Incorporating different data processing methods, Optical coherence tomography (OCT) has the ability for high-resolution micro-angiography and quantitative flow velocity measurement. However, OCT micro-angiography cannot provide quantitative measurement of flow velocity, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which are difficult for whole vascular network. In this study, we report a relative standard deviation OCT (RSD-OCT) for the mapping of the flow velocity in a vascular network without the calculation of Doppler angle. From the theoretical analysis and experimental validation, the RSD-OCT is angle-independent and can quantify the flow velocity conveniently after a calibration.
In this paper, we report a method for color image reconstruction by recording only one single multi-wavelength
hologram. In the recording process, three lasers of different wavelengths emitting in the red, green and blue regions are
used for illuminating on the object and the object diffraction fields will arrive at the hologram plane simultaneously.
Three reference beams with different spatial angles will interfere with the corresponding object diffraction fields on the
hologram plane, respectively. Finally, a series of sub-holograms incoherently overlapped on the CCD to be recorded as a
multi-wavelength hologram. Angular division multiplexing is employed to reference beams so that the spatial spectra of
the multiple recordings will be separated in the Fourier plane. In the reconstruction process, the multi-wavelength
hologram will be Fourier transformed into its Fourier plane, where the spatial spectra of different wavelengths are
separated and can be easily extracted by employing frequency filtering. The extracted spectra are used to reconstruct the
corresponding monochromatic complex amplitudes, which will be synthesized to reconstruct the color image. For singleexposure
recording technique, it is convenient for applications on the real-time image processing fields. However, the
quality of the reconstructed images is affected by speckle noise. How to improve the quality of the images needs for
A novel algorithm of multi-image hiding method is presented based on polarization multiplexing digital holography
(PMDH). In our single wavelength PMDH scheme, four beams, two p-polarized beams and two s-polarized beams, are
formed by two Polarization Beam Splitters (PBS) in the Mach-Zehnder interferometer. Then two different object waves
with mutually orthogonal polarization states interfere corresponding reference waves respectively. Therefore two objects
can be acquired from the compound holography recorded by CCD with proper incident angle between two reference
beams simultaneously. The hologram storing multi-image is then superposed on the discrete-cosine-transform (DCT)
domain of the content image, and the extraction process only requires the watermarked image without content image.
Simulation results also demonstrate that the embedded multi-image can be successfully extracted under different kinds of
Proc. SPIE. 7850, Optoelectronic Imaging and Multimedia Technology
KEYWORDS: Wavelet transforms, Principal component analysis, Digital holography, Data hiding, Wavelets, Digital watermarking, Discrete wavelet transforms, Image analysis, Image storage, Information security
In this paper, a hiding method is proposed to store vast quantities of image information based on PCA. A sequence
eigenimages of objects are obtained by using PCA method. Then, wavelet coefficients of eigenimages are embedded into
the wavelet domain of the carrying image. When the hiding information is extracted, we can take advantage of the
decomposition coefficients to reconstruct the objects. The proposed method does not store the object images directly, but
store the eigenimages which contain information of the objects. The experimental results show that the features of object
are effectively embedded into the carrying image, and the proposed algorithm has a high capacity.
Performance of quantum dot based on cross-gain in SOA NOR optical logic gate has been simulated. The saturation power and cross gain modulation of a QD SOA are numerically analysed with the rate equation model which takes into account the effect of the excited state and the wetting layer (WL). The calculated result will be used to study the NOR performance.