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.
摘要:
A loss of performance of slicer adaptation at high capacities due to the mismatch between the exact bits used in the computation of the RDS for the DC-control on the one hand and the often erroneous threshold decisions that are preliminarily made based on the HF waveform on the other hand, is resolved by performing a new method of DC-control at the encoder: the RDS is modified such that it is not based on the exact channel bits, but on the threshold decisions from a synthetic HF signal waveform that is generated based on a nominal MTF (modulation transfer function) or its IRF (impulse response function) of the channel. In this way, the impact of the erroneous threshold decisions in the receiver are already taken into account at the encoder, and the slicer control is no longer negatively affected thereby.
摘要:
A body parameter sensing arrangement comprising clothing (10) and a plurality of sensors (12, 20) for sensing body signals, located at mutually movable relative positions in the clothing (10). Processing circuit (26) coupled to the plurality of sensors (12, 20), is configured to identify selected ones of the sensors (12, 20) that carry valid body signals. The identification by clustering the sensors (12, 20) according to similarity between signals from the sensors (12, 20). A cluster of sensors (12, 20) is determined with a maximal count of sensors (12, 20) within a minimal cluster diameter A cluster diameter defined by a measure of similarity or distance between signals form the sensors is used. The cluster is used to select sensors (12, 20) to identify the selected ones of the sensors (12, 20) that carries valid body signals on the basis of membership of the cluster
摘要:
In a method of multi-dimensionally encoding a user data stream of user words into a channel data stream of channel words evolving in a one-dimensional direction of infinite extent, a user word is encoded into an NRZ channel word by selecting a NRZ channel word from a code table depending on the user word and the current state of an underlying finite-state-machine. A NRZ channel word comprises a sequence of NRZ channel symbols of NRZ channel bits having a one-dimensional interpretation along said one-dimensional direction and wherein states of an underlying finite-state-machine describing the characteristics of the multi-dimensional code are defined by NRZI channel bits of the previous channel work and by NRZ channel symbols of the current channel word. The NRZ channel symbols are transcoded into NRZI channel symbols by a one-dimensional 1T-precoding operation including an intergration modulo 2, said 1T-precoding operation being carried out along said one-dimensional direction of infinite extent. The finite-state-machine is put into a new state selected from the code table depending on said user word and the current state of said finite-state-machine together with encoding a user word into a channel word.
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:
The invention provides an efficient reading device in which, even if one radiation beam should fail, no information is lost and the information can still be read out without time-consuming recurring operations. The present invention solves this problem by providing a reading device (FIG. 5A) and a means (FIG. 4) for forming read-out spots (A, B, C, D, E) that are built up by multiple radiation beams from the radiation source (4). This has the advantage that each read-out spot will have energy contributions from different radiation beams and, should one radiation beam break down, the intensity of some of the read-out spots may indeed diminish, but the information can still be read out thanks to the contributions from other radiation beams.
摘要:
The present invention relates to a method and a corresponding device for embedding a secondary information signal in a channel data stream of encoded primary information signal. In order to make it more difficult for unauthorized persons or devices to retrieve the location of storage of the secondary information signal or its content itself a device is proposed according to the present invention comprising: an encoder (1) for encoding said primary information signal into a channel data stream, a control unit (3) for controlling the DC content of said channel data stream, a secondary information signal embedding unit (2) for embedding said secondary information signal in said channel data stream by using freedoms in the DC control, and an adaptation unit (4) for adapting the DC control by making non-optimal, arbitrary or random choices of the DC control at a number of locations of said channel data stream.