Did you know … SLM for holographic projection systems may be based on LC or mirrors
March 2019 Texas Instruments (TI) published a paper via SPIE decribing their work on mirror-based SLM (spatial light modulators). TI called these devices PLM (Phase Spatial Light Modulator). Initial prototye devices seemed to focus on principle function rather than bit depth and they were based on TI’s vast experience with binary switching micromirror devices, their DMD. Accordingly, addressing was done with the binary backplane combining singals for several virtual DMD pixels to drive one PLM pixel with more than 1 bit – quite clever and efficient.
In Februray 2020 TI published their progress and technical details of later prototpye generations. 960×540 PLM pixels with apitch of 10.8 microns were driven with 3-4 bits. The new devices exhibit improved mirror quality (better efficiency) and inter-pixel crosstalk.
Enabling phase modulation, which is mandatory for holography, based on micromirrors may very well complement existing SLM based on liquid crystal technology (LCoS). LCoS got a lead start and are already capable of 8 bit or more but PLM may become a tough competitor in the future …