Apparatus and method for phase-encoding off-axis spatial light modulators within holographic data systems

摘要

Embodiments of the invention include an off-axis amplitude and phase encoding optical system, apparatus and method of storage in which a holographic optical element (HOE) is used advantageously to reconstruct optical elements typically used to phaseencode an object beam emanating from a spatial light modulator (SLM). The optical system includes a spatial light modulator (SLM) such as a digital micro-mirror device (DMD), a data storage device such as a holographic memory cell (HMC), and the holographic optical element (HOE) for duplicating the phase-encoding functions typically performed on an object beam emanating from the SLM prior to alignment with the holographic memory cell (HMC). Conventionally, a phase mask along with one or more optical elements comprising a four-F lens system typically are needed to phase encode the amplitude-encoded light pattern that propagates from the SLM. According to embodiments of the invention, a holographic optical element (HOE) replaces the phase mask and other optical elements and performs the necessary phase encoding on the amplitude-encoded beam prior to the beam being aligned with the holographic memory cell (HMC) for storage therein. Once generated, the holographic optical element (HOE) replaces the complicated phase mask and conventional four-F lens system arrangement typically used to phase- encode an amplitude-encoded object beam emanating from the spatial light modulator (SLM) of the off-axis amplitude and phase encoding optical system.