Three dimensional moire pattern alignment

An apparatus is disclosed for determining three dimensional positioning relative to a predetermined point utilizing moire interference patterns such that the patterns are complementary when viewed on axis from the predetermined distance. Further, the invention includes means for determining rotational positioning in addition to three dimensional translational positioning

Optical joint correlator for real-time image tracking and retinal surgery

A method for tracking an object in a sequence of images is described. Such sequence of images may, for example, be a sequence of television frames. The object in the current frame is correlated with the object in the previous frame to obtain the relative location of the object in the two frames. An optical joint transform correlator apparatus is provided to carry out the process. Such joint transform correlator apparatus forms the basis for laser eye surgical apparatus where an image of the fundus of an eyeball is stabilized and forms the basis for the correlator apparatus to track the position of the eyeball caused by involuntary movement. With knowledge of the eyeball position, a surgical laser can be precisely pointed toward a position on the retina

Two dimensional vernier

A two-dimensional vernier scale is disclosed utilizing a cartesian grid on one plate member with a polar grid on an overlying transparent plate member. The polar grid has multiple concentric circles at a fractional spacing of the spacing of the cartesian grid lines. By locating the center of the polar grid on a location on the cartesian grid, interpolation can be made of both the X and Y fractional relationship to the cartesian grid by noting which circles coincide with a cartesian grid line for the X and Y direction

Programmable remapper for image processing

A video-rate coordinate remapper includes a memory for storing a plurality of transformations on look-up tables for remapping input images from one coordinate system to another. Such transformations are operator selectable. The remapper includes a collective processor by which certain input pixels of an input image are transformed to a portion of the output image in a many-to-one relationship. The remapper includes an interpolative processor by which the remaining input pixels of the input image are transformed to another portion of the output image in a one-to-many relationship. The invention includes certain specific transforms for creating output images useful for certain defects of visually impaired people. The invention also includes means for shifting input pixels and means for scrolling the output matrix

Spatial light modulators for full cross-connections in optical networks

A polarization-independent optical switch is disclosed for switching at least one incoming beam from at least one input source to at least one output drain. The switch includes a polarizing beam splitter to split each of the at least one incoming beam into a first input beam and a second input beam, wherein the first input beam and the second input beams are independently polarized; a wave plate optically coupled to the second input beam for converting the polarization of the second input beam to an appropriately polarized second input beam; a beam combiner optically coupled to the first input beam and the modified second input beam, wherein the beam combiner accepts the first input beam and the modified second input beam to produce a combined beam; the combined beam is invariant to the polarization state of the input source's polarization; and a controllable spatial light modulator optically coupled to the combined beam, wherein the combined beam is diffracted by the controllable spatial light modulator to place light at a plurality of output locations

Dual use of image based tracking techniques: Laser eye surgery and low vision prosthesis

With a concentration on Fourier optics pattern recognition, we have developed several methods of tracking objects in dynamic imagery to automate certain space applications such as orbital rendezvous and spacecraft capture, or planetary landing. We are developing two of these techniques for Earth applications in real-time medical image processing. The first is warping of a video image, developed to evoke shift invariance to scale and rotation in correlation pattern recognition. The technology is being applied to compensation for certain field defects in low vision humans. The second is using the optical joint Fourier transform to track the translation of unmodeled scenes. Developed as an image fixation tool to assist in calculating shape from motion, it is being applied to tracking motions of the eyeball quickly enough to keep a laser photocoagulation spot fixed on the retina, thus avoiding collateral damage

Apparatus and Method for Focusing a Light Beam in a Three-Dimensional Recording Medium by a Dynamic Holographic Device

An apparatus is disclosed for reading and/or writing information or to from an optical recording medium having a plurality of information storage layers. The apparatus includes a dynamic holographic optical element configured to focus light on the optical recording medium. a control circuit arranged to supply a drive signal to the holographic optical element, and a storage device in communication with the control circuit and storing at least a first drive signal and a second drive signal. The holographic optical element focusses light on a first one of the plurality of information storage layers when driven by the first drive signal on a second one of the plurality of information storage layers when driven by the second drive signal. An optical switch is also disclosed for connecting at least one light source in a source array to at least one light receiver in a receiver array. The switch includes a dynamic holographic optical element configured to receive light from the source array and to transmit light to the receiver array, a control circuit arranged to supply a drive signal to the holographic optical element, and a storage device in communication with the control circuit and storing at least a first drive signal and a second drive signal. The holographic optical element connects a first light source in the source array to a first light receiver in the receiver array when driven by the first drive signal and the holographic optical element connects the first light source with the first light receiver and a second light receiver when driven by the second drive signal

Correlation Techniques as Applied to Pose Estimation in Space Station Docking

The telerobotic assembly of space-station components has become the method of choice for the International Space Station (ISS) because it offers a safe alternative to the more hazardous option of space walks. The disadvantage of telerobotic assembly is that it does not provide for direct arbitrary views of mating interfaces for the teleoperator. Unless cameras are present very close to the interface positions, such views must be generated graphically, based on calculated pose relationships derived from images. To assist in this photogrammetric pose estimation, circular targets, or spots, of high contrast have been affixed on each connecting module at carefully surveyed positions. The appearance of a subset of spots essentially must form a constellation of specific relative positions in the incoming digital image stream in order for the docking to proceed. Spot positions are expressed in terms of their apparent centroids in an image. The precision of centroid estimation is required to be as fine as 1I20th pixel, in some cases. This paper presents an approach to spot centroid estimation using cross correlation between spot images and synthetic spot models of precise centration. Techniques for obtaining sub-pixel accuracy and for shadow, obscuration and lighting irregularity compensation are discussed

Outcomes of Second Combination Antiretroviral Therapy Regimens Among HIV-Infected Persons in Clinical Care: A Multicenter Cohort Study

Data on the effectiveness of second-line combination antiretroviral therapy (cART) are limited. We evaluated virologic outcomes of second cART in a multicenter cohort collaboration. The study population initiated first and second modern cART between 1996 and 2010. The second cART required a switch in at least the anchor agent of first cART. We evaluated time to virologic failure of second cART and factors associated with greater risk of failure using multivariable Cox proportional hazards models. Of 488 patients who switched to second-line cART, 67% were black and 32% were women. The median HIV-1 RNA at second cART initiation was 9,565 copies/ml [interquartile range (IQR); 123, 94,108]. The time to virologic failure of second cART was longer if HIV-1 RNA was undetectable at switch (p=0.001), although 12% and 17% of patients with undetectable and detectable HIV-1 RNA experienced virologic failure within 6 months of second cART initiation, respectively. A lower CD4 cell count at second cART initiation was associated with a greater risk of virologic failure. Failure rates decreased in more recent calendar years [adjusted relative hazard of 0.40 comparing 2008 to 2010 with 1996 to 1998 (95% confidence interval; 0.15, 1.00)]; however, type of anchor agent was not associated with failure. In conclusion, virologic failure of second cART was less likely if patients switched with undetectable HIV-1 RNA, although risk of early failure was similar. The effectiveness of second cART regimens improved over calendar time and was independent of the anchor agent in the regimen

Colorimetry and the multichannel image

Typescript (photocopy).The use of color theory (particularly color metrics) is shown in the display of 2-D vector fields. Extant concepts in color theory are applied to data spaces to facilitate mapping from data into color. Novel color transformations are shown; one is a direct improvement over standard Landsat imagery, one is a means of showing in a single image the results of analyzing an image of arbitrarily large dimensionality, and another is an improved method of displaying geophysical attributes that reduces the number of separate displays by a factor of three. A new model for the inversion of a dot-matrix color machine is given. A method is formulated and demonstrated to convert a numerical image to halftone printed copy and avoid several color-contaminating physical steps previously necessary. Analysis of a differentiable color image machine by its Jacobian matrix is explored and then extended to discrete (non-differentiable) machines. Finally, an inverse problem is formulated -- the extraction of quantitative information from color imager, in the case of one principal continuous variable and subsidiary variable having lesser color impact