An optical see-through head-mounted display for augmented reality is designed in this paper. Considering the factors, such as the optical performance, the utilization ratios of energy of real world and virtual world, the feelings of users when he wears it and etc., a structure of the optical see-through is adopted. With the characteristics of the particular negative dispersive and the power of realizing random-phase modulation, the diffractive surface is helpful for optical system of reducing weight, simplifying structure and etc., and a diffractive surface is introduced in our optical system. The optical system with 25 mm eye relief, 12 mm exit pupil and 20° (H)x15.4° (V) field-of-view is designed. The utilization ratios of energy of real world and virtual world are 1/4 and 1/2, respectively. The angular resolution of display is 0.27 mrad and it less than that of the minimum of human eyes. The diameter of this system is less than 46mm, and it applies the binocular. This diffractive-refractive optical system of see-through head-mounted display not only satisfies the demands of user’s factors in structure, but also with high resolution, very small chromatic aberration and distortion, and satisfies the need of augmented reality. In the end, the parameters of the diffractive surface are discussed.
The property of phase-mostly modulation of the SVGA1 spatial light modulator, which is manufactured by CRL Ltd. in UK., was investigated and the phase shift of (pi) was achieved. The Dammann grating of binary-phase device for fan-out up to 5x5 was designed and the data of the phase device were fed into the liquid crystal display. The 5x5 array of spots was produced. It has been found that the spatial light modulator can be used as a phase modulated binary optical device to realize some functions in the laboratory.