# Image Quality for Near-Eye Display Based on Holographic Waveguides
## 2 Materials and Methods
### Recording Setup  
The transmission relief-phase diffraction gratings on the surface of the waveguide substrate were recorded by analog holography method on a vibration-isolated stand, i.e., by dividing the laser beam into reference and subject branches and exposure of the photosensitive material with the resulting interference field. The scheme of the stand is shown in Figure 5.  
He-Cd laser HCL-100V(I) (PLASMA JSC, Ryazan, Russia) 1 was used as a source of continuous-wave coherent radiation, a wavelength of 0.44 \(\upmu\)m, and a power of 150 mW. The laser is followed by a shutter 2, which provides the necessary exposure time, i.e., the time of illumination of the photoresist by laser radiation. Then radiation is divided into two parts (two branches) by beam splitting cube 4. Mirrors 3 and 10 are for breaking the optical axis and reduction of light propagation direction by 90 degrees. In the case of manufacturing a DOE as a diffraction grating, it is necessary to superimpose two collimated light beams. For this purpose, all branch filtering systems were used as a combination of microobjective 5 (11) in the reverse beam path and pinhole diaphragm 6 (12), and then collimating lens 7 (13), which together create a beam expander unit. The presence of the point aperture (10\(-\)15 microns in diameter) is necessary to spatially filter the radiation and to increase the uniformity of illumination within the beam aperture of lenses 7 and 13. The field apertures 8 and 14 are set to additionally screen out the recording area.  
Mirror 9 provides the required recording angle of DOE (angle \(\alpha\) in Figure 5a). Two collimated beams are superimposed in the plane of the photoresist layer of the waveguide 15, which results in an interference pattern of straight fringes. To ensure the angle of convergence of the interfering beams and to adjust the setup it is necessary to install waveguide 15 on the linear and rotary translators. As the holographic waveguide has several composed DOEs, when recording each of them on the above-described setup the  
Figure 5: (**a**) The scheme of the recording setup: 1—He-Cd laser; 2—shutter; 3,10—mirrors; 4—beam splitter; 5, 11—micro objectives; 6, 12—pinhole diaphragm; 7, 13—collimating lenses; 8, 14—field diaphragm; 9—mirror placed on linear and angular positioners; 15—diaphragm corresponding with coupler shape; 16—waveguide plate with photoresist layer placed on linear and angular positioners, and rotation stage in the waveguide plane. (**b**) Photo of the recording area. (**c**) Photo of the setup (components 4–14).  
registration plate (waveguide) is rotated to provide the orientation of the diffraction grating. The aperture is used to provide the geometry configuration and size of the DOE. [PERSON]'s 1813 photoresist was used as the photosensitive medium. AZ303 was used as a developer, the developing time was \(\sim\)25 s when the developer was prepared in the proportion of 1:4 with distilled water. The resulting holographic waveguides in this work were an assembly of four stacked plates (1 mm thick), three of them were plates with diffraction gratings for RGB, and the fourth was a safety glass.