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Amorphous selenium (a-Se) is a photoconductive material that has been intensively investigated from its early application in xerography to its present application in flat panel X-ray imagers. It can be deposited up to a few millimeters thick over a large area. Its high vapor pressure yields uniform coverage in novel device structures for low-cost and large-area applications. The evidence of avalanche multiplication in a-Se and application of a-Se in high-gain avalanche rushing photoconductor video-tubes goes back to the early 1980s. Over the past decade there has been increasing research interest in novel detector structures and integration of a-Se with new materials to leverage the avalanche properties. We summarize some of the shortcomings of a-Se such as low charge carrier mobility, low charge conversion efficiency, depth dependence, and high dark current at high electric fields. We then highlight recent developments in a-Se-based devices to address these shortcomings and enable picosecond timing performance and high detection efficiency.

Triboelectrification is one of the most common effects in our daily life. When two materials come into frictional contact, they become electrically charged through triboelectric charging. Static electricity generated by triboelectrification, which has proven useful in many areas such as xerography, electrostatic air cleaning and electrostatic painting, on the other hand, can generate electric discharge, which is a hidden danger for petroleum transport and industrial production and may result in heavy casualties and economic losses. It is very important to reveal the mechanism of triboelectric charge generation and realize effective control of triboelectric charge quantity at the interface. Here we summarize the recent progress in the studies of interface control and utilization of triboelectrification. The challenge and prospective investigation trends of interface control and utilization of triboelectrification are also proposed and discussed.

Selenium is a semimetallic and covalent nonoxide amorphous semiconductor lying in Group VI of the periodic table. Selenium-based amorphous semiconductors have always been known as robust and hard materials, being utilized as high temperature semiconductors for advanced applications. Selenium-based thin films have very high electron conductivity and can be used as an ideal conductive layer (electrical conductivity lying between 10−13 to 10−3Ω−1cm−1) for a number of devices in the biomedical field that require electrical interface for biologic applications. Selenium as a biomedical material, helping out some basic technology, is used in various medical systems and devices. It can be produced in solid noncrystalline, monocrystalline, and polycrystalline forms owing to its operating capability under high temperature and high bond strength. Selenium is an essential nutrient in biologic tissues and also possesses antibacterial properties. Selenium, among different varieties of nanoparticles, has attracted huge attention owing to properties like good absorbing capacity, ability to interact with protein, higher bioavailability, and low toxicity, and it has accorded wide applications in medical diagnostics and use of nanobiotechnology for biologic systems. Presently, selenium nanoparticles are reported to have biofilm inhibiting properties besides being antioxidant and anticancer agents. It is contained in the active center of many functional proteins and antioxidant enzymes, and it plays a crucial role in reducing oxidative body stress. It also helps in preventing a number of diseases such as diabetes, cancer, hypercholesterolemia, and various cardiovascular diseases. Though selenium is crucial for numerous metabolic processes, its excess beyond the required concentration in body leads to selenium toxicity. selenium nanoparticles, therefore, have widespread application in solar cells, xerography, photographic exposure meters, and rectifiers.

Xerography digital printing technology is one of the main technologies of digital printing. Among them, toner xerography technology plays an important role in the invention and development of xerography digital printing technology. In order to study the origin and development of toner xerography technology, from the social needs Departing, on behalf of patented technology and representative products, by search of US patents related to toner xerography technology from 1938 to 2019 on the “State Intellectual Property Office” patent search platform and the research on technology and product development history of the manufacture of toner xerography digital printing equipment manufacturers, on the basis of analyzing the technology of patented and representative products of toner xerography, summarized the development history of toner xerography digital printing technology.

Amorphous Se is a well-known photoconductor from its early applications in xerography and ultra-sensitive photodetectors like the High-gain Avalanche Rushing Photoconductor (HARP) device. The established way of fabricating the photoconductor for the HARP is rotational thermal evaporation using multilayers of Se and As2Se3. However, the electronic effects of multilayering have not yet been clarified. In this report, we investigated the multilayer structure as a superlattice of Se and As2Se3 fabricated using rotational evaporation and show that the superlattice structure results in the uniformization of the defect levels in the base materials. We found four energy levels associated with defects in As2Se3 and three levels in amorphous Se. In comparison, the superlattice structure of the two materials shows two clear energy levels at EC,Se − 0.533 eV and EV,Se + 0.269 eV. The resulting two occupied energy levels explain the photoelectronic and transport properties observed in multilayer amorphous Se. This result “reinvents” the multilayer structure as a material with observed quantum effects, which significantly improves the material performance in photodetection.

The currently used digital printing methods e.g. Inkjet or Xerography are very costly on an industrial scale, because they use expensive consumables, specific inks and specially-coated substrates for the printing process. The laser-induced forward transfer of inks from a donor ribbon or roller to substrates allows for the use of inexpensive inks and paper as they are commonly used in today’s industrial rotogravure or offset printing. The challenge of this approach is to develop a fast direct laser writing unit which can cover an area of more than 1 m/min with a screen resolution of 300 dpi to 600 dpi and which allows for laser spot pointing accuracy of less than 4 μm and for a fine (8 bit) reproduction of each grey tone value of the printed image pixels. Due to the large area and the desired high printing speed, the laser power (mean) needs to be within a range of a few hundred Watts. At 20 to 25 MHz modulation rate of the high power laser beam and at a laser spot scanning speed of 800 to 2116 m/s over a scan field length of 530 mm, we demonstrated reproducible printing of commonly used, water-based environment-friendly and inexpensive inks.

1-Bis[4-[N,N-di(4-tolyl)amino]phenyl]-cyclohexane (TAPC) has been widely used in xerography and organic light-emitting diodes (OLEDs), but derivatives are little known. Here, a new series of solution-processable, crosslinkable hole conductors based on TAPC with varying highest occupied molecular orbital (HOMO) energies from −5.23 eV to −5.69 eV is implemented in blue phosphorescent OLEDs. Their superior perfomance compared with the well-known N4,N4,N4′,N4′-tetraphenylbiphenyl-4,4′-diamine (TPDs) analogues regarding hole-injection and mobility, electron and exciton blocking capabilities, efficiency, and efficiency roll-off is demonstrated. Overall, the TAPC-based devices feature higher luminous and power efficiency over a broader range of brightness levels and reduced efficiency roll off. A systematic broadening of the emission zone is observed as the hole-injection barrier between the anode and the hole-transporting layer increased.

We describe the progress in the science and technology of stabilized a-Se from its early use in xerography and xeroradiography to its present use in commercial modern flat panel X-ray imagers and ultrasensitive video tubes which utilize impact ionization of drifting holes. Both electrons and holes can drift in stabilized a-Se, which is a distinct advantage since X-ray photogeneration of charge carriers occurs throughout the bulk of the photoconductive layer. An a-Se photoconductor has to be operated at high fields to ensure that the photogeneration efficiency is sufficiently large to provide reasonable X-ray sensitivity. However, at high fields, the dark current is unacceptably large in simple metal/a-Se/metal devices, and special multilayer device structures need to be designed. The dark current decays with time and increases with the nominal applied field. The reduction of the dark current to a tolerable level was one of the key factors that lead to the commercialization of a-Se X-ray detectors. We discuss the origin of the dark current, and highlight some of the current challenges in the design of next generation detectors. We also discuss the origin of impact ionization in a-Se, and its fruitful utilization in ultrasensitive imaging devices, including the Harpicon, which are likely to lead to new high detective quantum efficiency detectors.

Semiconductor, Poly(vinyl pyrrolidone), Chemical reduction, SeleniumElemental selenium (Se) is a narrow band gap (~1.7 eV)semiconductor which has been extensively used in solarcells, xerography and rectifiers. It is also a photoconductorwith a relatively low melting point (~217 °C), high refrac-tive index and high reactivity leading to a wealth of func-tional materials such as Ag

Carbon-encapsulated magnetic nanoparticles are core-shell nanostructures with the mean size generally below 50 nm. Their unique properties result from the intrinsic nature of the encapsulated magnetic nanocrystallites and the high stability of the external carbon coating. Carbon-encapsulated magnetic nanoparticles may find different prospective applications, e.g., in magnetic data storage, catalysis, xerography, magnetic resonance imaging, and in biomedical applications. Herein, we present for the first time the results of the optical limiting properties of carbon-encapsulated magnetic nanoparticles. It was found that optical limiting performance strongly depends on the surface properties of carbon nanostructures rather than of their magnetic characteristics.

The xerographic process is one of the digital printing technologies with a potential for textile printing. One barrier to the use of xerography for printing textiles is the lack of textile-specific toners that produce the required textile properties. Attempts have been made to produce textile-specific toners through mechanical grinding processes such as jet milling, but mechanical grinding requires that the toner resins be sufficiently brittle. In our previous work, toner compounds containing resins that are sufficiently flexible for the required textile properties could not be ground to the required particle size for xerography. In this paper, thermally induced phase separation (TIPS) is used to overcome this difficulty. Isotactic polypropylene (IPP) and poly(ethylene-co-vinyl acetate) (EVA) are converted into toners by means of TIPS. The EVA polymers meet the flexibility and colorfastness require ments of textile printing.

We report the carrier transport properties of a furan-containing oligoaryl PF6, which contains no arylamine moiety in the molecular structure but exhibits competitive hole-transport capability in comparison with conventional arylamine-based hole-transport materials often used in organic light-emitting devices (OLEDs) and xerography. Thin films of this compound exhibit both morphological stability and appropriate energy levels for OLED applications. OLEDs using PF6 as the hole-transport layer show low turn-on voltage, high efficiency, and high brightness competitive with those using conventional hole-transport materials, strongly indicating superior hole-transport properties of PF6. The carrier mobility of PF6 was directly measured by the time-of-flight transient photocurrent technique under various temperatures and electric fields. Nondispersive hole transport was observed and a room-temperature hole mobility in excess of 10−3 cm2/V s was obtained under high fields. The field and temperature dependence of...

Amorphous selenium-based material could be used as the photoreceptor of a photocopy machine. For much more understanding of amorphous selenium (a-Se) photoreceptor, the aluminum oxide (Al 2 O 3 ) and amorphous tungsten trioxide (a-WO 3 ) were deposited onto polished aluminum substrates as the blocking layers using the thermal oxidation and vacuum sputtering systems, respectively. Next, we used a vacuum evaporation method for preparing the amorphous selenium film in order to complete the Al/Al 2 O 3 /a-Se and Al/a-WO 3 /a-Se photoreceptors. The optoelectronic properties of the samples were measured and compared. We produced photoinduced discharge curves (PIDC) using electrostatic paper analyzer, and the initial surface potential ( V so ), dark decay time ( t d ), photosensitivity ( E 1/2 ) and residual potential ( V r ) could be obtained. We can find that Al/a-WO 3 /a-Se photoreceptor has excellent optoelectronic properties. Furthermore, we also compared different blocking layers and isothermal annealing effects for the photoreceptors.

Over the past four decades xerography, the dry ink marking process developed by the photocopy industry, has grown from nothing into a $170 billion industry worldwide. This amazing commercial success is due to the fact that during this period, xerographic technology experienced constant and often-dramatic improvement created by sustained industrywide research and development. Indeed, the development of the xerographic copying and printing industry is one of the great applied surface science successes of all time. In this article we outline the story of the advances in xerographic technology during the past four decades, describe the profound dependence on these advances of the control of surface and interface properties of increasingly sophisticated multi-component materials systems, and indicate the potential impact on the industry of the continuing development of the surface and interface science of the multi-component materials packages used in xerographic technology.

We review here our recent work on a high dynamic range, subpicosecond x-ray streak camera. Our subpicosecond streak camera (PX1) has been coupled to a 10 Hz Ti: sapphire laser system and tested with 500 fs UV light pulses (266 nm) in jitter-free accumulation mode. A novel design for the photoconductive switches that are coupled to the camera’s deflection plates has been successfully used to eliminate the jitter induced by the laser intensity fluctuations and by the temporal shape of the laser beam. Results demonstrate that this detection system gives simultaneously a high dynamic range and a subpicosecond resolution at a repetition rate of 10 Hz.

This researchis a continuation of the development of 3D Xerography (3DX).The adhesion force between molten medium density polyethylene (MDPE) particles to a Teflon substratewas investigated. Special attention was placed on the molten state adhesion experiment as it is among the first of its kind to be performed. The experiment was done using the centrifuge method. The particles were placed on substrate, melted and spun at angular velocities up to 17000rpm and analyzed to determine the adhesion force. The experimental results show that the particle adhesion force increases as particle sizesincreases. In other words, the smaller the particle, the higher the tendency it detaches from the substrate. Due to the change in state from solid to liquid, wetting was observed to significantly increase adhesion force. It was further observed that the percentage of particles adhering to the substrate with respect to the adhesion force follows a log-normal distribution which conforms to results from earlier research. Published version

We demonstrate a photographic method to view the inversion of ferroelectric domains during the periodic electric field poling of KTiOPO4 by taking advantage of the electro-optic effect and a high speed charge coupled device (CCD) camera. The method is noninvasive and allows monitoring in situ and in real time. The high speed CCD camera opens up the possibility to observe the dynamics of the domains during poling and to probe the samples afterwards to evaluate the grating formed in the material. This monitoring method should be applicable to other ferroelectric crystals, as well.

The problem of stabilizing a single color tone reproduction curve of a xerographic printing engine is considered. This problem is critical to ensure high-fidelity color printing. The control system uses a small number of actuators and a small number of measurements to stabilize the potentially high-dimensional tone reproduction curve. The goal is to minimize the overall least squares deviation of the tone reproduction curve from the ideal nominal one in the face of disturbances like material changes, temperature, humidity, and uncertainty in the system description. The control design consists of the steps of (1) determining a robust optimally performing static controller and (2) realizing the controller that utilizes only past measurements. Numerical simulations and experiments validate the efficacy of the controller.

Xerographic printing of textiles was explored. A number of fabrics were printed using commercially available and synthesized polymers as toner vehicles. The polymers were characterized using standard methods (DSC, DMA, tensile tests). The performance of the prints was evaluated using textiles-specific tests (crockfastness, flexural rigidity). It was found that the initial modulus is a reasonable predictor of the performance of the printed fabrics. However, the requirements on toner vehicles for good textile performance (low initial modulus, flexibility) contradict the requirements for production of toner powders by grinding (brittle behavior). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2399–2407, 2001

The motion of single- and two-cavitation bubbles generated by laser beams directly beneath a free surface is studied experimentally, using high-speed photography, and theoretically using the highly accurate boundary integral method. Favorable comparisons of bubble shape history and centroid motion are observed while the numerical calculations provide information on the pressure field surrounding the bubbles. A range of responses, including the null impulse state, is obtained for the two bubbles depending on the bubble size ratio and the interbubble and bubble-free surface distances, although in all cases reported in this article, the bubble nearest the free surface yields a high-speed liquid jet directed away from the free surface. It is also found that when the free-surface–bubble interaction is strong, a fast free-surface spike is formed for both the single- and two-bubble cases.

Photogeneration of charge carriers in a methyl-substituted ladder-poly(para-phenylene) (LPPP) has been investigated by xerographic experiments. The quantum efficiency of charge carrier generation was calculated by evaluating the photoinduced discharge curves (PIDCs) and found to be independent of both excitation wavelength and temperature. The results can be described by a modified Braun theory with a simple exponential distribution of radii of thermalized electrons. LPPP shows a very high primary quantum efficiency of 80%, a low residual potential, and a small dark decay. Thus, LPPP represents a promising material to build single component single-layer photoreceptors.

Due to its superior photosensitivity in the visible wavelength region, amorphous selenium-based material is widely used as the basic photoreceptor material in xerography. The optoelectronic properties of the samples were measured and calculated with photoinduced discharge curve (PIDC) by using Electrostatic Paper Analyzer, and the initial surface potential (V so), dark decay time (t d), photosensitivity (E 1/2) and residual potential (V r) could be obtained. It is found that the contrast voltage which affects directly the resolution of image can be improved by the blocking layer between the bulk (such as a-Se, a-As2Se3) and substrate (Al). Furthermore, the relations between thickness and optoelectronic properties of photoreceptor could be identified, and compared with different blocking layers and isothermal annealing effect for the photoreceptors.

The xerographic properties of dual-layer photoreceptors having different molecular structure, are described with respect to their photosensitivities. A correlation between the absorption wavelength and the photosensitivity was found. A study on device optimization of 3,4,9,10-perylenetetracarboxylic diimides was carried out. The dual-layer photoreceptor device exhibited low dark decay and flat spectral response from 450–750 nm. The spectral sensitivity of the dual-layer photoreceptor extends to the near-IR region.

Textile printing systems are needed that will meet the requirements of time-driven, demand activated manufacturing. Xerography has the potential of meeting these requirements, but textile specific xerographic toners must be developed to gain acceptance of this technology by the textile industry. One thermoplastic and three thermoset-based toners were evaluated for xerographic printing on fabrics (cotton, silk, Dacron, nylon). The toners were successfully applied to the fabric using xerography, however, toner transfer efficiencies to fabrics were low. The textile print properties were compared with commercial rotary screen and hand screen printed fabrics. Color fastness to crocking (rubbing) varied with type of toner and fabric characteristics such as fiber type and fabric weight. Crosslinking of thermoset toners resulted in crockfastness that was superior to conventional screen print. Surface morphological studies were used to characterize the failure mechanisms occurring during the crocking tests. Wet and dry friction properties of the printed fabrics were studied in an effort to explain the crocking results. Fabric flexibility, a key component of fabric hand, depended significantly on fabric weight. The toner type significantly affected flexibility for the lighter weight fabric, but had little effect for the heavier weight fabric.

Based on the light extinction of total internal reflection by triangular prisms, very sensitive detection of the shock front and fast moving free surface has been demonstrated for 1 GPa shock waves in polymers. This is the first experimental verification of the feasibility of the inclined-prism technique for the relatively low shock stress region, which was originally proposed and used by Eden and Wright for obtaining the high-explosive generated shock Hugoniot of several condensed materials. The present method has the advantage that it only requires closing the gap between the free surface of the target and the reflected surface of the prisms. The feasibility and the limitation of the method have been discussed both theoretically and experimentally. A typical streak photograph for a PMMA specimen is shown to compare with the published data. It is seen that the present method is very sensitive for shock arrival detection even in the 1 GPa shock stress region.

Multilayer amorphous selenium-based photoreceptors were prepared by thermal evaporation in a vacuum at . Amorphous multilayers of Se/CdSe, as well as a combination of a thin film and multilayers were used as photogeneration layers. `Pure' Se or were the transport layers. The xerographic properties of the photoreceptors were studied and some peculiarities of the charge transport in different designed photoreceptors are discussed. Xerographic photosensitivity at illumination with different wevelengths was determined and a comparison with the sensitivity of conventional photoreceptors is made. All photoreceptors are photosensitive in the whole visible region. The photoreceptors including are also sensitive in the near-infrared region. The xerographic properties of the studied photoreceptors remained unaltered in air at room temperature for more than 12 months.

We examined both photoconductive and electro-optical properties of the monolithic photorefractive polymer. The photoconductive sensitivity of 1.2 × 10−12(S cm−1)/(W cm−2) was obtained under a field strength of 5 × 105V/cm and a wavelength of 534nm. The EO signals linearly increased with the poling electric field.

Ballistic Aerosol Marking (BAM) is a radically new printing concept that combines the simplicity of a direct marking technique such as inkjet printing with the quality and color range/stability of Xerography. This is achieved by using high-speed gas jets as the transport fluid and Xerographic toner particles as the marking material. In this paper we will provide an introduction into this novel concept, discuss design considerations from Computational Fluid Dynamics (CFD) and electrostatics simulations, and show some proof-of-concept results from single channel experiments.

This article examines the impact of copy machines on late twentieth-century print cultures. Specifically, this article makes a case for “dry copying,” the method of print reproduction perfected by Xerox in the late 1950s, as a unique medium rather than a weak imitation of other printing methods. Following the claim that the widespread availability of copy machines in the late twentieth century represented the arrival of a new medium, this article further examines how understandings of authorship, established with print culture, came undone in the era of the copy machine. Finally, this paper makes a case for understanding copy machines as a form of “social media” that opened up opportunities for writers, readers and publishers to create, share, exchange and comment on texts and images in communities and networks of their own making in the decades preceding the development of the web.

Electro-optic devices such as fast (>20 GHz) modulators are one application of ferroelectric-oxide thin-film waveguides. A compact, blue laser source of a few milliwatts power capable of lasting thousands of hours is of great interest as applied to optical data storage and xerography. Ferroelectric-oxide thin films offer several potential advantages over bulk materials for optical waveguides, though no electroceramic thin-film devices have replaced bulk devices yet. Bulk waveguides are defined by ion exchange, which produces only a small index difference. Thin films therefore permit higher intensity per unit power in the guide, and hence larger nonlinear effects and shorter interaction lengths.

The optimum x-ray spectra for acquisition of digital mammographic images using an amorphous selenium (a-Se) photoconductor are investigated. The recorded images consist of latent charge distributions on the surface of an a-Se plate, which are then read out using two methods, laser discharge, or flat panel recharge. The investigation is based on a model of the breast previously developed for a phosphor-based digital readout system, and has been extended to include the effects specific to the use of photoconductors. The effects of plate thickness, x-ray scatter, readout noise, dose, and the kind of breast tissue on the nature of the optimum spectrum are explored for the two readout methods. The results indicate that use of a kilovoltage setting in the current mammographic range, and a molybdenum target spectrum is appropriate for digital readout of a-Se detectors. This conclusion contrasts with the appreciably higher kilovoltages traditionally used with the xerographic (toner) readout of latent charge images on a-Se.

The spectral selective thermography with infrared filters can be used to determine or to distinguish materials such as contaminations on a metallic component. With additional visual information, the indications by the IR signal can be selectively accentuated or suppressed for easier evaluation of passive and active thermography measurements. For flash thermography the detected IR signal between 3.4 and 5.1 μm is analyzed with regard to the spectral material information. The presented hybrid camera uses beam overlapping to obtain combined images of both in the infrared and the visual range.

In the 1930s, Chester Floyd Carlson invented Electrophotographic Printing, which was later named xerography. Xerography has played an eminent role in the evolution of the Information Age. This invention has revolutionized the way information is processed and disseminated. It provides a cheap, simple, and reliable way of reproducing and creating documents. The development of xerography has led to new technologies that might eventually eradicate traditional offset printing machines. A crucial part of this technology is the photoreceptor, which optically captures information. Accurate photoreceptor performance requires the properties of photoelectronic, electrostatic, mechanical, and fabrication materials, which are amorphous. This chapter presents an overview of the xerographic process, its basic steps, and the relevant physical phenomena involved in the formation of latent imagery. Emphasis is placed on the electronic properties of amorphous selenium. This chapter also draws attention to the history and market of xerography and discusses alternative powder marketing technologies. It provides the physics within each step of the xerographic process.

The location and bonding of atoms and molecules on surfaces is of great interest to surface chemists and to those interested in the application of surfaces through exploitation of their unique properties. These properties include chemical properties that give rise to selective adsorption and heterogeneous catalysis; mechanical properties that control adhesion, fric­ tion, slide, or fracture; electrical properties utilized in microelectronic circuitry and xerography; magnetic properties used in information storage on tape or disk drives; and optical properties that give rise to nonlinear effects such as second harmonic and sum frequency generation. During the past 25 years, over 50 new techniques have been developed that permit the investigation of surfaces on the molecular level (l). The ability to study surfaces with increased time and spatial resolution (and energy resolution, when applicable) controls the development of many surface technologies. The contributions of science push and surface technology pull have resulted in an exponential growth in the field of surface science and pro­ pelled it among the frontier fields of physical chemistry. Several new surface science techniques permit quantitative deter

Dyes for optical recording systems such as laser optical recording systems, laser printing systems, cycolor and related systems, xerography and so on are reviewed. Infrared absorbing (IR) dyes are newly designed for laser optical recording systems such as DRAW and erasable type recording systems. The chemistry of IR dyes developed the new fields in dye chemistry. Many of functionalities in dye chromophores are newly developed for optical recording systems such as PHB and cycolor systems. New technology has developed new dye chemistry and new characteristics of dye chromophores advanced the technology for new optical recording systems.

We present a new type of streak camera to measure the temporal shape of pulses in the extreme ultraviolet (XUV) region: A cloud of noble gas atoms is used as a photocathode. The first results at 57 nm show a time resolution of 10 ps. Modifications to improve the time resolution are discussed. Using a noble gas as a photocathode has the potential to decrease the temporal resolution of the streak camera in the XUV to less than 0.5 ps.

This paper is devoted to the scientific study and engineering application of cyclic systems. Cyclic systems are non-traditional plants, containing devices with rotating dynamics along with actuators and sensors fixed in inertial space. The combination of rotating dynamics and inertially-fixed inputs and outputs leads to one-per-revolution (or stroboscopic) actuation and sensing. Control of cyclic systems amounts to designing a regulator that uses stroboscopic actuation and sensing to force the system into the desired regime. Although cyclic systems are periodic, the general theory of periodic control is not immediately applicable due to stroboscopic actuation and sensing. Because of rotating dynamics, the theory of impulsive control is not applicable as well. This work develops an approach to the control of systems with both rotating dynamics and stroboscopic instrumentation, and reports the initial application to a xerographic process.

The operating parameters required of a laser-scanning system to give optimum line and pixel reproduction are calculated. The shapes of isolated lines and pixels are predicted as a function of the output scanning parameters. Isophote maps for these lines and pixels are given for a sampling of scanning parameters. A sensitivity analysis demonstrates the effect of variations in laser power and variations in photoreceptor sensitivity. It is shown that laser-scanned xerographic systems are least sensitive to variations in laser power and to inhomogeneities in photoreceptor sensitivity when the system is operated in tight-focus conditions, i.e., the percent intensity at overlap is < or =50%.

Based on earlier publications it is shown that the theory of the modulation transfer function (MTF) may be applied to the vertical component of the electrostatic field. Whether the theory may be applied to the visible xerographic reproduction depends on the development method which also has an effect on the curve shape of the MTF. The MTF may be applied to pictorial reproductions but not to line copy with strong adjacency effect.

In order to visualize molecular interaction by the experimental electrostatic potential analysis we have optimized the optical parameters and developed the high‐resolution Debye‐Scherrer camera at the RIKEN materials science beamline, BL44B2 of SPring‐8. For the purpose the camera was designed to be equipped with the hybrid X‐ray detector system. One is the conventional detector, the imaging plate readout off‐line to carry out high d (interplanar spacing)‐resolution measurements and the other is the CCD detector, which can be operated in a camera at variable distances for high angle‐resolution measurements. In addition we have been developing an in‐situ properties measurement system to visualize the electrostatic interaction completely synchronized with material functions.

Publisher Summary Xerography (or electrophotography) is a dry photocopying technique. Xerographic techniques that were initially developed to characterize properties of electro photographic (xerographic) receptors seemed to be informative, suitable, and widely applicable for the study of amorphous thin films and photoconductive insulator thin films. Today this technology is used in photocopy machines, laser printers, and digital presses such as the Xerox iGen3 and Xeikon presses, which are slowly replacing many traditional offset presses in the printing industry for shorter runs. By using a cylinder to carry the photo sensor, automatic processing was enabled. A metal cylinder is mounted to rotate about a horizontal axis. This is called the drum. The end-to-end dimension is the width of print to be produced plus a generous tolerance. The drum in the copiers originally developed by Xerox Corporation was manufactured with a surface coating of amorphous selenium applied by vacuum deposition. Amorphous selenium will hold an electrostatic charge in darkness and will conduct away such a charge under light.

Laser scalpels are currently used as a form of laser treatment. However, their ablation mechanism has not been clarified because laser excision of biological tissue occurs over a short time scale. Biological tissue ablation generates sound (laser‐induced sound). This study seeks to clarify the ablation mechanism. The state of the gelatin ablation was determined using a high‐speed video camera and the power reduction of a He‐Ne laser beam. The aim of this study was to clarify the laser ablation mechanism by observing laser excision using the high‐speed video camera and monitoring the power reduction of the He‐Ne laser beam. We simulated laser excision of a biological tissue by irradiating gelatin (10 wt%) with radiation from a pulsed CO2 laser (wavelength: 10.6 μm; pulse width: 80 ns). In addition, a microphone was used to measure the laser‐induced sound. The first pulse caused ablation particles to be emitted in all directions; these particles were subsequently damped so that they formed a mushroom cloud....

Charged particles are involved in many applications such as electrophotography, electrostatic painting, and electrostatic precipitators. Electrophotography was invented in 1938 as a copying technology by C.F. Carlson who named it xerography. Its commercialization began with the Xerox 914 copying machine by the Xerox Corporation (the Haloid Company at that time) about a half century ago. A historical review of the development and success of the corresponding industry is beyond the scope of this book.

Publisher Summary For many years, amorphous semiconductors were not considered suitable as photovoltaic cell materials due to the difficulty experienced in doping such materials to produce the necessary p–n junctions. Eventually, the most familiar application of amorphous semiconductors came to be in the field of replication of printed matter. The xerography process, upon which many modern photocopiers are based, involves the ability of an electrostatically charged plate of amorphous chalcogenide (or similar material) to discharge under illumination. Residual charging of illuminated areas is employed in the transfer of “ink” onto the duplicator paper. Naturally, the mobility of photoinduced carriers in the amorphous semiconductor photoreceptor is of central importance in the validity of the process, and considerable commercial effort has been (and is being) devoted to the study of transport in disordered materials suitable for the process. A second major application of amorphous semiconductors, of comparatively recent emergence, concerns the conversion of solar energy into electrical power.

Amorphous Se–Te–P photoreceptor films of various compositions were deposited on to Al substrates by conventional vacuum evaporation techniques. Both xerographic and charge transport measurements have been carried out on the films to evaluate their possible suitability for photoreceptor applications. In xerographic measurements, the photoreceptor films were corona charged to a voltage (V0) and then photodischarged by illumination under light of preselected wavelength (λ) and constant intensity (I). Xerographic photosensitivity (S) was obtained from the photoinduced discharge characteristic via the empirical definition S = (V0 – V1/2)/V0t1/2I where V1/2 = V0/2 is half the initial voltage and t1/2 is the time taken to photo-discharge the surface potential to V1/2. The photosensitivity was studied as a function of illumination wavelength and material composition. Charge transport measurements were carried out using a time-of-flight transient photoconductivity technique to determine the electron and hole mobility – lifetime (μτ) products in the films. The results indicate that Se–Te–P alloys have poor xerographic photosensitivity in the short wavelength region (e.g., λ ~ 500 nm) owing to poor electron and hole transport, but in the long wavelength region (e.g., λ ~ 800 nm) the photosensitivity is considerably higher than the Se–Te system.