Diffractive Projection Engine for HOLOEYE Spatial Light Modulators
At the visible wavelengths range HOLOEYE’s Spatial Light Modulatos are used for a growing number of imaging-like applications (e.g. holographic projection, 3D holographic displays or structured illumination).
Especially in the field of AR / VR displays and Heads-up-Displays phase SLMs offer the advantage of superior light efficiency because the image is generated by diffraction (redistribution of light) instead of blocking light (amplitude modulation) like at conventional projection systems. Besides that the holographic approach of a phase SLM can be used to add additional optical functions like dynamic focusing or aberration correction.
The diffractive approach with a phase SLM is fairly simple as it only requires a linearly polarized light source and the SLM itself. However, as diffraction angles are limited (dependent on pixel size of the used SLM) it might be necessary to use additional optics to magnify the output image.
As the development of such a diffraction based projection system is complex and time consuming, HOLOEYE offers a compact standard Diffractive Projection Engine which works for a broad field of imaging applications.
The HOLOEYE Diffractive Projection Engine is compatible with the current versions of PLUTO-2, LETO, GAEA-2 and the LUNA Spatial Light Modulators.
The compact projection engine is designed to work with a linearly polarized laser source coupled into a polarization-maintaining single mode fiber with FC/APC connector. It can also be used with fiber coupled RGB laser sources for color sequential hologram projection using a fast SLM like the LETO device.
The angular magnification is in the area of 5.3x (slightly dependent on wavelengths and pixel pitch). The working distance ranges from 15 cm (for GAEA SLM) / 27 cm (for PLUTO SLM) to infinity. The field of view also depends on the used HOLOEYE SLM:
450 – 630 nm
75 % (@520 nm)
SLM Illumination Angle
< 7.5 degrees
50 x 40 x 30 mm
15 to 27 cm – infinity
Dependent on SLM / Wavelength