Multi-Level Data Write/Retrieve by Phase-Locked Collinear Holography

Abstract

New method called phase-locked collinear holography was proposed and its performance was demonstrated experimentally. In this method, each pixel data contains phase-modulated multi-level information. When readout, the phase level of each pixel is converted to the amplitude level applied by holographic interferometry to collinear holography. This method is based on phase interference between phase-modulated signal beam and reference-phase beam (phase-lock beam); both of beams are traveled through common optical path. Using the 32-levels phase-modulated data, i.e. 5 bits phase information contained in one pixel was written and retrieved with low phase error bit [%], which is sufficient for practical use. In this paper actual optical set up for this method and write/retrieve sequence was described. Additionally, over sampling phase shifting interferometry will be discussed at the conference in order to detect phase-modulated data pages directly.