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Intracavity active frequency shift, a unique method of shifting the frequency of pulsed lasers, was applied to a high-pressure CO2 laser which has a continuous gain profile over a wide range of the spectrum. In order to extend the amount of frequency shift, the dependence of the maximum frequency shift on the laser gas pressure was investigated. As a result, it was found that the maximum frequency shift was limited by the gain duration time rather than by the gain bandwidth at a pressure of 8–10 atm. By shortening the cavity length, the maximum frequency shift of 9 GHz was obtained at a pressure of 8 atm. Then, the grating-mirror cavity was applied to demonstrate the frequency shift starting from each lasing line of the CO2 laser. According to numerical calculations, the maximum frequency shifts starting from most lasing lines of a multi-isotope cw CO2 laser can exceed 10 GHz, resulting in coverage of almost the entire gain spectrum in the high-pressure CO2 laser.

Continuous frequency tuning of a transversely excited CO(2) laser was achieved for the 10-microm R branch with conventional gas mixtures at pressures as low as 5 atm. Tuning and spectral characteristics analyzed as a function of pressure are presented together with output energy characteristics.

For a pulsed high‐power laser with unstable resonator, the mode evolution time is important from the viewpoints of beam focusability and laser‐energy usefulness. We observed temporal and spatial behavior of the mode evolution in a several‐tens‐joule KrF laser with a positive branch confocal unstable resonator, which is pumped by electron beams with a pulse width of 65 ns (FWHM). The beam divergence angle was decreased by a factor of 1/M2 (M:magnification) per round trip in the resonator and resulted in a full angle divergence of 0.6 mrad.

For an electron-beam-excited KrF laser, we analyzed theoretically the dependence of the performance characteristics on the excitation rate and initial F 2 concentration. According to the analysis of KrF* formation processes, KrF* relaxation processes, 248 nm absorption processes, and their individual efficiencies, a novel optimization method for initial F 2 concentrations is necessary instead of a conventional method of a "constant" F 2 burn-up rate. Then, we determined optimum F 2 concentration as a function of the excitation rate for excitation pulses of 20-500 ns FWHM. Finally, we obtained the scaling law for the intrinsic KrF laser efficiency.

Output characteristics of the short‐pulse electron‐beam excited ArF (193 nm), KrF (248 nm), XeF (351 nm), KrCl (222 nm), and XeCl (308 nm) lasers were experimentally investigated at the same time on the same device for various mixtures all pumped at a high excitation rate of 2.3 MW/cm3. The optimum pressure of rare gas forming its rare‐gas halide excimer increased for the sequence of ArF, KrCl, KrF, XeCl, and XeF, indicating that rare‐gas halides were more quenched by the heavier rare gases, such as Xe, even at near‐atmospheric pressures. At nearly atmospheric pressures the Ar‐buffered mixtures gave higher laser energy than Ne‐buffered mixtures except for the XeF laser. Through a series of measurements, the ArF laser showed the best result on the output energy of 96 J (5 J/l ) with an intrinsic efficiency of 3.4%.

By developing a comprehensive computer code for e -beam excited XeCl lasers, we studied mainly the effect of Ar and Ne diluents on the performance characteristics of XeCl lasers. According to the analysis of the XeCl* formation process, the XeCl* relaxation process, and the 308 nm absorption process, it is found that the XeCl* formation efficiency is determined mainly by the rate of the charge transfer process (from Ar+ and Ne+ diluent ions to Xe+); in other words, by the difference between ionic potentials of Xe and the diluent gas used. The extraction efficiency is found to be decided mainly by the quenching rate of a three-body reaction for a short-pulse (55 ns) and a high-excitation-rate (∼ 3 MW/cm3) pumping, and by the absorption process for a long-pulse (500 ns) and a low-excitation-rate (∼ 0.2 MW/cm3) pumping. However, note that no appreciable difference in the intrinsic efficiency is found between the Ar/Xe/HCl and Ne/Xe/HCl mixtures. We also analyzed the dependence of the intrinsic XeCl laser efficiency on the pumping pulse width and excitation rate for Ar/Xe/HCl and Ne/Xe/HCl mixtures. As a result, the same intrinsic efficiencies are obtainable for both Ar- and Ne-based mixtures although the optimum operating conditions are slightly different. The maximum intrinsic efficiency of 5 percent is obtainable both for the Ar/Xe/HCl mixture at 3 atm and with 1.5 MW/cm3, 200 ns (FWHM) pumping and for the Ne/Xe/HCl mixture at 4 atm and with 2 MW/cm3, 200 ns (FWHM) pumping.

The area of the Kuroshio current or the North Pacific current is known as the quite excellent fishing ground of the Albacore. Albacore in this ground migrates southward during Autumn and early Spring, and is mainly caught by long-line. From Spring to Summer it migrates northward and is caught by rod and line with live bait. As to the former catch the author already reported it's size-composition1). In the present, the author reports the analysis of the size-composition of the latter. The principal informations obtained by this work are as follows. (1) Though the range of the size is confined within the limit between 50 to 100cm during the seasons of 1951 and 1954, there are the remarkable annual fluctuations. (2) The number of length-groups are not fixed by the seasons. 3 or 5 length-groups appear in each season from 1951 to 1954. (3) The modal length of each length-group shows remarkable annual fluctuation. (Table 1) (4) The relative abundance of each length-group is very unstable as shown in Table 2. In most cases, the most dominant length-group occupies the overwhelming proportion. Such a size-composition of the northward migrating Albacore differs from that of southward migrating one as follows. (1) Such advanced age groups* as seen in the sout ?? ward migrating fishes do not appear in these which migrate northward. (2) Size-composition of the northward migrating ones shows the remarkable annual fluctuation, therefore it is able to say that it is much more unstable than that of the southward migrating. (3) The dispersion of the length frequency of the northward migrating ones is much more small than that of the southward migrating ones. Then differences between the two groups seen to be based on ecological differences of them other than the difference of fishing method. In spite of these differences, the author hypothesized that there will be some relations between these two groups on a basis that the body-length of the most dominant size-groups are less than 100cm in both migrating groups. * Age is not determined, larger than 90cm.1)

The effect of various rare‐gas diluents on the operating performance of the e‐beam‐excited XeCl laser is theoretically analyzed. The analysis of the XeCl* pumping process and the extraction process could solve the dependence of the intrinsic efficiency, small‐signal gain, and absorption on the rare‐gas diluent. As a result, there is no appreciable difference in the intrinsic efficiency between the Ar‐based and the Ne‐based mixtures. Selecting the optimum excitation parameters, the highest intrinsic efficiency of 5% is achieved for both diluents. Although the highest small‐signal gain is achieved without a diluent gas, the extraction efficiency is reduced and the intrinsic efficiency is small due to the large amount of three‐body collisional quenching.

A multikilojoule deuterium fluoride (DF) chemical laser with a low‐pressure mixture of F2/D2/O2/SF6 was developed in which a Lambda‐type electron beam initiation scheme was used. The DF laser output obtained from a 27‐liter active volume was 2.5 kJ with a pulsewidth of about 500 ns. The corresponding electrical efficiency and chemical efficiency are 128% and 10.5%, respectively.

The output performance of the electron‐beam‐excited KrF laser operating at one atmosphere is theoretically analyzed because the KrF laser at one atmosphere can greatly reduce the design constraints on the large laser windows and the electron‐beam pressure foils in a huge laser system as the inertial confinement fusion energy driver. The KrF laser using the atmospheric pressure, argon‐free laser mixture is found to operate with an intrinsic laser efficiency as high as that of high‐pressure, aregon‐diluted mixtures. This is because three‐body collisional quenching is not a detrimental energy‐loss channel for the atmospheric pressure operation. By using higher excitation rate and shorter excitation pulse width pumping, higher intrinsic laser efficiency than conventional, argon‐diluted, high‐pressure mixtures is found to be attainable. Moreover, the specific laser energy (28 J/l, for 1‐atm Kr/F2 mixtures pumped by an electron beam of 100 ns, 600 keV, and 150 A/cm2) is comparable to that of two‐atm, argon‐rich...

High‐efficiency and high‐energy operation of HF chemical lasers was simultaneously realized using a low pressure mixture of H2/F2/O2/MoF6 initiated by an intense electron beam. The addition of small amounts of MoF6 gas to the mixture of H2/F2/O2 resulted in an increase in laser output energy and electrical and chemical efficiencies. A HF laser energy obtained from a mixture containing 17.9 Torr of MoF6 was 3.7 kJ (136 J/l) with a pulse width of 190 ns full width at half‐maximum. The corresponding electrical efficiency and chemical efficiency are 189% and 15.2%, respectively, with a low pressure (362.4 Torr) mixture of H2/F2/O2/MoF6=30/242/72.5/17.9 Torr.

Low‐pressure operation of an electron‐beam excited ArF laser was experimentally compared to KrF lasers, both of which were pumped at high excitation rate by a 65 ns electron beam. We obtained the ArF laser energy of 95 J with an intrinsic efficiency of 3.4% from a 650 Torr Ar/F2 mixture pumped at an excitation rate of 2.3 MW/cm3. In the low‐pressure region (near one atmosphere) the Ar/F2 mixture gave higher efficiency than that of Ne‐buffered mixtures, and moreover gave higher efficiency than those of the KrF lasers operating with various mixtures under the same excitation rate. As a result, the ArF laser operating in this regime is found to be a better candidate than the KrF laser as an inertial confinement fusion driver.

Atmospheric pressure operation of a KrF laser pumped by 50‐ns electron beams was experimentally investigated. For a 1‐atm mixture of Kr and F2 without diluent, a specific output energy of 4.2 J/1 was obtained at 1.7‐MW/cm3 excitation rate. Under this condition the intrinsic efficiency was about 5% (6% was maximum at 20% Kr in argon diluent) which was comparable to that from 1‐atm normal (10% Kr) mixtures.

Using a small electron beam device, we have observed time‐dependent competition among the 1.73, 2.03, 2.63, and 2.65 μm lines of the xenon laser in a high‐pressure argon buffer. The small‐signal gain and saturation intensity for each of these lines have also been measured. The maximum specific energy output of the laser was 1.7 J/l and the efficiency was 2.3%.

Amplifier characteristics of a KrF laser were investigated as a function of Kr concentration for a wide range of input intensity. The experiments were performed with atmospheric‐pressure mixtures excited by a 65‐ns (full width at half‐maximum), 160‐A/cm2 electron beam. The extracted intensity (output intensity minus input intensity) from a single‐pass (50 cm) amplifier was maximized at an input intensity around 5 MW/cm2 and then, the power efficiencies were 12.6, 13.7, 13.3, and 11.3% for Kr concentrations of 10, 20, 40, and 99.4%, respectively. The small‐signal gain, absorption coefficient, and saturation intensity were determined for each mixture by using an analysis due to Rigrod [J. Appl. Phys. 36, 2487 (1965)]. The KrF* formation efficiency and the extraction efficiency were also obtained as a function of Kr concentration.

The shortest wavelength (193 nm) of the ArF rare-gas halide laser has been used for microelectronics and photochemistry applications. The ArF laser holds the potential of being a high-power high-efficiency laser. According to recent results on the wavelength dependence of the laser beam absorption by a fuel pellet in laser-driven fusion experiments, the shorter-wavelength lasers were found to be absorbed more efficiently. Therefore, the 193-nm ArF lasers may become more efficient drivers than the 248-nm KrF laser. However, kinetics for the ArF laser has not been clarified, although kinetics for KrF and XeCl lasers is understood to a large extent. To our knowledge, not even the gain measurement of the ArF laser has yet been reported.

A novel spatial light modulator (SLM) made of an array of fused-silica plates was developed for the purpose of feedback control for intense femtosecond laser pulses over a wide spectral range. Dispersion compensation for 20-fs pulses from a Ti:sapphire oscillator was successfully demonstrated using the SLM with an adaptive feedback control system. The SLM was also applied to the output pulses from a Ti:sapphire amplifier for compensation of material.

The novel operational regime of high-efficiency KrF lasers is presented. The excitation sources are intense electron beams and intense proton beams. Theoretical evaluation of electron-beam-excited KrF laser using one atmospheric-pressure, argon-free mixtures showed that by using high-excitation-rate and shorter-excitation-pulsewidth pumping, higher intrinsic laser efficiency than conventional argon-rich, high-pressure mixtures is attainable. The experimental results are also presented.

Background The prevalence of smoking in patients with schizophrenia is higher than that in the general population and is an important medical issue. Short-term smoking cessation tends to worsen psychiatric symptoms in patients with schizophrenia but decreases sympathetic nervous system activity and improves plasma cholesterol levels in healthy people. Few studies have assessed the long-term effects of smoking cessation in patients with schizophrenia. Methods Subjects were 70 Japanese patients with schizophrenia (38 smokers, 32 non-smokers). We compared the following clinical parameters between the two groups at baseline (before smoking cessation) and in each group separately between baseline and at three years after smoking cessation: autonomic nervous system activity, plasma cholesterol levels, body weight, drug therapy, and Global Assessment of Functioning scores. We also compared the mean changes in clinical parameters throughout this study between the groups at both time points. Autonomic nervous system activity was assessed by power spectral analysis of heart rate variability. Results Parasympathetic nervous system activity and the doses of antiparkinsonian drugs in smokers were significantly higher than those in non-smokers at baseline. Smoking cessation was associated with significantly decreased sympathetic nervous system activity and decreased doses of antipsychotics and antiparkinsonian drugs at three years after smoking cessation. However, there was no significant difference in the mean change in clinical factors scores, except for Global Assessment of Functioning scores, between smokers and non-smokers at three years after smoking cessation. Conclusions Our results suggest that smoking reduces both autonomic nervous system activity and the effectiveness of drug therapy with antipsychotics and antiparkinsonian drugs in patients with schizophrenia, but that both factors could be ameliorated over the long term by smoking cessation. Taken together with the findings of previous studies, smoking cessation in patients with schizophrenia has many long-term positive physiological effects.

We have observed ablation patterns on metal surfaces made by focusing high-order harmonics in the soft-x-ray region. The ablation processes are investigated from the intensity dependence.

We have developed a novel autocorrelator composed of only reflective elements, which have functions as a beam splitter and an optical delay line for fringe-resolved autocorrelation. The measurement of femtosecond laser pulse is demonstrated in the visible region.

We characterized field emission from autoionization transition in atomic neon stimulated by isolated attosecond field. The spectrum of the emitted field broadens approximately 1 eV bandwidth, which corresponds to shorter than 2.5 fs-duration

By experimentally optimizing the operational parameters for the electron-beam-excited ArF laser, an intrinsic efficiency of 4.4% was obtained for a 4 atm Ne/Ar/F2 mixture pumped by a 50 ns pulse at an excitation rate of 1.4 MW/cm3. Under these conditions, the measured net gain was 5.5%cm-1, which agrees well with the value of 6.0%cm-1 estimated from a modified version of Rigrod's theory. Assuming an infinite V-T relaxation rate for ArF*(B), the small-signal gain and absorption were estimated as 6.4%cm-1 and 0.35%cm-1, respectively. With an Ar/F2 mixture, it was difficult to obtain efficient ArF lasing, while with a Ne/Ar/F2 mixture, efficient lasing was readily obtainable even at low excitation rates. This is attributed mainly to the fact that the ArF* deactivation rate to form Ar2F* trimer if faster with Ar gas than with Ne gas.