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Light therapy, also called phototherapy or bright light therapy is the exposure to direct sunlight or artificial light at controlled wavelengths in order to treat a variety of medical disorders, including seasonal affective disorder (SAD), circadian rhythm sleep-wake disorders, cancers, neonatal jaundice, and skin wound infections.
The history of light therapy can be traced back to ancient Egypt and India, where therapy with natural sunlight was first used to treat leucoderma. [3] In the 1850s, Florence Nightingale's advocacy of exposure to clean air and sunlight for health restoration also contributed to the initial development of light therapy for treatments. [4]
Star Diagonal: Used to change the angle of the light coming out of a telescope, for easier viewing. Herschel Wedge: Similar to a star diagonal with a wedge-shaped unsilvered prism reflector that reduces incoming light by up to 95% for solar viewing. Coma corrector a correcting lens used to reduce coma distortion in fast reflecting telescopes.
Light therapy is one treatment option for those diagnosed with Seasonal Affective Disorder (SAD), a type of depression that follows a seasonal pattern and is impacted by daylight hours, Dimitriu ...
An example system can consist of a light source (generally a laser or a lamp), a controller for the amount of light that enters, a guide for the light, and a delivery system. Often, the design function in such a way that a medium is met between the diffusing light that may cause additional, unwanted photolysis and light attenuation; both being ...
The telescope is more a discovery of optical craftsmen than an invention of a scientist. [1] [2] The lens and the properties of refracting and reflecting light had been known since antiquity, and theory on how they worked was developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the ...
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Photodynamic therapy (PDT) is a form of phototherapy involving light and a photosensitizing chemical substance used in conjunction with molecular oxygen to elicit cell death (phototoxicity). [ 1 ] PDT is used in treating acne , wet age-related macular degeneration , psoriasis , and herpes .