# Structured Light Patterns Work Like a Hologram
## 6 Discussion of Results  
In Figure 12a, one can see almost completely coinciding profiles shifted with respect to each other in the vertical direction artificially to provide a convenient comparison, while the profiles are combined in Figure 12b. One can see that the profiles almost coincide with each other. Small deviations may be caused by the inaccurate fixation of distortions of the structured light patterns. Their manifestation in the form of distortion of the restored wavefront is close in essence to the field aberrations of cushion-type distortion, which distorts the geometric dimensions of the image but does not determine the resolution. This is quite clear because the oblique projection of the vertically structured fringes falling on the 3D object (Figure 13a) produces their shift in the plane perpendicular to the optical axis of the photo recording device, similar to the shift of interference fringes during the recording of the hologram (Figure 13b). Comparing Figure 13a,b one can see a principal similarity between the mechanisms of distortion of the interference and structured fringes, which points to the fact that diffraction at structured fringes forms the 3D images of the initial object restored in minus first order, close in shape to the images restored by computer holograms. In the initial form, these patterns of structured fringes are usually close to the holograms of the radio range, which is determined by their frequency in the initial pattern of the project onto the object. However, their frequency may be increased by simple linear transformations without resource-intensive integration, leading to a frequency that is equivalent to the carrier frequency within any wavelength range including visible, infrared (IR), ultraviolet (UV), etc. The pattern of structured fringes shown in Figure 2c, before transformation that increases the carrier frequency (Figure 4b), may be considered as the diffraction structure operating as a hologram synthesized in the radio range of the electromagnetic spectrum. Comparing the obtained 3D images in Figures 8 and 10, one may see that the hologram and the system of structured fringes restore very similar, full-value 3D images. Their iso-projections demonstrating evident similarity are presented in Figures 14 and 15. Figure 13: Projection of structured (**a**) and interference (**b**) fringes at an angle of \(\theta\) onto the 3D object shaped as a prism. The shift \(\Delta_{i}\) of fringes is proportional to the local thickness of the 3D object. a—object beam; r—reference beam; \(dz\)—object depth. The image restored by the hologram and the image restored by the system of structured fringes possess both the horizontal and vertical quasi-continuous parallax, so they are full-value holograms. We use the term 'quasi-continuous' only in relation to the digital representation of the signal. The degree of parallax continuity is limited only by its digital representation and may be reduced to the desired minimum by increasing the array of numerical representations of the holographed object and the hologram. A small difference between the two restored 3D images of the living object is seen in the top part of the depth map of the object. In our case, this is the region of the nose of the 3D image. This is likely a consequence of the arising longitudinal aberrations, which will be the subject of a more detailed investigation. Attention should be paid to the non-trivial fact that the system of lateral vertical fringes illuminating a 3D object forms a structure that has information not only about the  
Figure 14: The living 3D object image is restored by the hologram: (**a**) horizontal parallax; (**b**) vertical parallax. Figure 15: The living 3D object image is restored by the system of structured fringes: (**a**) horizontal parallax; (**b**) vertical parallax. horizontal but also about the vertical parallax, almost the same as a hologram calculated in parallel in the traditional way.