Abstract:
The invention is an apparatus for determining the quality of optical equipment through measurement of the modulation transfer function of the equipment. The apparatus includes an elongated, opaque sheet member or reticle, uniformly curved about an axis substantially perpendicular to the longitudinal centerline thereof, which has a data pattern comprising at least one bar pattern of discrete spatial frequency positioned longitudinally thereon. Each of the data patterns has optical transmission characteristics that vary periodically along its length according to a predetermined spatial frequency distribution. A rotatable mirror with its axis of rotation coincident with the center of curvature of the reticle is mounted so that it reflects an incident image onto the stationary reticle. An illuminated image producing source projects a slit image through optical equipment whose quality is to be determined to produce a spread function response of the optical equipment and the response is projected onto the rotatable mirror. The mirror is rotated to cause the spread function response to be reflected therefrom and sweep the data pattern so that the light transmitted through the data pattern is modulated by the interaction of the data pattern with the spread function response. The intensity of the transmitted, modulated light from the slit image is converted into an electrical data signal and the amplitude of the fundamental frequency components of the electrical data signal is determined. These measurements determine the modulation transfer function of the optical equipment under test.
Abstract:
A pyramidal geotextile fabric comprising two sets of multi-lobe filament yarns interwoven in substantially perpendicular direction to each other, each of the multi-lobe filament yarns having pre-determined, different heat shrinkage characteristics such that, upon heating, the fabric forms a three-dimensional, cuspated profile. A method of stabilizing soil and reinforcing vegetation comprises the steps of placing a three-dimensional, high-profile woven fabric into soil, wherein the fabric comprises two sets of multi-lobe filament yarns interwoven in substantially perpendicular direction to each other, each of the multi-lobe filament yarns having pre-determined, different heat shrinkage characteristics such that, upon heating, the fabric forms a three-dimensional, cuspated profile; securing the fabric to the ground; and, distributing soil and seed onto the fabric such that the section of ground is quickly revegetated and thereby protected from further erosion.
Abstract:
A turf reinforcement mat (10) comprises at least one polymer net layer (11); a non-woven mat (13) comprising a plurality of multi-dimensional polymer fibers (15); and, a polymer yarn (80, 81), stitching the net layer to the non-woven mat. A method for erosion control and revegetation facilitation comprises providing a turf reinforcement mat comprising at least one polymer net layer; a non-woven mat comprising a plurality of multi-dimensional polymer fibers; and, a polymer yarn, stitching the net layer to the non-woven mat; laying the turf reinforcement mat on a section of ground to be reinforced; securing the turf reinforcement mat to the ground; distributing soil and seed onto the turf reinforcement mat such that the section of ground is quickly revegetated and thereby protected from further erosion.
Abstract:
A pyramidal geotextile fabric comprising two sets of multi-lobe filament yarns interwoven in substantially perpendicular direction to each other, each of the multi-lobe filament yarns having pre-determined, different heat shrinkage characteristics such that, upon heating, the fabric forms a three-dimensional, cuspated profile. A method of stabilizing soil and reinforcing vegetation comprises the steps of placing a three-dimensional, high-profile woven fabric into soil, wherein the fabric comprises two sets of multi-lobe filament yarns interwoven in substantially perpendicular direction to each other, each of the multi-lobe filament yarns having pre-determined, different heat shrinkage characteristics such that, upon heating, the fabric forms a three-dimensional, cuspated profile; securing the fabric to the ground; and, distributing soil and seed onto the fabric such that the section of ground is quickly revegetated and thereby protected from further erosion.
Abstract:
A specific small area of a crystal sample is scanned by a laser beam which rotates about an axis substantially perpendicular to the sample surface such that the intersection of the beam with a plane above and parallel to the surface describes a true spiral or a stepwise spiral pattern. The laser beam is reflected different amounts for different beam positions to produce a reflectance pattern indicative of crystallographic orientation.