摘要:
Proposed is a method and apparatus for writing/reading a data block onto/from an information carrier with M-spots schemes and such an information carrier. The method comprises the steps of dividing the data block into N portions according to predetermined writing capacities for each one of the N writers of the M-spots schemes, N and M being integers not less than 2 and N
摘要:
Presently known d=1 codes have long trains consisting of consecutive 2T runs and an overall high frequency of occurrence of the shortest 2T runs that reduce the performance of the bit detector By using a code with an MTR constraint of 2 an improvement in the bit detection is achieved. A code constructed in a systematic way that provides an MTR constraint of 2 is presented. A variation of such a code is disclosed where one sub-code is used, where coding states are divided into coding classes and where code words are divided into code word types. Then, for a given sub-code, an code word of type t can be concatenated with an code word of the next sub-code if said subsequent code word of said next sub-code belongs to one of coding states of the coding class with index Tmax+1 t. In the code according to the invention the overall code has the property that the respective channel bit sequences that are encoded from the same message-bit sequence, starting from any possible state of the finite-state-machine, for each of the two values of a DC-control bit, that is part of a given user word have opposite parities for the sequences generated from the starting state up to the state where both encoder paths merge. For the case that the encoder paths do not merge, there is no such constraint. Finally, a new d=1, k=10 sliding-block decodable RLL code is disclosed with the following properties: (i) it has an r=2 constraint which is the lowest MTR value that is compatible with a rate R=⅔; (ii) it enables practical SISO-RLL decoding because of its compact 2-to-3 mapping; and (iii) the new code uses a parity-complementary word assignment4 (PCWA) for DC-control.
摘要:
This ID proposes synchronization patterns for RLL codes with a (repeated) minimum transition run (RMTR) constraint, where the synchronization pattern comprises a synchronization pattern-body that contains a characteristic bit-pattern that represents a violation of the RMTR constraint. Using a violation of the RMTR constraint allows for short synchronization patterns.
摘要:
Presently known codes have long trains consisting of 2T runs that reduce the performance of the bit detector. By using a code with an RMTR constraint of 2 an improvement in the bit detection is achieved. A code constructed is a systematic way that provides an RMTR constraint of 2 is presented. Several variations of such a code are disclosed where one or more sub-codes are used, where coding states are divided into coding classes and where code words are divided into code word types. Then, for a given sub-code, a code word type t can be concatenated with a code word of the next sub-code if the subsequent code word of the next sub-code belongs to one of coding states of the coding class with index Tmax+1−t.
摘要:
An information system according to the invention comprises a record carrier and a playback apparatus. The record carrier has information marks along a track thereof and exhibits first variations caused by existence and nonexistence of the information marks along the track. The first variations represent an information signal recorded on said record carrier. The record carrier further exhibits second variations caused by variations associated with the information marks. The phase of the second variations is coupled to the phase of the first variations.
摘要:
A target for measuring an overlay error or a critical dimension of a substrate comprises a grating. In one example, lines of the grating are arranged at an angle of about 45° with respect to edges of the target. As a consequence, the diffraction order of the grating reflection has its sub-maxima not aligned along the line on which the other diffraction orders are positioned, and overlap of intensity with other diffraction orders is reduced.
摘要:
Calibration of an angularly resolved scatterometer is performed by measuring a target in two or more different arrangements. The different arrangements cause radiation being measured in an outgoing direction to be different combinations of radiation illuminating the target from ingoing directions. A reference mirror measurement may also be performed. The measurements and modeling of the difference between the first and second arrangements is used to estimate separately properties of the ingoing and outgoing optical systems. The modeling may account for symmetry of the respective periodic target. The modeling typically accounts for polarizing effects of the ingoing optical elements, the outgoing optical elements and the respective periodic target. The polarizing effects may be described in the modeling by Jones calculus or Mueller calculus. The modeling may include a parameterization in terms of basis functions such as Zernike polynomials.
摘要:
A metrology apparatus is arranged to illuminate a plurality of targets with an off-axis illumination mode. Images of the targets are obtained using only one first order diffracted beam. Where the target is a composite grating, overlay measurements can be obtained from the intensities of the images of the different gratings. Overlay measurements can be corrected for errors caused by variations in the position of the gratings in an image field.
摘要:
A method of determining an overlay error between two successive layers produced by a lithographic process on a substrate, including using the lithographic process to form a calibration structure including a periodic structure of the same pitch on each of the layers, such that an overlaid pair of periodic structures is formed, the structures being parallel, but offset relative to each other by an overlay amount. A spectrum produced by directing a beam of radiation onto the calibration structure is measured and compared with one or more modeled spectra so as to determine values of the grating parameters for the calibration structure from the measured spectrum. The lithographic process is used to form further overlaid periodic structures on the same or one or more subsequent substrates, the determined grating parameter values for the calibration structure being used to determine overlay amounts for the further overlaid periodic structures.
摘要:
The present invention discloses an optical drive and a method for preprocessing a disc readout signal rk of an optical drive on the basis of a set of low-pass filters. The cutoff frequency fC of the filters wk, more particularly, can be set within the optical bandwidth, which improves the Viterbi detection performance in the case of high speed drive operations. Three types of filters are described, in which a Type I shaping filter performs best given a limited hardware cost for the bit detector. Compared to other more advanced noise-whitening techniques, it is only speed dependent and requires little prior knowledge of the channel and noise, thus cheap and easy to design. The invention can be applied in connection with optical disc drives, in particular when high frequency noises are dominant, for example, in the case of high speed operations.