| Nowadays, two-dimensional (2D) display technology has been developed to extreme, no matter the color or the resolution. But it cannot cover up the lack-the distortion results from the lacking of depth of field. The three-dimensional (3D) display technology has this information, and can have a better display compared with 2D display. According to three-dimensional image reconstruction method, there are mainly two displaying method: holography-based display technology and (auto)stereoscopic display technology.The core idea of (auto)stereoscopic display technology is to play two different images for the observer. The observer will synthesize 3D image in the brain. Typically, observers are required to wear certain equipment (such as glasses, helmets, etc.) or stay at a specific location and watch from a specific direction. This is because the characteristics of the technology itself:As the record information is limited that it is only from a (few) particular position (recording position), so the viewer cannot see the parallax, from 3D image.The core idea of holography-based display technology is to record information of 3D objects in space, and rebuild the image of the object for watching. Typically, the observer don't need to wear equipment, can be located anywhere within the visible range. Sometimes, the display device requires special light source like laser. In summary, the advantages of this technology are:continuous parallaxes, a perspective effect, usually do not need to wear equipment; the disadvantages:relatively expensive equipments, relatively complicated, usually require a special light source (such as lasers, etc.), large amount of data related issues (acquisition and generation, storage, transmission, etc.), display poor (low resolution, limited size of objects, etc.).Integral Imaging (Ⅱ, Integral Photograph) is a important branch of holography-based display technology, which is first proposed by G. Lippmann in 1908. The biggest advantages of this technology are having continuous parallax, full color, perspective, no special light source (such as lasers, etc.). In Integral Imaging, the spatial information of 3D objects is recorded and encoded in the 2D media. The observer does not need to wear special glasses, and can view the full-color 3D objects in viewing range. Unlike the other technologies demanding special recording conditions, Integral Imaging does not require the use of coherent light source (laser, etc.), only need to use special micro lens array. The sampling and reconstruction are very simple, and it can easily switch between the 3D display and the 2D display.At present, the main disadvantages of Integral Imaging are low-resolution, limited perspective, inadequate depth of field, the larger amount of data. These are the problems needed to the overall. Integral Imaging is a important part of holography-based display technology, the study on it is very important.The low resolution of Integral Imaging, be a directly leads that it cannot display larger objects or scenes. One of the most basic factors limiting the resolution of reconstructed 3D image is the rate of a small lens array spatial sampling. However, due to light diffraction, industrial processing technology and other reasons, simply changing the lens array's parameters is very hard to get promotion. So the researchers began to search other ways, that Moving Array-Lenslet Technique (MALT) is a useful method. The use of MALT can effectively improve the spatial sampling rate.The limited depth of focus of Integral Imaging is always the problem needed to be solved. Usually, Integral Imaging only use virtual image field or real image field, when only use lens-array's front or back. Based on this, the researchers began to research, and put forward with the Technique of the large depth of focus by use of real and virtual image fields.Integral Imaging as a branch of holography-based display technology, with a lot of advantages, without naturally shortage, is a good technology with prospect. |
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