Illumination optics design for DMD Pico-projectors based on generalized functional method and microlens array

Abstract

The influence of incident angle and aberration of the microlens array on the optical efficiency in pico-projector is analyzed. By modifying the relevant parameters, a method to optimize the optical efficiency and uniformity of the illumination system is proposed. By changing the profile of the freeform double lens used for the concentrator of LED source, the incident angle can be reduced, thus the efficiency loss caused by large angle incident can be reduced. In addition, two spherical relay lenses instead of the Fourier lenses are used as integral component after the microlens array, which is not only low cost, but also more flexible in controlling aberrations. After system optimization, the illumination efficiency and uniformity of the pico-projector system can reach 60.51% and 86.2%, which verifies the feasibility and validity of the theoretical analysis.