A head-mounted projective optical system with double-layer Diffractive Optical Element (DOE) was designed and the detailed design procedure was given. The diffraction efficiency of the system at each wavelength in designed band is larger than 90%

which improves the image contrast and color reliability significantly. The Field of View (FOV) is 50° while the eye relief and exit pupil size are 25 mm and 10 mm. The features of 19.2 mm system size and 7.8 g overall weight guarantee the lightness and compactness of the optical system. The Modulation Transfer Function (MTF) value at 0° FOV is 0.6 for 38 lp/mm spatial frequency

and more than 0.3 for all FOV

which satisfies the requirement of the color micro-display sized 2.8 cm(1.1 in) diagonal with a SXGA resolution. The lateral color of 8.2 μm

field curvature of 0.4 m

-1

and the distortion less than 5% are obtained

which means the designed optical system has good performance in the field of virtual reality and collaborative environments. The phase and line frequency versus aperture of the two binary surfaces are given. When the number of etching levels is eight

the minimum feature sizes of both the diffractive surfaces are 6.3 μm

which is not a very high demand for technique.