Abstract The thickness of a monolayer graphene is extremely thin, ≈0.34 nm, so exact measurement of the optical path length and optical path length difference of graphene is challenging. This paper uses white‐light interferometry and a horizontal grating to obtain the optical characteristic curve of graphene. Then, the real existence of vacuum channels (VCs) in monolayer graphene is discovered. These VCs naturally eliminate the collision phenomena, and provide zero electrical resistance and superconductivity (SC) states. Multiple SC states (SCSs), SC persistence, magnetic field response, VCs transmitting a SC current with high efficiency, screen characteristics of VCs, etc. are discussed. Experiments show that only when a graphene ribbon is located at the exact position of the VC, does it transmit the SC current and provide a SCS. The duration of the persistence tests is 2 months. All experiments are conducted in a completely open space of a laboratory. Graphene SC at room‐temperatures of a wide range and standard atmosphere is achieved. This paper uses the optical technology to realize graphene SC, points out the basic reason of realizing it, and provides the experimental evidences.
Real-time is one of key points in the use of joint transform correlator.A new kind of real-time joint transform correlator was designed in this paper,which accomplished the control and identification of system.It realizes two dimension fast Fourier transform.Experimental results show that the speed of system is increased greatly.
In order to investigating the effect of wavelength on laser blood therapy, we test the fluorescent spectra of human blood. The wavelengths of exciting lights are 530 nm and 632.8 nm respectively. The result indicates that the light of 530 nm induces much stronger fluorescence, and the emitting spectra induced by 632.8 nm is rather different from the spectra induced by the light of 530 nm. This result suggests that the processes of interaction between laser and blood vary with the wavelength of the radiating lights, so the biological effects of the light to blood can differ with wavelength. These facts might have some meanings to the further research for explaining mechanisms of the laser blood therapy.
Based on the simple mathematical fact that the frequency spectrum of a constant is a δ function, and from the viewpoints of frequency spectrum analysis, two representative filters and the constant constraint criterion are analyzed. It is concluded that the constant constraint criterion is inconsistent.
A novel thin cloud removal method based on advanced multiscale Retinex algorithm is suggested for color remote sensing image. Typically,the image enhanced by multiscale Retinex algorithm can provide the information in the shadow area,but the cloud in remote sensing image can not be removed directly by Retinex algorithm if it is in the bright region.This new method uses two complementary color operations between which the advanced multiscale Retinex algorithm is applied.The experimental result shows that the new method can remove the thin cloud in the image effectively and provide adequate information.
Under the approximations of (1) the received irradiance fluctuations of an optical wave caused by small scale turbulent eddies are multiplicatively modulated by the fluctuations caused by large scale turbulent eddies; (2) the scintillations caused by small- and large-scale eddies, respectively, are statistically independent; (3) the Rytov method for optical scintillation collected by the finite-diameter receiving aperture is valid for light wave propagation under weak to saturation fluctuation regime, we develop the applicable aperture-averaging analytic formulas in the week-to-strong-fluctuation for the scintillations of plane and spherical waves, which include the outer- and inner-scale rules of turbulence.
Laser heterodyne interferometry is a kind of photoelectric phase measuring technique, it measures the optical path difference between the reference wavefront and the measured wavefront directly and needs not to deal with the interference figure. This technique can give very high phase measuring precision and can be used in dynamic optical phenomenon. This paper studies the basic principles of laser heterodyne interferometer, and the heterodyne interferometry has successfully been applied to the field of photoelastic properties of selected optical materials. A new method of measuring some parameters of photoelastic is presented. A device which brings atmosphere to bear on the optical materials has been developed to measure the change of refractive index at different pressures, and the relationship between the given pressure and the corresponding change of refractive index has been obtained through a series of experiments. Also, a careful analysis is given to the result of the experiments. At last, a feasible scheme is discussed on applying laser heterodyne interferometry to the measurement of refractive change.
The physical idea of Retinex theory that used in color image enhancement was revealed.The product of the convolution between a Gauss function and the original image,which was the smooth part of the original image,subtracted the original image in logarithm space.The left part was quick transform part of the original image.The details of the original image were highlighted.The sharper of the Gauss function was,the more details were highlighted.The smoother of the Gauss function was,the better hue of the image was showed.The result of multi-scale Retinex(MSR) has advantages in different single-scale Retinex(SSR).The method of standard deviation in intercepted region of handled image by MSR was researched.The result is obvious that the image quality intercepted in the region of [μ-σ,μ+σ],which μ is mean of image handled by MSR,is better than intercepted in the region of [μ-2σ,μ+2σ] and [μ-3σ,μ+3σ].
Low coherence optical tomography (OCT) is a novel technique with high resolution for rapid, noninvasive imaging in living biological tissues. With this technique, a thin 'optical section' within a thick biological specimen can be obtained. Using a combination of the principles of low-coherence interferometry and confocal microscopy, OCT can provide micron-scale tomographic imaging of internal tissue microstructures. In OCT, enhanced optical sectioning performance in biological tissues (highly scattering media) is achieved through high detection sensitivity and high contrast rejection of out-of-focus light. In this paper, basic principle and recent advances in optical coherence tomography are described. The emphasis is to analyze some key problems in OCT setup. Light attenuation and scanning system are studied in detail. A theoretical model for low-coherence optical tomography in highly scattering media (biological tissues) is given. The authors will show that OCT images may be significantly affected by multiple scattering associated with the refractive index inhomogeneities found in scattering media such as biological tissues. At last, a conclusion suggests that OCT is a very promising technique for clinical application because of its simple theory and low cost.
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