Optical techniques can assist engineering of tissue patches and implants by assessing implant structure, monitoring the implant fabrication process, controlling the machining of the implant, and monitoring in vivo the body's host response to the implant.

Tissue strongly scatters light. Therefore, virtually all techniques for probing tissue with light are dependent on the scattering interactions of light with tissue. In particular, noninvasive optical methods for determining tissue morphology are dependent on light scattering. A fundamental understanding of what cellular features scatter light and of how changes internal cellular structures affect the measurement of light transport are needed. In this work, we describe some of the recent progress made towards understanding the basic mechanisms of light scattering in tissue.

An angular spectrum algorithm is presented for fast, near-field diffraction tomographic imaging with diffuse photon density waves in highly scattering media. A general relation in K-space is derived that connects the spatial variations of the optical properties of heterogeneities to the spatial spectra of the measured scattered diffuse photon density waves. The theory is verified with experimental results. We further describe an approach to reconstruct the absorption and scattering simultaneously. We also present how to incorporate boundary conditions into this angular spectrum algorithm for a turbid medium of finite size, in particular, the slab medium.

By extending the technique of dynamic light scattering from single light scattering to high order multiple scattering, we are able to measure the dynamics of a turbid medium averaged over some deep scattering volume. One biological application is to measure blood flow in deep tissues like the brain. Furthermore, by moving the light source and detector positions to cover an extended area, we are able to reconstruct images of the dynamics.

The whole process of neutrophilic granulocyte phagocytosis of E.Coli BL₂₁-expressed green fluorescent protein gene was recorded with CCD coupled fluorescence microscopy in a real-time. This process contains of three stages: adhesion, ingestion, and exocytosis. The properties of each stages of phagocytosis were analyzed. The method opened new perspective in continuously observing the specific and non-specific immunity mechanism on alive cell.

In bio-fluorescence detection, short-exposure is proposed to minimize photo damage and tissue turbulence to some extent in in- vivo measurement, but suffering from image blur and lower signal to noise ratio. Triple correlation was proposed to improve image quality. In our experiment, a set of short-exposure images (photo-limited data) were recorded by a CCD camera, instead of long-exposure image. Algorithms based on triple correlation for the recovery of the object from the photon-limited data was discussed. It was proved to be effective by our experiment.

The light propagation in tissues has been simulated successfully by Monte Carlo method. Since the result of Monte Carlo simulation is discrete and statistic, the traditional optimizations and search algorithms encounter irresolvable difficulty in an inverse problem, but it can be overcome effectively by Genetic Algorithms due to their global search, robustness and self-adapting. In the present paper, we consider a tissue volume in which there is a spherical tumor with different optical parameters. A thin collimated NIR laser beam incidents normally on the surface. Monte Carlo method is used as a solution to the direct problem after some improvements, and in the inverse problem a genetic algorithm is applied to reconstruct the tumor. An appropriate evaluation function related to forward light distribution is designed to improve the stability and the speed of convergence. The selection based on fitness expectation is adopted as well as the random crossover and random mutation. Four parameters which determine the location and size of the tumor are to be reconstructed. The reconstructed tumor has a good agreement with the true tumor.

In this paper, we described a near infrared biomedical signal analysis system. The principle of this system is based on the Lambert-Beer Law. Being carefully designed, it can detect the weak changes of biology optical properties and a Fourier transform can be performed in real time mode. We use this system to monitor the coagulation process of rat liver in different constant temperature (55 approximately 95 degree(s)C). Some classic biomedical experiments are carried out and the result is encouraging. Further discussion on brain function research is given at the end of this paper.

Its very important to improve the sensitivity of the near- infrared tissue oximeter during practical non-invasive measurement on human muscle. It has been thought that this sensitivity is influenced by the existence of overlying tissues such as skin and fat because only those photons which have passed through the muscle bring back useful information. In this paper, the influences of fat layer, detecting distance, wavelength, and the oxygenation in muscle on photon partial path length in muscle layer are discussed based on Monte-Carlo simulation results. Also examined are the statistical error in simulation and the noise in detector. Finally, the experimental results of the cuff occlusion on forearm are given. The results show the relationship between the sensitivity of the tissue oximeter and the detecting distance, which has the same tendency as the simulation predicted.

A method for imaging the superficial epidermal and papillary dermal layers of the skin is needed when assessing many skin lesions. We have developed an imaging modality using a video camera whose mechanism of contrast is the reflectance of polarized light from superficial skin. By selecting only polarized light to create the image, one rejects the large amount of diffusely reflected light from the deeper dermis. The specular reflectance (or glare) from the skin surface is also avoided in the setup. The resulting polarization picture maximally accents the details of the superficial layer of the skin and removes the effects of melanin pigmentation from the image. For example, freckles simply disappear and nevi lose their dark pigmentation to reveal the details of abnormal cellular growth. An initial clinical study demonstrated that the polarization camera could identify the margins of sclerosing basal cell carcinoma while the eye of the doctor underestimated the margin estimate. The camera identified an 11-mm-diameter lesion while the unaided eye identified a 6-mm-diameter lesion.

This research is aimed at developing a novel `radiation- shielding, CCD scanning' technique for digital mammography. Using this technique, small size electronic imagers can be used effectively to cover a large field without losing spatial resolution.

Near infrared spectroscopy (NIRS) is used to quantify changes in oxy-hemoglobin (HbO) and deoxy-hemoglobin (Hb) concentrations in tissue. The analysis uses the modified Beer-Lambert law, which is generally valid for quantifying global concentration changes. We examine the errors that result from analyzing focal changes in HbO and Hb concentrations. We find that the measured focal change in HbO and Hb are linearly proportional to the actual focal changes but that the proportionally constants are different. Thus relative changes in HbO and Hb cannot, in general, be quantified. However, we show that under certain circumstances it is possible to quantify these relative changes. This builds the case for diffuse optical tomography (DOT) which in general should be able to quantify focal changes in HbO and Hb through the use of image reconstruction algorithms that deconvolve the photon diffusion point-spread-function. We demonstrate the differences between NIRS and DOT using a rat model of somatosensory stimulation.

Two imaging techniques combining ultrasound and light are reviewed. The motivation is to combine the advantages of optical information and acoustic imaging resolution. The first technique is sonoluminescence tomography, where a sonoluminescence signal generated internally in the media by continuous-wave ultrasound is used. 2D images can be produced for objects embedded in turbid media by raster scanning the media. The second technique is ultrasound-modulated optical tomography, where a frequency-swept ultrasonic wave was used to modulate the laser light passing through a scattering medium. Multiple 1D images obtained at various positions perpendicular to the ultrasonic axis were composed to obtain a 2D tomographic image of the medium.

A comparative analysis of spectra of diffuse reflection of the breast tissue obtained when performing operation for tumor neoplasms of the breast and during the diagnostic puncture biopsy has been done. Spectral characteristics of tissues of 74 patients with different pathology of the breast (cancer, fibroadenomas, mastopathies) have been under study. Bioptic samples received from 22 patients were examined in conditions in vitro, in 35 patients the reflection spectra were recorded in the course of operation (in vivo) and in 17 patients when performing a diagnostic puncture biopsy by means of a light probe. Spectra of pathological segments of tissues and normal ones were compared. The effect of vasoactive substances of spectral characteristics of the examined tissues was evaluated. There was obtained a diagnostic parameter evaluating integrally the character of the reflection spectrum profile. Under the influence of chemo- and radiotherapy the changes in characteristics of reflection spectra profiles of the examined tissues occur as well. The method of registration of diffuse reflections in vivo is considered to be highly sensitive, so for its further development it is necessary to elaborate the ways of preparing patients for spectral examinations in vivo, to create the data base of spectra of diffuse reflection of the normal and pathological tissues.

Human brain activity was studied with a real time functional Near-InfraRed Imager (fNIRI). The imager has 16 measurement channels and covers 4 cm by 9 cm detection area. Brain activities in occipital, motor and prefrontal area were studied with the fNIRI. In prefrontal stimulation, language cognition, analogies, forming memory for new associations, emotional thinking, and mental arithmetic were carried out. Experimental results measured with fNIRI are demonstrated in this paper. It was shown that fNIRI technique is able to reveal the occipital activity during visual stimulation, and co-register well with results of fMRI in the motor cortex activity during finger tapping. In the studies of the effects of left prefrontal lobe on forming memory for new associations, it is shown that left prefrontal lobe activated more under deep conditions than that under shallow encoding, especially the dorsal part. In the studies of emotional thinking, it was shown that the responses were different between positive- negative emotional thinking and negative-positive emotional thinking. In mental arithmetic studies, higher activation was found in the first task than in the second, regardless of the difficulty, and higher activation was measured in subtraction of 17 than in subtraction of 3.

A theoretical analysis of the x-ray phase imaging in the method of in-line holography setup with a finite size source is presented. Based on the transport of intensity equation (TIE) with a point source, we given an algorithm to quantitatively restore the phase from x-ray phase imaging with an incoherent finite size source. We show that the image intensity is a convolution of the source intensity distribution and the intensity got from the x-ray phase imaging with a point source. The algorithm needs the intensity distribution at the source plane, the plane just after the object and the image plane. Performing deconvolution and solving the TIE, the phase can be retrieved. Analytical investigation of a simple model suggests that our method is mainly applicable to the differential phase contrast case. Numerical examples are also presented.

This study was to explore the role of the left prefrontal lobe in semantically encoding unrelated word pairs. 22 subjects were studied unrelated Chinese pairs that were visually presented under both semantic and shallow conditions. Under semantic (or deep) conditions subjects were asked to form a sentence including two words, while under shallow (or deep) conditions they were asked to judge whether two words had the same structure. During the cognitive tasks, optical imager measured the relative changes of 760 nm and 850 nm absorption when the continuous light diffused through the left prefrontal lobe. In term of the intensity change, the regional blood volume change could be expected. The results showed that activation of left prefrontal lobe, especially the dorsal part, was stronger under deep conditions than that under shallow encoding. It was suggested that near infrared spectroscopy could be used to measure the higher brain function.

In this paper, we report, for the first time, sonoluminescence (SL) images of living body (nude mouse) injected with and without chemical agents under weak ultrasound field. We found FCLA (Fluoresceinyl Cypridina Luminescent Analog), a chemiluminescent analytic agent, could enhance SL and can work in vivo. We also makes use of sonosensitization to produce tumor-selective oxygen radicals that can react with FCLA to emit chemiluminescence. By detecting this luminescence, we obtained a clear diagnostic image. This novel method proposed by our group has potential application in clinics for tumor early-stage diagnosis.

No clear image of Ultraweak Biophoton Emission (UBE) from animal has been reported so far. With the detection system equipped with a back-illuminated cooled CCD (-60 degree(s)C), we have clearly observed UBE images of the wound tissues and the tumor tissues with long exposure time. The intensity of UBE from the wound tissue or the tumor tissue is higher than that from normal tissues. We proposed that the increase of UBE from wound response is the result from defense mechanism of body in which white blood cells' respiration burst is involved, the UBE from transplanted cancer tissue is related to the disorder of metabolism because of the malignant growth and multiplication of tumor cells. Non- invasive diagnosis might be realized in medicine by this technique following the further improvement of sensitivity of the detector.

Optical fiber biosensors offer great promise for rapid and sensitive detection of a variety of chemical and biological analyte. In this paper, we report our progress in developing an optical fiber biosensor for the characterization of solid phase nucleic acid hybridization. The principle of the measurement is based on the combination of photon counting and laser induced fluorescence in the evanescent field on the optical fiber surface. We used long, fused silica fibers that had several centimeters of cladding removed along the distal end for the fabrication of sensor probe. 5'-amino-terminal oligonucleotide probes were covalently immobilized via glutaraldehyde cross- linking to an aminosilane on the exposed fiber core to form a thin layer of oligonucleotide probes. The evanescent excitation of fluorescence was achieved through the evanescent wave penetrating into the oligonucleotide probes layer when an Ar ion laser beam was guided in the optical fiber. In situ hybridization of 5'-fluorescein isothiocyanate (FITC)-labeled complementary oligonucleotides to their immobilized probes was monitored at the proximal end of the sensing fiber through the fluorescent signal which generated in the evanescent wave region of the uncladded portion as they coupled back to the fiber core. Hybridization specificity was tested by addition of fluorescein isothiocyanate (FITC)-labeled noncomplementary oligonucleotides to the immobilized probes. Regeneration of the surface-immobilized probe was possible, allowing reuse without a significant loss of hybridization activity. Dilution experiments showed an apparent lower limit of detection at 1 nM oligonucleotides. This performance was comparable to other previously reported DNA biosensors.

Real-time immunological interaction analysis is of great importance for the understanding of relationship between the structure and function of immunomolecules. A fluorimetric evanescent wave optical fiber immunosensor has been developed for the quantitative analysis of ligand-reactor binding kinetics in real-time. The specific immunological reaction between IgG molecules and fluorescein isothiocyanate (FITC)-labeled anti-IgG antibodies was chosen as a model system. The optical fiber immunosensor probe used in this study consisted of a piece of silanized quartz optical fiber core on which IgG molecules were immobilized. The immunological reactions were monitored fluorimetrically in situ to follow the reaction dynamics on the optical fiber surface. A gradually increase in fluorescence signal was found upon binding of fluorescein isothiocyanate (FITC)-labeled anti-IgG antibodies to the surface immobilized IgG molecules. This signal was directly related to the surface concentration of the analyte and immunological reaction kinetic properties. Thus any change in analytical signal in this study would reflect the real process of ligand-receptor binding on the optical fiber probe surface. A flow injection system was introduced into the experiments to shift the immunological reaction from mass transport to reaction rate limited. The quantitative information obtained from the initial reaction phase of a immunological reaction was then studied with a theoretical model using one to one binding, which was a significant of the real-time binding events to evaluate the binding kinetic parameters. The association and dissociation rate constants for IgG/anti-IgG antibody were calculated to be 1.4 X 10⁶ M^-1s^-1 and 2.1 X 10^-4s^-1, respectively. The results presented in this paper confirmed that the optical fiber immunosensor described in this study might be used as a tool for rapid and sensitive biospecific interaction analysis.

Many authors have elucidated the theory about oxygenated hemoglobin, deoxygenated hemoglobin absorption in near-infrared spectrum. And the theory has opened a window to measure the hemodynamic changes caused by stroke. However, no proper animal model still has established to confirm the theory. The aim of this study was to validate near-infrared cerebral topography (NCT) as a practical tool and to try to trace the focal hemodynamic changes of ischemic stroke. In the present study, middle cerebral artery occlusion model and the photosensitizer induced intracranial infarct model had been established. NCT and functional magnetic resonance image (fMRI) were obtained during pre- and post-operation. The geometric shape and infarct area of NCT image was compared with the fMRI images and anatomical samples of each rat. The results of two occlusion models in different intervene factors showed the NCT for infarct focus matched well with fMRI and anatomic sample of each rats. The instrument might become a practical tool for short-term prediction of stroke and predicting the rehabilitation after stroke in real time.

The potential of some novel dansylamide derivatives to complex with polynucleotides in aqueous solution has been investigated primarily by absorption, circular dichroism and fluorescence spectroscopy. The results indicate that these spectroscopies are strongly affected upon complexation, which may be contributed to the stacking interactions of the aromatic units, specific electronic interaction, and/or conformational changes of host- guest system. Besides, the nanostructural images of the complexes by atomic force microscopy also provide fresh direct evidence for the relationship between the structures of supramolecules and the relative conformational changes of nucleic acids.

The potential development of optoelectronic devices based on the nonlinear optical response of organic donor-acceptor molecules has aroused much recent interest. In this paper, two new ionic species in the classes of merocyanine dye and stilbazolium salt are studied by the newly developed Hyper-Rayleigh scattering (HRS) technique. Both compounds are dissolved in methanol under the 1064 nm-laser radiation in the experiments. The results show that the value of the first-order hyperpolarizability (beta) for the merocyanine dye is very large and for the stabilization salt is abnormally too large. Further studies reveal that both the merocyanine dye and the stabilization salt has multi-photon fluorescence (MPF) emission which overlaps the HRS signal at 532 nm under the radiation of 1064 nm but the merocyanine dye's MPF is weaker. If we cut off the MPF from the HRS signal, the (beta) value for the merocyanine dye is in the range of 10^-28 esu and the (beta) value for the stilbazolium salt is approximately equals 10^-27 esu, which is among the largest solution value of (beta) for organic species.

The capability of the time-resolved photoacoustic (PA) technique for glucose concentration measurement in the near-infrared range was demonstrated. Both experimental and theoretical studies shown that the concentration dependence of the sound velocity, optical absorption coefficient and thermal property of glucose solution can be simultaneously determined by the time-resolved PA techniques. Good agreement between theory and experiment has been obtained.

In this paper we report attempts to directly detect the interaction behavior between erythrocyte and lectin concanavalin a (Con A) as well as phaseolus vulgaris (PHA) on the polystyrene film surface. In the procedure, an optical transducer based reflectance interferometry was set up and used to detect the film thickness change during the lectin adsorption and lectin- erythrocyte interaction. The specific interactions among Con A, PHA and erythrocyte were obtained. The solubility monosaccharide inhibition test confirmed that there is affinity between (alpha) - D-mannose and Con A.

Biomedical optics involves with individual index of refraction of biological tissue. A new method to measure refractive index and the accuracy analysis as well is presented. The characteristic includes the incident angle is changed with parallel movement of incident beam and the refractive index of sample is determined linearly. A narrow laser beam and quarter-cylindrical lens in contact with a sample are applied in the apparatus. The device can provide the index for various tissue samples with no complex mathematical analysis and the calibration of device is simple. A number of indices for human tissue have been determined at 632.8 nm.

Raman spectrum of poly(dA) * poly(dT) in 0.2 M NaCl solution was recorded over the spectral range 750 - 1000 cm^-1. Normal mode analysis of heteronomous secondary structure from poly(dA) * poly(dT) fibers was carried out by the lattice dynamics. The calculated frequencies are good agreement with the observed Raman spectrum. This indicated that poly(dA) * poly(dT) in solution probably has the same structure as poly(dA) * poly(dT) fiber.

A phase modulation spectroscopy system was designed to monitor the dynamic changes of optical properties of rat liver at various constant temperatures. The experimental results show the Frequency-Resolved Spectroscopy can be applied in non-invasive monitoring of process of thermotherapy.

Imaging of inhomogeneities in a turbid medium with transmitted optical signal represents a crucial technique for optical diagnosis of abnormal cells in human tissues, particularly important for early detection of female breast cancer. In this paper, we present the results of our simulation and experimental studies. In the simulation study, we propose a new technique using transient diffuse photon density waves for imaging reconstruction. In the experimental study, we demonstrate the assistance of ultrasounds to optical imaging through a turbid medium. For the imaging, we basically utilize transmitted ballistic and snake photons.

Various NIRS studies have evaluated brain activity with intriguing and promising results. In this paper, results of an experiment using NIRS to evaluate brain activation induced by mental subtraction are discussed. The investigation evaluates activation responses of three NIR parameters, oxygenated- hemoglobin (Oxy-Hb), deoxygenated-Hb (Deoxy-Hb), and total-Hb (Tot-Hb). NIRS parameters were sensitive to mental subtraction; however, they were not sensitive to subtle variations in task difficulty. An important result was that order of presentation was significant, with activity during the first task being far greater than during the second task. Such findings raise questions about how to design cognitive studies using multiple task approaches commonly applied in brain activation research. A second topic addresses in this research was how to reduce brain activity during recovery. During nontask interval, subjects either rested or counted, which was used to reduce post-task mental activity. The nontask interval before mental subtraction (interval #1) was always lower than that of the two nontask intervals that followed cognitive performance (intervals #2 and 3). Recovery after activation was incomplete, regardless of type of nontask procedure. This suggests that recovery is still an issue needing elucidation and consideration in future designs.

We have developed an optical coherence tomographic system which uses a high power low-coherence laser source and a Michelson interferometer. A heterodyne detection method has been used for detecting feeble reflection from object. We discuss the application of this imaging system for neuron activities and in vivo imaging of tissues.

Two optical sectioning imaging technologies with visible laser and near infrared laser illumination to apply industrial and biologic detection are presented respectively in this paper. One of them is based on fiber optical confocal scanning microscopy, the other is imaging-relay arrangement with small visible field. The systems have resolution of submicron at lateral direction and nanometer resolution in axial direction and wider work range about submillimeter magnitude.

Diffuse Photon Density Waves (DPDW) is new concept and principle, which takes advantage of the difference of absorption and scattering coefficients of different tissues to study the law of photon density fluctuation during a modulated light traveling through the tissues, thus to explore the structure and function of tissues. With the combination of image reconstruction technology, we can directly `visualize' the tissues. As a non- invasive exam, it has highly extensive applied prospect in medical field and brain cognition study. In this paper, the behavior of DPDW traveling through simulated breast tissue is tentatively examined. Under various conditions, we observed the characteristics of DPDW. We observed the reasonability of the distribution of sources and detectors, the factors that influence the distortion of DPDW. Simulation results could be used as a good theoretical guideline for experiments.

To measure low frequency small displacement vibration, a non- contact sensor based on the optical feedback effect in a laser diode is developed. The principle and experiment setup are described. The optical laser diode power vibration is processed to measure the low-frequency small-amplitude vibration generated by a buzzer. Clinical experiments are proceeded. Three subjects are measured on their flexor digitorum muscle belly with the optical probe. Experimental results are analyzed with fast Fourier transform.

The statement of the problem concerning the formation of speckled biospeckles with a small number of scatterers has been reviewed briefly in this paper. Formulas relating to diffraction of focused Gaussian beam from narrow random flow to bioliquid have been discussed. Flow has been considered as a set of moving random screens. Statistical properties of doubly scattered speckles have been investigated. The correlation function of intensity fluctuations of statistically inhomogeneous speckled speckles has been studied with regard to bioflow measurement. Dependencies of statistical characteristics of small-N cascade speckles on the number of scattering screens have been discussed. It has been shown that the value of Doppler bandwidth in the scattered light essentially depends on the spatial velocity distribution in the flow. Mechanism of formation of output signal of speckle-microscope for measurements of blood and lymph flow in narrow vessels has been also considered. Output characteristics of measuring system have been studied. Dependence of spectral moments of output signal of speckle-microscope on the velocity of bioflow and its scattering characteristics has been analyzed.

An optical coherence tomography system capable of imaging subsurface objects in turbid media is described and the obtained cross-sectional image of a small region of lotus root by OCT is presented. The deconvolution algorithm with wiener filter was implemented to reconstruct this cross-sectional image. The imaging mechanism of OCT is investigated by Monte Carlo method.

A fast method is developed to quantitatively characterize the shape of human corneal endothelial cells with fractal theory and applied to analyze microscopic photographs of human corneal endothelial cells. The results show that human corneal endothelial cells possess the third characterization parameter-- fractal dimension, besides another two characterization parameter (its size and shape). Compared with tradition method, this method has many advantages, such as automatism, speediness, parallel processing and can be used to analyze large numbers of endothelial cells, the obtained values are statistically significant, it offers a new approach for clinic diagnosis of endothelial cells.

Monte Carlo method is employed to simulate optical path-length- resolved reflectance from samples in optical coherence tomography. Four different models are often used in such simulations to treat the scattering and absorption process. This paper presents a detailed probability analysis on the equivalence of the four different models under certain conditions. We found that the photon's statistical contributions after the same times of scattering are equal in these four models.

Optical coherence tomography (OCT) takes the advantage of the low coherence property of a light source to get the image of biological tissue structures. It provides important information on the contour and thickness of tissue structures, which can be of great help for clinical diagnostic procedures. Usually, the resolution of OCT image ranges from 2 to 20 microns. At the beginning of tissue pathologic changes, the foci could be located with OCT and cured in time. In this paper, some images of rabbit' femoral artery wall taken by our OCT system are presented. From these pictures, the three-layered structure coincides with the atlas well. In addition, the image of femoral artery wall with fat deposit is shown and the tunica media is thicker than that of normal vessel wall. The ability of OCT to image tissue microstructure near the cellular level make it potential for minimally invasive probing of tissue diseases. The high resolution of OCT, which is greater than any other conventional clinic imaging modality, and based on fiber, makes it particularly attractive for the assessment of early cardiovascular plaque.

This paper summarizes our experiences on the development of a Light Induced Fluorescence Endoscopy (LIFE) imaging system for early cancer detection in the respiratory and gastrointestinal tract. The system utilizes tissue autofluorescence to provide real time video imaging of the examined organ. No exogenous fluorescent tumor markers are needed. It is used by a physician in adjunct to conventional white-light endoscopy. Suspicious areas are identified in pseudo color to guide biopsy. A multi- center clinical trial has demonstrated that in the lung, the relative sensitivity of white-light imaging + LIFE imaging vs. white-light imaging alone was 6.3 for intraepithelial neoplastic lesion detection and 2.71 when invasive carcinomas were also included. The following issues will be discussed: (1) spectroscopy study design for imaging system development; (2) architecture of the imaging systems; (3) different imaging modalities (white-light imaging, dual channel fluorescence imaging, and combined fluorescence/reflectance imaging); and (4) clinical applications.

Imaging an object embedded in turbid media has become considerably active during the last ten years because of its potential applications including tumor diagnoses in medical and biomedical studies. One method in this area is called transillumination imaging, in which case, image resolution is in the millimeter scale. To increase image resolution, an objective is needed to focus an illumination beam onto a sample. However, the time-gating method, which is usually used in transillumination imaging, becomes less efficient. To solve this problem, we have proposed an angle-grating method for microscopic imaging through a turbid medium. In our experiment, the angle- gating mechanism is implemented by the use of a pair of matched annular filters in the illumination and collection optical paths. The experimental results show that image resolution in a tens-of- micrometer scale is feasible with angle-gating. This new method is then combined with polarization-gating for selecting photons maintaining the incident polarization state, which carry more information of an object embedded in a turbid medium. In the case of a thick turbid medium, the differential polarization intensity can be achieved by subtracting the perpendicular-polarization intensity from the parallel-polarization intensity. Our experimental results on imaging through milk suspension demonstrate that image resolution is significantly improved when differential polarization-gating is employed. Image resolution of tens of micrometer has been achieved in a thick turbid medium, which is 15 times better than that achieved using the transillumination imaging method in a similar medium. With the concept of an effective point spread function derived in a turbid medium, image resolution through a turbid medium may further improve in post image processing.

The photon counting image system is able to detect the ultra-weak bioluminescence, but it only can detect the macro image of organisms. In the research of the luminescence of cell or molecules level, the microscopic photon counting image system is necessary. In this paper the microscopic photon counting image system is discussed. The difference of both systems is that the microscopic photon counting image system is a noise limited system. The light source of radioisotope ¹⁴c is used for examination the state to ensure the limit detect of system. The fundamental capability of system is to measure the distribution and function of extremely small amounts of biomolecules, to realize time visualization of oxyradical burst activities, continuous observation of calcium ion wave moving, and monitor of gene expression etc. It will be important develop to transform from photon image to molecule image and from image of histology to image of function. It will provide prettify future for application in the field of biology and medical science.

On the basis of the differentiation of molecular structures between healthy and diseased tissue, spectroscopic information could be used for tissue discrimination. The experimental results on laser induced fluorescence of atherosclerotic deposits through the new exogenous photosensitizer Hypocrellin A (HA) was reported and algorithms implemented to on the arterial fluorescence system has been developed to be capable of discriminating normal from atherosclerotic tissue in this paper, indicating that Hypocrellin (HA) could be used as a clinical probe for both atherosclerotic lesions. Better discriminatory effect was found on fatty and calcified tissue.

Laser induced auto-fluorescence and Raman spectra of serum from cancerous and normal people are measured and analyzed. The content of (beta) -carotene in the serum from normal man is higher than that from the cancerous one, this result agrees with other reports.

A suit of human gallstones was investigated by a new type of grating Raman spectrometer. The spectra of cholesterol stone, mixed stone, and brown pigment stone were obtained. A strong Raman band at 1748 cm^-1 attributed to fatty salts indicates that some stones may contain more fatty salts than other gallstones. The results suggest that fatty salts may play an important rule for some gallstones. The formation mechanism is discussed in the paper. Such information is very useful to clinical application.

Early detection of lung cancer has been a significant area of interest due to the large number of cancer-related deaths. The microscopic fluorescence and imaging of excised lung tissue sections were studied using a novel microspectrophotometric system. The intrinsic autofluorescence distributions in different tissue layers of the lung were observed in normal and malignant tissues. The preliminary results show that the microscopic fluorescence analysis on different tissue layers can provide a powerful means to explore the origin of spectral differences between normal and abnormal lung tissues.

Using an excitation wavelength of 442 nm from a He-Cd laser, autofluorescence emissions from various layers of human colonic tissues were analyzed by a microspectrophotometric system. The cross section view on the sectioned colonic tissues reveals three distinct tissue layers for fluorescence, i.e., the mucosa, the submucosa and the muscularis propria, with submucosa being the most fluorescent. It was found that the acquired fluorescence imaging from different tissue layers could be used for localizing fluorescence as well as describing tissue architectural details of areas of distinct pathology that are essential for differentiating between normal and abnormal tissues by laser spectroscopic diagnostic approaches.

Pupil filters for improving optical sectioning property of confocal microscope are presented. These pupil filters reduce the central lobe of the axial point spread function (PSF), accompanied by a sever increase of strength of the second lobes, which make them impossible to use in conventional imaging systems. While to confocal scanning microscope, an important reduction of the central lobe in axial PSF is achieved with low sidelobe.

In confocal scanning imaging system, using apodization masks can improve the system resolution. A mask based on circle grating function with different spacing is presented and made, which is simple and easy to practically make and apply. The experiments of using a mask are performed in a reflection-mode fiber confocal scanning microscope. The intensity response curves in transverse and axial direction of this system are given. A sharp straight edge of a flat object is measured. And the 2D image of a biological organism is also given. The results demonstrate that adding this apodization mask does not reduce the axial resolution while improve the transverse resolution.

In fiber optical confocal scanning imaging system of reflection mode, interference of the reflection light beams from terminal face of the fiber coupling tip and from the surface of the sample will always destroy the image of low reflection index samples, such as CD-R pregroove basal disc and biotic samples. A quantitative analysis was given to find out the influence of fiber terminal face reflection on the system axial response. In order to avoid the influence of the fiber reflected light, the reflectivity ratio of the fiber tip to the sample should be low. Interference noise was effectively reduced by immersing the unused fiber tip into glycerol and cleaving the fiber tip end face at an angle. The proof experimental results of axial response have been shown. Finally, good quality confocal images of the recordable CD pregroove and the chromosome were presented.

With gene marking technique, green fluorescent protein (GFP) and nodule bacteria gene has been linked together to form a single fusion gene expression vector. Then the vector is transferred into the nodule bacteria and the astragalus sinicus is invaded by the vector. With laser confocal scanning microscope, some important morphological information in plant nitrogen fixation research about the invading of nodule bacteria and the formation process of root nodule has been obtained through the 3D imaging of GFP reporting fluorescence.

With a high sensitivity ultraweak bioluminescence imaging system, we have obtained the emission spectra of ultraweak bioluminescence from Chinese cabbage leaf and isolated chloroplasts during the period 20 - 85 s after the cessation of illumination. Emission spectra demonstrate that chloroplast is the main origin of ultraweak bioluminescence from leaf. We suggest that the emission of leaf may be related to charge recombination in reaction center of photosystem II and deexcitation of antenna pigments.

The effect of divalent and trivalent salts on the micelle formation of C₈-lecithin micellar solution was investigated using the technique of static and dynamic light scattering. The standard Gibbs free energy, enthalpy and entropy of the micellization process are also deduced from the experimental data for evaluating the thermodynamics of the micelle formation.

In this paper, we present theoretical model which treats the effects of pulsed laser irradiating ocular tissues. The effects involve both thermal damage and mechanical damage. The thermal effect is the energy absorption, depositing and heating in ocular tissues. This results in a non-well-distribution temperature field. As the deposited energy increasing, the melting, vaporization, and recoiling-loading of the ocular tissues would be produced. This produces the shock waves of high pressures and the shock propagate in the ocular tissues. The shock front would produce reflectance and transmission in the back front of the ocular tissues, and this results in a mechanical damage in the ocular tissues.

The photoacoustic technique (laser-induced acoustic waves), which is less affected by light scattering than the optical method, is based on optical absorption and the heat properties of illuminated media. Although photoacoustic techniques have been used to study tissues, only a few authors discuss the laser- induced photoacoustic source u the acoustic transmitter. This paper employs the Monte Carlo method to simulate a laser-induced acoustic transmitter in a two-layered tissue model. The shape and location of the transmitter is dependent not only on the optical parameters and heat properties of the tissue, but also on the diameter of the laser beam. A thin beam produces a cylindrical transmitter in a shallow layer of the tissue, whereas a sturdy beam tends to generate a plate-like transmitter and drive it deeply into the tissue. Studying the properties of the transmitter may provide useful insights in several respects: it may facilitate the reception of the acoustic signal, the measuring of the distribution of optical parameters, and the determination of layer thickness and the inner structure of tissues. The results of this paper also indicate that although a thin laser beam can produce a high transverse resolution in photoacoustic imaging, there may be a trade-off in imaging depth.

The effect of micromanipulative bioparticle by the gradient force, which the laser microbeam produces on the bioparticle, is analyzed by means of quantum theory. The result of analysis accords with the result of our experiment.

This thesis analyzed the principle of photon-forceps and explained the effects that a laser beam acts on a transparent particle using the simple theory of radial optics. We also established a model of ray-trap which can catch particles easily and simulated a photon-forceps which is produced by a highly focused laser beam. And with computer we calculated the catching power of this forceps to the transparent tiny balls whose diameters are from 1 micrometers to 10 micrometers . In addition, to realize the photon-forceps we carry out a new focusing system. On the base of analyzing the value gotten in computing process, an improved forceps was achieved.

Because of the >= 250 microsecond(s) pulsewidth emitted by the Ho:YAG laser used in clinical lithotripsy, it is unlikely that stress confinement occurs within the irradiated stones. Experimental data supports a thermal mechanism for Ho:YAG laser stone ablation. Previous work has shown that stone fragmentation occurs soon after the onset of the laser pulse, is uncorrelated to cavitation bubble formation or collapse, and is associated with low pressures. Moreover, lithotripsy proceeds fastest with desiccated stones in air (data based on laser ablation of calcium oxalate monohydrate stones), indicating that direct absorption of the laser radiation by the stone material is required for the most efficient ablation. Lowering the initial temperature of calculi reduces the stone mass-loss following 20 J of delivered laser energy: 2.2 +/- 1.1 mg vs 5.2 +/- 1.6 mg for calcium oxalate monohydrate (COM) stones (-80 vs 23 degree(s)C), and 0.8 +/- 0.4 mg vs 2.2 +/- 1.1 mg for cystine stones (-80 vs 23 degree(s)C), p <EQ 0.5. In all of the stone compositions examined, thermal breakdown products have been detected, e.g. CaCO₃ from COM; free sulfur and cysteine from cystine; Ca₂O₇P₂ from calcium hydrogen phosphate dihydrate, and cyanide and alloxan from uric acid. All of these observations are most consistent with a photothermal breakdown process induced by Ho:YAG laser lithotripsy.

The tuberculosis of an urine bladder in men develops less often, and recovery is authentic more often, than in women. In 39.1% of the female patients with nephrotuberculosis, a specific cystitis is finished in postturberculous cystalgia. One of starting mechanisms of disuria after urocystis tuberculosis in the women in menopause is hormonal insufficiency. The method of laserheatpuncturing, developed by us, for the treatment this complication is highly effective, does not require additional introduction of medicines, can be executed as in hospitals, and in out-patient.

CO₂ laser-tissue interaction was investigated by the autodyne detection method of backscattered radiation. Doppler spectra obtained in the course of pulse ablation of various pig tissues in vitro are presented. The interrelation between these spectra and some properties of biotissues was established. The possibility of the instants of time determination of the laser radiation passage through the demarcation line of biotissues is demonstrated.

Sutureless end to end ureteral anastomoses was successfully constructed in acute and chronic experiments. A photothermal sensitive hydrolyzable (PSH) albumin stent played roles as solder and intraluminal supporter to adhesion and position the anastomosed ureter by end to end fashion. The anastomosis seam was lased with 810 nm diode laser energy supplied through hand- held 600 micrometers noncontact optical fiber. A continuous 1 watt wave of power was applied for laser anastomosis. Integrity, welding strength, bursting pressures of anastomosis and histological reaction, and radiological phenomena were compared to those of anastomoses constructed using a liquidity soldering technique. The acute results of two methods were equivalent at welding strengths, but the liquid soldering showed more energy consumption. At chronic study, the radiological and histological studies were performed to evaluate the complications of the anastomosis. Excellent heating and varied degrees of complications were observed. We conclude that PSH stent showed great promise for ureteral anastomosis using laser welding.

Thermal coagulation of biological tissue leads to a significant change of the scattering coefficient. We use continuous wave transillumination techniques to monitor this change process of rat liver in different constant temperature (55 approximately 95 degree(s)C). To our knowledge, this is the first experiment about dynamic investigation. Based on light intensity measured, the change of scattering coefficient as a function of time is deduced, which show that this method is valid to monitor thermotherapy.

In this paper we will analyze laser heat effect of biology by means of quantum theory. The relation formulas of biomolecule vibration freedom are obtained. The transition probability of each individual chain and bond in biomolecule from original state to final state after photon is presented.

Cholesteryl oleate can be selectively removed with an infrared free-electron laser (IFEL). To determine the mechanisms that are involved in the effects induced by IFEL, we compared the effect of FEL exposure and the effect of heating on a sample film and bulk sample of cholesteryl oleate. Heating is regarded as one of the mechanisms by which FEL ablates cholesteryl oleate that has accumulated on the arteriosclerotic region of arterial walls. FEL was applied at a wavelength of 5.75 micrometers and at several average powers (2 - 15 mW). FEL exposure induced melting and a decrease in the number of ester bonds. Using the value of absorbed IFEL- macropulse energy for each power density, the temperature was assumed to be 50 - 300 degree(s)C. In the heating experiment, the sample was heated from room temperature to 500 degree(s)C. Melting and carbonization were observed at 50 degree(s)C and 300 degree(s)C, respectively. We found that FEL exposure and heating each induced melting. FEL exposure induced chemical changes and ablation of cholesteryl oleate, although heating did not. Heating the cholesteryl oleate above 305 degree(s)C induced carbonization, although FEL exposure to the same temperature did not.

The heat effect of laser biology widely apply to laser medical attendance, laser breeding and laser biotechnology, but the micromechanism research of the heat effect of laser biology is very few. In this paper, we study the micromechanism of the heat effect of laser biology by means of quantum theory. The major expression of the heat effect of laser biology is temperature- rising of biomolecule system after laser action. We can take biomolecule system as harmonic oscillation system due to the problem of our discussion is resonance absorption for photon of low frequency of CO₂ laser (infrared absorption). Based upon above harmonic oscillation model we derived formula. We further discussed the relation of temperature-rising ΔT and absorption photon number and the micromechanism of absorbent photon and the problems of infrared absorption of protein soliton.

The pigments of the retinal pigment epithelium, i.e. the intracellular granules of melanin, lipofuscin, and melanolipofuscin, have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. An important question is whether these reactions are sufficient to produce oxidative damage in the eye. To address this question, the relative photoreactivity of isolated RPE pigment granules towards polyunsaturated fatty acids has been determined, including the dark as well as the light-stimulated reactions. Hydroperoxide derivatives of docosahexaenoic acid were produced by irradiation with short wavelength (< 550 nm) visible light when RPE pigments were present. Although melanosomes exhibited the greatest light-induced activity in these reactions, lipofuscin granules induced peroxidation of fatty acids in the dark. In intact, cultured RPE cells, the existence of pigment-medicated photo-reactions were demonstrated with a fluorescent indicator probe of oxidation, 2',7'- dichlorofluorescein, that was photooxidized in probe-labeled cells in a wavelength dependence fashion with peak activity in the 450 to 500 nm region. This behavior resembled the action spectrum for melanin reactivity. These findings support the hypotheses that the RPE pigments contribute to general photooxidative stress in ocular tissue, and that accumulation of lipofuscin pigment contributes to age-related oxidative stress in the RPE.

A psoralen-oligonucleotide conjugate was designed to photoinduce a cross-link at a specific sequence of c-fos oncogene. Psoralen was attached to its C-3 position of a 20-base mer oligonucleotide, which binds to a synthetic 49 bp duplex containing the c-fos gene polypurine site, where it forms a triple stranded DNA. Upon near-UV-irradiation, the two strand of DNA are crosslinked at the TpA step present at the triple-duplex junction. Results show that the yield of the photoinduce cross- linking reaction is quite high. We treated HeLa cells with above 2-mer oligonucleotide conjugated to psoralen. The expression of c-fos oncogene was significant reduced, no significant effect on the level of c-myc mRNA. These data indicate that such psoralen- oligonucleotide conjugates could be used to selectively control gene expression or to induce sequence-specific damages.

In this paper, we showed that the photon-cell interaction of low intensity laser effects on cells is non-resonant. Although the non-resonant interaction itself is extraordinarily weak, it can be amplified by the coherent interaction. We then put forward the biological information model of low intensity laser (BIML) on cells and the biological information transformation model (BITML). According to BIML: laser couples with intracellular messenger through the chromophore absorption in the cell membrane: cold-color (green, blue, violet) actives cAMP photophodiesterase through G_i protein or activates phospholipase C through G_q protein, or actives one of receptor-linked enzyme: cAMP$ARDN; hot-color (red, orange, yellow) activates adenylate cyclase through G_s protein: cAMP$ARUP. According to BITML, if the laser irradiation dose is greater than the corresponding threshold value, its function would be the function of its complementary color under the non- damage condition. Their successful applications at the cellular level showed that BIML and BITML hold for laser-cell interaction.

The objective is to find out clinical curvature effect application of therapeutic apparatus of blood irradiation with lasers quanta in curing cerebrovascular diseases. Stochastic selected 237 cases made up of treatment group, these cases were partitioned into three groups: (1) acute attack period of cerebral apoplexia group; (2) non-acute attack period of cerebral apoplexia group; (3) other cerebrovascular diseases. The control groups for group 1 and group 2 are composed of 100 cases. Patients in treatment group and control group were made a routine medication, and at the same time patients in the treatment group were made a blood irradiation cure with laser quanta in addition. The validity rates for treatment group 1 is 96%, the validity rates for treatment group 2 is 83%, which are distinctly different from the validity rates of their control group (P < 0.05). The validity rates for treatment group 3 is 88%. The total curative effect of treated groups which patients were made a blood irradiation cure with laser quanta are significant difference from their control group, and minus effect was not found. There are assumed curative effect for application the therapeutic apparatus of blood irradiation with lasers quanta in curing cerebrovascular diseases.

The paper reports that penicillin-producing strains and lovastatin-producing strains were irradiated by UV and subsequently by laser (632.8 nm), and the reparation rate reached 297% and 264%. High-yield mutant was selected with improved potency of 24.5% and 30%, respectively; Gibberellin producing strains were treated with chemical agent LiCl, and then irradiated with 632.8 nm laser. One mutant with 189.6% increased potency was obtained. The experimental results indicated that using laser irradiation after UV or chemical agent mutation was a new useful method in breeding high-yield strains.

We are going to report the mutagenic effect of frequency-doubling pulse Nd:YAG laser (532 nm) on microbe. After irradiation with pulse laser, mutants of abscisic acid producing strains and erythromycin producing strains were obtained, one of which could produce 62.1% and 57% more products than control, respectively. In the study of mutagenization of Spirulina platensis caused by pulse laser, we selected a high photosynthetic strains, with improved productivity of protein and exocellular ploysaccharides of 12% and 246%, respectively. The experimental results indicate that frequency-doubling pulse laser (532 nm) is a potential new type of physical mutagenic factor.

Many clinical results showed that intravascular low-reaction- lever laser irradiation therapy (ILLLI) could improve the hemorheologic characteristics. The red blood cell (RBC) aggregation index, the blood viscosity and the erythrocyte sedimentation rate (ESR) were reduced significantly by treatment with ILLLI. In this paper, a physical process is proposed that laser makes the H-bond parted, which would give rise to a decrease in the RBC aggregation index. According to the principle of hemorheologic characteristics, the blood viscosity and the ESR reduce with the decrease in the RBC aggregation index.

Photodynamic Therapy (PDT) is accepted for treatment of superficial and lumen-occluding tumors in regions accessible to activating light and is now known to be effective in closure of choroidal neovasculature in Age Related Macular Degeneration. PDT utilizes light absorbing drugs (photosensitizers) that generate the localized formation of reactive oxygen species after light exposure. In a number of systems, PDT has immunomodulatory effects; Photodynamic Immune Modulation (PIM). Using low- intensity photodynamic regimens applied over a large body surface area, progression of mouse autoimmune disease could be inhibited. Further, this treatment strongly inhibited the immunologically- medicated contact hypersensitivity response to topically applied chemical haptens. Immune modulation appears to result from selective targeting of activated T lymphocytes and reduction in immunostimulation by antigen presenting cells. Psoriasis, an immune-mediated skin condition, exhibits heightened epidermal cell proliferation, epidermal layer thickening and plaque formation at different body sites. In a recent clinical trial, approximately one-third of patients with psoriasis and arthritis symptoms (psoriatic arthritis) displayed a significant clinical improvement in several psoriasis-related parameters after four weekly whole-body PIM treatments with verteporfin. The safety profile was favorable. The capacity of PIM to influence other human immune disorders including rheumatoid arthritis is under extensive evaluation.

In this paper, the roles that the light of PDT plays were classified into two kinds, PDT1 and PDT2. PDT1 is mediated by photosensitizer. PDT2 results from the direct interaction of light with target cells. As only the photosensitizers in the membrane of a cell can be in the coherent state, PDT1 is mediated by the coherent interaction of membrane photosensitizers, and its main target is the membranes of a cell. PDT2 is governed by the biological information model of low intensity laser (BIML) put forward by Liu TCY et al. According to BIML under the dose of PDT, cold-color (green, blue or violet) laser irradiation activates adenylate cyclase through G_s protein: cAMP$ARUP; hot color (red, orange or yellow) laser irradiation activates cAMP phosphodiesterase through G_i protein or activates phosphoinositide phospholipase C through G_q protein or activates one of receptor-linked enzyme: cAMP$ARDN. After reviewing simply the PDT effects on cells from the viewpoint of information biology and the research on them by use of optical spectroscopic approach, we arrived at the conclusion that cold color light PDT is better than hot color light PDT from the viewpoint of the effects on cell and the short term effects on cancer, but hot color light PDT is superior to cold color light PDT with respect to the long term effects on cancer.

Present paper summarizes results obtained at the Department of Oxidation in the above Institute performed studying the mechanism and kinetics of photodynamic effects applied in medicine. In addition to Type I and II mechanisms, Type III, mechanism has been suggested being an interaction between excited triplet photosensitizers and native free radicals generated in tumor cells. Supporting experimental results using laser flash photolysis, chemiluminescence and ESR techniques are briefly described.

Photostability studies of porphyrin-type sensitizers performed in aqueous solutions, model systems (sensitizers bound to human serum albumin or in a suspension of released erythrocyte ghosts) and in tumor tissue reveal that similar photomodification takes place in all investigated environments: photobleaching during exposure to light is followed by the formation of red-absorbing photoproducts. Photoproducts are not formed in the solutions of the less photostable sensitizer chlorin e₆ and the most photostable sensitizer aluminum phthalocyanine tetrasulphonate. Interaction with photooxidizable biomolecules increases the photobleaching rate of porphyrin-type sensitizers. This should be taken into account in the estimation of optimal photodynamic doses. The modified formula including photodestruction of sensitizer and formation of photoproduct is suggested.

Conventional Photo-Dynamic Diagnosis has several serious limitations, such as autofluorescence disturbance, poor penetration ability of the exciting laser etc. All these problems are because the exciting laser wavelength at the main absorption peak of the photosensitizer (e.g. HpD) is too short. But to our knowledge, long wavelength He-Ne laser can sensitize appropriate sensitizer to produce singlet oxygen (¹O₂) without autofluorescence of the normal tissues. The ¹O₂ can react with FCLA (5-Fluoresceinyl Cypridina Luminescent Analog) to emit chemiluminescence at the peak wavelength 532 nm, thus we can use a high sensitivity detector to image the emission from FCLA to make a localization of the cancer. This is a novel idea proposed by our group, and its feasibility was proved by our experiments.

We brought forward a scheme for knubbly therapy with laser and designed a multifunctional therapeutical equipment applying two wavelengths KTP/YAG laser. Applied in clinic, it showed excellent performance and could treated the knub with multiform ways.

Er_x:Y_3-xAl₅O₁₂ is one of the new type laser materials. The output characteristics of the Er:YAG laser pumped by flashlamp and the influence of resonator length to the output characteristics are performed. The threshold energy is 192 J and the highest output energy is 425.6 mJ. It is discovered that the threshold energy would fall and the slope efficiency would rise when the resonator length shortening and can be proved that this phenomenon is due to the consuming absorb by the moisture in the air.

Under the normal temperature, Nd:YAG crystal has three fluorescence spectrums, the strength of 1.06 micrometers spectrum is nearly 4 times to that of 1.32 micrometers 's, only by selecting frequency method, 1.32 micrometers oscillation can be obtained. Modulating the 1.32 micrometers wavelength and doubling its frequency, 0.66 micrometers the SHG of 1.32 micrometers can be output. In this experiment, we obtain 23.7 W 1.32 micrometers maximum laser output and 500 mW 0.66 micrometers red laser output.

Laser microbeam system consists of a third harmonic generation Nd:YAG laser and an inverted biological microscope. It is the first time that laser microbeam is applied in immobilized cell to produce midecamycin (MDM). After laser irradiation, the penetrance of immobilized granule greatly increased, probably through the microchannel made by laser. The results showed that the MDM productivity was increased greatly and the half-life of immobilized mycelia prolonged over three times as long as that of the control. In another experiment, plasmid pS65T (including green fluorescent protein genes) and plasmid pUH-10 (including Amp resistant gene) were successfully introduced into E. coli by laser microbeam. The results show that laser microbeam has a bright perspective on biopharmacy.

Current data demonstrate that laser coronary angioplasty is most useful in complex lesions not well suited for percutaneous transluminal coronary angioplasty (PTCA). It is not `stand-alone' procedure, and should be considered an adjunct to PTCA or stenting. To date, there are not data supporting reduction of restenosis. Direct myocardial revascularization (DMR), either transmyocardial revascularization (TMR) or percutaneous (catheter-based) myocardial revascularization (PMR), uses laser to create channels between ischemic myocardium and left ventricular cavity. Candidates include patients with chronic, severe, refractory angina and those unable to undergo angioplasty or bypass surgery because conduits or acceptable target vessels are lacking. Although the mechanisms of action of DMR have not yet been clearly elucidated, but several theories have been proposed, including channel patency, angiogenesis, and denervation. TMR, typically requiring open thoracotomy, is effective for improving myocardial perfusion and reducing angina. Pilot studies demonstrate that clinical application of PMR is feasible and safe and effective for decreasing angina. Late sequelae also remain to be determined. An ongoing randomized clinical trial is comparing PMR with conventional medical therapy in patients with severe, refractory angina and disease unamenable to angioplasty or bypass surgery.

We reported our experience using diode laser under microscope to resect a sphenoidal crest, orbit and infratemporal fossa communicative meningioma through fronto-tempo-preauricular approach. We used contacting, un-contacting and inserting methods and the power was in the range of 5 - 30 watt. The tumor was totally removed and the patient received radiotherapy post- operation. Follow up showed that the patient survived for two years after operation. The result showed that combination of laser application during surgery and radiotherapy post-operation was an effective method to delay or prevent tumor recurrence.

The ULTRAPULSE CO₂ laser relies on extremely high pulse energy delivered in very short pulse, causing immediate coagulation of small predictable volumes of tissue. The almost instantaneous hearing of tissue prevents unwanted heat diffusion from the target, which reduces or eliminates the chance of scaring associated with the use of order CO₂ laser. This paper reports 283 case of laser resurfacing over the past years in our center.

In this paper, we will present 996 patients of Skin Vascular Diseased, Roscea and Port Wine Stain birthmarks by Candela laser SPTL-Ib in our laser medical center.

The objective of this paper is to evaluate the effectiveness of Q-switched double frequency Nd:YAG laser treatment of 5 kinds of dermal pigmented lesions. All of the lesions showed a significant improvement in the color. Average of 3 laser treatments was regarded to effect an average clinical of improvement of 50%. Q- switched double frequency Nd:YAG laser can effectively eliminate dermal pigmented lesions without untoward side effects, such as scarring, hyperpigmentation.

This paper reports the clinical experience in transmyocardial laser revascularization (TMLR) with high power CO₂ laser and evaluates the preliminary results of TMLR. TMLR may improve angina pectoris and myocardial perfusion significantly. To switch on the laser in proper order may be helpful to shorten duration of surgery. A gentle removal of fat on the apex may increase the successful transmyocardial penetration.

Rigid Endoscopes like celioscopes have been finding their widespread use in the medical diagnosis and micro-operations, because they have long optical path and small diameter and then can be inserted into such parts of human body as vagina, bladder, and abdomen. The optical designs of them are keys to their quality and manufacturing techincs. The optical design method ofa new rigid endoscope lens is introduced in this paper.

A new optical bio-molecular sensors was developed for bio- molecular sensing based on light-excited surface plasmon resonance. Thickness of bio-molecule films absorbed onto a gold film is measured by the resonance condition of the surface plasmon on the sensing mental surface. The resonance condition is given by thickness of bio-molecule films faced on the mental. The developed sensor can be compact and simple, because of the absence of mechanical moving parts, by using a wedge of laser beam to obtain incident angle scanning and multi-channel angular light intensity detection with a charge coupled device. The sensor using Kretschmann configuration includes three parts: an optical measuring unit, a power source of laser, and a microcomputer used as data collection and handling. The adsorption of ferritin from phosphate buffered saline onto a gold film has been examined using the sensor. Application of the sensor allows elucidation of the surface layer thickness of dry ferritin on gold. Experiment results suggest less than monolayer coverage of ferritin on gold.

Primate inferotemporal cortex (IT) is thought to be essential for object recognition. To investigate the functional organization in IT, optical imaging based on intrinsic signals was carried out. The features critical for the activation of single cells were first determined in unit recordings with electrodes. In the subsequent optical imaging, presentation of the critical features activated patchy regions covering the site of the electrode penetration at which the critical feature had been determined. These results directly indicate the regional clustering of cells with similar stimulus selectivity and demonstrate the feasibility of optical imaging technique for the study of association cortex.

The Nd:YAG laser application in medicine is presented, the clinical results to treat the dental diseases, bleeding and wart, nevus, skin tumor, corn etc. are reported.

We present a novel technique for determination the stereopsis dynamic response, using as stimulus a random dot stereopair. Stereopsis can be evoked or depressed by continuous or flash illumination of the stimulus with simultaneous control of a special light scattering obstacle build in the visual path of one eye. The obstacle--a thin plate of electrooptical PLZT ceramics-- exposes (by applying of the voltage to semitransparent gold electrodes deposited on both surfaces of the plate) light scattering so blurring the retinal image, similar as for an eye with a cataract, depressing stereopsis. The random dot stereopair contains contours of images with a different stereodisparity. The PLZT plates active (covered with electrodes and light scattering) part influences a part of the image of one eye so ensuring the continuous fusion of both eye stimuli and supplying a reference stereoimage in the clear range of the stimulus.

Q-switching of the Er:Cr:YSGG laser at 2.79 micrometers is realized using electrooptic modulators of PLZT X/65/35 ceramics. The high (but slow as compared with single crystals) electrooptical effect in PLZT allowed to construct Q-switches with an aperture larger than 4 X 4 mm², small lengths of 3 - 6 mm, with a control voltage of 1000 - 1500 V. Q-switching is realized using modulators in two modes--as a (lambda) /2 switch placed into the laser cavity at the Brewster angle avoiding reflection losses and as a (lambda) /4 switch with higher single pass losses due to Fresnel reflections. A higher laser output was obtained using (lambda) /2 switching. The obtained pulses had a halfwidth of 150 ns, a pulse build-up time of 1.8 - 2.5 microsecond(s) , a single pulse energy of 10 - 12 mJ as compared with 30 mJ output of the laser for the free-running mode.