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We report a method for fabricating inexpensive microfluidic platforms on paper using laser treatment. Any paper with a hydrophobic surface coating (e. g., parchment paper, wax paper, palette paper) can be used for this purpose. We were able to selectively modify the surface structure and property (hydrophobic to hydrophilic) of several such papers using a CO(2) laser. We created patterns down to a minimum feature size of 62 +/- 1 mu m. The modified surface exhibited a highly porous structure which helped to trap/localize chemical and biological aqueous reagents for analysis. The treated surfaces were stable over time and were used to self-assemble arrays of aqueous droplets. Furthermore, we selectively deposited silica microparticles on patterned areas to allow lateral diffusion from one end of a channel to the other. Finally, we demonstrated the applicability of this platform to perform chemical reactions using luminol-based hemoglobin detection.

Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.

In this study, we demonstrate the precise control of fluid flow using femtosecond (FS) laser-induced microstructures. A microgroove structure inscribed on a poly(methyl methacrylate) (PMMA) substrate functions as a superhydrophilic membrane similar to paper. We first estimated the flow rate for pure water on microgrooves fabricated at various laser fluences in the range from 9.2 to 100.8 J/cm2. The results showed that the flow rate could be tuned in the range from 0.30 to 12.07 μL/s by varying the laser irradiation parameters. The fluid flow was reproducible, with a calculated relative standard deviation (RSD%) of less than 8% in the flow rate. We then fabricated a microfilter for blood separation and estimated its filtration ability using artificial blood containing resin microparticles. This method would be useful in a technology related to a paper-based diagnostic device for precise reagent manipulation.

We report a simple hydrochloric acid (HCl) impregnation method to substantially improve the lyophobicity of a paper against gallium-based liquid metal. Based on the HCl-impregnated paper, we also propose an extremely simple fabrication method of microfluidic channel for gallium-based liquid metal, Galinstan®. Due to its low cost, easy fabrication, and flexibility, recently paper has drawn attention as microfluidic platforms for various applications. We have treated two different types of paper (paper towel and printing paper) with various treatment methods such as laser printer flattening, fluorocarbon polymer coating, HCl-impregnation, and combination of these methods. We then studied their lyophobicity characteristics by measuring static and dynamic contact angles as well as bouncing experiment. We found that HCl-impregnation is a simple yet powerful method to engineer certain types of papers to make them super-lyophobic substrates against gallium-based liquid metals and effective for more than 30-days after impregnation. To show the feasibility, we demonstrated manipulation of a Galinstan® droplet along microfluidic channels formed on the HCl-impregnated paper.

We report the use of a new laser-based direct-write technique that allows programmable and timed fluid delivery in channels within a paper substrate which enables implementation of multi-step analytical assays. The technique is based on laser-induced photo-polymerisation, and through adjustment of the laser writing parameters such as the laser power and scan speed we can control the depth and/or the porosity of hydrophobic barriers which, when fabricated in the fluid path, produce controllable fluid delay. We have patterned these flow delaying barriers at pre-defined locations in the fluidic channels using either a continuous wave laser at 405 nm, or a pulsed laser operating at 266 nm. Using this delay patterning protocol we generated flow delays spanning from a few minutes to over half an hour. Since the channels and flow delay barriers can be written via a common laser-writing process, this is a distinct improvement over other methods that require specialist operating environments, or custom-designed equipment. This technique can therefore be used for rapid fabrication of paper-based microfluidic devices that can perform single or multistep analytical assays.

In this work, results on laser processing of thin metal films deposited on paper are presented. Au, Ag, Cu, and Ni films are deposited by classical pulsed laser deposition method on different paper types—standard printer, glossy, and silicone paper. The produced films are then processed by nanosecond pulses delivered by Nd:YAG laser system operating at the basic wavelength of 1064 nm. The laser processing parameters are varied and their influence on the film modification is presented. It is shown that at certain conditions, the laser treatment of the films leads to formation of a discrete nanostructure, composed of a monolayer of spherical nanoparticles. The structure and morphology of the fabricated samples are presented and discussed. Results on the use of these structures in Surface Enhanced Raman Spectroscopy are also presented. The demonstrated method is an alternative way for fabrication of metal nanostructures with application in low cost sensor device fabrication.

We developed novel laser carved micro-crack (LCC) paper-based channels to significantly accelerate the liquid flow without an external pump. For the aqueous solutions they increased the flow velocity 59 times in 16% laser power-8 micro-cracks-LCC channel compared with it in solely-printed channels. All experimental data from both LCC and solely-printed channels were well-fitted by the time-distance quadratic trinomial that we developed on laser power and micro-crack number. We designed and fabricated T-junction microstructures of LCCs. Further, the microfluidic paper-based analytical device (μPAD) of LCC on dye mixing gradient and pH gradient were developed with the characteristics, fast self-acting transportation and high-performance mixing of liquid flows. In the dye mixing gradient the time cost was reduced from 2355 s in the solely-printed one to only 123 s in the five-stage of this LCC-μPAD. It was useful for quick and long-distance transferences through the multiple units of μPADs. Certainly, this LCC-μPAD was inexpensive, disposable, portable and applicable to resource-limited environments.

A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 μm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate was strongly perturbed by protruding fibers of the base paper. Such fibers together with the surface topography of the base paper seem to be the major factors that control the leveling of toner and its penetration into a thinly coated paper substrate.

Ground wood cellulose paper exhibits a practicable cleaning laser fluence window during middle-UV radiation processing. In this case, a minimum dose volume density should be applied. However, cleaning of bleached cellulose paper is accompanied by strong yellowing and destruction. The presence of charcoal graphite particulates shows substantial influence on the yellowing with increasing coverage.

In this study, we demonstrate up to 30% increase in power density of carbon paper electrodes for vanadium redox flow batteries (VRFB) by introducing perforations into the structure of electrodes. A CO 2 laser was used to generate holes ranging from 171 to 421 μm diameter, and hole densities from 96.8 to 649.8 holes cm −2 . Perforation of the carbon paper electrodes was observed to improve cell performance in the activation region due to thermal treatment of the area around the perforations. Results also demonstrate improved mass transport, resulting in enhanced peak power and limiting current density. However, excessive perforation of the electrode yielded a decrease in performance due to reduced available surface area. A 30% increase in peak power density (478 mW cm −2 ) was observed for the laser perforated electrode with 234 μm diameter holes and 352.8 holes cm −2 (1764 holes per 5 cm 2 electrode), despite a 15% decrease in total surface area compared to the raw un-perforated electrode. Additionally, the effect of perforation on VRFB performance was studied at different flow rates (up to 120 mL min −1 ) for the optimized electrode architecture. A maximum power density of 543 mW cm −2 was achieved at 120 mL min −1 .

The potential of laser ablation in conservation of paper artifacts of cultural interest is under investigation since the second half of nineties. However, the works carried out on the topic are relatively a few as compared with those dedicated to stone, metal and painted artworks. Furthermore, in the latter cases, widespread applications have been successfully carried out, whereas laser cleaning of aged paper is still far from the conservation practice. There are serious risks to produce short- and/or long-term chemical alterations and/or mechanical damages at relatively low fluences. Here, we report a systematic investigation on laser removal of mold growths from prepared and naturally aged paper samples. Fundamental wavelength and second harmonic of QS Nd:YAG laser are tested and compared through optical and spectroscopic characterizations. This allowed defining optimized irradiation conditions and foreseeing further improvements from pulse duration optimization.

This paper presents an Advanced Excimer Laser Annealing (AELA) process for large-sized OLED displays. Achieving good uniformity and performance characteristics of LTPS TFTs using cost-effective processes are important issues for the production of OLED displays. The AELA uses a conventional ELA system, XeCl laser, large optics and positioning stage, with improved processes and existing technology such as a selective crystallization function. The selective crystallization function of the AELA process has been optimized to obtain uniform microstructure of the crystallized Si films at the TFTs and interconnection region. Specifically, the 7/20 (W/L) TFTs via AELA processed Si films have mobility of 73.81 cm2/V-sec, threshold voltage of −2.07 V and sub-threshold swing of 0.40 V/dec. 55″ FHD OLED displays have been fabricated using the AELA process. The advantages and challenges of AELA technology will be further discussed.

Lasers have served as cleaning tools for historical objects and artworks for about 40 years. In many cases, superior results of laser cleaning were achieved with respect to traditional methods. In this technique, contaminations on the surface of the object are ablated by laser irradiation. In order to apply laser cleaning method to fragile materials such as paper made of cellulose or parchment, heat deposition to the bulk should be minimal, to prevent damage. In this work, it is demonstrated that laser pulses with femtosecond (fs) duration can exhibit non-thermal ablation of contaminants on paper samples. In particular, laser cleaning studies are concentrated on paper samples with sizing. Fs laser cleaning is performed on artificially soiled and aged samples, as well as on historical ones. The laser used in the experiments has pulse duration of 550 fs and 1030 nm center wavelength. The fluence of the laser is varied and the post-cleaning statuses of samples are investigated. The analyses are color changes, fiber integrity, chemical composition changes and mechanical strengths. These results show that fs lasers can be very efficient in cleaning paper samples, yielding minimal discoloration and no damage to fibers distinguishable on microscopic examination. The presence of sizing also provides further protection against possible side effects.

In the present work, the analytical potential of laser induced breakdown spectroscopy (LIBS) for the discrimination of paper types and prints made by digital printers on these papers was assessed. Six different paper types (including standard office papers, color paper and non-bleached paper), and eight printers (including laser and inkjet, as well as color and black printers) were included in the study. Only one or two laser shots were delivered to each sample in order to cause minimal sample destruction and provide maximum spatial resolution. The statistical evaluation of LIBS spectra was performed by multiple methods including three comparative functions (linear correlation, sum of squared deviations and overlapping integral) as well as two advanced statistical methods (multivariate curve resolution alternating least squares (MCR-ALS) combined with classification tree and discriminant analysis (DA)). The best classification results were obtained with the newly introduced MCR-ALS/DA approach, which proved to be 96.3% accurate in the identification of the paper type and 83.3% accurate in the identification of the printer type, based on the LIBS spectrum collected from just a single laser shot to the sample. It was found that the UV part of the LIBS spectrum can be used most efficiently for the discrimination.

Today’s demands for high quality digital printing emphasise the importance of paper surface. This work demonstrates the effects of surface topography and appearance on printing quality. Samples were printed in black and white with a laser jet printer under identical conditions, using different types of paper in order to have different surface properties. The papers and printed samples were evaluated with atomic force microscopy (AFM), scanning electron microscopy (SEM), gloss meter, spectrophotometer, and densitometer. Results showed that the decrease in surface roughness increased optical density and print quality. Moreover, the gloss of the papers significantly influenced print quality by decreasing it. The effect of the colourimetric values of the papers on the colourimetric values of the final printed samples were less significant in higher optical density printed samples.

The objective of this research was to apply Fourier transform infrared spectroscopy (FTIR) and tunable infrared laser differential absorption spectroscopy (TILDAS) for measuring selected gaseous constituents in mainstream (MS) and sidestream (SS) smoke for experimental cigarettes designed to reduce MS CO using iron oxide cigarette papers. These two complimentary analytical techniques are well suited for providing per puff smoke deliveries and intra-puff evolution profiles in cigarette smoke respectively. The quad quantum cascade (QC) laser high resolution infrared spectroscopy system has the necessary temporal and spectral resolution and whole smoke analysis capabilities to provide detailed information for CO and CO 2 as they are being formed in both MS and SS smoke. The QC laser system has an optimal data rate of 20 Hz and a unique puffing system, with a square wave shaped puff, that allows whole smoke to enter an 18 m, 0.3 L multi-pass gas cell in real time (0.1 s cell response time) requiring no syringe or Cambridge filter pad. Another similar multi-pass gas cell with a 36 m pathlength simultaneously monitors the sidestream cigarette smoke. The smoke from experimental cigarettes manufactured with two types of iron oxide papers were compared to the smoke from cigarettes manufactured similarly without iron oxide in the paper using both instrument systems. The delivery per puff determined by the QC laser method agreed with FTIR results. MS CO intra-puff evolution profiles for iron oxide prototype cigarettes demonstrated CO reduction when compared to cigarettes without iron oxide paper. Additionally, both CO and CO 2 intra-puff evolution profiles of the cigarettes with iron oxide paper showed a significant reduction at the initial portion of the 2 s puff not observed in the non-iron oxide prototype cigarettes. This effect also was observed for ammonia and ethylene, suggesting that physical parameters such as paper porosity and burn rate are important. The SS CO and CO 2 deliveries for the experimental cigarettes evaluated remained unaffected. The iron oxide paper technology remains under development and continues to be evaluated.

Samples of artificially contaminated model papers were cleaned by the use of pulsed Nd:YAG laser at 1064 nm and 532 nm and the ArF excimer laser 193 nm. The post-processing effects were analysed basing on comparison of DRIFT spectra and colorimetric data obtained before and after accelerated ageing. In the DRIFT spectra measured after the laser surface cleaning at 1064 nm, the largest long-term changes were observed for the gelatin-sized paper. This paper revealed higher oxidization than the non-sized one after irradiation at 193 nm, too. Presence of gelatin resulted also in yellowing and darkening of the laser treated paper after prolonged ageing.

Colorless polyimide liquid crystal display (CPI-LCD) was successfully fabricated by PI-LCD handling process which contained substrate coating, LCD manufacture and dualsubstrate laser lift-off (LLO) process. Plastic substrate was made by high transmittance CPI material (T > 91%). Total cell thickness without polarizer is less than 25 µm.

In this article, lasers in the ultraviolet, visible and infrared light spectra working with pulse widths in the nanosecond range are applied to a range of toner-paper combinations to determine their ability to remove toner. If the laser energy fluence can be chosen to stay below the ablation threshold of paper at the same time that it surpasses that of toner, paper could be cleaned and re-used instead of being recycled or disposed into a landfill. This could significantly reduce the environmental impact of paper production and use. Although there are a variety of paper conservation studies which have investigated the effects of laser radiation on blank and soiled paper, none has previously explored toner-print removal from paper by laser ablation. Colour analysis under the L∗a∗b∗ colour space and SEM examination of the outcome indicate that it is possible to remove toner from paper without damaging and discolouring the substrate. Best results are obtained when employing visible radiation at a wavelength of 532 nm working with a pulse width of 4 ns and energy fluences under 1.6 J/cm2. This means that it is technically feasible to remove toner-print for paper re-use.

International audience; Laser cutting of paper is widely used in the paper conversion industry. CO 2 lasers are well suited for this type of applications. Desktop printing is a large market both for digital photography, document management and graphics applications, but it still lacks advanced cutting and scoring ability, and CO 2 lasers seem costly to be integrated in mass-market printers. For that reason, mass-scalable and low-cost semiconductor laser diodes would be very advantageous to add paper cutting and scoring features in desktop printers. However, common paper can not be cut properly using visible or Near Infrared (NIR) laser diode since it has a very poor absorption at these wavelengths. We report here an innovative solution to achieve paper cutting or scoring using a 1 W single emitter NIR laser diode, within an inkjet printer. A special ink that absorbs the NIR light, and that penetrates all through the paper, is first disposed on the lines to be cut. Then, the laser diode goes along the lines to be cut. We show that a cutting speed of 2m/min can be achieved on 80g/m 2 conventional paper. The influence of the optical properties of the ink on the cutting speed are discussed, as well as focussing issues. In particular, we show that invisible inks are suitable, and very clear-cut edges can be obtained. The perspective of this technique are discussed.

"Here, we are reporting on the 337.1 nm radiation scattering and fluorescence spectra for white and colored bond paper (100 µm thick) usingan N2 laser of 1 µJ pulse energy (tFWHM = 3.8 ns). Fluorescence lifetimes in the order of 10 ns and transit-times in the order of 1 ns wereobtained. No fluorescence changes were caused by the short term paper irradiation."

In this paper, a glasses-free (autostereoscopic) display is described where the controlled illumination for a liquid crystal display (LCD) backlight is derived from a laser source where the laser is used not for its coherence properties but for its ability to have close control on its direction. This allows light exiting the LCD to be directed to the left and right eyes of several viewers who can move freely in both the X and Z directions. Light directions are determined by a spatial light modulator (SLM) that is controlled by a multiuser head tracker. This paper is principally concerned with the SLM and the Gabor superlens screen that is used to provide the angular magnification required to give a sufficiently wide viewing field

This paper studies the correlation between the time-of-flight (TOF) of laser pulses and paper density, basis weight, thickness and the beating of pulp. Paper samples made from unbeaten and beaten pulp were compressed from 500kg/m3 to 1100kg/m3 and laser pulses were shot through them during pressing. Changes were observed in the thickness of the samples and in the TOF of the laser pulses. The results show that TOF decreases during comrpession. This indicates that distances between the various scattering surfaces decrease. This phenomenon becomes more pronounced as the basis weight increases. The beating of the pulp before papermaking increases the number of scattering surfaces, thus broadening the laser pulse and causing delay. These two effects cannot be separated with the equipment used. Papers made from different pulp types each have unique delay constants.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new modular multi-projection multi-user multiview autostereoscopic display structure based on microelectromechanical systems (MEMS) laser projectors is presented. The system contains an array of MEMS laser projectors, a vertical diffuser, and the driving electronics. Each projector provides a slit of the whole image observed through the vertical diffuser. The structure does not require super position of the content among the projectors. Unlike similar type of displays, the size of the projection display hardware decreased dramatically. The structure has the capability to provide horizontal expansion in the screen size, and in number of different perspectives shown. Mentioned capabilities can be enhanced by using more projectors, by increasing the distance between projectors and the screen, and by changing the diffusion angle of the vertical diffuser in the minor axis. The inhouse built prototype with 18 projectors displays an image with a resolution of 234times848, and 36 different perspectives. The size of the image at the screen is 16 cm x 72 cm

We report the technical recommendations of the International GreenLight User Group on photoselective vaporization of the prostate in men with benign prostatic hyperplasia using the GreenLight HPS system (American Medical Systems, Minnetonka, Minnesota, USA). This high-power system employs a 120-W laser, which is a modification of the previous 80-W potassium-titanyl-phosphate (KTP) laser. The objective of this report is to optimize the efficacy and safety of the procedure by drawing on the experience of this multicentre international group. In this regard, recommendations for training are made, which relate to existing users of the 80-W KTP laser as well as to new laser users. (c) 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved

In this paper, we initially report a new type of wax printing method for rapid fabrication of microfluidic devices in paper using a commercially available, cheap, minitype (home-use) CO2laser engraving machine. This method combines the two core operations commonly involved in all previous wax printing methods, namely the printing and heating (melting) of wax patterns into one operation of engraving home-made wax slice (put in contact with the surface of paper) by laser. The heat produced by the laser makes the wax being engraved melt and then spread into paper to form complete hydrophobic barriers which are used to define the hydrophilic flow channels or separate test microzones. Under the optimized experimental conditions, a typical device on a 3 cm × 3 cm piece of paper could be fabricated separately within ~320 sec and is ready for use once the engraving process is completed. The fabrication resolution and multiplexed analytical capability of the wax-patterned paper were additionally characterized.

This study involves measurements of pulp consistency in cuvette and by an online apparatus, by innovatively scattering photoacoustic (SPA) method. The theoretical aspects were described at first. Then, a few kinds of wood fiber suspensions with consistencies from 0.5% to 5% were studied in cuvette. After that, a pilot of online apparatus was built to measure suspensions with fiber consistency lower than 1% and filler content up to 3%. The results showed that although there were many fiber flocks in cuvette which strongly affected the measurement accuracy of samples consistencies, the apparatus can sense fiber types with different optical and acoustic properties. The measurement accuracy can be greatly improved in the online style apparatus, by pumping suspension fluids in a circulating system to improve the suspension homogeneity. The results demonstrated that wood fibers cause larger attenuation of acoustic waves but fillers do not. On the other hand, fillers cause stronger scattering of incident light. Therefore, our SPA apparatus has a potential ability to simultaneously determine fiber and filler fractions in pulp suspensions with consistency up to 5%.

Conservation of cultural heritage treasures is the most important issue for transferring knowledge to the public through the next generation of students, academics, and researchers. Although this century is authenticating e-books and information by means of electronic text, still historical manuscripts as content as well as objects are the main original recourses of keeping a record of this transformation. The current work focuses on cleaning paper samples by the application of pulsed light, which is interventional. Experiments carried out using paper samples that are artificially colonized with Ulocladium chartarum. Paper is treated by Nd:YAG laser light. The available wavelength is 1064 nm, at various fluences, repetition rates and number of pulses. Two types of paper are stained with fungi colonies, which grow on substrates of clean paper, as well as on paper with ink text. The first type of paper is Whatman No.1056, which is closer to pure cellulose. The second type of paper is a page of a cultural heritage book published in 1926. Cleaning is performed using laser irradiation, thus defining the damage threshold of each sample. The treatment on paper Watman showed a yellowing, especially on areas with high concentration of fungi. The second sample was more durable to the exposure, performing the best results at higher fluences. Eventually, the paper samples are characterized, with optical microscopy and SEM/EDX analyses, prior to and after cleaning.

I have never encountered any controversy as to the fact that I created the world’s first laser. It’s also a fact that I obtained a patent on that laser and it was assigned to Hughes Aircraft Company. As a result of that issued and validated patent, I was installed in the National Inventors Hall of Fame.

In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

In this paper, we present the properties of flexi- ble planar optical waveguides made of siloxane-based polymer deposited on Xerox transparent paper and PLEXI- GLAS foil substrate. Measurement of optical properties such as the waveguiding properties and refractive index is carried out by the prism coupling technique for five wave- lengths (473, 632.8, 964, 1311 and 1552 nm) and propa- gation optical loss were measured by the fiber probe tech- nique at a wavelength of 632.8 nm (He-Ne laser). The measurement proved waveguiding properties for all meas- ured wavelengths and the losses generally did not exceed 0.40 dB·cm -1 ; the best samples had optical losses around 0.24 dB·cm -1 .

In this work we present a promising method for fabrication of conductive tracks on paper based substrates by laser assisted reduction of Graphene Oxide (GO). Printed electronics on paper based substrates is be coming more popular due to lower cost and recyclability. Fabrication of conductive tracks is of great importance where metal, carbon and polymer inks are commonly used. An emerging option is reduced graphene oxide (r-GO), which can be a good conductor. Here we have evaluated reduction of GO by using a 532 nm laser source, showing promising results with a decrease of sheet resistance from >100 M Ω/Sqr for unreduced GO down to 126 Ω/Sqr. without any observable damage to the paper substrates.

Mode-locked fiber lasers emitting short pulses of light at wavelengths of 2 μm and longer are reviewed. Rare-earth doped silica and fluoride fiber lasers operating in the mode-locked regime in the mid-IR (2–5 μm) have attracted attention due to their usefulness to spectroscopy, nonlinear optics, laser surgery, remote sensing and ranging to name a few. While silica fiber lasers are fundamentally limited to emission wavelengths below 2.2 μm, fluoride fiber lasers can reach to nearly 4 μm. The relative infancy of fluoride fibers as compared to silica fibers means the field has work to do to translate the mode-locking techniques to systems beyond 2 μm. However, with the recent demonstration of a stable, mode-locked 3 μm fiber laser, the possibility of achieving high performance 3 μm class mode-locked fiber lasers looks promising.

A class of energy light structures in nonlinear wave physics, so-called diffraction-beam tubes in a self-focusing dissipative medium, has been studied. It is shown that their interaction along a high-power femtosecond laser radiation propagation path produces areas of light energy localization, stable in physical characteristics, i.e., a filament and a post-filamentation channel, as well as an energy-conservative periphery. Stabilization of boundaries of the above areas is provided by additional contraction of a diffractive nature from the side of the periphery. The dependencies of filamentation length of a laser pulse on the power and beam radius and the fact of high intensity conservation in the post-filamentation light channel are interpreted using this concept.

A complete characterization of the inkjet printing process using metallic nanoparticle inks on a paper substrate for microwave frequencies up to 12.5 GHz as well as its application to low-cost, high gain and wideband antenna design are demonstrated in this work. Laser and heat sintering of metallic nanoparticles are compared on paper substrate for the first time which demonstrate immense cost and time benefits of laser sintering. The antennas fabricated using the characterized process include a Vivaldi for the UWB band which exhibits a significantly higher gain of up to 8 dBi as compared to the currently published inkjet printed antennas, and a novel slow-wave log periodic dipole array which employs a new miniaturization technique to show 20% width reduction.

We will introduce a new, direct view technology that can be configured in multiple shapes, form factors, and resolutions with examples of initial commercial deployment from large to ultra large sizes. This new display boasts high quality, real-time video with low power consumption, long life and low cost manufacturing infrastructure. In this paper, we will describe this new technology and its attributes in detail.

A novel and low-cost wall paper single-walled carbon nanotubes (SWCNTs) absorber was fabricated by high viscosity of polyvinyl alcohol (PVA) aqueous solution and vertical evaporation technique. Sandwich structure wall paper SWCNT (SSWA-SWCNT) absorber was constructed by a piece of wall paper SWCNT absorber, a piece of round quartz and an output coupler mirror. We exploited it to realize mode locking operation in a diode-pumped Nd: GdVO 4 laser. A pulse duration of 9.6 ps was produced with an average power of 870 mW. The stable mode locking operation was obtained when the average power is less than 300 mW.

Toner-print removal from paper would allow paper to be re-used instead of being recycled, incinerated or disposed of in landfill. This could significantly reduce the environmental impact of paper production and use. Previous work on the subject has explored the applicability of ultraviolet, visible and infrared (IR) lasers under nanosecond pulses for toner removal. This article expands on this work by testing a wider range of ultrafast and long-pulsed lasers. Results from 10 distinct laser set-ups are used to propose an operating window for the toner-removal process. Colour analysis under the L * a * b * colour space, scanning electron microscope examination and attenuated total reflectance–Fourier transform IR spectroscopy measurements of the outcome show that, with the right laser, it is possible to remove toner from paper to enable its re-use. Theoretical models to predict the laser ablation of toner are discussed, and, while imperfect, provide sufficient evidence to support a physical explanation of toner ablation.

Though it is said that the paperless age arrived with the spread of personal computers, the amount of office paper used shows no tendency to decrease. In general, used paper is recovered and recycled in order to preserve the environment. But labor and expense are required for the recovery of used paper and the recycled paper is lower in quality. If we could reuse used paper repeatedly without these disadvantages, for example, by using copying machines that could print again by removing the toner on used paper, it would be very convenient and ecological. We therefore studied the removal of toner from used paper by the laser ablation technique. As an optical source, an SHG-YAG laser was chosen. The energy density of irradiation with an SHG-YAG laser for the removal of toner from used paper was examined. At an energy density of approximately 12 mJ/mm2, which was the average value, the toner was removed sufficiently to allow reuse of the paper. The conditions of the laser irradiation, specifically the laser scanning speed and the number of irradiations, were studied. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 8–14, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21214