An automated photomask inspection apparatus including an XY state (12) for transporting a substrate (14) under test in a serpentine path in an XY plane, an optical system (16) comprising a laser (30), a transmission light detector (34), a reflected light detector (36), optical elements defining reference beam paths and illuminating beam paths between the laser, the substrate and the detectors and an acousto-optical beam scanner (40, 42) for reciprocatingly scanning the illuminating and reference beams relative to the substrate surface, and an electronic control, analysis and display system for controlling the operation of the stage and optical system and for interpreting and storing the signals output by the detectors. The apparatus can operate in a die-to-die comparison mode or a die-to-database mode.

Automated photomask inspection apparatus

In a presently preferred embodiment of the invention, a three-dimensional scene (10) is reproduced on a specialized light display (19) which offers full multiviewpoint capability and autostereoscopic views. The displayed image is produced using a set of M two-dimensional images of the scene collected at a set of distinct spatial locations. These M two-dimensional images are processed through a specialized mathematical encoding scheme to obtain a set of N x K display-excitation electrical-input signals, where K is the number of pixels in the display, and N ≤ M is the number of individual light-radiating elements within one pixel. The display is thus comprised of a total of N x K light-radiating elements. Each of the K pixels is adapted for control of their associated radiance patterns. The display is connected for response to the set of N x K display-excitation electrical-input signals. In this manner, the display provides a multiviewpoint and autostereoscopic three-dimensional image associated with the original three-dimensional scene. An alternative embodiment of the invention is utilized to provide efficient storage and display of 3D computer graphics images.

Three-dimensional display system: apparatus and method

A method for detecting an amount of rotation or magnification in a modified image, includes the steps of: embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle α in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image; performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and comparing the separation d' and orientation α' of the autocorrelation peaks with the separation d and orientation α of the features in the marker image to determine the amount of rotation and magnification in the modified image.

Method for detecting rotation and magnification in images

Flash correlation instantaneously compares (52) two or more patterns (20, 50) to determine whether they are the same or essentially the same regardless of the complexity of the images, and in spite of the addition of noise, local changes, and variations in resolution and focus. Flash correlation artifacts (58) also provide cues to quantitative assessment of relative movement, stretching, blurring, and warping of one image with respect to the other. Presence of a flash correlation artifact between two stacks of patterns (58) is sufficient to identify the stacks as containing at least one pair of massively correlated patterns (62). Precise control of registration, image size and orientation is not required. An image may be combined with other images, either by overlays or concatenation, and still be identified. A flash correlation engine may utilize optical, analog or digital processing to provide rapid sorting, classification, and identification functions with minimal computational complexity.

Method and apparatus for flash correlation.

A VSB reception system includes a sequence generator for decoding a symbol corresponding to the supplemental data and generating a predefined sequence included in the supplemental data at VSB transmission system. The reception system also includes a modified legacy VSB receiver for processing the data received from the VSB transmission system in a reverse order of the VSB transmission system by using the sequence, and a demultiplexer for demultiplexing the data from the modified legacy VSB receiver into the MPEG data and the supplemental data. The VSB reception system also includes a supplemental data processor for processing the supplemental data segment from the demultiplexer in a reverse order of the transmission system, to obtain the supplemental data, thereby carrying out the slicer prediction, decoding, and symbol decision more accurately by using the predefined sequence, to improve a performance.

VSB reception system with enhanced signal detection for processing supplemental data

An optical notching or filtering system in which a beam of optical radiation is passed through the optical filtering means a multiplicity of times. The optical filtering means has an optical Fourier transform means (12), a spatial filter (14), optical inverse Fourier transform means (16), and a reflector array (18). After an input optical signal beam undergoes a filtering pass by being directed through the transform means, the filter, and the inverse transform means, the reflector array re-introduces the beam for a multiplicity of subsequent filtering passes. Four embodiments of the system of the invention having various configurations of the reflector arrays for use with one- and two-dimensional spatial filters are disclosed. The various embodiments are set forth as being used in a heterodyning optical notching filter systsm.

Recursive optical filter system

A tracking receiver is disclosed which utilizes optical processing for detecting and tracking input broadband chirp like emission signals. The tracking receiver includes a scanning local oscillator, the output signal of which is caused to be scanned in frequency. A mixer mixes the unknown input signal and the local oscillator output signal to produce an intermediate frequency (IF), frequency difference signal. The IF signal is analyzed in an optical spectrum analyzer which includes an acoustooptical modulator for modulating a beam of radiation, as a laser beam, with the intermediate frequency signal, and optical means, as a lens, for producing a spatial frequency distribution of the intermediate frequency spectrum in a Fourier plane. A photodetector array is provided in the Fourier plane for detecting the spatial spectrum. A processor processes the output of the photodetector for temporally stable grouped intensity patterns caused by an input spectra signal varying in frequency near the scan rate of the local oscillator. The processor is responsive thereto to control a programmer which controls the frequency of the local oscillator to cause it to approach and become equal to the frequency of the input spectra signal. A recorder is provided for recording the output of the scanning local oscillator, and the scanning local oscillator is controlled to proceed through a programmed frequency scan pattern.

Tracking receiver for broadband chirp emissions

An optical recursive filtering system in which a signal beam of optical radiation is passed through the optical filtering means a multiplicity of times. The filtering system has an optical Fourier transform means, a spatial filter, optical inverse Fourier transform means and a pair of reflectors in the Fourier plane of the spatial filter. An input signal beam to be filtered is optically Fourier transformed by the transform means and is passed through the spatial filter where unwanted frequencies of the signal beam are attenuated. The filtered beam is reflected by one of the reflectors back through the filter and the second mirror reflects it back through the filter a third time. Subsequent reflections back through the filter with a consequent further filtering of the signal beam can be accomplished by appropriately positioning the reflectors. After multiple filtering passes, the filtered beam is extracted for utilization. By maintaining the recursions of the beam in the Fourier plane of the filter, which preferably is of a programmable type, the optical throw of the filter system can be significantly reduced and a flexible imaging system without the restraints of external recursion is realizable in a robust structure with fewer components. An embodiment of the system being used in a heterodyning RF optical filtering system is described.

Fourier plane recursive optical filter

An optical notching filter is disclosed in which an optical spatial filter therein is formed by a spatial light modulator which is written into by light. The optical notching filter system of the present invention provides a linear phase and amplitude response with applications for high speed adaptive filtering to filter out noise and signals of no interest. In one particular disclosed embodiment, the write with light optical notching filter system of the present invention is designed to adaptively excise interference from Radio Frequency (RF) signals, such as are utilized in communications or radar systems. The technical approach of the present invention provides a more compact system design than similar electronically addressed optical notching filtering systems, and also significantly reduces the complexity and attendant power requirements of the system. Different embodiments of a write with light optical notching filter system can operate with either nonochromatic or polychromatic light sources. Moreover, the write light source can be independent of the read light source, such that any suitable write or read light source can be utilized therein, either with single pass or recursive optical arrangements.

Write with light optical notching filter

A neural network processing element uses primarily optical components to model a biological neuron having both spatial and temporal dependence. The neural network processing element includes a switch-controlled laser source, a multiple holographic lens, a spatial/temporal light modulator, and a photodetector array. Laser beam control may be optical, electrical or acoustical, or a combination of these.

Robert W. Brandstetter

Papers

Recursive optical filter system

Tracking receiver for broadband chirp emissions

Fourier plane recursive optical filter

Write with light optical notching filter

Optical neural network processing element with multiple holographic element interconnects