360° display of 3D objects by cylindrical holography
Computer-Generated Holography (CGH) and Spatial Light Modulators (SLM) form the core duo in 3D Holographic displays, with SLM serving as the critical hardware foundation for implementing CGH technology. As the primary device for electrically controlling and modulating light field parameters, SLM converts the digital holograms generated by CGH into physical light fields, acting as the "physical carrier" that bridges digital signals and optical displays.
Paper Information:
Cylindrical Computer-Generated Holograms (CCGH) have attracted considerable attention due to their ability to provide a 360° viewing angle. However, generating CCGHs capable of reconstructing multiple realistic 3D objects remains a significant challenge under constrained computational resources.
This paper proposes a novel CCGH generation algorithm that enables the reconstruction of 3D objects across a full 360° viewing angle even with limited computational resources. The algorithm achieves segmented generation of CCGHs by calculating the light field distribution of 3D objects on tangential planes. Both numerical simulations and optical experiments validate the effectiveness of the proposed method, demonstrating its superior capability to reconstruct realistic 3D objects throughout the entire 360° Field Of View.
This work represents an important advance for the practical application of CCGH technology.
Experimental Setup and Results (Partial)
The experimental light source is a 532 nm all-solid-state laser. The cylindrical computer-generated hologram (CCGH) has a radius of 230 mm, and the recording region is confined within a concentric cylindrical surface of radius 11.6 mm. The light field distribution on each tangential plane is computed using a 5×5 parallel projection method, with a 1° normal angle between adjacent tangential planes. The complete CCGH comprises 180,720 × 1,080 sampling points with a pixel size of 8 μm, whereas the retained region of each tangential plane contains 502 × 1,080 sampling points.
In the optical experiment, the hologram is loaded onto an FSLM-2K70-P02 spatial light modulator (SLM) featuring a resolution of 1920 × 1080 pixels and a pixel pitch of 8 μm. The final reconstructed images are captured using a digital single-lens reflex (DSLR) camera.
Figure 1. Schematic illustration of the reconstruction process.
(a) Relative position between the cylindrical computer-generated hologram (CCGH) and the 3D object.
(b) Schematic diagram of the distance distribution that needs to be compensated in the hologram.
(c) Schematic of the optical experimental setup.
Figure 2. Schematic of the cylindrical computer-generated hologram (CCGH) optical system and the diffracted wavefront of the 3D object.
Figure 3. Cylindrical light field distribution computed using the multi-parallel projection method.
Figure 4. Numerical and optical reconstruction results of different segmented cylindrical computer-generated holograms (CCGH) in the single-depth model.
Figure 5. Numerical and optical reconstruction results for the multi-depth model.
(a) and (d) Focusing results at a depth of 235 mm from the 0° viewing angle;
(b) and (e) Focusing results at a depth of 225 mm from the 0° viewing angle;
(c) and (f) Focusing results at a depth of 230 mm from the 45° viewing angle.
Parameters of the phase-only spatial light modulator (SLM) used in this experiment are as follows:
| Model | FSLM-2K70-P02 | Modulation Type | Phase |
| LCOS Type | Reflective | Greyscale | 8bit, 256step |
| Liquid crystal mode | PAN | Drive mode | Digital |
| Resolution | 1920×1080 | Pixel Size | 8.0μm |
| Active area | 0.69" 15.36mm×8.64mm | Opening rate/Fill factor | 87% |
| Optical Utilization Efficiency | 64% @532nm | Wavefront correction | Supported (532nm/635nm) |
| Phase Modulation | ≥2π@532nm | Spectrum Range | 420nm-700nm |
| Response time | ≤16.7ms | Phase calibration | (450nm/532nm/635nm) |
| Gamma correction | Yes | Damage Threshold | 20W/cm²(No water cooling) 100W/cm2(water cooling) |
| Refresh Rate | 60Hz | Data interface | HDMI |
| Power Input | 12V 3A | LC alignment direction° | 0° |
Note: Different models vary in phase modulation range and optical efficiency. For specific requirements, please contact the sales manager for your region.
Additionally, we also offer a high-reflectivity, high optical efficiency version of the same series. The detailed parameters are as follows:
| Model | FSLM-2K70-P02HR | Optical Utilization Efficiency | 95%±5%@420nm-650nm 75%±5%@650nm-810nm |
Conclusion
As the core hardware carrier of the CCGH system, the performance of the spatial light modulator (SLM) directly determines the reconstruction quality and application potential of cylindrical computer-generated holograms. The current CCGH implementation has already achieved ultra-high-resolution reconstruction at 180,720 × 1080 pixels. With ongoing improvements in SLM resolution and refresh rate, CCGH is poised to become a cornerstone of next-generation display technology, bringing revolutionary changes to human visual experience.
Paper Information: