1. A method of performing 3-D holographic microscopy of an optically trapped structure, comprising the steps of: providing an optical microscope; providing a light source; generating a coherent light beam from the light source and the coherent light beam having an associated imaging wavelength input to the optical microscope; generating a plurality of optical traps with wave fronts of a trapping laser beam having a phase only hologram encoding a desired optical trapping pattern and the trapping laser beam having an associated trapping wavelength; providing an objective lens for the optical microscope, the objective lens both projecting the plurality of optical traps and collecting in-line holographic images of the optically trapped structure; processing the in-line holographic images by a normalization procedure using illumination intensity I 0 (r) for the coherent light beam to obtain a normalized intensity b(r), thereby reducing additive artifacts to an additive constant and suppressing multiplicative artifacts to output a processed image; providing the processed image of the optically trapped structure to a CCD camera for three-dimensional holographic microscopy of the optically trapped structure.