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Specialty. Neurology, ophthalmology. Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. [1] Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary.
Lunar Laser Ranging (LLR) is the practice of measuring the distance between the surfaces of the Earth and the Moon using laser ranging. The distance can be calculated from the round-trip time of laser light pulses travelling at the speed of light , which are reflected back to Earth by the Moon's surface or by one of several retroreflectors ...
Correction pen. A correction fluid is an opaque, usually white fluid applied to paper to mask errors in text. Once dried, it can be handwritten or typed upon. It is typically packaged in small bottles, with lids attached to brushes (or triangular pieces of foam) that dip into the fluid. The brush applies the fluid to the paper.
The history of the single-lens reflex camera (SLR) begins with the use of a reflex mirror in a camera obscura described in 1676, but it took a long time for the design to succeed for photographic cameras. The first patent was granted in 1861, and the first cameras were produced in 1884, but while elegantly simple in concept, they were very ...
Glasses, surgery [3] Frequency. ~2% (children) [3] Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. [2] The eye that is pointed at an object can alternate. [3] The condition may be present occasionally or constantly. [3]
The Space Pen (also known as the Zero Gravity Pen ), marketed by Fisher Space Pen Company, is a pen that uses pressurized ink cartridges and is able to write in zero gravity, underwater, over wet and greasy paper, at any angle, and in a very wide range of temperatures. Astronaut Walter Cunningham, Apollo 7 lunar module pilot, writes with space ...
A laser weapon [2] is a type of directed-energy weapon that uses lasers to inflict damage. Whether they will be deployed as practical, high-performance military weapons remains to be seen. [3] [4] One of the major issues with laser weapons is atmospheric thermal blooming, which is still largely unsolved.
A blue laser emits electromagnetic radiation with a wavelength between 400 and 500 nanometers, which the human eye sees in the visible spectrum as blue or violet. [1] Blue lasers can be produced by: direct, inorganic diode semiconductor lasers based on quantum wells of gallium (III) nitride at 380-417nm [2] [3] or indium gallium nitride at 450 ...