Freeform and precise irradiance tailoring in arbitrarily oriented planes is an ultimate goal of nonimaging optics and has not been well addressed. In this paper, we develop a general formulation for arbitrary and precise irradiance tailoring in three-dimensional (3D) space using freeform lenses. This method breaks any symmetric constraints imposed on the geometrical arrangement of conventional beam shaping systems, yielding high-performance beam shaping systems with new functions and flexible geometrical arrangements in 3D space. This method paves a way for the broad application of freeform optics. The robustness and effectiveness of the method is demonstrated by two interesting but challenging designs.

We develop a compact full-color augmented reality near-eye display system with a multicolor holographic optical combiner and a freeform relay system. The digital image is produced by a full-color micro organic light-emitting diode (Micro-OLED) display module. The freeform relay system includes four freeform optics and a holographic optical mirror, which are employed to correct both the monochromatic and chromatic aberrations caused by the holographic optical combiner. The two multicolor holographic mirrors have a three-layer laminated structure and are delicately fabricated to yield an improved diffractive efficiency and a reduced efficiency difference for red, green, and blue colors. The high degrees of freedom of freeform optics, and the thin and light nature of the holographic optical combiner yield a compact form factor near-eye display system with a diagonal field of view (FOV) of 20° and the eye-box of 5 mm × 5 mm. Two prototypes are built to demonstrate the feasibility of the proposed display system.

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