Free-form surfaces (FFSs) provide more freedom to design an optical system with fewer elements and hence to reduce the size and weight of the overall system than rotationally symmetric optical surfaces. In this paper, an optical see-through (OST), head-mounted display (HMD) consisting of a free-form, wedge-shaped prism and a free-form lens is designed and fabricated through the injection molding method. The free-form prism for the projection system is designed with a field-of-view (FOV) of 36°; the free-form lens is cemented to the prism for the see-through system to achieve a FOV of 50°. The free-form prism and lens are expanded at the edge area during the design stage in order to reduce the effects of surface deformation in the working area in molding fabrication process and to improve ergonomic fit with the head of a user. The tolerance analyzes considering the mold design for the free-form optical systems are carried out using the Monte Carlo method. The FFS optical elements are successfully fabricated and the system performance is carefully examined. The results indicate that the performance of the OST-HMD is sufficient for both entertainment and scientific applications.

No abstract

The available polarizers either cannot afford gigawatt-class high-power microwave applications or are large in length. In this letter, a novel grooved polarizer is proposed. The grooves are proposed to be created in an over-mode circular waveguide to improve the power capacity and bandwidth. Moreover, the symmetric elliptical grooves are adopted to suppress high-order modes and realize the desired phase difference. An X-band polarizer prototype is designed and manufactured with length of 91 mm. Simulated results show that the power capacity of the polarizer is more than 1.5 GW. Measured results in accordance with simulations show that the axial ratio is less than 3 dB from 8.6 to 12.2 GHz, with relative bandwidth of 34.6%. The measured return losses are better than −12.7 dB in the same frequency range.

No abstract