results show that small transverse misalignments can be tracked by monitoring the location of the Moire pattern. It is proposed that Moire patterns can be used to detect and correct optical misalignments in more complex optical systems.