Enhance Holographic Reconstructed Image Displayed by DMD
|School||Kunming University of Science and Technology|
|Keywords||DMD display holographic reconstructed image lensless Fourier transform digital holography synthetic aperture image enhancement|
Traditional letter picture and video are two-dimensional information, how to make the two-dimensional information converted into the particular three-dimensional information that include more details is what we expect at all times. The expectation achieved until holography appears, meanwhile, strongly absorb scholar’s attention is how to make method of image reappearance more convenient and effective.Early holography, holographic plate as a medium record interference stripe and diffractive optical field is attained by real laser beam illuminate that restrict its application:The development of computer technology and photo-electricity converter parts precipitate digital holography appeared and rapidly applied. In digital holography, entire the record and the reappearance are implemented with full digitalization, image reappearance is came true with simulated diffraction calculation. Nevertheless, the simulated diffraction calculation demand definite machine time that will result in hardly achieve real-time holographic image reappearance.DMD (Digital Micro-mirror Device) has inherent characteristics such as upper resolution、wide response rang、fast response speed、high SNR(signal noise ratio)、high utility rate of luminous energy、wide operation temperature rang、polarization independent、significant diffraction efficiency and others, so it is rapidly applied to holographic image reappearance, moreover, its extraordinary real-time reappearance diffraction effect became a research highlight.In research of holographic restructured image displayed by DMD, influence factors on the quality of the reappearance holographic image like still more, so gain high-quality holographic restructured image is an interest of scholars.For instance, the zero order diffraction image appeared in the centre of reconstructed image take up large area that restrict application of the technique, and the ordinary Fresnel holographic restructured distinct imaging plane is related with many parameters, such as wavelength of reconstruction and recording and their ratio, and the distance of recording hologram and so on that is not easy to design projector system compatible with DMD.In this dissertation, discussing topic is how to enhance holographic restructured image basis on principle of operation and diffraction effect of DMD.A characteristic found by analyzing lensless Fourier transform hologram and synthetic aperture holography is that, the imaging plane of reconstructed image just is focus plane of positive lens that is propitious to solve the problem of DMD display caused by unstable holographic imaging plane.Zero order diffraction image is focused on the center of focal plane and imaging zone rapidly contracted that improved quality of reconstructed image. Meanwhile, position of holographic reconstructed image is not altered when parallel moving lensless Fourier transform digital hologram on the holographic image plane that is easier to improve hologram duty cycle, DMD availability and quality of reconstructed image. According to this analysis, a new method is proposed that combines lensless Fourier transform digital holography with synthetic aperture that could improve quality of DMD reconstructed image. Theoretic analyze and experimental results prove the method is available that will bring into playing unique advantage of DMD in the development of 3D display technology.