Phase modulated dynamic illumination for HDR laser projection using off-axis diffraction and spatial superposition.

The dynamic range of laser projection is constrained by light leakage from the spatial light modulator (SLM), remaining significantly below the limits of human visual perception. By redistributing the illumination intensity with a phase-only SLM, the dynamic range of the laser projection system can be effectively extended. However, phase modulation inevitably generates a zero-order beam, which prevents the formation of a pure dark state in the illumination field and limits further improvement in dynamic range. Although various zero-order beam suppression methods have been proposed, they often reduce diffraction efficiency or decrease the contrast of the modulated illumination field. In this research, we propose a dynamic illumination method for High Dynamic Range (HDR) laser projection. The proposed method generates a high contrast ratio illumination field while maintaining a uniformity of 95.85%. Based on this method, we further construct an HDR laser projection system using a phase light modulator (PLM) and a digital micromirror device (DMD). Experimental results based on the Video Electronics Standards Association (VESA) contrast test pattern demonstrate that the maximum luminance reaches 190.31 cd/m2, the minimum luminance is reduced to 0.14 cd/m2, and the dynamic range is extended by 8.47 times. These results provide effective support for the development of HDR laser projection technology.