Studies Of Color Imaging In The Multi-wavelength Digital Holography

The recording, reconstruction, perfectly superimposition of reconstructed images and color fusion of the composite image in multi-wavelength digital holography are demonstrated. From the fundamentals of digital holography, combined with the theory of optics and colorimetry, and methods of digital image processing, one of the hot research spots in multi-wavelength digital holography, the color imaging, is presented. Through theoretical analysis and corresponding experiments, some new methods which could solve the perfectly superimposition of reconstructed images, color fusion of the composite image, and recording are given.Firstly, two important guestions in theory of digital holography and imaging character, which are related to color imaging in multi-wavelength digital holography, are proposed: The one is that the convolution method is more appropriate for recording at smaller distances, whereas the Fresnel transform method is useful for longer distances and is more popular used in multi-wavelength digital holography, from the quantities of imformation brought by Function Transfer at different distances. The other is that from reconstruction by the Fresenel transform, the formula of the focal depth and the field depth, which could give the range of changing recording and reconstruction distances, and maintain the clear degree of reconstructed image at same time are discussed.Next, the idea and the feasibility of this methods proved by corresponding experiments that multi-wavelength digital holograms could be recorded with monochromatic CCD respectly is presented. The reason why reconstructed images from the holograms recorded by different wavelengths could not perfectly superimposition dirctly in reconstruction by use of the Fresenel transform and its solution are also discussed. And then compared the way changing the recording distance according to the wavelength with other means changing the display size of reconstructed images in order to get perfectly superimposited color image.At last, the question of color reconstructed image fusion in multi-wavelength digital holography and the way of digital image processing (the gray levelsequalization which could solve the aberrations in theory, and the gray levels linear-transformation which could solve the aberrations in practice) which could improve the results of color display and vision are proposed.The main innovative ideas are shown as following: 1. Give the idea and the corresponding experiments that multi-wavelength digital holograms could be recorded with monochromatic CCD firstly in domestic. 2. Give the the idea and the corresponding experiments that changing the recording distance according to the wavelength in order to get perfectly superimposited color image.