Polarization active imager technology obtains images encoded by parameters different than just the
reflectivity and therefore provides new information on the image. So polarization active imager systems represent a very
powerful observation tool. However, automatic interpretation of the information contained in the reflected intensity of the
polarization active image data is extremely difficult because of the speckle phenomenon. An approach for speckle
reduction of polarization active image based on the concepts of compressive sensing (CS) theory and edge detection.
First, A Canny operator is first utilized to detect and remove edges from the polarization active image. Then, a dictionary
learning algorithm which is applied to sparse image representation. The dictionary learning problem is expressed as a
box-constrained quadratic program and a fast projected gradient method is introduced to solve it. The Gradient
Projection for Square Reconstruction (GPSR) algorithm for solving bound constrained quadratic programming to reduce
the speckle noise in the polarization active images. The block-matching 3-D (BM3D) algorithm is used to reduce speckle
nosie, it works in two steps: The first one uses hard thresholding to build a relatively clean image for estimating statistics,
while the second one performs the actual denoising through empirical Wiener filtering in the transform domain. Finally,
the removed edges are added to the reconstructed image. Experimental results show that the visual quality and evaluation
indexes outperform the other methods with no edge preservation. The proposed algorithm effectively realizes both
despeckling and edge preservation and reaches the state-of-the-art performance.
Photoacoustic spectroscopy (PAS) is a powerful tool for the study of the absorption spectra of solid samples. Scattered light, which used to be a main error source in conventional absorption spectroscopy, is not a problem for PAS, and furthermore, in this paper it is helpful for photoacoustic spectroscopy measurement. In this work, the photoacoustic spectra of an olanzapine tablet and its powder have been investigated. Differential analysis was used to eliminate the background signal generated by the photoacoustic cell. It is found that the photoacoustic spectrum of olanzapine in the powdered olanzapine tablet has the same spectral features as that of the pure olanzapine powder, while the photoacoustic spectrum of the olanzapine tablet does not have, although the ingredients in both are completely the same. This phenomenon can be interpreted as the light scattering effects in the powdered olanzapine tablet. The light scattering effects in a solid mixture amplify the photoacoustic spectral features of the main light-absorbing ingredient in the mixture, rather than enhance the measured photoacoustic signal over the whole measured wavelength range, which is different from the influence of light scattering effects on a single-ingredient solid powder. Based on this work, a method is proposed to preliminarily fast identify the light-absorbing ingredient in a solid mixture. Using the method, a drug tablet can be measured directly in solid state and hardly need sample preprocessing, and thus the time for composition analyses will be reduced significantly.
The high-frequency method for solving the Radar Cross Section (RCS) of Terahertz conductive targets in free space is presented in this paper. Consider the environment of free space, the free space physical optics integral equation is deduced by introducing the free space Green’s function into the Physical Optics (PO) method. Combined with the GRaphical-Electromagnetic COmputing (GRECO) method, the shadow regions are eliminated quickly and the geometry information is attained by reading the color and depths of each pixel. The RCS of Terahertz conductive targets can be exactly calculated in free space. The numerical results show that this method is efficient and accurate.