periscope


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periscope

(pĕr`ĭskōp) [Gr.,=view around], instrument to enable a person to see objects not in his direct line of vision or concealed by some intervening body. Its essential parts are a tube, prisms, lenses, mirrors, and an eyepiece. The image is received in one mirror and reflected through the tube with its lenses to a mirror visible to the viewer. Periscopes used in submarines are so arranged that they can be turned to permit a view of the entire horizon, with built-in rangefinders and typically six times magnification. Submarine periscopes are of noncorrosive metal, have tubes up to 30 ft (9.1 m) long and about 6 in. (15 cm) in diameter (only a small section projects above the water), and may be withdrawn into the submarine. Many smaller types of periscopes are used in trenches and tanks. With the development of fiber optics, periscopes (known as cystoscopes or endoscopes) have become useful in medicine.

Periscope

 

an optical instrument for viewing from such military shelters as trenches and dugouts, from tanks, and from submarines. Many periscopes permit measurement of horizontal and vertical angles on the terrain and also range-finding. The design and optical characteristics of a periscope are determined by its purpose, place of installation, and the depth from which observations are to be made.

The simplest periscope is the vertical type, consisting of a vertical sighting tube and two mirrors. Set at 45° angles to the axis of the tube, the mirrors form an optical system that refracts light rays coming from the observed object and directs them toward the observer’s eye. Periscopes in which right-angle prisms are installed in the tube instead of mirrors are common, as are telescopic lens systems and rotating systems, which can be used to obtain an erect magnified image. The field of vision of a periscope with low magnification (up to 1.5 power) is about 40°; it usually decreases with greater magnification. Certain types of periscopes give panoramic vision.

periscope

[′per·ə‚skōp]
(optics)
An optical instrument used to provide a raised line of vision where it may not be practical or possible, as in entrenchments, tanks, or submarines; the raised line of vision is obtained by the use of mirrors or prisms within the structure of the item; it may have single or dual optical systems.
A thin astigmatic lens which approximates a meniscus shape and has a base curve of ±1.25 diopters.
References in periodicals archive ?
Bell, founder of the Periscope Community Summit, referring to the inaugural gathering in September.
Brands like Adidas, Spotify, Red Bull and General Electric are already successfully leveraging the power of Periscope to engage with consumers.
Ekol, who earlier attracted attention after the CEO of Periscope expressed his gratitude to the teacher, announced on Thursday that YouTube suspended his channel without providing any explanation to him.
Because you can't schedule Periscope broadcasts in advance, you won't have a direct link you can send people to other than your Periscope profile," Whaling says.
Plus, Periscope appeals to the Snapchat crowd because 'scopes' disappear after 24 hours, so there's no need to worry about a video from years ago hanging around or blotting your digital history.
They may have the consent of the congregation, but, in other cases, "scopers" have been told to remove videos such as the TV show Game Of Thrones and highprofile sporting events that violate copyright, even though Periscope policy "prohibits the broadcast of copyright-protected material".
In Dubai, they blocked Skype but that didn't go very well, hope they'll unblock periscope soon:/" a user said on Twitter.
net has tested both Periscope and Meerkat on the Etisalat network, with neither app allowing users to log in.
Personally, I'm far more excited about Periscope and Meerkat than Snapchat.
Non-hull penetrating masts also can be reconfigured with relative ease with new systems and capabilities, and have fewer moving parts, thus reducing overall periscope life cycle costs and correspondingly the maintenance, repair and overhaul burden.
Live streaming technology is not new (Ustream and a Japanese-based app called Twitcast have been around for several years), but having Twitter's resources and established network behind it catapults Periscope squarely into the lead.
And Periscope users can upload their video streams for on-demand playback over the next 24 hours.