Imaging with two spiral diffracting elements intermediated by a pinhole
  A pseudoscopic (inverted depth) image made with spiral diffracting elements intermediated by a pinhole is explained by its symmetry properties. The whole process is made under common white light illumination and allows the projection of images. The analysis of this projection demonstrates that the images of two objects pointing away longitudinally have the main features of standard pseudoscopic image points. An orthoscopic (normal depth) image has also been obtained with the breaking of the symmetry conditions. 
Jose J. Lunazzi, Noemi I. R. Rivera, and Daniel S. F. Magalhaes