Search results
Results from the WOW.Com Content Network
A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia. Because light passes only through the center of the ...
When selecting an anchor, consider the element formwork and the ease of placement and securing of the anchor prior and during the pouring of the concrete. For example, some of the anchors shown in figures 4-6, can be placed into thin wall elements as the anchor chair maintains the position relative to the element thickness.
Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. Similar to the workings of a pinhole camera , each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the circle of confusion on the ...
A pinhole occluder is then placed before the patient's eye, and their vision is then tested again (each eye separately) to determine if the patient's poor visual acuity is a result of optical irregularities, or pathological issues.
Wide-field micrograph of a damaged 80 μm pinhole Natural pinholes formed by tree leaves – Solar eclipse of August 21, 2017 in Washington state. A pinhole is a small circular hole, as could be made with the point of a pin. In optics, pinholes with diameter between a few micrometers and a hundred micrometers are used as apertures in optical ...
The image plane is parallel to axes X1 and X2 and is located at distance from the origin O in the negative direction of the X3 axis, where f is the focal length of the pinhole camera. A practical implementation of a pinhole camera implies that the image plane is located such that it intersects the X3 axis at coordinate -f where f > 0.
A bughole (or pinhole) is a small hole in the surface of a concrete structure caused by the expansion and eventual outgassing of trapped pockets of air in setting concrete. [ 1 ] [ 2 ] [ 3 ] Bugholes are undesirable, as they may compromise the structural integrity of concrete emplacements.
Single box girder bridge , flyover above eastern approach of the San Francisco–Oakland Bay Bridge. A box girder bridge, or box section bridge, is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinforced concrete.