The light trigger and light quench static induction thyristor (LTLQ-SIThy) is described on the optical triggering and quenching mechanism. The static induction gate structure provides the high turn-on gain. Static induction photo transistor (SIPT) is used for the quenching device. The SIPT gives the high gain of the LTLQ-SIThy at turn-off. This functionally integrated power device propose the high efficiency to switch the large energy. The new LTLQ-SIThy which utilizes the LQ-SIThy for the quenching device is reported. This LTLQ-SIThy is improved the switching ability in the large current, the dependency of temperature and the controllability by the trigger/quench light.
We consider quantum-effect devices based on the resonant tunneling and charge-injection devices based on the real-space transfer. These devices can be operated at high speed and can perform complex and novel circuit functions with reduced component counts. Therefore, these devices will find important applications in future microelectronics.
Scanning tunneling microscopy (STM) is used to study the surface roughness of thin film magnetic recording disks obtained from various vendors. The height distributions of the disk surfaces are obtained and the bearing area curves are examined using `probability scaling.'' Skewness and kurtosis of the individual disk surfaces are calculated and deviation of the height distributions and bearing area curves from Gaussian behavior is determined. Surface roughness data from scanning tunneling microscopy measurements are compared qualitatively with those obtained from optical noncontact profilometry.
An application of digital servo control on a high-performance voice coil motor positioning system in hard disk drive is discussed. Modern digital control theory is used in servo algorithm design, and the servo algorithm is implemented by a high-speed microprocessor, OES 22040 model. The experimental results show the excellent properties in time domain and frequency domain.
This paper investigates the validity of fuzzy algorithms applied to the control of head- positioning of hard disk drives, which require faster response and higher accuracy compared with other industrial products.
In order to divide the disk surface into optimum zones, the head/media margin characteristic curve at various transfer rate throughout disk surface is needed. Margin is derived from half window minus bit-shift value. According to the curve, once the constant margin threshold is set, then the optimum zone number is also determined. Each zone is determined by the intersection of a particular threshold and margins curve at different transfer rate. In this paper, two new methods are developed to divide zones. First, the setting threshold to a constant margin (nsec), one third of the half window of the inner-most transfer rate, 13.3 Mb/s, six zones can be obtained and total capacity is 42.0 MB, which is 26.3 increment by comparing with the capacity of the single zone. Second, setting the threshold to a relative margin ( of the half window, the same number of zones also can be obtained with 44.4 MB total capacity, which is 33.5 increment by comparing with the capacity of the single zone.
Information storage in DASDs is a key part of a computer system. The worldwide revenue opportunity for DASD products is more than $50 billion. In order to meet the ever-increasing demand in capacity, performance, and cost-savings, rapid technological advances in magnetic recording have been carried out in laboratories around the world. The recent development for laptop and notepad PCs further demands the need for low power and smaller files. The technology trends in magnetic recording in terms of areal density, volumetric efficiency, and material advances based on published data are reviewed. Optical storage including read-only, write-once, and read/write drives becomes an emerging technology with a removability feature, which may complement magnetic recording DASDs. The recent advances in optical storage media and drives and their comparisons with magnetic recording technology are discussed.
In the optical system of a split type magneto-optical disk drive, the most serious problem is that optical axis tilt and position shift of the moving part could induce large tracking offset. In this research, a mask is used to confine the beam reflected from the disk, such that focus and tracking error signal can be modified. In this way, tracking error signal drift caused by the actuator, while track following, can be decreased. In addition, the DC tracking offset of the moving part, while moving along the guide rod, can be reduced. Crosstalk between tracking and focus signal also can be lowered. In this paper, the optical system simulated by ray tracing and the design of the mask are studied. The test results of the system show that the mask can successfully decrease the tracking offset caused by optical axis tilt and position shift of the moving part.
High frequency (HF) modulation method is commonly used in magneto-optic (MO) disk drive to reduce the laser noise, which is mainly caused by optical feedback (OFB). In this paper, the noise behavior of three commercial laser diodes is studied, to find their optimum operating conditions. It shows that their optimum conditions are significantly different. In addition, two of them are very sensitive to temperature while the other one is not.
Using the error diffusion method to print documents through a medium resolution (typically between 300 dpi and 600 dpi) printer has three drawbacks: (1) the snake-like noise disturbs the white background; (2) the printed image is too dark to distinguish the details; (3) the printed text exhibits a coarse edge. In this paper, the authors propose some methods to overcome these shortcomings. In order to eliminate the first shortcoming, a white minimum threshold value is set to calibrate the diffused errors. For the second shortcoming, a tone-scale adjustment function is used to lighten the images. Finally, an edge enhancement algorithm is introduced to overcome the third shortcoming.
Coupling efficiencies for 32-wide, batch-aligned arrays of laser-fiber interconnects were measured and compared to the efficiency obtainable with individual alignment. The tests were carried out using 1300 nm, InP ridge lasers and Corning SMF-28, single-mode optical fibers. In this paper, the associated fabrication and alignment techniques are described briefly. Results are given showing how coupling efficiency depends on misalignment, on laser-to-fiber distance, on fiber bevel angle, and on piece-to-piece variations among lasers and fibers. A direct comparison of batch alignment versus individual alignment is also given, which shows that the average batch-aligned efficiency is about 88 percent as large as the individually aligned (optimal) efficiency. This result, which reflects a particular packaging methodology and best-effort alignment, gives a good indication of the coupling efficiencies which may be typically expected for wide, batch-aligned arrays.
The optical lens quality is traditionally justified by resolution. But the modulation transfer function (MTF) is a better way to measure the optical lens quality than resolution. Before the introduction of linear CCD, it was very difficult to measure the MTF because it was both time consuming and costly. A low cost, high speed MTF measurement by linear CCD has been successfully developed here. Besides the MTF measurement, the important lens characteristics like distortion, optical axis misalignment, relative F number, magnification, and back focus length also can be measured by this system with a very high speed and low cost fully computerized system using a personal computer (PC). This system has been applied in industry and has been proven to be a useful instrument for optical lens characteristics measurement.
A roseet scanning pattern is expressed as the vector sum of two counter-rotating vectors. For a Cassegrain system, the scanning pattern is a function of system parameters such as the canted angle, the scanning rate ratio, the configuration of each scanning element, and the distance between them. Using the optical ray tracing method along the direction of the system axis, an algorithm to compute the pattern is derived. This method can be employed to design a scanning-pattern system. By adjusting the system parameters, the desired scanning pattern can be obtained. Finally, by computer simulation with this design algorithm, the results including the effect due to the deflection error are consistent with the experimental observation.
A novel tunable optical filter with a tuning speed of 2 microsecond(s) , a tuning range of approximately 60 nm at 1.55 micrometers , and a resolution of 0.5 angstrom (6.3 GHz) has been proposed and demonstrated for application in wavelength division multiaccess computer network. The principle of operation is by positioning an optical beam emitting from an optical fiber that carries all wavelengths onto two crossed wedge etalons. Depending on the location of the optical beam incident on the etalon assembly, only a certain wavelength that matches the thickness of the etalons at that location is transmitted. The optical beam positioning is achieved by two single-axis acousto-optical deflectors. The number of channels supported by the filter is estimated to be approximately 600.
The readout process of magneto-optic disk is analyzed to develop a statistic method of measuring the parameters of micron-sized laser beam and geometric parameters of recorded information. Real-time, fast, and high accuracy measurement can be achieved with the method.