Increasing brightness in multiphoton microscopy with low-repetition-rate, wavelength-tunable femtosecond fiber laser

Many experiments in biological and medical sciences currently use multiphoton microscopy as a core imaging technique. To date, solid-state lasers are most commonly used as excitation beam sources. However, the most demanding applications require precisely adjusted excitation laser parameters to enhance image quality. Still, the lag in developing easy-to-use laser sources with tunable output parameters makes it challenging. Here, we show that manipulating the temporal and spectral properties of the excitation beam can significantly improve the quality of images. We have developed a wavelength-tunable femtosecond fiber laser that operates within the 760 - 800 nm spectral range and produces ultrashort pulses (below 70 fs) with a clean temporal profile and high pulse energy (1 nJ). The repetition rate could be easily adjusted using an integrated pulse picker unit within the 1 - 25 MHz range and without strongly influencing other parameters of the generated pulses. We integrated the laser with a two-photon excited fluorescence (TPEF) scanning laser microscope and investigated the effect of tunable wavelength and reducing the pulse repetition rate on the quality of obtained images. Using our laser, we substantially improved the images brightness and penetration depth of native fluorescence and stained samples compared with a standard fiber laser. Our results will contribute to developing imaging techniques using lower average laser power and broader use of tailored fiber-based sources

Optical Frequency Comb Fourier Transform Spectroscopy of 14^{14}N2_216^{16}O at 7.8 {\mu}m

We use a Fourier transform spectrometer based on a compact mid-infrared difference frequency generation comb source to perform broadband high-resolution measurements of nitrous oxide, $^{14}$N$_2$$^{16}$O, and retrieve line center frequencies of the $\nu$$_1$ fundamental band and the $\nu$$_1$ + $\nu$$_2$ - $\nu$$_2$ hot band. The spectrum spans 90 cm$^{-1}$ around 1285 cm$^{-1}$ with a sample point spacing of 3 ${\times}$ 10$^{-4}$ cm$^{-1}$ (9 MHz). We report line positions of 67 lines in the $\nu$$_1$ fundamental band between P(37) and R(39), and 78 lines in the $\nu$$_1$ + $\nu$$_2$ - $\nu$$_2$ hot band (split into two components with e/f rotationless parity) between P(34) and R(33), with uncertainties in the range of 90-600 kHz. We derive upper state constants of both bands from a fit of the effective ro-vibrational Hamiltonian to the line center positions. For the fundamental band, we observe excellent agreement in the retrieved line positions and upper state constants with those reported in a recent study by AlSaif et al. using a comb-referenced quantum cascade laser [J Quant Spectrosc Radiat Transf, 2018;211:172-178]. We determine the origin of the hot band with precision one order of magnitude better than previous work based on FTIR measurements by Toth [http://mark4sun.jpl.nasa.gov/n2o.html], which is the source of the HITRAN2016 data for these bands

Sub-Doppler optical-optical double-resonance spectroscopy using a cavity-enhanced frequency comb probe

Accurate parameters of molecular hot-band transitions, i.e., those starting from vibrationally excited levels, are needed to accurately model high-temperature spectra in astrophysics and combustion, yet laboratory spectra measured at high temperatures are often unresolved and difficult to assign. Optical-optical double-resonance (OODR) spectroscopy allows the measurement and assignment of individual hot-band transitions from selectively pumped energy levels without the need to heat the sample. However, previous demonstrations lacked either sufficient resolution, spectral coverage, absorption sensitivity, or frequency accuracy. Here we demonstrate OODR spectroscopy using a cavity-enhanced frequency comb probe that combines all these advantages. We detect and assign sub-Doppler transitions in the 3${\nu}$${_3}$${\leftarrow}$${\nu}$${_3}$ spectral range of methane with frequency accuracy and sensitivity more than an order of magnitude better than before. This technique will provide high-accuracy data about excited states of a wide range of molecules that is urgently needed for theoretical modeling of high-temperature data and cannot be obtained using other methods

Rachunek ekonomiczny i słabe sygnały : zapobieganie niejasnej sytuacji

Cel: Decyzje inwestycyjne podejmowane są na podstawie rachunku ekonomicznego z uwzględnieniem analizy zróżnicowanego i częściowo nieprzewidywalnego otoczenia gospodarczego. Rachunek ekonomiczny każdego przedsiębiorstwa traktowany jest jako racjonalna decyzja i służy jako instrument wspomagający wybór środka inwestycyjnego. Pomimo różnych badań istnieje luka badawcza w wykorzystaniu słabych sygnałów w rachunku ekonomicznym. Tymczasem spektakularne upadki uznanych firm wynikały ze słabej identyfikacji nadchodzących niepowodzeń. Podejście / Metodologia / Projekt: Autorzy przeprowadzili integracyjny przegląd literatury w celu wygenerowania nowej wiedzy na temat wykorzystania słabych sygnałów w rachunku ekonomicznym. Wgląd w tym artykule pojawił się iteracyjnie. Wnioski: Na podstawie integracyjnego przeglądu literatury autorzy proponują potencjalnie radykalne uogólnienie, że firmy muszą stosować analizę słabych sygnałów podczas tworzenia rachunku ekonomicznego. Praktyczne implikacje: Artykuł przynosi kilka cennych informacji, które mogą być materiałem bazowym i odniesieniem do dalszych badań. Wyniki badań mogą stanowić punkt wyjścia do dyskusji i analizy każdej firmy, zarówno z sektora publicznego, jak i prywatnego. Oryginalność / wartość: oryginalne badanie ma na celu zainicjowanie dyskusji i dalsze badanie analizy słabych sygnałów w rachunku ekonomicznym.Purpose: Investment decisions are taken based on an economic calculation, considering the analysis of a diverse and partially unpredictable economic environment. Each enterprise's economic calculus is treated as a decision based on rationality and serves as an instrument to support the investment measure's selection. Despite different studies, there is a research gap in the usage of weak signals in economic calculus. Meanwhile, the spectacular collapses of well-recognised firms resulted from weak identification of coming failures. Approach/Methodology/Design: The authors carried out an integrative literature review to generate new knowledge on the usage of weak signals in economic calculus insights in this paper have emerged iteratively. Findings: Based on an integrative literature review, the authors offer the potentially radical generalisation that firms must use weak signal analysis during the process of economic calculus creation. Practical Implications: The article brings several valuable information that can be the base material and reference to further research. Study results can be a starting point of discussion and analysis on each firm, both from the public and private sectors. Originality/Value: The original study aims to initiate discussion and further research weak signal analysis in economic calculus. It is the first such research.Zweck: Investitionsentscheidungen werden auf der Grundlage einer wirtschaftlichen Berechnung unter Berücksichtigung der Analyse eines vielfältigen und teilweise unvorhersehbaren wirtschaftlichen Umfelds getroffen. Die Wirtschaftsrechnung jedes Unternehmens wird als eine auf Rationalität beruhende Entscheidung behandelt und dient als Instrument zur Unterstützung der Auswahl der Investitionsmaßnahme. Trotz unterschiedlicher Studien besteht eine Forschungslücke bei der Verwendung schwacher Signale in der Wirtschaftsrechnung. In der Zwischenzeit resultierten die spektakulären Zusammenbrüche anerkannter Unternehmen aus der schwachen Identifizierung kommender Ausfälle. Ansatz / Methodik / Design: Die Autoren führten eine integrative Literaturrecherche durch, um neues Wissen über die Verwendung schwacher Signale in ökonomischen Berechnungen zu generieren. Ergebnisse: Basierend auf einer integrativen Literaturrecherche bieten die Autoren die potenziell radikale Verallgemeinerung, dass Unternehmen während des Prozesses der Erstellung wirtschaftlicher Kalküle eine Analyse schwacher Signale verwenden müssen. Praktische Implikationen: Der Artikel enthält mehrere wertvolle Informationen, die als Grundmaterial und Referenz für weitere Forschung dienen können. Die Studienergebnisse können ein Ausgangspunkt für Diskussionen und Analysen zu jedem Unternehmen sein, sowohl aus dem öffentlichen als auch aus dem privaten Sektor. Originalität / Wert: Die ursprüngliche Studie zielt darauf ab, eine Diskussion einzuleiten und die Analyse schwacher Signale in der Wirtschaftsrechnung weiter zu erforschen. Es ist die erste derartige Forschung

Mode-Locking Dynamics in an All-PM Figure-Nine Tm-Doped Fiber Laser

We report a study on pulse dynamics in figure-nine Tm-doped all-polarization maintaining fiber laser. We analyzed laser operation from self-starting with multi-pulse dynamic to single-pulse operation by decreasing the pump power from the mode-locking threshold. By choosing a reliable setting of waveplates, our laser was generating pulses at the central wavelength of 1985 nm with a half-width of the spectrum, pulse duration, and pulse energy equal 6.4 nm, 650 fs, 177 pJ for the output port and 19.2 nm, 1279 fs, 57 pJ for the reject port in the single-pulse state. In the multi-pulse state, we recorded optical spectra, temporal waveforms, and average power at both exit ports. By analyzing temporal traces and output to reject port ratio power, we can distinguish between eight states of operation which follow an exact pattern. In the case of the single-pulse regime, we performed a further laser characterization, including relative intensity noise

Opportunities for the Application of 3D Printing in the Critical Infrastructure System

The present article presents an analysis of the potential application of 3D printing in the critical infrastructure system. An attempt has been made to develop case studies for selected critical infrastructure areas, particularly with reference to the area of energy supply. The need for 3D printing applications is identified based on expert research in the energy industry. It identifies the application schemes determined by the technical and logistical possibilities associated with 3D printing in its broadest sense. A review of additive technologies with a view to their application in selected phases of critical infrastructure operation, including in crisis situations, is also carried out. Furthermore, a methodology for incorporating 3D printing into the existing critical infrastructure system is proposed. As a result, the following research hypothesis is adopted: the use of 3D printing can be an important part of measures to ensure the full functionality and efficiency of critical infrastructures, particularly in crisis situations

Mode-Locking Dynamics in an All-PM Figure-Nine Tm-Doped Fiber Laser

We report a study on pulse dynamics in figure-nine Tm-doped all-polarization maintaining fiber laser. We analyzed laser operation from self-starting with multi-pulse dynamic to single-pulse operation by decreasing the pump power from the mode-locking threshold. By choosing a reliable setting of waveplates, our laser was generating pulses at the central wavelength of 1985 nm with a half-width of the spectrum, pulse duration, and pulse energy equal 6.4 nm, 650 fs, 177 pJ for the output port and 19.2 nm, 1279 fs, 57 pJ for the reject port in the single-pulse state. In the multi-pulse state, we recorded optical spectra, temporal waveforms, and average power at both exit ports. By analyzing temporal traces and output to reject port ratio power, we can distinguish between eight states of operation which follow an exact pattern. In the case of the single-pulse regime, we performed a further laser characterization, including relative intensity noise