Optical telescope
"Observable world" describes what can be seen using a telescope, when viewing an object or range the observer may use many different techniques. Understanding what can be viewed and how to view it depends on the field of view. Viewing an object at a size that fits entirely in the field of view is measured using the two telescope properties—focal length and aperture, with the inclusion of an ocular eyepiece with suitable focal length (or diameter). Comparing the observable world and the angular diameter of an object shows how much of the object we see. However, the relationship with the optical system may not result in high surface brightness. Celestial objects are often dim because of their vast distance, and detail may be limited by diffraction or unsuitable optical properties.
NEOSTEL
The fly eye aspect of the telescope refers to the use of compound optics, as opposed to the single set of optics used in a conventional telescope. Historically, telescopes have been designed around a single human observer looking through an eye piece. As technology has developed astrographs have been used where either a photographic plate or CCD records the image, which a human observer can then view. With the human eye no longer directly observing the image there is no longer a restriction on a single viewing point. Further, as asteroid detection technology has developed, software has become fully automated and no longer requires a human observer to view the majority of images at all. Light enters the telescope through the aperture and is reflected off the primary mirror onto a beam splitter, which is a hexadecagonal pyramid in shape. The split beam then passes into 16 separate aspheric lenses and on to 16 corresponding CCD image sensors. NEOSTEL uses the 16 CCD cameras to view 45 square degrees of light entering the telescope aperture. The resolution is 1.5 arc seconds per pixel across the whole field of view.