We describe a fabrication method for arrays of microlenses of low f-number by using a surface coating and dispensing technology. We demonstrate how to achieve a low f-number by selectively changing the surface wettability, as well as how to precisely control the f-number through control of the dispensing time. This advance enables the fabrication of arrays of microlenses with diameters varying from 400 to 1400 μm, f-number as low as 0.95. In addition, the optical performance tests indicate that this method is suitable for high performance microlens array fabrication. This dispensing technology may be low cost and allow fast fabrication of high-speed microlens arrays, and may thus be particularly useful for biologically inspired advanced optical systems.
With smaller pits and lands in multi-level optical disks using signal waveform modulation than those in DVD disks, the ISI and nonlinear attenuation of the read-out signal become more serious. One ordinary way is using an equalizer at sample rate 1/T, we proposed one method of designing the equalizer in fixed sample rate with digital interpolation. According to the analysis of the multi-level optical disk channel, we get the target frequency-response cure and implement it with seven order FIR filter. From the result of the read out experiment with multi-level optical disk, the clock of the RF signal could be recovered with the proposed equalizer.
This paper presents a novel adaptive signal quality evaluation method for Signal Waveform Modulation Multi-Level (SWM-ML) disc. The experimental results show the adaptive signal quality evaluation method is useful and proper for SWM ML disc.
A new jitter measurement method for multi-level discs is presented in this paper. This method, with merits such as high precision, flexible and low cost, combines the traditional pulse counting method and interpolation algorithm. The principle of this method is explained in detail, and its precision is analyzed. The analysis result is shown to be very effective. It has a broad application prospect and practical value in quality evaluation of multi-level discs.
A new kind of multi-level recordable disc is presented in this paper. By improving the recording control signal in DVD-R/RW burning process, a Multi-level disc with signal waveform modulation can be achieved. The multi-level recording method increases the recording density but also the channel noise. The optimally designed partial response maximum likelihood (PRML) equalizer is effective in recovering channel symbol, and the original error rate reach 10E-4. This kind of multi-level method can be used for the purpose such as increasing the capacity of disc, hiding data and burning disc identification information etc.
This paper presents the new development of the signal waveform modulation optical disc. The signal waveform
modulation optical disc is realized through inserting a sub-pit/sub-land into an original land/pit. More storage states are
realized with changing the size and position of the sub-pits/sub-lands, which influence the corresponding readout signal
waveforms. Modulation code and its realization are key technologies for signal waveform modulation optical disc. In this
study, we employ maximum run transition code and level modulation process as the modulation code of signal waveform
modulation optical disc. A 5/6MTR (2, 10) code is designed as the first step of the proposed modulation code, and the
level modulation process are used to avoid multilevel on shortest runs. The realization process of the proposed code is
presented, and the maximum level numbers for different run-length marks are investigated with the calculated readout
This paper presents the improved readout system of multi-level signal waveform modulation read-only disk. The
experimental results show the performance of the improved readout system is better than that of the former system.
Multilevel modulation coding is the core technology for multilevel optical storage. The technology is employed to
increase the capacity of the read-only disc with no change on original recording symbols size. With the combination of
multilevel modulation and the run-length limited modulation, short run-length with low levels can form long run-length
with high levels while it also suitable for long run-length by short run-lengths. And the DC-suppression can be controlled
by the allowance of long run-length without sacrifice effective bits. This double-modulation scheme not only can
improve coding efficiency, but also can greatly increase the recording density. In this paper, the theory of multilevel
run-length limited modulation coding is discussed. And a high rate of 6/7, five level (1,8) code scheme is proposed. This
scheme can increase the recording density compared to that in of DVD. Therefore, it is expected that this proposed
scheme could be used for the next high-density multilevel run-length limited modulation optical storage system.
Our team have proposed and implemented a new type of multi-level DVD, which features in using the waveform to
differentiate levels. Servo accuracy is an important issue for an optical disk system, since it can directly influence the
quality of readout signal. This paper analyses the influence of servo error on the readout signal for our multi-level DVD
using numerical simulation. A readout model is established, where focus error (FE) and tracking error (TE) is introduced.
A new parameter, waveform deviation, is proposed to quantitatively evaluate the influence. Simulation results show that
the influences of TE/FE on readout signal are similar. Each of them will shrink the dynamic range of readout signal.
When TE/FE exceeds a threshold, the waveform deviation will increase sharply.
Multilevel storage is the easiest two-dimensional storage technology. On the basis of recording and read-out optical
system of Digital Versatile Disc (DVD), by the method of multilevel run-length coding, the storage capacity can be
increased by 60 percent of DVD9's, reaching 14 Giga Bytes.
In order to meet the requirement of a 10-4 raw Bit Error Rate (BER) of data readout, this paper presents a method of
multilevel run-length coding with changeable level numbers. This method can take advantage of run-length redundancy
to the utmost and reduce Inter-Symbol Interference (ISI) caused by multilevel run-length. Multilevel run-length coding
uses the method of two steps modulation. This paper introduces a coding method of DK (1, 9) and R=1 code rate.
Realized by Pulse Width Modulation, multilevel run-length modulation coding with changeable level has good
symmetry. Its readout characteristics are the same as that of DVD with normal run-length modulation, therefore the
servo control system needn't be changed. Also the signal can be recognized in two aspects respectively, run-length and
level. In the sample disc, average raw BER in the two aspects is less than 10-3.
Multilevel run-length modulation coding could be applied in various systems of run-length modulation coding. On the
basis of the structure and characteristics of the primitive system, the comprehensive efficiency of coding could be
increased by 33 to 50 percent.
A novel design of physical format coding system (PFCS) is presented based on Multi-level read-only memory disc (ML
ROM) in order to solve the problem of low efficiency and long period of disc testing during system development. The
PFCS is composed of four units, which are 'Encode', 'Add Noise', 'Decode', 'Error Rate', and 'Information'. It is
developed with MFC under the environment of VC++ 6.0, and capable to visually simulate the procedure of data
processing for ML ROM. This system can also be used for developing other optical disc storage system or similar
channel coding system.
Nowadays, OMNERC research group is going to advance the capacity to 15GB by reducing the 3T pit length and
increasing the level of long pit based on the signal waveform modulation (SWM) ML recording technology. In order to
prove this method is realizable, this paper proposes the restriction points of consideration to reduce the minimum pit
length which influence the basic specification design of multi-level disk and the difficulty of the following signal
processing. Firstly the restriction of optical pick-up resolution is considered. Secondly, the restriction caused by read-out
channel is discussed in the paper. At the same time as write strategy has its limit based on the previous research, this
paper finally discuss the influence caused by minimize shortest pit length for level design of long length pit.
Multi-level run-length limited (ML-RLL) recording technology can increase the capacity of the read-only disc without changing the optical and mechanical units. The characteristic of the push-pull signal of the multi-level run-length limited read-only disc is analyzed and compared with that of the conventional DVD read-only disc. Experimental results show the effect of the variation of pit depth is more than other parameters and the peak-to-peak amplitude of the push-pull signal in the ML-RLL read-only disc is about 2.9 times of that in the DVD read-only disc while the variance is nearly 3.2 times. The push-pull method in the ML-RLL read-only disc is more sensitive than that in the conventional DVD read-only disc.
In this paper, we discuss a bus sharing architecture to implement a minimal unit for DVD jukebox. The bandwidth of host channel is usually tens times of the data rate of one disk. We integrate several DVD-ROM by sharing one ATA bus. It can fill the host channel by data transfer phase as much as possible. The shared ATA bus can be one or more to reach the bandwidth of host. And a queue and buffer algorithm to improve the performance of response time and synchronize is also introduced.
With the development of computer network, information sharing is becoming the necessity in human life. The rapid development of CD-ROM and CD-ROM driver techniques makes it possible to issue large database online. After comparing many designs of dummy CD mirror database, which are the embodiment of a main product in CD-ROM database now and in near future, we proposed and realized a new PC based scheme. Our system has the following merits, such as, supporting all kinds of CD format; supporting many network protocol; the independence of mirror network server and the main server; low price, super large capacity, without the need of any special hardware. Preliminarily experiments have verified the validity of the proposed scheme. Encouraged by the promising application future, we are now preparing to put it into market. This paper discusses the design and implement of the CD-ROM server detailedly.
How an eight-terabyte CD-ROM storage system could behave as a standard CD-ROM peripheral device without a specifically designed device driver on any operation system is discussed in this paper. Because normal tertiary storage systems can hardly hold a capacity with terabyte magnitudes, so a new file system based on Small Computer System Interface (SCSI) is presented, which can address as many as eight-terabyte storage memories. An experimental system called 'Virtual CD-ROM' system of this idea is discussed, and some techniques critical to the fulfillment of such a system are considered.
A holographic element for the common CD pick-up to play DVD is designed in this paper. The focus of holographic element is the same as that of the objective lens of CD player. The holographic element is fixed before the objective lens. The focus of DVD player with this holographic element is 8.5 mm, the number aperture is 0.75, and the focusing beam spot is 0.5 um. DVD player with the holographic element is characteristic of compensating the main optical error met in the common CD player well.
A real time non-contact dynamic testing method for an optical disk is proposed in this paper. The axial run-out and the tilt of the optical disk are measured by two quadrant detectors when the disk is turning at high speed in the drive. The analysis of the results is given with a brief discussion on the error in measurement.
A fully separated optical head means that the carrier and the actuator are separated completely. It causes the mass of the carrier to be less than 10 grams, or even less. It can increase the access rate greatly and avoid the cross interference between two stage seekings.