The coherence of light will be destroyed when propagate through scattering medium, which scrambles the transmitted light and thus forms speckle pattern behind. In order to understand the scattering process and implement applications such as imaging through scattering medium, theory for transmission matrix, eigenvectors have been studied and exploited. However, the Huygens–Fresnel principle implies that regional local effect of scattering process is existing, which could be involved in spatially engineered effective scattering particles, we name it scattering tunnels. We demonstrate the scattering tunneling effect in our experiment and implement this effect to achieve super resolution modes manipulation on input plane of scattering system. The scattering tunnels might introduce another perspective to study the scattering process, and provide researchers a way to improve efficiency of light control through scattering medium.
Blood is a crucial body fluid which contains erythrocytes and leukocytes and platelets, the number and status of which directly indicate the physiological state of the body. The first response to the infection is mediated by the number of leukocytes in the blood. The number and type of immune cells change vary in the disease state and identification of the type of immune cell provides information about the healthy state of body. Determining the identities of cells of the immune system usually involves destructive fixation and chemical staining, or labeling with fluorescently labeled antibodies. Raman microscopy is ideal for live cell studies or real-time diagnosis of disease, because it does not require the use of labels that may harm cells. It has potential to be carried out in vivo conditions. Raman spectroscopy has been used to investigate the differences between the leukocytes subtypes. The complex chemical composition of cells leads to complex Raman spectra, it is difficult to distinguish the categary of five subtypes white blood cells. We propose a partition principal component analysis (PPCA) method based on Raman spectroscopy using wavelet anlysis at the single cell level to separate Raman spectra of five subtypes of leukocytes, which are respectively lymphocytes, nuetrophils, monocytes, eosinophils and basophils. We achieved the identification and differentiation of five subtypes with a minimum discrimination efficiency of 85%. Systematic studies of five leukocyte subtypes have important guiding significance for the study of various leukocyte-associated cancers.
Raman spectroscopy provides vibration and rotation modes of the molecule, and directly reflects the molecular structure of the analyte. Surface enhanced Raman spectroscopy may be applied to practical applications because greater Raman scattering cross section. This paper proposed a large-area nanoslit array Surface Enhanced Raman Scattering (SERS) substrate which is cost effective. By exciting two resonance modes and coupling them together simultaneously, a strong local electromagnetic field was obtained. Up to 108 Raman signals enhancement factor was achieved. Down to 10-15 M minimum detection concentration was achieved. This substrate can be used as surface plasmonic resonance (SPR). Super-high electromagnetic field enhancement effect also can improve the sensitivity of SPR detection.