## 3 Experimental Results  
### Experimental Conditions  
Since the simulation results can visualize a clear accommodation effect from the CGH image, we first tested observations derived from numerical computation by directly using the encoded CGH database prepared via the aforementioned process. Figure 7 shows the numerically reconstructed images with a focus on the fore-positioned object in the cases of CAO encoding (a), MAO encoding (b), [PERSON]'s encoding (c), and [PERSON]'s encoding (d). Another example of numerical reconstruction under the same conditions, except focused on the back-positioned object, is shown in Figure 8. Through these simulations, we could expect that the four encoded kinds of CGH content will support both the depth cue and accommodation effect. The experimental observations of optical reconstruction from these four kinds of encoded holograms were taken in a darkroom by using a DSLR camera (Canon EOD 5D Mark III and Canon EF 70-200 mm F2.8 IS USM Lens). Photographs of holographic reconstructions were captured with the camera's lens positioned near the focal position of the field lens, i.e., the eye position of the observer at the VW (see Figure 2a). The camera settings for this experiment are as follows: shutter speed is 1/30 s, aperture size f 2.8, ISO 8000, and the focal length of the optical lens (Canon EF 70-200 mm F2.8) attached to the camera to take the pictures is about 1.45 m. Figures 9 and 10 show photographs of optically reconstructed scenes obtained by the NHD, which displays four kinds of encoded holograms and which manifest clear depth discrimination. Figure 7: Numerical reconstructions using holograms in the case of CAO encoding (a), MAO encoding (b), [PERSON]’s encoding (c), and [PERSON]’s encoding (d) where the left eye of the observer is focused on the front-positioned 3D cube. The object focused is indicated by a blue arrow mark. We observed that background light and speckle patterns prominently appear in the 3D scene reconstructed from the CAO-encoded hologram, as shown in Figure 9a. On the other hand, we found that non-diffracted background light is efficiently suppressed in the holograms of the other three encoding methods (see Figure 9b-d). We noticed that the diffraction efficiency of [PERSON]'s hologram and [PERSON]'s hologram are much lower than that of the MAO hologram. Furthermore, Figure 9b indicates that both background noise and speckle noise are dominantly attenuated in the case of MAO encoding in comparison with the rest of the encodings. Figure 11 shows the comparison result with a surface intensity map that plots the surface of the grey-level, \(\mathrm{g}(x_{i},\ y_{i})\), according to each encoding within the bright area to be scanned on a selected, focused object. We supposed that an object with an ideally speckle-free region has a surface intensity map with a regularly uniform feature. Hence, as an alternative approach for a speckle-noise analysis, the work to plot the surface intensity of the holographically reconstructed object indicates that better uniformity corresponds to less speckle noise. Through an examination of the surface-intensity indicator (see Figure 11), we found that the surface quality of the H3D scene regenerated by MAO encoding is the best among the four different encodings. Figure 8: Numerical observations using holograms in the case of CAO encoding (**a**), MAO encoding (**b**), [PERSON]’s encoding (**c**), and [PERSON]’s encoding (**d**) where the left eye of the observer is focused on the back-positioned 3D cube. The object focused is indicated by a blue arrow mark. Figure 10: Experimental optical observations reconstructed from each hologram in the case of CAO encoding (**a**), MAO encoding (**b**), [PERSON]’s encoding (**c**), and [PERSON]’s encoding (**d**) where the left eye of the observer is focused on the back-positioned 3D cube that each arrow indicates.