160 results about "Spatial coherence" patented technology

The present invention provides methods and devices for fabricating 3D structures and patterns of 3D structures on substrate surfaces, including symmetrical and asymmetrical patterns of 3D structures. Methods of the present invention provide a means of fabricating 3D structures having accurately selected physical dimensions, including lateral and vertical dimensions ranging from 10 s of nanometers to 1000 s of nanometers. In one aspect, methods are provided using a mask element comprising a conformable, elastomeric phase mask capable of establishing conformal contact with a radiation sensitive material undergoing photoprocessing. In another aspect, the temporal and/or spatial coherence of electromagnetic radiation using for photoprocessing is selected to fabricate complex structures having nanoscale features that do not extend entirely through the thickness of the structure fabricated.

The present invention is related to a compact microscope able to work in digital holography for obtaining high quality 3D images of samples, including fluorescent samples and relatively thick samples such as biological samples, said microscope comprising illumination means (1,41) at least partially spatially coherent for illuminating a sample (2) to be studied and a differential interferometer (5) for generating interfering beams from said sample (2) on the sensor (33) of an electronic imaging device (7), said interferometer (5) comprising namely tilting means (17) for tilting by a defined angle one the interfering beams (28 or 29) relatively to the other, said tilting resulting into a defined shift (27) of said interfering beam on the sensor of the electronic imaging device (7), said shift (27) being smaller than spatial coherence width of each beam, said microscope being able to be quasi totally preadjusted independently from the samples so that minimum additional adjustments are required for obtaining reliable 3D images of samples.

Methods and systems are provided for suppressing speckle and/or diffraction artifacts in coherent structured illumination sensing systems. A coherent radiation pattern forms an interference pattern at an illumination image plane and illuminates an object. Radiation scattered or otherwise emitted by the object is detected to produce a signal, which is integrated in time. Coherent artifact suppression is attained by using a spatial modulator, such as an acousto-optic device, to vary a phase gradient at the illumination image plane during the signal integration time. Various embodiments are provided for purposes including without limitation: preserving the depth of field of the coherent illumination; using the same acousto-optic device for pattern generation and coherent artifact suppression; electronically controlling the effective spatial coherence of the illumination system; and reducing errors due to coherent artifacts in a laser-based three dimensional imaging system.

A projection exposure apparatus for transferring a pattern formed on a mask onto a photosensitive substrate by a scanning exposure method, includes a light source for generating a light beam having a predetermined spatial coherence, an illumination optical system for receiving the light beam from the light source and illuminating a local area on the mask with the light beam, and a device for synchronously moving the mask and the photosensitive substrate so as to transfer the pattern on the mask onto the photosensitive substrate. A direction, corresponding to a higher spatial coherence of the light beam, is made to coincide with the direction of relative scanning an illumination area and the mask in the illumination area.

Methods and apparatus are disclosed for detecting a thickness of a surficial layer (e.g., metal or insulating layer) on a workpiece (e.g., semiconductor wafer) during a process for planarizing the layer, so as to stop the process when a suitable process endpoint is reached. Layer thickness is detected based on a spectral-characteristic signal of reflected or transmitted signal light, obtained by directing a probe light onto the surface of the workpiece. Example spectral characteristics are local maxima and minima of signal-light waveform, differences or quotients of the same, a dispersion of the signal-light waveform, a component of a Fourier transform of the signal waveform, a cross-correlation function of the signal waveform. Alternatively, the zeroth order of signal light is selected for measurement, or a spatial coherence length of the probe light is compared with the degree of fineness of the pattern on the surface illuminated with the probe light. An optical model can be determined based on the comparison, and at least one of the layer thickness and the process endpoint is detected by comparing the measured signal-light intensity with the calculated theoretical signal light intensity.

The invention relates to a two-stage laser system well fit for semiconductor aligners, which is reduced in terms of spatial coherence while taking advantage of the high stability, high output efficiency and fine line width of the MOPO mode. The two-stage laser system for aligners comprises an oscillation-stage laser (50) and an amplification-stage laser (60). Oscillation laser light having divergence is used as the oscillation-stage laser (50), and the amplification-stage laser (60) comprises a Fabry-Perot etalon resonator made up of an input side mirror (1) and an output side mirror (2). The resonator is configured as a stable resonator.

Speckle of a laser beam is reduced by inserting an anti-speckle apparatus in the beam path to disrupt its spatial coherence while maintaining its temporal coherence. In one embodiment, the anti-speckle apparatus is a phase retarder plate bearing periodic optically-coated regions. Transmission or reflection of the beam through coated and uncoated regions causes an internal phase shift of first beam portions relative to second beam portions, thereby disrupting spatial coherence. Size and thickness of the coated regions can be carefully tailored to meet requirements of stepper and scanner equipment manufacturers for maximum allowable spatial coherence expressed as a minimum permissible number of coherent cells across the beam cross-section. An alternative embodiment of an anti-speckle apparatus is a scattering plate bearing a roughened surface. Transmission or reflection of the beam by the roughened surface disrupts the beam's spatial coherence. The correlation length and/or surface height of structures on the roughened surface of the scattering plate may be adjusted to achieve desired divergency and spatial coherence. A liquid matching medium or solid overcoating may be contacted with the roughened surface to adjust the index of refraction at the interface with the roughened surface. The anti-speckle apparatus may serve to outcouple the laser beam, as well, and a fly eye lens may be positioned after the anti-speckle appartus.

According to one embodiment, a method for reducing speckle in an image produced from a coherent light source includes directing a beam of coherent light at an electrically controlled diffuser. An electrical signal is applied to the electrically controlled diffuser to produce an electrical field across the electrically controlled diffuser layer. At least one of an amplitude and a frequency of the electrical signal are varied to transition the controlled diffuser between a first state and a second state. The varied application of the electrical signal operates to reduce spatial coherence in an image projected through the electrically controlled diffuser.

A lithographic apparatus has an alignment system including a radiation source configured to convert narrow-band radiation into continuous, flat and broad-band radiation. An acoustically tunable narrow pass-band filter filters the broad-band radiation into narrow-band linearly polarized radiation. The narrow-band radiation may be focused on alignment targets of a wafer so as to enable alignment of the wafer. In an embodiment, the filter is configured to modulate an intensity and wavelength of radiation produced by the radiation source and to have multiple simultaneous pass-bands. The radiation source generates radiation that has high spatial coherence and low temporal coherence.

For increasing the power emitted by surface emitting lasers and for improving the spatial coherence of the laser beam, emitted in particular by disk lasers, microchip lasers and VCSELs having a relatively wide emitting area, the invention proposes to select a low order transverse cavity mode by means of a mirror structure (12) of high reflectivity, and of high angular selectivity. The mirror structure comprises a multilayer (14) receiving the optical beam (24) and a resonant grating mirror (16) following the multilayer and arranged for highly reflecting the optical beam in a narrow angular range at each side of a determined incidence angle.

In the frequency domain, the method comprises the following steps:

• • a) calculating a first noise reference by analyzing the spatial coherence of the signals picked up;
  • b) calculating a second noise reference by analyzing the directions of incidence of the signals picked up;
  • c) estimating a main direction of incidence of the signals picked up;
  • d) selecting as a referent noise signal one or the other of the noise references as a function of the estimated main direction;
  • e) combining the signals picked up into a noisy combined signal;
  • f) calculating a probability that speech is absent in the noisy combined signal on the basis of the respective spectral energy levels of the noisy combined signal and of the referent noise signal; and
  • g) selectively reducing the noise by applying variable gain that is specific to each frequency band and to each time frame.

The invention discloses a dynamic probabilistic power flow (PPF) calculating method considering wind speed predication error temporal-spatial coherence. The method is to analyze the node voltage and dynamic probability distribution of branch power flow of a wind power station built power system, so as to enable operators to analyze a system state conveniently. The method comprises the steps of describing the input variable predication error process according to autocorrelation coefficient stationary process; directly fitting to obtain the predication error distribution on the basis of nonparametric kernel density estimation and according to historical predication error data; performing Nataf transformation technology on the basis of the iso-probability transformation theory to obtain an error sample of temporal-spatial coherence; performing dynamic PPF calculation by the monte carlo simulation method on the basis of latin hypercube sampling so as to obtain the node voltage amplitude value and the digital characteristics and dynamic probability distribution of the branch power flow. By adopting the method, the node voltage and the dynamic probability distribution of the branch power flow can be effectively analyzed; the method has the advantages of being accurate in result and convenient to realize.

A method of performing a DFT (discrete Fourier transform) or a DFT derived transform on data, comprising: providing spatially modulated light having spatial coherence, said spatially modulated light representing the data to be transformed; Fourier transforming said spatially modulated light, using an at least one optical element; and compensating for at least one of a scaling effect and a dispersion effect of said at least one optical element, using an at least one dispersive optical element.

The invention discloses a laser speckle optical path and a laser projection light source system, and relates to the technical field of laser display. The system comprises a diffusion assembly and a lens assembly used for collimation and spotlight, the diffusion assembly is composed of at least two diffusion parts, wherein one of the diffusion parts is a dynamic speckle device, the other diffusionparts are static speckle devices, and the movement mode of the dynamic speckle device is cyclical rotation; and the lens assembly is arranged among the diffusion parts. The laser speckle optical pathand the laser projection light source system have the advantages that better speckle and facula homogenization functions can be achieved through the combined use of the dynamic diffusion assembly andstatic diffusion assemblies; the laser beams are diverged and collimated repeatedly to greatly reduce the spatial coherence of the laser beams, thereby effectively solving the problem of speckle; thelaser speckle optical path is simple in structure and small is size, and can be integrated easily in a laser display system to make the structure of an x ray machine more compact.

The invention relates to an online projection objective wave aberration detection device and method. The detection device comprises a light source, a rotary scatterer, a first focusing lens, an optical fiber array, a second focusing lens, a scattering optical element, an object plane optical grating, an image plane optical grating, a two-dimensional photoelectric sensor, a phase-shift control module and a computer, wherein the rotary scatterer is composed of a support, an electric motor and a circular diffusion scattering optical element, and is combined with the multimode optical fiber array for converting a coherent light or partially coherent light source into incoherent light; ten interference fringe patterns with phase shifting amounts of 0, pi/6, pi/3, pi/2, 2pi/3, 5pi/6, pi, 5pi/3, 3pi/2 and 11pi/6 respectively are acquired to calculate a phase position and the influence of multilevel diffraction light interference of the optical grating on the phase position extraction precision is eliminated. The device and the method can improve the modulation effect of the object plane optical grating on the optical field spatial coherence so as to achieve a high-precision alignment effect, reduce the system error of phase position extraction in wave aberration detection and improve the wave aberration detection precision of an optical system.

The invention relates to a collinear femto-second laser polarized pump detecting system, comprising that a pulse laser is output by a polarized output pulse laser; the laser is rotated in the polarization direction by a wave plate; a light-splitting device divides the laser beam into two beams vertical to each other in the polarization direction; a reflector receives and reflects the laser beams; an acoustooptic modulator modulates the laser beams; an aperture transmits the modulated laser beams; an acoustooptic modulator driver transmits modulation signals for the acoustooptic modulator; an electrically controlled travelling carriage moves forward and backward; an analyzer transmits the laser beams which are vertical to each other in the polarization direction; a photodetector receives the laser transmitted by the analyzer; a magnet fixes an adjusting rack so as to fix a sample; a focusing lens irradiates the laser on the surface of the sample; and an electrically controlled revolving stage fixes the wave plate. The invention combines the two beams of light vertical to each other in the polarization direction by polarized coupling; therefore, the system can ensure spatial coherence of the two beams of light on the sample, thereby avoiding the problem of adjusting direction of light beam; thus, the operation is simpler.

The invention is a system and method that enable obtaining ultra-high resolution interference, phase and OCT images at high speed. The system uses neither mechanical moving elements nor any optical/electro optical modulating means for obtaining the OCT images. Two OCT operating modes are available: for ultra-high resolution the system allows either spatial coherence TD-FF-OCT or temporal coherence TD-FF-OCT imaging, whereas for high resolution and ultra-high speed the system allows FD-FF-OCT imaging with full range imaging. In the TD mode, the OCT enface images are obtained in real time. In the FD mode, the 2D complex signal is reconstructed in real time. In both cases the method has the advantage of very high speed imaging with great immunity to noise.