Minimally-invasive laser surgeries could benefit from a fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) setup for real-time tissue characterization. In FO-LIBS, the sample receives limited light irradiance due to the fiber's low damage threshold and diminished laser beam quality. Therefore, the plasma created with FO-LIBS is less luminant than that of free-space LIBS. Furthermore, only a small portion of plasma emission can be collected, as the lens's size at the fiber tip is restricted to fit inside the narrow channel of an endoscope. A high optical throughput Echelle spectrometer was developed to compensate for low-intensity light collection with FO-LIBS. The Echelle spectrometer was tested for tissue differentiation when combined with a flexible fiber bundle delivery setup and a small lens at the bundle's tip. The customized FO-LIBS setup, coupled with multivariate data analysis, successfully differentiated bone from surrounding soft tissue (muscle, fat, and bone marrow) with 100% cross-validated (CV) sensitivity and specificity. The CV sensitivity and specificity for differentiation between all tissues were 90.2% and 96.7%, respectively. The results demonstrate, to the best of our knowledge, the first flexible FO-LIBS system, which may provide a further step towards the development of a smart endoscopic laser scalpel.@en

The preparation of small-sized biological samples is traditionally performed manually utilizing mechanical tools such as scalpels. The main drawbacks of such methods are a lack of accuracy and repeatability of the resulting cuts and damage to the surrounding tissue due to the high interaction forces and the accompanying mechanical stresses. One way to circumvent these issues is to substitute the mechanical tools for laser light. When used in conjunction with a high-accuracy positioning system, such a preparation procedure enables repeatable cutting of arbitrary geometries while largely preserving the integrity of the surrounding tissue. In this paper, a system leveraging the potential of laser-based ablation for bio-sample preparation is proposed. It integrates and synchronizes all key components with extensive safety features and an intuitive user interface, allowing novice operators to perform sample preparations easily. As a first application, the proposed system has been utilized to create microdamages in mouse tail tendon fascicles. Promising results could be obtained, but careful tuning of the laser parameters and further optimization of the mechanical setup is still required to attain the high repeatability striven for.@en

Silver oxide (AgO) thin films were prepared by using a cylindrical direct current reactive magnetron sputtering system at 10−5 torr initial pressure on BK7 glass substrate. Samples deposited for 3, 5 and 7 minutes. Surface characterization of AgO thin films in the nanometer scale can be accurately determined using the atomic force microscopy (AFM) and X-ray diffraction (XRD). The average roughness (Ravg), maximum peak to valley height (Rt) and root mean square (Rrms) roughness are used to analyze the surface morphology of AgO films. The linear optical absorption data were measured in the visible-near infrared spectral regions and the nonlinear refractive index (n2) of thin films is evaluated by the moiré deflectometery technique. The investigation indicates that, increase in AgO thickness leads to reduction in nonlinear refractive index.@en

A clear margin is an important prognostic factor for most solid tumours treated by surgery. Intraoperative fluorescence imaging using exogenous tumour-specific fluorescent agents has shown particular benefit in improving complete resection of tumour tissue. However, signal processing for fluorescence imaging is complex, and fluorescence signal intensity does not always perfectly correlate with tumour location. Raman spectroscopy has the capacity to accurately differentiate between malignant and healthy tissue based on their molecular composition. In Raman spectroscopy, specificity is uniquely high, but signal intensity is weak and Raman measurements are mainly performed in a point-wise manner on microscopic tissue volumes, making whole-field assessment temporally unfeasible. In this review, we describe the state-of-the-art of both optical techniques, paying special attention to the combined intraoperative application of fluorescence imaging and Raman spectroscopy in current clinical research. We demonstrate how these techniques are complementary and address the technical challenges that have traditionally led them to be considered mutually exclusive for clinical implementation. Finally, we present a novel strategy that exploits the optimal characteristics of both modalities to facilitate resection with clear surgical margins.@en

Although laserosteotomes have become generally accepted devices in surgical applications, they still suffer from a lack of information about the type of tissue currently being ablated; as a result, critical structures of the body under or near the focal spot of the laser beam are prone to inadvertent ablation. The lack of information about the properties of the ablated tissue can be solved by connecting the laserosteotome to an optical detection setup which can differentiate various types of tissues, especially bone from connective soft tissues. This study examines the applicability of laser-induced breakdown spectroscopy (LIBS) as a potential technique to differentiate bone from surrounding soft tissue (fat and muscle). In this experiment, fresh porcine femur bone, muscle, and fat were used as hard and soft tissue samples. The beam of a nanosecond frequency-doubled Nd:YAG laser was used to ablate the tissue samples and generate the plasma. The plasma light emitted from the ablated spot, which corresponds to the recombination spectra of ionized atoms and molecules, was gathered with a collection optic (including a reflective light collector and a fiber optic) and sent to an Echelle spectrometer for resolving the atomic composition of the ablated sample. Afterwards, Discriminant Function Analysis (DFA) based on the ratio of the intensity of selected peak pairs was performed to classify three sample groups (bone, muscle, and fat). Lastly, the sensitivity, specificity, and accuracy of the proposed method were calculated. Sensitivity and specificity of 100 % and 99 % were achieved, respectively, to differentiate bone from surrounding soft tissue.@en

The aim of this paper is to examine the effect of pig bone immersion in different levels of cooling water during laser ablation with a Er:YAG laser. The laser worked at 2940 nm wavelength and 10 Hz repetition rate in microseconds pulse duration regime. The bone was immersed in different levels of cooling water in a sample container for preventing carbonization. The bone samples were ablated with fixed deposited energy to investigate at which water level Er:YAG lasers start ablating bone through a layer of water. Results showed that the maximum level of water that laser can pass through to start the ablation nonlinearly depends on pulse energy.@en

The aim of this paper is to study degradation of a bromophenol blue molecule (C19H10Br4O5S) using direct irradiation of cold atmospheric argon plasma jet. The pH of the bromophenol blue solution has been measured as well as its absorbance spectra and conductivity before and after the irradiation of non-thermal plasma jet in various time durations. The results indicated that the lengths of conjugated systems in the molecular structure of bromophenol blue decreased, and that the bromophenol blue solution was decolorized as a result of the decomposition of bromophenol blue. This result shows that non-thermal plasma jet irradiation is capable of decomposing, and can also be used for water purification.@en

During the past half-century, laser osteotomy has been studied for a broad range of lasers, which almost covers the entire range of available laser systems in the market, from early unsuccessful experiments with CW lasers to newly developed ultrashort pulse lasers. Although a large variety of laser parameters including wavelength, pulse energy, pulse duration, and repetition rate have been investigated to find an optimum laser system as an alternative osteotomy tool, there is not a universal agreement on a specific type of laser to replace conventional mechanical saws. The only universal agreement is on the speed of cutting (ablation rate) which went to longpulse Er:YAG and CO2 lasers. Microsecond pulse Er:YAG and CO2 lasers perform osteotomy by inducing efficient photothermal effect to the bone with the help of high absorption peak of water in the bone. However, having a speedy cut is not the only effective parameter to pave the way for transferring lasers to the operating room. Other parameters including cutting with the lowest thermal damage, ability for deep cutting, and compatibility with integrating sensors are among the other determinant parameters. Moreover, being able to be delivered through the fiber optic and as a consequence fit inside the endoscope channel could extend their application from the open surgery to minimally invasive ones. This chapter besides proving the necessary information on the physics behind the laser-bone interaction provides a short review on the history of bone surgery with laser and state-of-the-art studies in this field.@en

In the present work, a hyperspectral imaging system (imaging spectrometer) using a commercial webcam has been designed and developed. This system was able to capture two-dimensional spectra (in emission, transmission and reflection modes) directly from the scene in the desired wavelengths. Imaging of the object is done directly by linear sweep (pushbroom method). To do so, the spectrometer is equipped with a suitable collecting lens and a linear travel stage. A 1920 x 1080 pixel CMOS webcam was used as a detector. The spectrometer has been calibrated by the reference spectral lines of standard lamps. The spectral resolution of this system was about 2nm and its spatial resolution was about 1 mm for a 10 cm long object. The hardware solution is based on data acquisition working on the USB platform and controlled by a LabVIEW program. In this system, the initial output was a three-dimensional matrix in which two dimensions of the matrix were related to the spatial information of the object and the third dimension was the spectrum of any point of the object. Finally, the images in different wavelengths were created by reforming the data of the matrix. The free spectral range (FSR) of the system was 400 to 1100 nm. The system was successfully tested for some applications, such as plasma diagnosis as well as applications in food and agriculture sciences.@en

In this paper, tunability of three near-infrared semiconductor lasers which typically lase at 808 nm, 892 nm and 980 nm is studied. Both Littrow (wavelength dependent beam direction setup) and Littman (wavelength independent beam direction setup) configurations have been used. The wavelength and the power of the output beam of the laser have been measured. In all three cases, Littrow configuration shows a little better tuning range. In both Littrow and Littman configurations the wavelengths near the main wavelength of the laser had more power. The highest achieved power of these lasers in the Littrow setup was more than that of the Littman setup.@en

In this paper we report the synthesis of gold nanoparticles during laser ablation of a metal gold plate in distilled water. The experiments were performed with a first harmonic (1064 nm, 6 ns, 10 Hz) output of a Nd:YAG laser varying the operative fluency between 5 Jcm-2 and 15 Jcm -2. The results indicate that gold nanoparticles are synthesized at room temperature.In this paper we give an overview of the properties of gold relevant to its potential application in molecular-scale devices absorption spectroscopy and Transmission Electron Microscopy (TEM) were employed to determine the optical properties and size of gold nanoparticles. And novel applications of gold nanoparticles have been studied in various fields.@en

A cost-effective method employing a smartphone sensor to measure the laser-induced sound pressure level (SPL) has been introduced for lens-to-sample distance (LTSD) adjustment in micro laser-induced breakdown spectroscopy (µLIBS).@en

In this paper, current pulse that propagates in Terahertz antenna was simulated as a propagated surface wave. The surface wave modes which propagate in electrode were studied. It was found that the current pulse propagates as a bulk electromagnetic wave in the antenna gap and that the current pulse propagates as a surface wave in the electrodes. Phase velocity and loss of each mode were investigated. The relation between thickness of the antenna electrode and optical properties of the substrate, such as absorption and refraction index, with surface wave characteristics was studied. After solving surface wave equation for the three-layer structure, dielectric-metal-dielectric, it was found that two surface wave modes, slow mode and fast mode are allowed to propagate in the electrode layer and that surface wave cannot propagate in the antenna gap region.@en

We present a simple setup for laser-induced breakdown spectroscopy using the spatially resolved technique (SRLIBS). We show that, without any need for time-gated ICCD and pulse generator, the signal-to-background ratio is enhanced. We develop a homemade spectrograph with a movable slit located at its entrance to detect different parts of the plasma emission. For optimizing the position of the slit, we use the shadowgraphy technique to study the plasma expansion. In this low cost setup, with nanosecond laser pulses, we perform SRLIBS experiments on the plasma induced in air and iron. Our results show that the signal-to-background ratio for iron and air is enhanced up to 15 and 8 times, respectively.@en

The aim of the present study is to investigate the effect of laser pulse duration on ablation efficiency of hard bones. The bones were ablated using a microsecond pulsed Er-YAG laser. The laser wavelength was 2.94 μm and the repetition rate was 10Hz. Three samples of porcine femur were used and several areas were ablated with a fixed pulse energy of 280mJ and different pulse durations. The ablation procedure was applied during five seconds for all the experiments, therefore, the same amount of energy (14 J) was deposited in each trial. The ablation efficiency was determined by measuring the ablated volume per second for each experiment.@en

Echelle spectrometers offer high-resolution (ca. one Angstrom or higher) and wide range (ca. half a micron or wider), simultaneously, without having a mechanical moving part. However, they require a complicated optical set-up as compared to conventional one-dimensional-dispersion/diffraction spectrometers, e.g., Czerny-Turner. Therefore, the simulation of the Echellogram is required before building the spectrometer. This paper aims to develop an application for visualizing the Echellogram using MATLAB App Designer followed by simulation of the optical aberrations by Zemax OpticStudio to optimize the spectrometer parameters. The developed application provides an interactive graphical interface with a user-friendly dashboard to control and monitor the required parameters. This spectrometer is being used in laser-induced breakdown spectroscopy (LIBS) system application lied of robot-guided laser ablation of biological tissues.@en

In minimal invasive laser osteotomy precise information about the ablation process can be obtained with LIBS in order to avoid carbonization, or cutting of wrong types of tissue. Therefore, the collecting fiber for LIBS needs to be optimally placed in narrow cavities in the endoscope. To determine this optimal placement, the plasma plume expansion dynamics in ablation of bone tissue by the second harmonic of a nanosecond Nd:YAG laser at 532 nm has been studied. The laserinduced plasma plume was monitored in different time delays, from one nanosecond up to one hundred microseconds. Measurements were performed using high-speed gated illumination imaging. The expansion features were studied using illumination of the overall visible emission by using a gated intensified charged coupled device (ICCD). The camera was capable of having a minimum gate width (Optical FWHM) of 3 ns and the timing resolution (minimum temporal shift of the gate) of 10 ps. The imaging data were used to generate position-time data of the luminous plasma-front. Moreover, the velocity of the plasma plume expansion was studied based on the time-resolved intensity data. By knowing the plasma plume profile over time, the optimum position (axial distance from the laser spot) of the collecting fiber and optimal time delay (to have the best signal to noise ratio) in spatial-resolved and time-resolved laser-induced breakdown spectroscopy (LIBS) can be determined. Additionally, the function of plasma plume expansion could be used to study the shock wave of the plasma plume.@en

A micro-discharge air plasma jet was developed operated at low frequency (50 Hz) ac high voltage (kV). The micro-discharge plasma jet was generated by feeding air through a dielectric installed between two disk-shaped electrodes with a hole of 1 mm diameter in the center. Both of the electrodes were made of copper. The micro-discharge in the dielectric is evolved as a plasma jet from the outer electrode through its hole. The ac power supply was a neon light transformer. Optical emission spectroscopy was employed to study the plasma discharge characteristics. Specair software was used to analyze the collected spectrum. The reduced electric field and electron density of plasma as well as rotational and vibrational temperatures, referring to ion or gas and electron temperature respectively were measured by processing emission spectrum.@en

In this paper, tunability of four near-infrared semiconductor lasers which typically lase at 783nm, 808 nm, 892 nm and 980 nm is studied. Both Littrow (wavelength dependent beam direction setup) and Littman (wavelength independent beam direction setup) configurations have been used for single mode tuning. In addition, the tunability of 783 nm laser in dual mode tuning is studied in both Littrow and Litman configurations. The wavelength and the power of the output beam of the laser have been measured. In all four cases, Littrow configuration shows a little better tuning range. In both Littrow and Littman configurations, the wavelengths near the main wavelength of the laser had more power. The highest achieved power of these lasers in the Littrow setup was more than that of the Littman setup. Moreover, the tuning speed and effect of tuning on the bandwidth of the laser were investigated.@en

In this work we report the preparation of colloidal silver nanoparticles. In order to prepare the silver nanoparticles laser ablation method has been used. A silver coin as a target (purity 99.9 %) was ablated by a Q-Switched Nd:YAG laser with a fluence of about 91 mJ/cm 2 at a repetition rate of 10 Hz at room temperature. In order to evaluate these particles transmission electron microscopy (TEM) and spectrophotometry (from UV to NIR) have been used. The average size of prepared nanoparticles is ∼ 20 nm. The importance of morphology of nanoparticles has been investigated. Developed applications of silver nanoparticles have been studied, silver nanoparticles are considered as biocompatible and low in toxicity and have good potential for biological applications. Lately silver nanoparticles have found a novel approach in different fields of medicine, biology and industry.@en