This PDF file contains the front matter associated with SPIE Proceedings Volume 7507, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

We study the dynamics of a micron-sized colloidal sphere in two cases; one is for a particle near a single flat wall and the other is for a particle confined between two parallel flat walls. In this geometry, the force felt by a moving particle is quite different from that of a moving particle in unbounded space. Even though the presence of wall(s) complicates the flow field surrounding the colloidal sphere, the dynamics of a colloidal sphere near flat walls provides a model system with which to understand the phenomenon of more complex systems whose boundaries can be modeled as effective walls.[1] In this work, hydrodynamic interactions of colloidal sphere with nearby plat wall(s) are studied by using oscillating optical tweezers and compared with known theories and other experimental results using different techniques.

Time-sharing optical tweezers shares a single laser beam between several trap positions. The sharing rate or trap switching frequency is an extremely important parameter in time-sharing optical tweezers especially when it performs in low frequency ranges. The effective stiffness of a novel time-sharing optical tweezers is investigated with different switching frequencies. Our experimental results show that the larger the frequency is, the stiffer the trap is in low frequency range from 5Hz to 50Hz.

We described and characterized an experimental system for micro-Raman spectroscopy of individual floating-particle or living cell trapped by single beam gradient optical trap (optical tweezers). This system combined a micro-Raman spectroscopy and optical tweezers technique, equipped an IR laser and another visible laser as trapping and Raman excitation beams, respectively. The Raman spectrum of floating-cell trapped by optical trap in liquid media has the advantage of eliminating the interference of cover-slips and confining cell Brownian motion. Moreover, using independent lasers enables optimizing the laser parameters for separately purpose, and modulating the Raman exciting beam position relative to trapping beam, also it is necessary for Raman imaging. Applying this system the Raman spectra of single living rat erythrocyte and saccharomyces cells was obtained with high spatial resolution. The results showed that this approach significantly improved the signal-to-noise ratio of Raman spectra of living cell compared with conventional way that immobilizes the floating-cell on the surface of cover-slips. This technique would provide a wide useful approach for the Raman spectroscopy of suspended micro-objects in aqueous solution, especial for single floatingcells.

According to the theory of electromagnetic field, the orbital angular momentum density formula of a general beam was deduced. From the electric field intensity of a Gauss Vortex Beam, the orbital angular momentum density calculation formula of a Gaussian vortex beam was also deduced. A MATLAB program was applied to simulate the optical field distributions and the orbital angular momentum density distributions of Gauss Vortex Beams, and found the size and the direction of orbital angular momentum were closely related to the order of a Gaussian vortex beam.

In this paper, a system of two lenses is designed, which can efficiently convert a collimated Gaussian beam to a ring shaped pattern beam. The surfaces distribution of the two lenses is determined by using the energy conservation and the constant optical path-length condition. The design consideration is analyzed in detail. The intensity distribution of the ring shaped pattern beam can be controlled. The reshaping effect has been numerically simulated with Fourier optics methods. The influences of the waist change and decenter of the Gaussian beam have also been discussed in detail. In addition, the phase profile has been calculated after laser reshaping. The result is verified experimentally by using the phase only liquid crystal spatial light modulator (LC-SLM).

DNA translocase SpoIIIE protein is a kind of motor proteins, which transports DNA from one side of the membrane to the other side, so it plays an important role in cell division. In experiment, λDNA is labeled on one end with biotin and the other with digoxigenin. In this work we study kinetics of DNA translocase SpoIIIE by means of dual optical tweezers. In our experiment, λDNA is tethered between streptavidin-coated polystyrene bead and antidigoxigenin-coated polystyrene bead held by dual optical tweezers. One trap is immovable, and the other is movable. When SpoIIIE protein transports DNA, the length of DNA changes. The length change can be calculated according to the displacement of the trapped bead, which is detected by quadrant photodiode. When SpoIIIE transports DNA, DNA is shortened by up to about 500nm, then as the translocation stops, the DNA returns to its normal length, and this process repeats time and time again. The most probable speed that SpoIIIE transports DNA is 710nm/s.

Optical trapping is of great practical importance in various fields such as physics, biology and nanofluidics or microfluidics. In order to trap and move particles efficiently, it is necessary to theoretically study the radiation pressure face exerted on the particles firstly. We introduce Debye series expansion (DSE), which can give physical explanation of each scattering process, to analyze radiation pressure force exerted on a spherical particle generated by focused beams. The DSE is employed to the study of radiation pressure force corresponding to single scattering process, and to the research on the effect of various parameters such as beam position and mode p on radiation pressure force.

The radiation force on a Rayleigh dielectric sphere induced by focused anomalous hollow beams is investigated theoretically. The results show that the highly focused anomalous hollow beam can be used to trap and manipulate the particles with the refractive index larger than that of ambient at the focus point, and in the neighborhood of the focal plane simultaneously, it appears two equilibrium points along transverse direction at the focus plane in the neighborhood of the focus point, but it cannot stably trap the particles owing to the longitudinal gradient force which could not act as a restoring force at the corresponding position. And in the neighborhood of the focus plane there also exist three equilibrium points along transverse direction. It is further found that there exist two equilibrium points off axis position along longitudinal direction. Finally, the stability conditions for trapping particles are also discussed.

Radiation force of a focused scalar twisted Gaussian Schell-model (TGSM) beam on a Rayleigh dielectric sphere is investigated. It is found that the twist phase affects the radiation force and by raising the absolute value of the twist factor it is possible to increase both transverse and longitudinal trapping ranges at the focus. The trapping stability is also discussed.

Optical coherence tomography is a new emerging technique for cross-sectional imaging with high spatial resolution of micrometer scale. It enables in vivo and non-invasive imaging with no need to contact the sample and is widely used in biological and clinic application. In this paper optical coherence tomography is demonstrated for both biological and clinic applications. For biological application, a white-light interference microscope is developed for ultrahigh-resolution full-field optical coherence tomography (full-field OCT) to implement 3D imaging of biological tissue. Spatial resolution of 0.9μm×1.1μm (transverse×axial) is achieved A system sensitivity of 85 dB is obtained at an acquisition time of 5s per image. The development of a mouse embryo is studied layer by layer with our ultrahigh-resolution full-filed OCT. For clinic application, a handheld optical coherence tomography system is designed for real-time and in situ imaging of the port wine stains (PWS) patient and supplying surgery guidance for photodynamic therapy (PDT) treatment. The light source with center wavelength of 1310nm, -3 dB wavelength range of 90 nm and optical power of 9mw is utilized. Lateral resolution of 8 μm and axial resolution of 7μm at a rate of 2 frames per second and with 102dB sensitivity are achieved in biological tissue. It is shown that OCT images distinguish very well the normal and PWS tissues in clinic and are good to serve as a valuable diagnosis tool for PDT treatment.

We develop a high speed multi-functional spectral domain (SD-OCT) system, using a broadband light source centered at 835nm and a custom-built spectrometer with a spectral resolution of 0.0674nm. After precise spectral calibration of the spectrometer, non-uniform discrete Fourier transform (NDFT) of the acquired spectral data is adopted for image reconstruction. In vivo imaging of human finger from volunteer at A-scan rate of 29 kHz with different reconstruction methods reveal that with the NDFT method, improved sensitivity fall-off especially at large depth is achieved in contrast to the conventional discrete Fourier transform (DFT) with interpolation method. And the phase information of the spectral data is used for functional extension to velocity mapping, Doppler images of rats' cerebral arteries at A-scan rate of 20 kHz are demonstrated. Furthermore, based on the spatial sinusoidal modulation in the reference arm, the complex spectral interferogram can be retrieved by harmonics analysis and digital synchronous demodulation which is free of mirror image and the coherence noise. Double imaging depth range on fresh shrimp at A-scan rate of 10 kHz is achieved and the resulting complex conjugate rejection ratio is up to 41dB.

Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) is a promising approach for quantitative analysis without using certified samples and calibration curves. It can overcome the matrix effects. However this method is based on the hypothesis that in the actual temporal observation window the plasma is in local thermal equilibrium (LTE). In this paper, the plasma is generated using a Q-switched Nd:YAG laser hits on certified soil samples in air at atmospheric pressure. The local values of the parameters that characterize laser induced plasma (temperature, electron density) have been derived from the recorded spectra with different observation window. The electron density in the plasma at different time delay after laser firing has been investigated in detail, which can be served as a criterion of the existence of the LTE. As a result, an appropriate time delay is obtained. By comparing the temperatures deduced from the spectroscopy line intensity of neutral atom and ion emissions at different gate width, the optimized time duration which satisfies the LTE is obtained. Finally, we analyze the importance of observation window and its effect on the accuracy and precision of this method.

Nitric oxide (NO) is a biologically active molecule which has multi-functional in different species. As a second messenger and neurotransmitter, NO is not only an important regulatory factor between cells' information transmission, but also an important messenger in cell-mediated immunity and cytotoxicity. On the other side, NO is involving in some diseases' pathological process. In pathological conditions, the macrophages are activated to produce a large quantity of nitric oxide synthase (iNOS), which can use L-arginine to produce an excessive amount of NO, thereby killing bacteria, viruses, parasites, fungi, tumor cells, as well as in other series of the immune process. In this paper, photofrin-based photodynamic therapy (PDT) was used to treat EMT6 mammary tumors in vitro to induce apoptotic cells, and then co-incubation both apoptotic cells and macrophages, which could activate macrophage to induce a series of cytotoxic factors, especially NO. This, in turn, utilizes macrophages to activate a cytotoxic response towards neighboring tumor cells. These results provided a new idea for us to further study the immunological mechanism involved in damaging effects of PDT, also revealed the important function of the immune effect of apoptotic cells in PDT.

White light interferometry has been widely used in 3D profile mapping during the past two decades. However, it has a shortcoming when the measured structure is coated with transparent film. A new algorithm based on the combination of white light interferometry and image segmentation technology for measuring the thick transparent film is presented in this paper. The new algorithm can derive the surface topography of the upper and the lower surfaces as well as the thickness of the thick film simultaneously. The system equips Mirau objectives controlled by a high precision piezoelectric transducer to perform the vertical scanning. When the film is thick enough, the extracted interferogram will have two separate sets of waveform or two independent zero-order-OPDs (optical path difference). Then a dynamic threshold setting process is achieved by the Otsu's method which is originally used in image segmentation. A comparison of a variety of coherent peak detecting algorithms is firstly given in this paper, followed by a brief introduction of Otsu's method. After the computer simulation testing, a film thickness standard is measured to illustrate the capabilities of the new algorithm.

We developed a multifocus excitation coherent anti-Stokes Raman scattering microscope using a microlens array scanner for realtime molecular imaging. Two picoseond mode-locked lasers tightly synchronized were splited to a few tens of foci with the microlens array, the foci excited the sample parallely and the generated CARS from each spot was detected with an image sensor at once. By the multifocus excitation, exposure time was prolonged proportionally to the number of the foci because of parallel excitation and detection. The video-rate (frame rate of 30 fps) imaging of polystyrene beads in water was demonstrated, and the Brownian motion of beads were clearly obtained. The three-dimensional reconstructed imaging of living HeLa cells (frame rate of 5 fps, 85 images) was also demonstrated.

Lysosomal photosensitizers have been used in photodynamic therapy (PDT). Combination of such photosensitizers and light causes lysosomal photodamage, inducing cell death. The lysosomal disruption can lead to apoptosis but its signaling pathways remain to be elucidated. In this study, we selected N-aspartyl chlorin e6 (NPe6), an effective photosensitizer which preferentially accumulates in lysosomes, to study the mechanism of apoptosis caused by lysosomal photodamage. Apoptosis in living human lung adenocarcinoma cells treated by NPe6-PDT was studied using real-time single-cell analysis. In this study, the fluorescence probes Cyto c-GFP and DsRed-Mit were used to detect the spatial and temporal changes of cytochrome c in real-time in sub-cell level; the Rhodamine 123 dyes were used to monitor the changes of mitochondrial membrane potential. The results showed that, after PDT treatment,the mitochondrial membrane potential decreased, and cytochrome c released from mitochondria; The caspase-3 was activated obviously. These results suggested that lysosomal photodamage activates mitochondrial apoptotic pathway to induce cell death.

Optical tweezers has been used to manipulate micro-sized particles for many years, and has been widely used in various applications. The axial trapping stiffness is one of the most important parameters to evaluate the trapping ability of an optical tweezers. In this paper, we calibrated the axial optical stiffnesses for micro-sized polystyrene spheres. When an external force was applied to particle held by an optical trap, the particle was displaced from the trap center by an amount proportional to the applied force. We displaced the particle from the trap center by applying triangular waves of varying velocity, and the varying velocity was obtained by altering the frequency of the triangular waves. In this case the particle has two balance position distributed at two-side of the trap center. The calibration of the axial position was critical to the measurement of axial optical stiffness. In this paper, the axial displacement between the balance position and the trap center was calibrated with image information entropy signals. According to Stokes Law, when the axial displacement of the particle relative to the external force was known, the axial optical stiffness can be measured, and this method was known as viscous drag method. The stiffnesses for a 2μm-diameter at different trapped depth were measured. Typical values for axial optical stiffness of our optical tweezers were between 4.0 and 7.5 pN/μm when the laser power was 35mW. Dependence of axial optical trapping stiffness on the diameter of the particles was measured with viscous drag method. At last, the origin of the measurement error was discussed.

A novel fiber optical tweezers is proposed to trap subwavelength particles in 3-dimension, the Fresnel Zone Plate (FZP) structure is designed with a high numerical aperture (N.A.) and prepared on the flat fiber end face. According to the core area of 633nm single mode polarization-maintaining fibers, a FZP structure with three zones is designed. The transmitted field distribution is simulated by Finite-difference time-domain (FDTD) method, and the optical force on a 500 nm diameter polystyrene particle in water is calculated from Maxwell Stress Tensor (MST). The results indicate that the FZP structure can generate a subwavelength focal spot and the optical force can trap subwavelength particle in 3D. With focused ion beam (FIB) etching and depositing system, a fiber optical tweezers with the designed FZP structure is fabricated, which could be used widely due to its easy-operating and capability to manipulate subwavelength particles in 3D.

The exercise-induced fatigue eliminated by Chinese medicine offers advantages including good efficiency and smaller side-effects, however, the exact mechanisms have not been classified. A lot of literatures indicated the cytosolic free Ca²⁺ concentrations of skeletal muscle cells increased significantly during exercise-induced fatigue. This study is aimed to establish a rat skeletal muscle cell model of exercise-induced fatigue. We applied cytoplasmic Ca²⁺ fluorescence imaging techniques to study the molecular mechanisms of exercise-induced fatigue eliminated by Chinese medicine ginseng extract. In our research, the muscle tissues from the newborn 3 days rats were taken out and digested into cells. The cells were randomly divided into the ginseng extract group and the control group. The cells from the two groups were cultured in the medium respectively added 2mg/ml ginseng extract and 2mg/ml D-hanks solution. After differentiating into myotubes, the two groups of cells treated with a fluorescent probe Fluo-3 AM were put on the confocal microscope and the fluorescence intensity of cells pre- and post- stimulation with dexamethasone were detected. It was found that cytoplasmic Ca²⁺ concentrations of the two groups of cells both increased post-stimulation, however, the increasing amplitude of fluorescence intensity of the ginseng extract group was significantly lower than that of the control group. In conclusion, stimulating the cells with dexamethasone is a kind of workable cell models of exercise-induced fatigue, and the molecular mechanisms of exercise-induced fatigue eliminated by ginseng extract may be connected to regulatating cytosolic free Ca²⁺ concentrations.

As so-called VRML (Virtual Reality Modeling Language), is a kind of language used to establish a model of the real world or a colorful world made by people. As in international standard, VRML is the main kind of program language based on the "www" net building, which is defined by ISO, the kind of MIME is x-world or x-VRML. The most important is that it has no relationship with the operating system. Otherwise, because of the birth of VRML 2.0, its ability of describing the dynamic condition gets better, and the interaction of the internet evolved too. The use of VRML will bring a revolutionary change of confocal microscope. For example, we could send different kinds of swatch in virtual 3D style to the net. On the other hand, scientists in different countries could use the same microscope in the same time to watch the same samples by the internet. The mode of sending original data in the model of text has many advantages, such as: the faster transporting, the fewer data, the more convenient updating and fewer errors. In the following words we shall discuss the basic elements of using VRML in the field of Optical Microscopic imaging.

In this paper, the characteristics of Fraunhofer digital holography are investigated. With Fraunhofer digital holography, we could simplify the calculational and reconstructed process. Moreover, the spectrum of the hologram did not contain the original images and the limitation of recording frame caused by the size of objects was reduced. The number of recording frame could be increased, especially for the objects of concentrative spectrum. Thus, with Fraunhofer digital holography, it could not only simplify the process of reconstruction and calculation, but also improve the framing capability in high-speed photography.