Reflective grayscale pattern by superposed layers of microcylindrical lenses

Thanks to their striking visual appeal, grayscale moiré pattern have a high potential for document, security, art, and decoration. In recent years, researchers have paid extensive attention to using microlens arrays instead of micrographic arrays as the base layer to achieve novel moiré effects in moiré magnifiers. In order to reduce the thickness of the grayscale imaging device and increase the dots per inch (DPI) of the grayscale image, we proposed a reflective grayscale moiré imaging device. By using a curved microcylindrical lens array (CMCLA) with a metal reflector layer deposited on the surface as the base layer, the reflective device achieves a similar grayscale effect as the transmissive device with a smaller offset in the base layer, thereby increasing the fill factor of CMCLA. Applications of such devices can be found in the protection of valuable items against forgery.