Fresnel diffraction method with object wave rotation for numerical reconstruction of digital hologram on tilted plane

Optik ◽  
2013 ◽  
Vol 124 (20) ◽  
pp. 4328-4330
Author(s):  
Weiqing Pan ◽  
Yongjian Zhu
Keyword(s):  
Diffraction Method ◽  
Fresnel Diffraction ◽  
Object Wave ◽  
Digital Hologram ◽  
Numerical Reconstruction ◽  
Tilted Plane ◽  
Wave Rotation

Electron holography in materials science

1991 ◽  
Vol 49 ◽  
pp. 670-671
Author(s):  
Hannes Lichte ◽  
Edgar Voelkl
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Materials Science ◽  
Fourier Spectrum ◽  
Object Wave ◽  
Electron Holography ◽  
Reconstruction Procedure ◽  
Numerical Reconstruction ◽  
Transmission Electron ◽  
Unique Interpretation

The object wave o(x,y) = a(x,y)exp(iφ(x,y)) at the exit face of the specimen is described by two real functions, i.e. amplitude a(x,y) and phase φ(x,y). In stead of o(x,y), however, in conventional transmission electron microscopy one records only the real intensity I(x,y) of the image wave b(x,y) loosing the image phase. In addition, referred to the object wave, b(x,y) is heavily distorted by the aberrations of the microscope giving rise to loss of resolution. Dealing with strong objects, a unique interpretation of the micrograph in terms of amplitude and phase of the object is not possible. According to Gabor, holography helps in that it records the image wave completely by both amplitude and phase. Subsequently, by means of a numerical reconstruction procedure, b(x,y) is deconvoluted from aberrations to retrieve o(x,y). Likewise, the Fourier spectrum of the object wave is at hand. Without the restrictions sketched above, the investigation of the object can be performed by different reconstruction procedures on one hologram. The holograms were taken by means of a Philips EM420-FEG with an electron biprism at 100 kV.

Compression of Digital Hologram Based on Binary Holographic Interference

2013 ◽  
Vol 760-762 ◽  
pp. 497-501
Author(s):  
Yan Gao ◽  
Hao Zhou ◽  
Ji Hua Gu ◽  
Tao Yang
Keyword(s):  
Diffraction Efficiency ◽  
Fresnel Diffraction ◽  
Phase Information ◽  
High Quality ◽  
Digital Hologram ◽  
Digital Holograms

Since the resolution of digital micro-mirror device (DMD) which is used to reconstruct the digital holograms captured in experiments is relatively low, only a part of the digital hologram can be effectively reproduced in the experiment. For the hologram has the feature of high redundancy, in this paper, we propose that compress holograms based on Binary holographic interference. First, only the amplitude of the digital hologram is retained after Fresnel diffraction, recover the phase information from the amplitude, then generate a new compressed digital hologram with the phase and amplitude, and then process the new hologram according to the principle of binary holographic interference to improve the diffraction efficiency and to obtain a high-quality reconstruction.

scholarly journals Calculating the Fresnel diffraction of light from a shifted and tilted plane

2012 ◽  
Vol 20 (12) ◽  
pp. 12949 ◽  
Author(s):  
Kenji Yamamoto ◽  
Yasuyuki Ichihashi ◽  
Takanori Senoh ◽  
Ryutaro Oi ◽  
Taiichiro Kurita
Keyword(s):  
Fresnel Diffraction ◽  
Diffraction Of Light ◽  
Tilted Plane

Numerical reconstruction and twin-image suppression using an off-axis Fresnel digital hologram

2008 ◽  
Vol 90 (3-4) ◽  
pp. 527-532 ◽  
Author(s):  
G.L. Chen ◽  
C.Y. Lin ◽  
M.K. Kuo ◽  
C.C. Chang
Keyword(s):  
Digital Hologram ◽  
Numerical Reconstruction

scholarly journals Digital Hologram Encryption Algorithm using Fresnel Diffraction

2015 ◽  
Vol 20 (6) ◽  
pp. 807-817
Author(s):  
Yoon-Hyuk Lee ◽  
Young-Ho Seo ◽  
Dong-Wook Kim
Keyword(s):  
Fresnel Diffraction ◽  
Encryption Algorithm ◽  
Digital Hologram

scholarly journals A Content Hiding Method for Digital Hologram Using Multiple Fresnel Diffraction

2020 ◽  
Vol 10 (14) ◽  
pp. 4897
Author(s):  
Young-Ho Seo ◽  
Yoon-Hyuk Lee ◽  
Dong-Wook Kim
Keyword(s):  
Small Region ◽  
Fresnel Diffraction ◽  
Encrypted Data ◽  
Diffraction Plane ◽  
Digital Hologram ◽  
Visual Distortion ◽  
Digital Holograms ◽  
Fresnel Transform ◽  
Processing Techniques ◽  
Signal Processing Techniques

A digital hologram (DH) is so highly valued that it needs to be protected from exposure to an unpermitted person, which could be done by a content encryption. We propose an encryption scheme for digital holograms, whose goal is to hide their information with maximal visual distortion and minimal ration of the encrypted data. It uses the characteristics of the Fresnel transform and signal processing techniques. As the diffraction distance increases the region containing the object information relative to the whole diffraction plane becomes smaller. Therefore our scheme diffracts a given digital hologram twice: the first transform for reconstructing the image contained by the hologram and the second transform for concentrating the energy of the object into a small region. Then only the energy-concentrated region is encrypted to reduce the amount of data to be encrypted. Experimental results show that when the diffraction distance of the second transform is about 20 m, the encryption ratio is only 0.0058% of the hologram data, which is enough to hide the object information unrecognizably.

Sign in / Sign up

Export Citation Format

Share Document