Virtual Reality (VR) products serve for human eyes ultimately, and the optical properties of VR optical systems must be consistent with the characteristic of human eyes. The monocular coaxial VR optical system is simulated in ZEMAX. A diffraction grating is added to the optical surface next to the eye, and the lights emitted from the diffraction grating are deflected, which can forming an asymmetrical field of view(FOV). Then the lateral chromatic aberration caused by the diffraction grating was corrected by the chromatic dispersion of the prism. Finally, the aspheric surface was added to further optimum design. During the optical design of the system, how to balance the dispersion of the diffraction grating and the prism is the main problem. The balance was achieved by adjusting the parameters of the grating and the prism constantly, and then using aspheric surfaces finally. In order to make the asymmetric FOV of the system consistent with the angle of the visual axis, and to ensure the stereo vision area clear, the smaller half FOV of monocular system is required to reach 30°. Eventually, a system with asymmetrical FOV of 30°+40° was designed. In addition, the aberration curve of the system was analyzed by ZEMAX, and the binocular FOV was calculated according to the principle of binocular overlap. The results show that the asymmetry of FOV of VR monocular optical system can fit to human eyes and the imaging quality match for the human visual characteristics. At the same time, the diffraction grating increases binocular FOV, which decreases the requirement for the design FOV of monocular system.
Low temperature glass molding technology is the main method on volume-producing high precision middle and small
diameter optical cells in the future. While the accuracy of the molding die will effect the cell precision, so the high
precision molding die development is one of the most important part of the low temperature glass molding technology.
The molding die is manufactured from high rigid and crisp metal alloy, with the ultrasonic vibration character of high
vibration frequency and concentrative energy distribution; abrasive particles will impact the rigid metal alloy surface
with very high speed that will remove the material from the work piece. Ultrasonic can make the rigid metal alloy
molding die controllable polishing and reduce the roughness and surface error. Different from other ultrasonic fabrication
method, untouched ultrasonic polishing is applied on polish the molding die, that means the tool does not touch the work
piece in the process of polishing. The abrasive particles vibrate around the balance position with high speed and
frequency under the drive of ultrasonic vibration in the liquid medium and impact the workspace surface, the energy of
abrasive particles come from ultrasonic vibration, while not from the direct hammer blow of the tool. So a nummular
vibrator simple harmonic vibrates on an infinity plane surface is considered as a model of ultrasonic polishing working
condition. According to Huygens theory the sound field distribution on a plane surface is analyzed and calculated, the
tool removing function is also deduced from this distribution. Then the simple point ultrasonic polishing experiment is
proceeded to certificate the theory validity.