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The carbon-dioxide laser ( CO2 laser) was one of the earliest gas lasers to be developed. It was invented by Kumar Patel of Bell Labs in 1964 [1] and is still one of the most useful types of laser. Carbon-dioxide lasers are the highest-power continuous-wave lasers that are currently available. They are also quite efficient: the ratio of output ...
Corrective lens. A pair of contact lenses, positioned with the concave side facing upward. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia.
Cataract surgery is the most common application of lens removal surgery, and is usually associated with lens replacement. It is used to remove the natural lens of the eye when it has developed a cataract, a cloudy area in the lens that causes visual impairment. [4] [10] Cataracts usually develop slowly and can affect one or both eyes. [4]
LCA-Vision is a provider of photorefractive keratectomy in the United States under the LasikPlus brand. [1] The company performs Custom LASIK, PRK and monovision treatment to correct nearsightedness, farsightedness, astigmatism and reduce the effects of presbyopia. According to the company, one million laser vision correction procedures have ...
Corrective lenses. The simplest form of treatment for far-sightedness is the use of corrective lenses, i.e. eyeglasses or contact lenses. Eyeglasses used to correct far-sightedness have convex lenses. Surgery. There are also surgical treatments for far-sightedness: Laser procedures
Laser pointer. Red (635 nm), blueish violet (445 nm), and green (520 nm) laser pointers. A laser pointer or laser pen is a (typically battery-powered) handheld device that uses a laser diode to emit a narrow low-power visible laser beam (i.e. coherent light) to highlight something of interest with a small bright colored spot.
In economics, an externality or external cost is an indirect cost or benefit to an uninvolved third party that arises as an effect of another party's (or parties') activity. Externalities can be considered as unpriced components that are involved in either consumer or producer market transactions. Air pollution from motor vehicles is one example.
Roof prism. A roof pentaprism used in Single-lens reflex cameras; the lower right face is the roof ( dach ). A roof prism, also called a Dachkanten prism or Dach prism (from German: Dachkante, lit. "roof edge"), is a reflective prism containing a section where two faces meet at a 90° angle, resembling the roof of a building and thus the name.