A thin and lensless two-dimensional (2D) to three-dimensional (3D) convertible display based on integral imaging using an edge-lit light guide plate (LGP) is proposed with improved optical efficiency. The proposed system is composed of a general flat backlight and an edge-lit LGP which is commonly used in the backlight of LCD and a LC panel. The edge lit LGP is a waveguide (an acrylic sheet) that is drilled by laser to form a diffuser dot array at the bottom and edge illuminated with LEDs. Light from the LEDs is channeled through the waveguide to the opposite side except where it encounters the diffuser dots, which scatter light and cause bright spots to appear. A point light source array for 3D mode is created then. A general flat backlight behind the transparent LGP is turned on for 2D mode meanwhile edge-lit light is turned off. The 2D and the 3D display modes can be simply modulated by turning on different light source. The explanation of the proposed system is provided and the experimental results are also presented.
In this paper, a new integral imaging method is proposed for depth extraction in an optical tweezer system. A mutual coherence algorithm of stereo matching are theoretically analyzed and demonstrated feasible by virtual simulation. In our design, optical tweezer technique is combined with integral imaging in a single microscopy system by inserting a lens array into the optical train. On one hand, the optical tweezer subsystem is built based on the modulated light field from a solid laser, and the strong focused beam forms a light trap to capture tiny specimens. On the other hand, through parameters optimization, the microscopic integral imaging subsystem is composed of a microscope objective, a lens array (150x150 array with 0.192mm unit size and 9mm focal length) and a single lens reflex (SLR). Pre-magnified by the microscope objective, the specimens formed multiple images through the lens array. A single photograph of a series of multiple sub-images has recorded perspective views of the specimens. The differences between adjacent sub-images have been analyzed for depth extraction with the mutual coherence algorithm. The experimental results show that the axial resolution can reach to 1μm -1 and lateral resolution can reach to 2 μm -1.
In this paper, the relationship between the spatial coherence of light field and the speckle contrast in a laser based projection display system is studied under the consideration of human visual percept. By using a varifocal liquid-crystal lens and a monochromatic CCD, a system which is used for simulating the human eye is set up to record the speckle pattern. An efficient method for controlling the spatial coherence by using a dielectric elastomer actuator (DEA) is proposed. The results show that the total efficiency for energy utilization is more than 60% during our experiment. When the distance between the observer and the screen is large enough (<3 meters), the speckle contrast can be eliminated well at last (<4%) and the observer won’t feel the speckle phenomenon.