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Background: The objective of the study was to investigate the impact of timing of surgery on liver function in a cohort of patients undergoing elective abdominal surgery. Methods: We retrospectively analysed 14584 patients who underwent elective abdominal surgery at the First Affiliated Hospital, College of Medicine, Zhejiang University, from January to June, 2014. The patients were divided into three groups according to the start time of their surgery: CT1 (06:00 to 12:00), CT2 (12:01 to 18:00), and CT3 (18:01 to 05:59). The liver function of all subjects was assessed at 24 h post-surgery, using biomarkers. Results: The blood glucose level at 24 h post-surgery was significantly increased in CT3 group. Notably, the total and indirect bilirubin and alkaline phosphate (ALP) were all increased in CT3 group control to the other groups (one-way ANOVA, P < 0.05). Conclusions: We observed that the Child-Pugh score did not differ significantly among the three study groups. However, total and indirect bilirubin, glucose and ALP levels were significantly higher in subjects who underwent surgery between 18:01 and 05:59 hours of the day, implying that biomarkers of liver function varied with the time of surgery.

Objective To evaluate the efficacy, safety and tolerability of different doses of rifaximin in Chinese patients with liver cirrhosis. Methods This random prospective study included a screening visit, a 2-week treatment period and a subsequent 4-week observation phase. Patients with liver cirrhosis were randomly assigned to a low-dose rifaximin group, a high-dose rifaximin group and the control group in a ratio of 1:1:1. The low-dose and high-dose groups received 400 mg or 600 mg rifaximin per 12 h for 2 weeks, respectively. All other therapeutic strategies remained unchanged in the three groups as long as possible. Results In total, 60 patients with liver cirrhosis were screened and 43 of them met the eligibility criteria. After 2-week treatment serum endotoxin levels in the low-dose (1.1 ± 0.8 EU/mL) and high-dose rifaximin groups (1.0 ± 0.8 EU/mL) were significantly lower than that in the control group (2.5 ± 1.8 EU/mL), while no significant difference was found between the two rifaximin-treated groups. The effect of high-dose rifaximin on endotoxemia lasted for at least 4 weeks after drug withdrawal. A significant reduction in the abundance of the Veillonellaceae taxa and an increase in the abundance of Bacteroidaceae were shown after 2 weeks of rifaximin therapy. The incidence of adverse events and severe adverse events was similar among the three groups. Conclusion Low-dose (800 mg/day) rifaximin could be analogous to high-dose (1200 mg/day) rifaximin to reduce the serum endotoxin level after 2 weeks of treatment.

Experimental equipments are designed for the zero-crossing method of dynamic laser speckles to investigate the moving nature of nanoparticles in flowing nanofluids. After the experiments the velocity of nanoparticles in flowing nanofluids is determined according to its relationship with the zero-crossing rate of speckle intensity fluctuation. The results show that the zero-crossing rate is very sensitive to the velocity of nanoparticles when the velocity of nanofluids ranges from 17.6 mm/s to 60.2 mm/s. A TEM10 mode–like laser beam is designed and taken as an incident light to detect the moving direction of nanoparticles in flowing nanofluids. The moving direction of nanoparticles is parallel to the horizontal axis of the TEM10 mode-like laser beam when the zero-crossing rate reaches maximum. Experimental results show that the moving direction of nanoparticles can also be detected by using the zero-crossing method.

Early diagnosis of liver fibrosis is critical for early intervention and prognosis of various chronic liver diseases. Conventional repeated histological assessment is impractical due to the associated invasiveness. In the current study, we evaluated circulating miR-185 as a potential biomarker to predict initiation and progression of liver fibrosis. We found that miR-185 was significantly up-regulated in blood specimens from patients with HBV-liver fibrosis and rats with liver fibrosis, the miR-185 levels were correlated with liver fibrosis progression, but not with the different viral loads in HBV-infected patients. miR-185 was observed in collagen deposition regions during advanced liver fibrosis. We found that differences in miR-185 levels facilitated the discrimination between early-staged or advanced-staged liver fibrosis and the healthy controls with high specificity, sensitivity, and likelihood ratio using receiver-operator characteristic analysis. miR-185 targeted SREBF1, and increased expression of COL1A1 and a-SMA genes that are hallmarks of liver fibrosis. Our data supported that circulating miR-185 levels could be used as potential biomarkers for the early diagnosis of liver fibrosis.

With the aim of improving the efficiency of laser drilling, an upward drilling method is proposed. In the experiment, a long pulsed laser beam was arranged to propagate upwards, in the opposite direction to gravity, and was used to drill hole at the bottom of an aluminum slab. A semi-infinite axisymmetric model of this system was also established. The analytical solution for the hole shape was derived by assuming that material, once it melted, was removed from hole with the aid of gravity. The calculation results agreed well with the experimental results. For further verification of the effects of gravity, the removed molten material and the hole shape for the downward (along the gravity direction) and the upward drilling cases were compared experimentally. In addition, the relationships between gravity, the inertia force, the surface tension and the viscosity were discussed. The results show that more molten material is expelled with the assistance of the gravity, and the laser energy is used more efficiently to melt the aluminum slab in the upward drilling.

The associations of nucleotide substitution mutations in the preS region of hepatitis B virus (HBV) with hepatocellular carcinoma (HCC) and cirrhosis remain unknown. We aimed to determine the associations of preS mutations with HCC or cirrhosis.HBV from 603 asymptomatic hepatitis B surface antigen carriers (ASCs), 219 chronic hepatitis B (CHB) patients, 119 cirrhosis patients, and 231 HCC patients were genotyped and sequenced in the preS region. Nucleotides with the highest frequencies in HBV from the hepatitis B e antigen (HBeAg)-positive ASCs were treated as "wild-type" nucleotides. Twenty-one preS1 mutations and 14 preS2 mutations were evaluated. Multivariate regression analyses were applied to determine factors independently associated with cirrhosis or HCC.Most (85.7%) preS2 mutations were associated with CHB compared with ASCs, whereas most preS1 mutations were associated with HCC compared with the cirrhosis patients or CHB patients. Compared with the CHB patients, 81.0% preS1 mutations in genotype C were inversely associated with cirrhosis. Multivariate regression analyses showed that C2964A, C3116T, and C7A were novel factors associated with HCC compared with those without HCC, whereas A2964C and T3116C were independently associated with cirrhosis compared with ASCs and the CHB patients. Combined preS1 mutations had specificities greater than 95%, while C3116T and C7A had moderate sensitivities and specificities, for HCC.C2964A, C3116T, and C7A are novel markers independently associated with an increased risk of HCC, while A2964C and T3116C are novel markers independently associated with an increased risk of cirrhosis. Combined preS1 mutations are specific for HCC.

The effect of surface tension on the behavior of a liquid-jet is investigated experimentally by means of a fiber-coupled optical beam deflection (OBD) technique. It is found that a target under water is impacted in turn by a laser-plasma ablation force and by a high-speed liquid-jet impulse induced by bubble collapse in the vicinity of a rigid boundary. The liquid-jet impact is found to be the main damage mechanism in cavitation erosion. Furthermore, the liquid-jet increases monotonously with surface tension, so cavitation erosion rises sharply with increasing surface tension. Surface tension also reduces bubble collapse duration. From the experimental results and the modified Rayleigh theory, the maximum bubble radius is obtained and it is found to reduce with increasing surface tension.

The scanning laser line source (SLLS) technique is a novel laser-based inspection method for the ultrasonic detection of small surface-breaking defects. The SLLS approach is based on monitoring the change in laser generated ultrasound as a laser line source is scanning over a defect. It has provided enhanced signal-to-noise performance compared to the traditional pitch-catch or pulse-echo ultrasonic methods. In this paper, an experimental method is presented to detect surface acoustic waves (SAW) with polyvinylindene fluoride(PVDF) transducer. The ultrasonic signal is converted into electric signal by piezoelectricity of the PVDF, which is attached to a micro-knife edge clamped on a metal device. The SAW are excited by employing a pulsed Nd:YAG laser on aluminum plate with artificial surface-breaking defects. The laser line source is accurately shifted by the motorized translation stage, while the PVDF is located at a fixed position on the specimen. When the laser line source is scanning over the defect, the ultrasonic signals are monitored, meanwhile the characteristic changes in the amplitude and frequency content are observed. Consequently, the position of the defect can be determined by analyzing the obtained signals. The experimental system with high sensitivity provides a detection method of small surface-breaking defects on metal and gives convincing experimental evidence for the interaction mechanism between the SAW and the surface-breaking defects.

Our recent work [1] theoretically revealed that speckles can be formed when nanofluids containing a modest volume fraction of nanoparticles are illuminated by a monochromatic laser beam. This paper focuses on the key issues, including the experimental setup, the particle volume fraction of the nanofluid, the flow velocity of the nanofluid and the diameter of the pipe, in measuring the velocities of nanoparticles in nanofluids with laser speckle velocimetry (LSV). First an experimental setup is established according to the optical characteristics of nanoparticle and the measuring principles of particle image velocimetry (PIV) and LSV. Then a conclusion is made from the experimental results that clear speckle patterns can be formed when the particle volume fraction is between 0.0005% and 0.002% is able to form. Finally, in order to make it applicable to utilize LSV to measure the velocities of nanoparticles in nanofluids that flow in pipe, nanofluids can not flow too fast and the diameter of the pipe should not be too small.

We aimed to evaluate whether hepatitis B virus (HBV) mutations at the core promoter region could improve the prediction and specific prophylaxis of hepatocellular carcinoma (HCC) in chronic HBV-infected patients. A total of 2,114 HBV-infected patients enrolled between August 1998 and December 2007 were followed-up for 18,406 person-years. Of those, 612 received ≥48 week treatments with nucleos(t)ide analogue (NA) and/or IFNα. Baseline HBV mutations were identified by sequencing. Propensity score matching was applied to reduce baseline differences between antiviral and control cohorts. Multivariate Cox regression analyses, including baseline characteristics of 2,114 patients, showed that age, male, cirrhosis, and HBV mutations (C1653T, T1753V, and A1762T/G1764A) independently increased HCC risk. In control patients carrying A1762T/G1764A, addition of C1653T and/or T1753V significantly increased HCC risk (HR, 1.57; P = 0.038); combo mutations with C1653T, T1753V, and A1762T/G1764A improved the validity of HCC prediction by age, male, and cirrhosis (P = 0.002). In the matched cohorts, antiviral treatment reduced HCC incidence (13.90/1,000 vs. 7.70/1,000 person-years, P = 0.005); NA treatment for ≥60 months was required for the prophylaxis of HCC in cirrhotic patients (P = 0.03); antiviral treatment reduced HCC risk in patients carrying A1762T/G1764A (HR, 0.40; P = 0.002) or C1653T (HR, 0.45; P = 0.04) and in those without T1753V (HR, 0.42; P = 0.005), but could not reduce HCC risk in patients without A1762T/G1764A or C1653T and in those with T1753V. In summary, HBV mutation A1762T/G1764A, C1653T, and T1753V in combination improve HCC prediction in HBV-infected patients. To prevent HCC, patients infected with HBV carrying A1762T/G1764A or C1653T, but not T1753V, should be given priority of receiving antiviral treatments. Cancer Prev Res; 8(10); 978–88. ©2015 AACR.

The mechanisms of the liquid jet formation from the interaction of the laser-induced and gas bubble pair are investigated and compared with the jet formation from the interaction of the laser-induced anti-phase bubble pair. The strobe photography experimental method and numerical simulations are implemented to obtain the parameter space of the optimum liquid jet, i.e. highest speed and lowest diameter. It is found that due to the enhanced “catapult effect”, which is induced by the protrusion of the first bubble into the second bubble and the flip back of the elongated part of the first bubble, the optimum liquid jet of the second bubble of the laser-induced anti-phase bubble pair compared to that of the laser-induced and gas bubble pair is 54 %, 65 % and 11 % faster in speed, and 4 %, 44 % and 64 % smaller in diameter, for the 500 μm, 50 μm and 5 μm sized bubbles, respectively. The optimum dimensionless distance for the optimum jet of the laser-induced and the gas bubble is around 0.7, when the maximum bubble radius increases from ∼ 5μm to ∼500 μm, which is different from the laser-induced anti-phase bubble pairs. Besides, the optimum jet of the laser-induced bubble appeared when the bubbles are equal sized, while that of the gas bubble is independent of the relative bubble size, i.e. the liquid jet of the gas bubble has higher robustness in real liquid jet assisted applications when the laser-induced bubble size varies. However, the jet of bubble 2 could maintain a high speed (20 m/s - 35 m/s) and a low diameter (∼5 % of the maximum bubble diameter) over a big range of the dimensionless distance (0.6 - 0.9) for both of the 50 μm and 500 μm sized laser-induced equal sized anti-phase bubble pairs.

In this paper, the LSD wave ignition process is analyzed. Interaction of an Nd:YAG laser and a pure Al target is investigated synchronously with a Mach-Zehnder interferometer, and series of interferograms of the ignition of an LSD wave and its propagation are obtained first. The propagating speed of the LSD wave and the pressure behind the LSD wave are obtained.

Myeloid sarcoma (MS) is a neoplasm of immature granulocytes, monocytes, or both involving extramedullary sites. MS with no evidence of leukemia (nonleukemic MS) is very rare and the initial diagnosis can be difficult. This report describes an unusual case of nonleukemic MS of the liver in a 16-year-old patient presenting as debilitating hepatomegaly. A liver biopsy revealed diffuse infiltration by neoplastic cells of myeloid lineage (CD68, myeloperoxidase). A bone marrow biopsy showed no evidence of medullary involvement. The patient subsequently developed heart failure. Autopsy revealed infiltration of most organs by neoplastic cells but failed to identify abnormal myeloid cells in bone marrow.

High-grade bleeding is a serious adverse event associated with bevacizumab, a humanized monoclonal antibody targeting vascular endothelial growth factor and widely used in the current cancer treatments. The aim of this study was to gain a better understanding of the overall incidence and risk of high-grade bleeding in cancer patients who receive bevacizumab therapy.We performed a meta-analysis of relevant randomized controlled trials (RCTs) identified in PubMed, Cochrane library, Embase, and American Society of Clinical Oncology conferences. Overall relative risks (RRs), incidence rates, and 95% confidence intervals (CIs) were calculated using a random-effects model. The primary clinical endpoint was high-grade bleeding (grade 3 or above).A total of 14,277 patients with a variety of solid tumors from 22 RCTs were included in the present analysis. The addition of bevacizumab to cancer chemotherapy significantly increased the risk of high-grade bleeding (RR 1.60, 95% CI 1.19-2.15), with RRs of high-grade bleeding among patients receiving bevacizumab at 2.5 and 5 mg/kg per week of 1.27 (95% CI 0.95-1.71) and 3.02 (95% CI 1.85-4.95), respectively. The overall incidence of high-grade bleeding among patients receiving bevacizumab was 2.8% (95% CI 2.1-3.8). Higher risks were observed in patients with non-small-cell lung cancer (RR 3.41, 95% CI 1.68-6.91), renal cell carcinoma (RR 6.37, 95% CI 1.43-28.33), and colorectal cancer (RR 9.11, 95% CI 1.70-48.79) who were receiving bevacizumab at 5 mg/kg per week.Among the patients included in the trials analyzed in this meta-analysis, the addition of bevacizumab to cancer chemotherapy significantly increased the risk of high-grade bleeding. The risk may be dose-dependent and may vary with tumor type.

Problems that cumber the development of the laser propulsion in atmosphere and vacuum are discussed. Based on the theory of interaction between high‐intensity laser and materials, as air and water, it is proved that transport in water environment can be impulsed by laser. The process of laser propulsion in water is investigated theoretically and numerically. It shows that not only the laser induced plasma shock wave, but also the laser induced bubble oscillation shock waves and the pressure induced by the collapsing bubble can be used. Many experimental results show that the theory and the numerical results are valid. The numerical result of the contribution of every propulsion source is given in percentage. And the maximum momentum coupling coefficient Cm is given. Laser propulsion in water environment can be applied in many fields. For example, it can provide highly controllable forces of the order of micro‐Newton (μN) in microsystems, such as the MEMS (Micro‐electromechanical Systems). It can be used as minimally invasive surgery tools of high temporal and spatial resolution. It can be used as the propulsion source in marine survey and exploitation.

Background Nosocomial infections are a major threat to patients in the intensive care unit (ICU). Limited data exist on the epidemiology of ICU-acquired infections in China. This retrospective study was carried out to determine the current status of nosocomial infection in China. Methods A retrospective review of nococomial infections in the ICU of a tertiary hospital in East China between 2003 and 2007 was performed. Nosocomial infections were defined according to the definitions of Centers for Disease Control and Prevention. The overall patient nosocomial infection rate, the incidence density rate of nosocomial infections, the excess length of stay, and distribution of nosocomial infection sites were determined. Then, pathogen and antimicrobial susceptibility profiles were further investigated. Results Among 1980 patients admitted over the period of time, the overall patient nosocomial infection rate was 26.8% or 51.0 per 1000 patient days., Lower respiratory tract infections (LRTI) accounted for most of the infections (68.4%), followed by urinary tract infections (UTI, 15.9%), bloodstream (BSI, 5.9%), and gastrointestinal tract (GI, 2.5%) infections. There was no significant change in LRTI, UTI and BSI infection rates during the 5 years. However, GI rate was significantly decreased from 5.5% in 2003 to 0.4% in 2007. In addition, A. baumannii, C. albicans and S. epidermidis were the most frequent pathogens isolated in patients with LRTIs, UTIs and BSIs, respectively. The rates of isolates resistant to commonly used antibiotics ranged from 24.0% to 93.1%. Conclusion There was a high and relatively stable rate of nosocomial infections in the ICU of a tertiary hospital in China through year 2003–2007, with some differences in the distribution of the infection sites, and pathogen and antibiotic susceptibility profiles from those reported from the Western countries. Guidelines for surveillance and prevention of nosocomial infections must be implemented in order to reduce the rate.

A new sensor based on optical beam shading technique for the investigation of mechanical effects during laser-metal interaction is developed. This sensor is applied to detect the laser-induced plasma explosive impact and deformation process during the explosion when a Q-switched laser is focused on a metal. The experimental results indicate that elastic deformation and plastic deformation associated with the event induced by laser plasma the same time. This technique has the advantages of high-frequency response, simple structure, and nondestructive examination.

A theoretical and experimental study is conducted to investigate applicability of a single-mode fiber ultrasonic sensor for detecting the shock-wave in optical breakdown in air induced by a high power laser pulse. The sensor is based on the ultrasonically induced modal birefringence which alters the polarization state of the optical beam propagating through the fiber. The shock-wave signals have been gotten by using the sensor. It is shown that the single-mode fiber sensor has enough sensibility to detect shock-wave in air, but it is dependent on the fiber- ultrasonic interaction length and the intensity of shock- wave.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The interaction process of a high-power laser and a PIN-junction optoelectronic diode has been studied theoretically and experimentally. It has been put forward that the thermal effect of laser beams and the eroding and washing effect while the laser plasmas expand out, results in the silicon photodiode to be damaged. The thermal distribution, the expression of the maximum temperature, have been obtained for the first time when a Q-switched Nd:YAG laser irradiated upon the PIN junction optoelectronic diode.

In this paper, the interaction process of high-power Q-switched YAG laser and MNOS-type charge-coupled devices (CCD) is studied with the help of plasma shape and structure under the repeated actions of laser pulses. Mach-Zehnder interferograms of plasmas and related experimental results produced by a 1064 nm laser beam with a pulse width of 15 ns acted upon the MNOS-type CCD are obtained for the first time.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A zero-crossing dynamic speckle method is proposed to determine the velocities of nanoparticles in nanofluids. A Gaussian laser beam is used to illuminate nanofluids in a pipe, and the dynamic speckles are detected by a spatially integrating detector with an aperture. The integrated speckle intensity signal is processed by a computer and the zero-crossing rate is counted. The velocity of the nanoparticles can be determined from its relationship to zero-crossing rate. The results show that the nanoparticles exhibit features of flowing nanofluids, and when the average velocity of the nanofluids is 53.4mm/s, the average velocity of the nanoparticles is 51.8 ? 5.1 mm/s.

An ophthalmic laser system is reported, when this laser is used to perform an operation, an interference effect can produce, then the laser power density acted upon local eye tissue is increased.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, LSD wave ignition process is analyzed according to aerodynamics, and expressions of speed of LSD wave, pressure, internal energy is derived. Interaction of YAG laser and Al target is investigated synchronously with a Mach-Zehnder interferometer, and series of interferograms of ignition and propagation of LSD wave at the initial stage are obtained first. It presents reliable experimental datum for theoretical study of LSD wave.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The recording of multiplexing hologram on one holo film has been studied theoretically and verified experimentally in this paper, and it has been put forward that when multiframe holograms are recorded on one holo film, superposition and modulation of the interference fringes is the main cause to reduce the diffraction efficiency of some holograms having disperse fringes in the multiframe holograms.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Production of surface pressure, plasma formation and momentum transfer of target is analyzed in interaction between laser and target material in this paper, a low-energy and high-power 1.06 micrometers YAG laser with a pulse width of 15 ns is applied to act upon different target material surfaces, and by using a pendulum shift technique to measure displacement of the target surface, momentum transfer and momentum coupling coefficient are obtained at different conditions.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, we used shapes of plasmas, which a Q-switched YAG laser acted repeatedly upon a CCD having MOS structure to produce, to investigate the destroying process of the optoelectronic device, and first obtained related experimental results of CCD to be destroyed by a 1.06 micrometers laser beam with a pulse width of 15 ns.

In this paper, 30 cases of extracapsular cataract extractions with the assistance of an Nd:YAG laser are reported. Myosis phenomenon in laser operation is observed and its producing mechanism is discussed. Laser ophthalmology was the earliest field in laser application research, and pulse Nd:YAG laser ophthalmic instruments have been developed rapidly because of unique advantages in the anterior and posterior capsulotomy and trabecula shaping method.

A treatment for eleven eyes on posterior capsular opacifications after artificial intraocular lens (IOL) implantations with an Nd:YAG laser is reported, and a secure range of laser energy under which IOLs are not injured in the operations is given in this paper.

The anti-CD20 monoclonal antibody rituximab has been used extensively in the treatment of B-cell lymphoma. However, several studies reported hepatitis B virus (HBV) reactivation after rituximab administration. The majority of these cases have been described in chronic carriers of HBV, whereas reactivation in occult hepatitis B carriers is relatively rare. We report a fatal case of fulminant hepatitis B that occurred in a B-cell lymphoma patient with occult hepatitis B after rituximab-containing chemotherapy, which raised the necessity of antiviral prophylaxis in this setting.

In this paper, 30 cases of extracapsular cataract extractions with a Nd:YAG laser are reported. Myosis phenomenon in laser operation is observed and its producing mechanism is discussed. Laser ophthalmology was the earliest field in laser application research, and pulse Nd:YAG laser ophthalmic instruments have been developed rapidly because of unique advantages in the anterior and posterior capsulotomy and trabecula shaping method. Thirty cases of extracapsular cataract extractions with the assistance of a Nd:YAG laser are reported in this paper. In laser operation, myosis phenomenon is observed, and its production mechanism is discussed.

Microplasma and shock waves produced by a Q-switched YAG pulse laser worked near the optical breakdown threshold of physiological saline are investigated by using optical shadowing exploring method. A series of optical shadowgraphs of microplasma and shock waves versus the incident laser energy and the delay time is obtained. The mechanical action of shock waves is discussed.

By using a Q-switched YAG laser and an optical path delay set-up, we study the process in which as laser induces breakdown to produce plasma in air. We obtained time-resolved Mach- Zehnder interferograms and optical shadowgrams of the initial stage of the plasma, and shock waves produced in the process are obtained.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

By using an optical path delay set-up, the instantaneous process in which a Q-switched YAG laser induces breakdown on an aluminum surface is studied. A series of time-resolved Mach- Zehnder interferograms and optical shadowgrams of the plasma and the shock wave during the initial stage is obtained. Plasma refractivity distribution and electron density on the shock front are computed.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The plasmas produced in Q-switched laser actting repeatedly on two kinds of single-layer optical thin films are detected, and the field effect in this interaction process is analysed.

An application of ASA 5 black and white cinefilm combined with a specialized developer instead of holo film as a new recording medium for double pulse YAG laser speckle is reported. With this recording medium, multi-frame dynamic laser speckle patterns for relatively distant, real bodies are obtained.

The influence of thermal effect induced by optical pumping on YAG crystal rod in a pulse solid laser on the wave surface of the output laser beam is studied in this paper. A series of time-resolved instantaneous interferograms during and after the pumping is obtained with a Mach—Zehnder interferometer, and three-dimension time-resolved pictures of the distorting wave surfaces and the curve of thermal focal length of laser rod versus time are gained after the treatment and calculation for interferograms.

The mechanism of laser-induced damage to thin films is described in this paper, and a definition of laser breakdown threshold to thin film, optical breakdown threshold is presented. The new definition is clearer than the existing one. The measurement results and comparison for various samples are given on the basis of the two above-mentioned definitions.

By using optical interference method, we have studied the process in which a Q—switched YAG laser induced an eye model to break down. It showed that the mechanical effect of the shock results in local discuption of iris. We have investigated the plasma shielding in the lipuid eye model, and put forward both the plasma shielding and the focusing angle of the incident laser are two important factors to protect the retina from injury in high power laser ophthalmology. I . INTRODUCTION Laser application in medicine, especially in ophthalmology has had a very rapid and great development for recent years 1,2) But it seems that people have overlooked the study of the physical mechanism about laser medicine. In this paper, experimental investigation for the physical mechanism of pulse laserophthalmology is tried. By using optical exploring method, the instantaneous physical process in whichhigh—power laser induced an eye model to break down to produce plasma is investigated, and a series of

By using optical interference and shadowing methods and an optical path delay set-up, the initial process of laser-induced self-focusing in H2 is studied on one Q-switched YAG laser and a series of time-resolved Mach-Zehnder interferograms and shadows are obtained. Some phenomena during the self-focusing are observed and explained. The theoretical model of moving foci is demonstrated by the experiments discussed in this paper.