Magnetic field control of moiré fringes on guanine crystal plate surface using its optical interference pattern

摘要

Moiré fringes are created by superimposing two periodic or quasi-periodic networks of lines. This established technique is an important metrological tool for methods such as super-resolution microscopy. Biogenic guanine crystals show light and dark striped patterns on the broadest surface of their crystal plates when optical interference occurs because of the flatness and transparency of the crystal. In this work, using the optical interference pattern of a goldfish guanine crystal plate, we successfully observe the appearance of moiré fringes on a guanine crystal plate floating in water above herringbone patterns with micron and sub-micron periods. It is demonstrated experimentally that a variety of moiré fringes can be obtained by varying the long-axis direction of the guanine crystal plate using an in-plane magnetic field, which corresponds to a change in the direction of the structured illumination, because of the diamagnetic anisotropy of the crystal. The results of observation of the moiré fringes formed when the tilt angle of the guanine crystal’s (102) plane relative to the substrate is varied using a vertical magnetic field are also presented.