Double side lenslet array for illumination optics of laser projector

Laser is an ideal illumination light source for liquid crystal projection displays in terms of source Etendue and polarization. In order to make a conversion from a circular Gaussian laser beam profile to a rectangular uniform distribution on the microdisplay, a double side microlens array has been proposed as a homogenizer, and a cylindrical lens is exploited for shaping the aspect ratio of illumination pattern. The design and simulation based on scalar diffraction theory have shown that two identical lenslet arrays on each side of a thin plastic substrate with a lateral shift of half diagonal pitch can convert laser beam into a uniform square illumination at a specified near field. The pitch and curvature of the lenslet are major parameters for modifying the illumination distance, area and uniformity. The proposed lenslet array will provide an economical solution for the illumination optics of laser based light valve projector due to its regular and circular lenslet profile.