A novel real-time and non-destructive method for differentiating soft from hard tissue in laser osteotomy has been introduced and tested in a closed-loop fashion. Two laser beams were combined: a low energy frequency-doubled nanosecond Nd:YAG for detecting the type of tissue, and a high energy microsecond Er:YAG for ablating bone. The working principle is based on adjusting the energy of the Nd:YAG laser until it is low enough to create a microplasma in the hard tissue only (different energies are required to create plasma in different tissue types). Analyzing the light emitted from the generated microplasma enables real-time feedback to a shutter that prevents the Er:YAG laser from ablating the soft tissue.

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).

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.

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.

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.

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.

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.

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.

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.

Over the past several years, the demand for high quality agricultural products has been remarkably increased. Thus, it is important to use non-destructive methods for product quality monitoring. LED-induced fluorescence spectroscopy has proved its potential for nondestructive detection of some defects in agricultural products, such as tissue browning and bruising. Due to such defects, changes in the polyphenol and chlorophyll contents occur which can be considered as the visible marks of decreasing fruit quality. In the present work, a fluorescence spectrometer (spectrofluorometer) controlled by LabVIEW software was designed and developed. In this spectrometer, a consumer-grade webcam was used as an imaging sensor. The spectrometer was able to measure the fluorescence spectra directly from the fruit and vegetable surface in the desired regions. To do so, the spectrometer was equipped with a suitable fiber-optic probe. The hardware solution was based on data acquisition working on the USB platform and controlled by the application running on the PC. In this system, light emitting diodes with different wavelengths were used as the excitation sources for inducing fluorescence spectra of some famous fruits and vegetables.

Displayers tend to become three-dimensional. The most advantage of holographic 3D displays is the possibility to observe 3D images without using glasses. The quality of created images by this method has surprised everyone. In this paper, the experimental steps of making a transmission hologram have been mentioned. In what follows, current advances of this science-art will be discussed. The aim of this paper is to study the recent improvements in creating three-dimensional images and videos by means of holographic techniques. In the last section we discuss the potentials of holography to be applied in future.

In this paper, applications of holography in the solar energy, photovoltaic concentration, daylighting, illumination, and thermal blocking have been investigated. Holographic elements can be used to concentrate the radiation of the sun onto photovoltaic cells. Moreover the sun radiation is diffracted by the hologram. This has the advantage that proper photovoltaic cells can be installed in different spectral regions. Holographic daylighting systems can diffract sunlight efficiently up to the ceiling in the room. Holograms can be fabricated to reflect or block certain wavelength regions. Holograms are designed for a wavelength in the infrared region and a typical incidence angle of the summer sunlight. In this case the infrared radiation is reflected in the summer and heating of the rooms can be reduced, also, energy for cooling by air conditioners can be reduced. In winter, that the angle of incidence is smaller, a larger wavelength region is reflected, where the infrared intensity is very low.

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.