Objects located in highly scattering biomedical media can be imaged with sub-millimeter spatial resolution using the early light selected by time, spatial, and polarization gates. Spectroscopic fingerprints can provide diagnostic potentials for medical screening by utilizing fluorescence, excitation, absorption, and Raman approaches.

Photons are seriously scattered when entering turbid medium; this the images of objects hidden in turbid medium can not be obtained by just collecting the transmitted photons. Early-arriving photons, which are also called ballistic or snake protons, are much less scattered when passing through turbid medium, and contains more image information than the late-arriving ones. Therefore, objects embedded in turbid medium can be imaged by gathering the ballistic and snake photons. In the present research we try to recover images of objects in turbid medium by simultaneously time-gate and polarization-gate to obtain the snake photons. An Argon-pumped Ti-Sapphire laser with 100fs pulses was employed as a light source. A streak camera with a 2ps temporal resolution was used to extract the ballistic and snake photons. Two pieces of lean swine meat, measured 4mmX3mm and 5xxX4mm, respectively, were placed in a 10cmX10cmX3cm acrylic tank, which was full of diluted milk. A pair of polarizer and an analyzer was used to extract the light that keeps polarization unchanged. The combination of time gating and polarization gating resulted in good images of objects hidden in turbid medium.

Optical tomography (OT) is a method for visualizing brain functions noninvasively. In an OT measurement system, near- infrared light, to which living tissue is highly permeable, is irradiated from the scale of the subject, and the scattered light reflected from the cerebral cortex is detected elsewhere on the scalp. The spatio-temporal blood volume change in the cortex is visualized based on the signal detected using two-dimensionally arranged optodes. The measurement imposes few constraints on the subject, either physically or mentally, thus the subject is in a natural and relaxed condition during measurement. Here we describe our OT system, then report on an experiment to evaluate the system using a phantom. We found that OT can accurately locate the activated region in the cortex. Also, as an example of a clinical application of OT, we used our system to measure the language function, demonstrating the system's ability to measure the activity of Broca's area.

Near infrared spectroscopy has recently been used to measure changes of optical parameters (i.e., light absorption or scattering) of brain tissue. The fact that the equipment is generally compact, portable, noninvasive, and reasonably prices makes it ideal for clinical and nonclinical evaluation and monitoring of brain function. Clinical and nonclinical studies evaluating changes related to light absorption are discussed, with an emphasis on cerebral blood oxygenation (CBO) changes and hemodynamic responses while performing cognitive tasks. With respect to the clinical studies, the focus is on variations in patterns of oxygenated hemoglobin (Oxy-Hb), deoxygentated hemoglobin (Deoxy-Hb) and Total-Hb (sum of Oxy-Hb and Deoxy-Hb). The studies about clinical applications includes research we have conducted with older adults and aphasics. Implications regarding the use of NIRS for clincal purposes are considered.

The purpose of the study is to compare computed tomography optical imaging with traditional breast imaging techniques. Images produced by computed tomography laser mammography (CTLM^TM) scanner are compared with images obtained from mammography, and in some cases ultrasound and/or magnetic resonance imaging (MRI). During the CTLM procedure, a near infrared laser irradiates the breast and an array of photodiodes detectors records light scattered through the breast tissue. The laser and detectors rotate synchronously around the breast to acquire a series of slice data along the coronal place. The procedure is performed without any breast compression or optical matching fluid. Cross-sectional slices of the breast are produced using a reconstruction algorithm. Reconstruction based on the diffusion theory is used to produce cross-sectional slices of the breast. Multiple slice images are combined to produce a three dimensional volumetric array of the imaged breast. This array is used to derive axial and sagittal images of the breast corresponding to cranio-caudal and medio-lateral images used in mammography. Over 200 women and 3 men have been scanned in clinical trials. The most obvious features seen in images produced by the optical tomography scanner are vascularization and significant lesions. Breast features caused by fibrocystic changes and cysts are less obvious. Breast density does not appear to be a significant factor in the quality of the image. We see correlation of the optical image structure with that seen with traditional breast imaging techniques. Further testing is being conducted to explore the sensitivity and specificity of optical tomography of the breast.

Near-infrared spectroscopy (NIRS) is a very useful technique for noninvasive measurement of tissue oxygenation. Among various methods of NIRS, continuous wave near-infrared spectroscopy (CW- NIRS) is especially suitable for real-time measurement and for practical use. CW-NIRS has recently been applied in vivo reflectance imaging of muscle oxygenation and brain activity. However, conventional mapping systems do not have a sufficient mapping area at present. Moreover, they do not enable quantitative measurement of tissue oxygenation because conventional NIRS is based on the inappropriate assumption that tissue is homogeneous. In this study, we developed a 200-channel mapping system that enables measurement of changes in oxygenation and blood volume and that covers a wider area (30 cm x 20 cm) than do conventional systems. The spatial resolution (source- detector separation) of this system is 15 mm. As for the effcts of tissue inhomogeneity on muscle oxygenation measurement, subcutaneous adipose tissue greatly reduces measurement sensitivity. Therefore, we also used a correction method for influence of the subcutaneous fat layer so that we could obtain quantitative changes in concentrations of oxy- and deoxy- hemoglobin. We conducted exercise tests and measured the changed in hemoglobin concentration in the thigh using the new system. The working muscles in the exercises could be imaged, and the heterogeneity of the muscles was shown. These results demonstrated the new 200-channel mapping system enables observation of the distribution of muscle metabolism and localization of muscle function.

A white-light Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen source and Kohler illumination with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. Infinity tube length objectives are used in the two arms. Images are recorded with a CCD camera. Different algorithms have been investigated for extraction of information from the image data. These are basd on phase stepping, which is achieved based on the principle of the geometric phase, using a polarizing beam splitter, a quarter wave plate and a rotating polarizer. Image information extracted from the visibility of the fringes and also from the phase of the interference fringes has been investigated.

We propose a technique for 3-D microscopic imaging with extended depth-of-focus using a novel illumination scheme in a laser scanning optical microscope. The novel illumination scheme creates an effective annular pupil, called the difference-of- Gaussian annular pupil, without the critical drawback of stopping and wasting the light. Two laser beams of difference Gaussian pupils with different temporal frequencies are first generated. The laser beams are then combined spatially and used to scan the specimen. The scattered light from the object is picked up by a photodetector whose output consists of a DC and an AC current (due to the optical heterodyning of the two optical beams). The DC signal is no difference from the DC output of a conventional laser scanning microscope with the processing pupil as a Gaussian function, whereas the AC signal is derived from the mixing of the two Gaussian beams and would be given by effectively a Gaussian pupil with a different size than that generated by the DC signal. The AC and the DC signals are then subtracted by electronics and hence the effective pupil function would be given by the difference of the two Gaussian pupil functions. By properly choosing the size of the two Gaussian laser beams, we could realize the difference of the two Gaussian pupils which becomes a new type of annular pupil called the difference-of-Gaussian annular pupil.

Breast tissues were investigated using diffuse reflectance spectroscopy to yield the absorption spectrum from Kubelka-Munk Function (KMF). A specified spectral feature measured in adipose tissue was assign to (beta) -carotene, which can be used to separate fat from other molecular components in breast tissues. The peaks of (KMF) at 260nm and 280nm were attributed to DNA and proteins.

Near-infrared spectroscopy (NIRS) is a useful technique for noninvasive measurement of oxygenation of the brain and muscle. However, no accurate, quantitative algorithms for continuous wave NIRS (CW-NIRS) have yet been presented due to the following two problems. The first is that inhomogeneous tissue structure greatly affects measurement sensitivity. We previously reported on the influence of a fat layer on muscle oxygenation measurement and proposed a method for correcting the sensitivity. The second problem is that almost all algorithms for CW-NIRS have been experimentally determined, although al algorithm can be theoretically determined on the basis of diffusion theory if the mean optical pathlength in muscle in an in vivo state is known. In this study, we derived basic equations for a CW-NIRS algorithm based on diffusion theory, and we determined linear and nonlinear algorithms from mean optical pathlengths and validated them by results obtained from phantom experiments. For the determination of pathlength, the absorption and scattering coefficients of the muscle must be obtained by taking into account the influence of the fat layer. Laser pulses at 752 and 871 nm were applied to the forearms of the subjects, and the temporal point spread function (TPSF) was obtained by using a streak camera. The absorption and scattering coefficients of the muscle were determined by fitting the measured TPSF with that obtained by a Monte Carlo model consistingof skin, fat and muscle layers. From these coefficients, the mean optical pathlengths were obtained and the algorithms were determined.

Multi-photon fluorescence spectra of a number of commonly used biological probes were measured in this study. Significant spectral variation has been detected between single and multi- photon excitation. The result is important for the proper selection of spectral setting/dichroic beam splitter in the set- up of a multi-photon fluorescence microscope. The information can also be useful in the detection of multi-photon fluorescence in bio-chip technology. In addition, we have investigated a few highly fluorescent bio-molecules commonly found in plant cells.

In this study, epilayers of packaged indium gallium nitride light emitting diodes (LED's) are characterized by optical beam induced current (OBIC) and photoluminescence laser scanning microscopy through two-photon excitation. OBIC reveals spatial and electrical characteristics of LED's which can not be distinguished by photoluminescence. When compared with single- photon OBIC, two-photon OBIC imaging not only exhibits superior image quality but also reveals more clearly the characteristics of the epilayers that are being focused on. The uniformity of these LED's OBIC images can also be related to their light emitting efficiency.

The non-linear nature of multi-photon fluorescence excitation restricts the fluorescing volume to the vicinity of the focal point. As a result, the technology has the capacity for micro- spectroscopy of biological specimen at high spatial resolution. Chloroplasts in mesophyll protoplast of Arabidopsis thaliana and maize stem sections were used to demonstrate the feasibility of multi-photon fluorescence micro-spectroscopy at subcellular compartments. Time-lapse spectral recording provides a means for studying the response of cell organelles to high intensity illumination.

Based on the non-linear excitation of fluorescence molecules, two-photon fluorescence microscopy has become a significant new tool for biological imaging. The point-like excitation characteristic of this technique enhances image quality by the virtual elimination of off-focal fluorescence. Furthermore, sample photodamage is greatly reduced because fluorescence excitation is limited to the focal region. For deep tissue imaging, two-photon microscopy has the additional benefit in the greatly improved imaging depth penetration. Since the near- infrared laser sources used in two-photon microscopy scatter less than their UV/glue-green counterparts, in-depth imaging of highly scattering specimen can be greatly improved. In this work, we will present data characterizing both the imaging characteristics (point-spread-functions) and tissue samples (skin) images using this novel technology. In particular, we will demonstrate how blind deconvolution can be used further improve two-photon image quality and how this technique can be used to study mechanisms of chemically-enhanced, transdermal drug delivery.

Simultaneous two-photo excited fluorescence (TPF) and second- harmonic generation (SHG) imaging is demonstrated using a single femtosecond laser and a scanning microscope. This composite nonlinear microscopic technique was applied to imaging DNA and chromosomes, and it was shown that the two different interaction mechanisms provide complementary information on the structure and nonlinear properties of these biological materials beyond that achievable using either TPF or SHG imaging alone. The use of separate modes of detection, in reflection and transmission respectively, and the simultaneous nature of the acquisition of the two images allows pure TPF and SHG images in precise registration to be obtained.

In this study, we have developed a high performance microscopic system to perform second-harmonic (SH)imaging on a tooth. The high sensitivity of the system allows an acquisition rate of 300 seconds/frame with a resolution at 512x512 pixels. The surface SH signal generated from the tooth is also carefully verified through micro-spectroscopy, polarization rotation, and wavelength tuning. In this way, we can ensure the authenticity of the signal. The enamel that encapsulates the dentine is known to possess highly ordered structures. The anisotrophy of the structure is revealed in the microscopic SH images of the tooth sample.

Giant unilamellar lipsomes (diameter $GTR 10 (mu) m) are important for cell-membrane research and controlled drug delivery. Mechanical properties of unilamellar lipsomes in different physiological conditions are crucial for their applications. For example, liquid-gel phase transition of the bilayer membrane under different temperatures determines the stability and activity of liposomes. Bending rigidity is the most closely related mechanical property to phase transition. Owing to the flexible nature of bilayer membranes, accurate measurements of the bending rigidity of membranes are difficult. Here we report an all-optical technique to directly measure the bending modulus of unilamellar lipsomes. We use differential confocal microscopy, a far-field optical profilmetry with 2-nm depth resolution to monitor the thermal fluctuations and the deformation of unilamellar lipsomes. From the amplitude changes of thermal fluctuations along with temperature we can directly determine the phase-transition temperature of the membrane structure. We then employ optical force to induce sub-micrometer deformation of the unilamellar lipsomes. From the deformation we can obtain their bending rigidity with simple calculation. We find the bending modulus decreases from 8-11 pico-erg to 0.5 to 0.9 pico-erg as the liposomes are heated across the phase-transition temperature. All measurements are done without contacting the samples and the shapes of the liposomes remain the same after the experiments.

Recent development in multi-photon fluorescence microscopy, second and third harmonic generation microscopy (SHG and THG) and CARS open new dimensions in biological studies. Not only the technologies allow probing the biological specimen both functionally and structurally with increasing spatial and temporal resolution, but also raise the interest in how biological specimens respond to high intensity illumination commonly used in these types of microscopy. We have used maize leaf protoplast as a model system to evaluate the photo-induced response of living sample under high intensity illumination. It was found that cells can be seriously damaged by high intensity NIR irradiation even the linear absorption coefficient in low in these wavelengths. Micro-spectroscopy of single chloroplast also allows us to gain insight on the possible photo-damage mechanism. In addition to fluorescence emission, second harmonic generation was observed in the maize protoplasts.

An optical fiber needle probe was developed that can be inserted into a hollow metallic needle for tumor diagnosis using fluorescence at key wavelengths for breast, kidney, liver, and brain. The optical fiber needle probe is based on fluorescence ration method which will allow to detect tumor in vivo for a real time evaluation. This method will be couple with other current modalities such as X-ray, ultrasound and MRI.

Previous results showed that the non-reversible (hystersis loop) of Bragg wave length shifting in thermal cycling of the Fiber Bragg Grating which is a high germanium doped optical fiber and high pressure hydrogen loaded was due to the diffusion out of the H₂ residue in thermal annealing. In addition, the O-H absorption peak (1.38nm) causes signal attenuation and stability problem in FBG applications. We demonstrated up to 250 degree(s) C. The spectrum characteristics of the D₂ loaded FBG compared to the H₂ loaded FBG is presented. In general, (Delta) (Lambda) _B of the D₂ loaded FBG is narrower than H₂ loaded, and (Lambda) _B of the D₂ loaded FBG is more stable than H₂ loaded in thermal annealing. A model base on the UV photo-induced index change in the BFG core with D₂ and H₂ loaded to explain the spectrum characteristics between D₂ and H₂ loaded FBG is discussed.

A wavelength-division-multiplier (WDM) was used to extract the Ramam scattering signal from a data fiber. The temperature performance of Raman scattering spectrum was studied theoretically and experimentally. On the base of this study a distributed fiber-optic temperature sensor (DFTS) system was developed. The sensing distance was 4km. The temperature accuracy and the distance resolution reached to +/- 1 degree(s)C and +/- 1m, respectively. The system is stable and adequate for commercial usage, such as the power industry, the underground tunnel, the subway, the pipe laying, and also for the mission applications, such as the warship and airplane.

A novel fiber grating sensing technology based on the torsion beam is reported for the first time. The Bragg wavelength change is linear with the torsional angle and the torque. The fiber Bragg grating (FBG) is firmly mounted on the surface of the torsion beam with a determinate angle along the direction of the axes of the torsion beam. The range of the torsional angle is between -45 degree(s) and +45 degree(s). The sensing sensitivity of the torsional angle is up to 11.534 degree/nm and that of the torque is up to 0.1595 Nm/nm, respectively. The formulas have been derived theoretically and the experimental results basically accord with the theoretical ones. This technology has many advantages, such as two dimensional tuning, the high sensitivity, the good repetitiveness and no chirping for the torsional angle within the range -45 degree(s) and +45 degree(s), etc. It has potential applications in the area of the fiber sensing, the fiber communication and laser technology.

Recent advancements in several genome-sequencing projects have stimulated an enormous interest in microarray DNA chip technology, especially in the biomedical sciences and pharmaceutical industries. The DNA chips facilitated the miniaturization of conventional nucleic acid hybridizations, by either robotically spotting thousands of library cDNAs or in situ synthesis of high-density oligonucleotides onto solid supports. These innovations have found a wide range of applications in molecular biology, especially in studying gene expression and discovering new genes from the global view of genomic analysis. The research and development of this powerful tool has also received great attentions in Taiwan. In this paper, we report the current progresses of our DNA chip project, along with the current status of other biochip projects in Taiwan, such as protein chip, PCR chip, electrophoresis chip, olfactory chip, etc. The new development of biochip technologies integrates the biotechnology with the semiconductor processing, the micro- electro-mechanical, optoelectronic, and digital signal processing technologies. Most of these biochip technologies utilitze optical detection methods for data acquisition and analysis. The strengths and advantages of different approaches are compared and discussed in this report.

A novel CMOS photosensor with a gate-body tied NMOSFET structure realized in the triple is well presented. The photocurrent is amplified by the lateral and vertical BJT action, which results in two different output photocurrents, which can be used for different applications within a pixel. The lateral action results in the drain current with a higher sensitivity at low light intensity. And the vertical action results in the collector current with uniform responsivity over wider range of the light intensity. The proposed photosensor in compatible with CMOS circuits.

This paper focuses on developing the platform technology of real- time biomolecular-interaction analysis (BIA) sensor chips. A detection scheme using the electro-optically modulated surface plasmon resonance (SPR) is suggested to advance the sensor features in reducing measurement complexity and time. The SPR method of a BIA sensing system detects slight changes of refractive index due to the biomolecular interaction at the solid-liquid interface. The most sensitive interrogation method among the possible conventional schemes is to measure the SPR angle of the attenuated total reflection. The electro-optical modulation replaces the mechanism of angle measurement not only to increase the speed but also to increase the size. Recent progress of the multilayer SPR provides an effective mean of tailoring the microchip. Several multilayer configurations have been studied in this paper to realize the electro-optical SPR sensing. Especially, the long-range mode of surface plasmon was investigated to achieve the high resolution and high sensitivity detection.

An amplitude sensitive optical heterodyne polarimeter was setup in order to monitor noninvasively the aqueous glucose concentration in rabbit's eye. A range of the blood glucose from 35 mg/dl to 135 mg/dl was measured in vivo by biological glucose assay (BGA), while the optional rotation of the aqueous glucose was measured by a polarimeter simultaneously. The experimental results showed the consistence between these two independent measurements. There was no time delay between the blood glucose and the aqueous glucose when the blood glucose was descending after the insulin was injected. It was in contract to a 10 minutes time delay when the blood glucose was ascending. The detection sensitivity of the polarimeter was 4 mg/dl in the measurement.

A graphic user interface and real-time laser Doppler velocimeter (LDV) based on the digital signal processor (DSP) had been designed and developed. The hardware setup included the Michelson inteferrrometer optics, photo-detector, current to voltage converter, AC amplifer and filtering circuits, as well as a DSP module. The software system on the Dsp module was also developed to access data and to perform the moment weighting algorithms. In addition, the processed data was transmitted to the personal computer and advanced analysis could be achieved. The velocity measurement using developed LDV device was calibrated by a mirror mounted on a linear vibrator. The outcomes presented high linearity and good accuracy. In vitro experiment employing this LDV system was also carried out. The results showed that the developed LDV instrument offered a flexible tool to investigate the blood flow of microcirculation system.

Particle-trapped near-field scanning optical microscopy utilises a laser-trapped dielectric or metallic particle as a near-field scatterer to probe the high spatial frequency information from a sample. Scattering and depolarization by a trapped particle in an evanescent wave are two important issues in such an imaging system. These two issues are addressed in this paper. The strength of scattered evanescent waves was measured for particles of different sizes (.01 (mu) m to 2 (mu) m in diameter) and different materials (polystyrene, gold and silver). It has been found that the signal strength of scattered evanescent waves increases appreciably with the size of the particle. As a result, image contrast in improved significantly with laser-trapped metallic particles of large size. It has also been found that the depolarization of scattered evanescent waves under s polarised illumination is stronger than that under p polarized beam illumination, and that image contrast of the evanescent wave interference pattern can be improved by a factor of 3 with a parallel analyser under s polarized beam illumination. This result suggests that less depolarized scattered evanescent photons carry more information of an object and should be utilised for the imaging in particle-trapped near-field scanning optical microscopy.

Optical tweezers are useful for manipulating biological samples and measuring biological forces. In the present study, we have integrated a forward scatter analysis (FORSA) module in the single-beam gradient force optical tweezers. The entire set-up was then incorporated onto an inverted microscope. In the FORSA module an Helium-Neon probing laser was spotted (at a slightly out-of-focus way) onto the object being trapped by the infrared laser-based tweezers and generated a diffraction pattern. Imagines of the diffraction pattern were captured by a charge- coupled device (CCD), and digitized and processed by a computer. Wed demonstrated that tracking the amplified diffraction pattern war much more precise to determine the movement of the object within the trap than analyzing the minute motion of the object itself. Displacement of the object could then be translated into the force being applied by the tweezers. Also, using an algorithm developed in the lab, we were able to follow the movement of the scattering pattern at a temporal resolution close to video rate. We have used this system to investigate the binding force associate with cell-cell interactions and modular interactions. In these studies. A cell was carefully positioned to make contact with another cell or a microparticle coated with proteins of interest by optical tweezers in a well-controlled manner. During these events, we noted a progressive increase of cell adhesion at the immediate early period (i.e., a few minutes after initial contact) of cell-cell interactions. Also, binding of a disintegrin, rhodostomin, and its mutant to the counterpart integrin on the cell surface could be assessed with great convenience and accuracy. Our results demonstrated that addition of the forward scatter analysis module to convention optical tweezers provides an effective and convenient way for monitoring biological activities in situ and measuring changes of biological forces with precision.

In this paper, we compare the performance of the single beam gradient-firce trap (SBGFT) and the counter propagating dual-beam trap (CPDBT) quantitively in terms of three performance parameters, namely, the transverse trapping efficiency, the width of the stable trapping zone, and the axial stiffness. Ray-Optics Model (for optical trapping of Mie particles) was used to obtain the numerical results. In the SBGFT, the particle is trapped in the vicinity of the focal spot of a strongly focused (N.A. ~ 0.65 to 1.3) laser beam by gradient forces in both the transverse and the axial directions. In the CPDBT, with the two counter- propagating beams often mildly focused (N.A. <0.6), the particle is confined transversely by the transverse gradient forces of the two beams and stabilized axially by balancing the scattering forces from the two beams. Depending on the separation between the two beam waists, there can be more than one stable trapping zones in the CPDBT. Qualitatively, one obvious key advantage of SBGFT is that it is very simple to implement. In contrast, the CPDBT requires precised alignment of the two beams. The latter, however, allows longer working distance and offers more degrees of freedom. The theoretical values of the aforementioned performance parameters for the CPDBT vary over a wide range because they depend on the distance between two beam waists. This extra degree of freedom in the CPDBT allows us to trade off one performance parameter against the others. We have also measured these performance parameters experimentally to verify the general trend predicted by the theoretical model.

Optical tweezers is a newly developed instrument, which makes possible the manipulation of micro-optical particles under a microscope. In this paper, we present the automation of an optical tweezers which consists of a modified optical tweezers, equipped with two motorized actuators to deflect a 1 W argon laser beam, and a computer control system including a joystick. The trapping of a single bead and a group of lactoacidofilus was shown, separately. With the aid of the joystick and two auxiliary cursers superimposed on the real-time image of a trapped bead, we demonstrated the simple and convenient operation of the automated optical tweezers. By steering the joystick and then pressing a button on it, we assign a new location for the trapped bead to move to. The increment of the motion 0.04 (mu) m for a 20X objective, is negligible. With a fast computer for image processing, the manipulation of the trapped bead is smooth and accurate. The automation of the optical tweezers is also programmable. This technique may be applied to accelerate the DNA hybridization in a gene chip. The combination of the modified optical tweezers with the computer control system provides a tool for precise manipulation of micro particles in many scientific fields.

We present the observation of the activity of artemia, one of the popular marine micro-biota species, in free space by the application of Fourier optics imaging technique. The Fourier optic imaging system is consisted by a collimated laser beam source, a Fourier spatial filter, an non-coherent IR source, and a CCD imaging system. By recording the images of Artemia's motion in real life, we are able to study the fundamental patterns of artemia motion mechanism, and the response of the motion pattern to the variation of its environment. Characteristic patterns of artemia's motion, such as linear motion, spiral motion, and mating collision are observed. It is shown that the increasing of the environment temperature driving the motion of the artemia's moving faster and more frequently, and still stays alive even at the environment temperature up to 38 C.

Measurement of tissue radiation damage quantitatively in radiation therapy is very important to optimize the therapeutic treatment. Ionized radiation induces homogenization of the extracellular matrix which is synthesized by fibroblast and the randomization of the orientation of the collagen fibers in dermis. If the dermis is exposed by ionized radiation, a thermal acoustic shear wave which propagates in dermis becomes harmonic wave. Otherwise, an inharmonic wave is expected because of inhomogeneous and the anisotropic properties of dermis. A polarized optical heterodyne interferometer was setup in order to measure the transverse displacement of the shear wave in order to analyze the propagation mode of the shear wave in dermis. The detection sensitivity of the displacement was 1nm and the dynamic range was 300 nm in this arrangement. The lowest does that can be detected by the exposure of 4 MeV radiation on porcine dermis was 1cGy.

The ASR-PET detector is designed by coupling a 7x8 array of BGO scintillation crystals to a PSPMT (Position Sensitive Photo- Multiplier Tube). Reflectors between the crystals confine the light from a gamma ray interaction and control the distribution of light to the PSPMT. The output signals of the PSPMT are used to identify the crystal scintillation and the energy being released from the gamma ray interaction. The subject of this study is to generate a LUT (Lookup Table) from the position response distribution of the block detector and to analyze the PHS (Pulse Height Spectrum) of each crystal. By combining the image-processing and neural network data fitting techniques, this system gives a flexible, user-friendly and powerful approach to perform the analysis with satisfactory accuracy.

Non-linear ultrafast optical gate has been used to detect back- scattered images of objects hidden in diluted Intralipid solutions. The gain from the optical parametric amplification greatly improves the detection sensitivity.

A tightly bending loss technique is developed for application in biomedical WDM fiber sensors. In this paper, we present the measurement and comparison of bending sensor in 1.3 (mu) m and 1.55 (mu) m wavelength region, respectively. A two-wavelength measurement setup is built for bending loss testing. Various wrapping method and turns are invested for studying the bending loss for broadband biomedical sensing system. We found that as the bending loss increases, the oblique angle of wrapping becomes large. These research results is helpful for multi-channel multi- array fiber optic biomedical sensor systems.

A new electric current sensor based on fiber Bragg grating tuned by giant magnetrostrictive material rod is demonstrated in this paper. A fiber Braff grating is firmly clung on a giant magnetrostrictive rod that is put into the central part of a solenoid. The Bragg wavelength of the fiber grating will shift when the uniform magnetic field in the solenoid changes. The rod will have elastic lengthening along the direction of the magnetic field. The grating resonant wavelength of the fiber grating will shift as consequence of the rod lengthening. The relationship between the electric current and the wavelength shift is basically linear. The wavelength range of linear tuning is about 0.9 nm. The tuning sensitivity is about 0.001nm/mA.

A new silicon-on-insulator (SOI) waveguide Michelson interferometer with Bragg reflective gratings as a biomedical temperature sensing array head is presented in this paper. The waveguide Bragg reflective gratings work as mirrors for adjusting the transfer function of the Michelson interferometer sensor. We will show the comparison of the temperature sensing accuracies of the fiber Bragg grating and SOI waveguide Michelson interferometers in biomedical applications. The grating length and perturbation period of waveguide Bragg grating in SOI waveguide Michelson interferometer will increase as temperature rises, that is, the thermal effects of the reflective Bragg gratings are considered in our analysis. According to the numerical analysis of power reflective spectra of waveguide Michelson interferometers, the temperature sensing waveguide of the Michelson interferometer can improve at least 20 times than the traditional fiber Bragg grating temperature sensor. Moreover, the SOI waveguide interferometer sensor we designed presents high sensitivity than pure single waveguide Bragg grating sensor and fiber Bragg grating sensor by adjusting the length of the two interferometric arms. The full width of half maximum (FWHM) of the frequency responses of passband of SOI waveguide Michelson interferometer can be designed smaller than fiber and waveguide Bragg grating sensors for sensitivity improvement.

In this paper, we present a new broadband light source covers 1280-1380nm region for application in a wavelength division multiplexing biomedical fiber-optic Bragg grating spectra reflective sensors. We cascade two optical amplifiers for achieving the 100nm broadband light source. The cascaded two optical amplifiers are praseodymium fluoride fiber amplifer (PDFA) and multiple quantum well optical semiconductor amplifier MQW-SOA, respectively. The optimal driving current of MQW-SOA and the optimal pumping power of PDFA are experimentally searched. We find the bandwidth can reach 100nm from 1280nm to 1380nm with driving current 50mA and pumping power 885mW of MQW-SOA and PDFA respectively.

The transient electric field of highly intense electromagnetic pulse (EMP) will seriously damage the military and civil installations, so it is significantly important to measure such electric field of EMP with high frequency. This paper describes a fiber-optic sensor for measuring highly intense electric field with high frequency. The sensor consists of a probe of electrooptic (EO) crystal, optic fiber, polarizer, photodetector, processing circuits and single-chip microprocessor. According to Pockels effect, the polarized light will be modulated by the electric field to be measured when it penetrates the EO crystal. Then, its polarized direction will vary following the variation of electric field. The change of polarized direction is converted to the variation of light intensity by polarizer. In order to gain good performance, it is important to choose suitable crystal carefully. The interrelated optical axises of the components are adjusted on the basis of the theoretical analysis and calculations. A special temperature compensating method is used to decrease the temperature effect. At the meantime, the low circuit is used. The testing results show that the linearity is 0.2%, the error of the measurement is approximately 0.5% and the risetime is less than 4ns.

A channel-switching add/drop multiplexer with tunable fiber grating tuned by cantilever beam is proposed and experimentally demonstrated. The device consists of two 3dB couplers and a fiber Bragg grating with 99% peak reflectivity at 1557.86nm and 0.2nm bandwidth. The grating is firmly clung on an organic glass cantilever beam and we can continuously tune the reflectivity wavelength through tuning the cantilever beam manually. The no- chirped linerly tuning signal range is about 6.1nm which may permit 7 channels with channel spacing of 0.8nm (100GHz) to insert or drop signal. A broadband light source and a 4- wavelength all fiber laser are used to test its capability in experiment. The adjacent channel isolation is not less than 23dB. The device shows good performance, but suffers from a high insertion loss.

A novel wavelength scanning optical fiber dual-interferometer for measuring small distance has been developed in this paper. A wavelength-scanning source is used to simultaneously illuminate Fabry-Perot (F-P) cavities. One is as the sensing cavity, the other is as a reference cavity. If the length of the reference cavity is pre-calibrated and maintain constant, and the scanning wavelength is taken as an inter-converter to compare the gap length of the sensing cavity with the reference cavity length, using the frequency spectrum separator, absolute measurement can be obtained.

A novel grating angular displacement transducer using a multiplex Fabry-Perot interface technology has been developed. The Fabry- Perot interferometer (FPI) has been traditionally used to examine either small spectral ranges or relatively simple spectra. Recently, however, the studies have shown that the FPI can be competitive with the Michelson interferometer over extended spectral ranges. A relatively new FPI is described based on two gratings.

A new scheme for optical trapping is presented in this paper. The method is based on a tapered filter probe with a tip diameter less than a light wavelength. A three-dimension gradient optical field is formed within the optical near field of the filter probe, and a particle approaching the fiber probe tip will be trapped. The evanescent eletromagnetic field in the vicinity of the fiber tip is calculated by the multiple multipole method (MMP). The intensity distributions and the trapping potentioal of the near fields of the tip versus the longitudinal and transverse distances from the tip are analyzed respectively. The trapping force is obtained for a dielectric particle. The numerical calculating results show the availability of this method.

As we approach the new millennium, the ongoing aim of human society is not only for promoting scientific technology but also creating new industries. To achieve this goal, each person in industry must recognize anew that the real meaning of science is to explore the absolute truth. It is also important that people recognize that there are unlimited matters which we humans do now yet know.