Spatial frequency and fractal complexity in single-to-triple beam holograms

摘要

A new method of assessing the efficiency and uniformity of particular application of a single-to-triple beam conversion for obtaining structured beam configurations is investigated. Conversion efficiency and signal uniformity in the object space are related to the fractal properties in the DOE spatial frequencies as revealed by the multifractal spectrum (MFS), and the associated complex microstructure measured by the Lempel-Ziv complexity (LZC). By directly evaluating MFC and LZC in the DOE plane one can have a complementary instrument when designing phase holograms. These quantities are furnishing valuable technological information for the manufacturing stage: higher values for MFS require greater imprinting finesse, precision, and control, while higher values for LZC need more gray levels, more complex algorithms and more processing resources. In the exploitable range for optical tweezers applications there were revealed correlations of the pairs MFS <-> efficiency and LZC <-> uniformity. Experimental implementation qualitatively confirms the computational simulations.