Abstract:The light field microscope has the potential of recording the 3D information of biological specimens in real time with a conventional light source. To further extend the depth of field to broaden its applications, in this paper, we proposed a multifocal high-resistance liquid crystal microlens array instead of the fixed microlens array. The developed multifocal liquid crystal microlens array can provide high quality point spread function in multiple focal lengths. By adjusting the focal length of the liquid crystal microlens array sequentially, the total working range of the light field microscope can be much extended. Furthermore, in our proposed system, the intermediate image was placed in the virtual image space of the microlens array, where the condition of the lenslets numerical aperture was considerably smaller. Consequently, a thin-cell-gap liquid crystal microlens array with fast response time can be implemented for time-multiplexed scanning.
In this paper, we proposed a hexagonal liquid crystal micro‐lens array (HLC‐MLA) to instead of fixed micro‐lens array for 3D light field microscope. The focal length of liquid crystal lens can be adjusted electrically. With this property, the depth of the field (DoF) of light field microscopy was well extended. Besides, the dense packing design of hexagonal liquid crystal micro‐lens array can reduce pixels consuming.
Stereoscopic / Light Field Hybrid Head-mounted Display was proposed to avoid accommodation -convergence conflict and improve the resolution of light field image. This new system generate images in LF and stereoscopic mode, further producing hybrid images by the visual persistence of human eyes. To build a mechanism for the time-multiplexing of the polarized light, we designed and fabricated a micro-lens array with the liquid crystal material. Specifically, with the function of TN cell and LC MLA, Hybrid HMD could time-multiplex two images in flicker-free frame rate. In our results, the resolution of hybrid image can be significantly enhanced from 5.5 ppd to 10 ppd in horizontal direction and 6.2 ppd to 15.9 ppd in vertical direction.
Author Keywordsvirtual reality, light field, head-mounted display, micro-lens array 1.
In this study, we developed a new type of water-to-water two-stage screw heat pump with a vapor injection flash tank and investigated the performance of the heat pump under various condensation temperatures of the refrigeration cycle. In addition to the flash tank, a floodedtype evaporator and a shell-tube oil cooler for refrigeration oil heat recovery are implemented in the heat pump system. Suitable vapor injection pressures corresponding to different condensation temperatures were found. It was also found in this study, that with a suitable vapor injection pressure for operation, the average coefficient of heating performance can be enhanced by the investigated heat pump system under various condensation temperatures. An intelligent controlling strategy in terms of the subcooled degree was developed to attain the dynamic high performance of the heat pump under different condensation temperatures. From the performance measurements, it can be found that the average heating capacity improvement of 29% and the performance enhancement of 11% can be achieved by the two-stage water-towater heat pump by utilizing the controlling strategy to adjust the vapor injection and the oil heat recovery under different condensation temperatures.
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