Encyclopedia - Refracting Telescope: Encyclopedia Ii - Refracting Telescope - Notable Refracting Telescopes
The 50 cm refractor at Nice Observatory. 20 inch refractor at the Observatories at Chabot Space and Science Center in Oakland, California...   » Read the article

Encyclopedia - History Of Telescopes: Encyclopedia Ii - History Of Telescopes - Refracting Telescopes
There is an archeological finding of lenses is from Gotlandia in Sweden. These so-called Visby lenses can be dated to the second half of ...   » Read the article

Encyclopedia - Refracting Telescope: Encyclopedia Ii - Refracting Telescope - Technical Difficulties
Refractors are criticized for their relatively high-degree of residual chromatic and spherical aberration. In very large apertures, there...   » Read the article

Encyclopedia - Yerkes Observatory: Encyclopedia - Yerkes Observatory
The Yerkes Observatory is an astronomy observatory of the University of Chicago, in Williams Bay, Wisconsin. It was created in 1897 by G...   » Read the article

Encyclopedia - Telescope: Encyclopedia - Telescope
A telescope (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') is an optical tool which gathers and ...   » Read the article

Encyclopedia - Alvan Graham Clark: Encyclopedia - Alvan Graham Clark
Alvan Graham Clark (July 10, 1832 – June 9, 1897), born in Fall River, Massachusetts, was an American astronomer and telescope-maker. H...   » Read the article

Encyclopedia - Adaptive Optics: Encyclopedia - Adaptive Optics
Adaptive optics is a technology to improve the performance of (usually) astronomical telescopes by reducing the effects of atmospheric di...   » Read the article

Encyclopedia - Anti-reflective Coating: Encyclopedia - Anti-reflective Coating
Anti-reflective or antireflection (AR) coatings are a type of optical coating applied to lenses and other devices to reduce reflection fr...   » Read the article

Encyclopedia - Astronomical Seeing: Encyclopedia - Astronomical Seeing
Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by the Earth's atmosphere. The astr...   » Read the article

Encyclopedia - Amateur Telescope Making: Encyclopedia - Amateur Telescope Making
There is a strong tradition of amateur telescope making within the amateur astronomy community. The classic amateur telescope is the Newt...   » Read the article

Encyclopedia - Angular Resolution: Encyclopedia - Angular Resolution
Angular resolution describes the resolving power of a telescope. Angular resolution - Definition of terms. Resolving power is the abili...   » Read the article

Encyclopedia - Borosilicate Glass: Encyclopedia - Borosilicate Glass
Borosilicate glass is a particular type of glass, better known under the brand names Pyrex and Kimax. It was first developed by German gl...   » Read the article

Encyclopedia - David Brewster: Encyclopedia - David Brewster
Sir David Brewster, (December 11, 1781 – February 10, 1868) was a Scottish scientist and writer. He was born at Jedburgh, where his fat...   » Read the article

Encyclopedia - Binoculars: Encyclopedia - Binoculars
Binocular telescopes or binoculars are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accuratel...   » Read the article

Encyclopedia - Aberration In Optical Systems: Encyclopedia - Aberration In Optical Systems
Aberration in optical systems (lenses, prisms, mirrors or series of them intended to produce a sharp image) generally leads to blurring o...   » Read the article

Encyclopedia - Refracting Telescope: Encyclopedia Ii - Refracting Telescope - Technical Difficulties
Refractors are criticized for their relatively high-degree of residual chromatic and spherical aberration. This affects shorter focal len...   » Read the article

Encyclopedia - Skygazing: Encyclopedia Ii - Skygazing - Observations With A Refracting Telescope
A refracting telescope is an instrument that is constituted of one or several lenses and that focuses the luminous rays toward one point ...   » Read the article

Encyclopedia - History Of Telescopes: Encyclopedia Ii - History Of Telescopes - Achromatic Telescope
The historical sequence of events now brings us to the discovery of the achromatic telescope. The first person who succeeded in making ac...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Types
Telescopes are broadly classified into two main types. Optical telescopes Radio telescopes Optical telescopes are also divided into two...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Types
The telescopes are broadly classified into two main categories. Optical telescopes Radio telescopes The optical telescopes are again di...   » Read the article

Encyclopedia - History Of Telescopes: Encyclopedia Ii - History Of Telescopes - Reflecting Telescopes
Until Newton's discovery of the different refrangibility of light of different colours, it was generally supposed that object-glasses of ...   » Read the article

Encyclopedia - Skygazing: Encyclopedia Ii - Skygazing - Naked Eye Skygazing
Skygazing - Diurnal observation. The extreme brightness of the Sun saturates the sky and prevents the observation of less luminous obje...   » Read the article

Encyclopedia - Skygazing: Encyclopedia Ii - Skygazing - The Observation With A Reflecting Telescope
A reflecting telescope is constituted not of lenses but of mirrors. It being less costly to manufacture, one can, for the price of a refr...   » Read the article

Encyclopedia - Skygazing: Encyclopedia Ii - Skygazing - Binocular Gazing
Binoculars are very useful when you wish to observe bright, large astronomical objects. Thanks to them it is possible to see lunar crater...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Imperfect Images
No telescope can form a perfect image. Even if a reflecting telescope could have a perfect mirror, or a refracting telescope could have a...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Focal Planes
Reflecting telescope - Prime focus. In a prime focus design in large observatory telescopes, the observer sits inside the telescope, at...   » Read the article

Encyclopedia - Lick Observatory: Encyclopedia Ii - Lick Observatory - Early History
Lick Observatory was the world's first mountain-top observatory. The observatory was constructed between 1876 and 1887, from a bequest fr...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - History
The first telescopes may have been Assyrian crystal lenses. Article The Visby lenses tentatively suggest that the technology was known to...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Focal Planes
Reflecting telescope - Prime focus. In a prime focus design, the observer sits inside the telescope, at the focal point of the reflecte...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - History
The first telescopes may have been Assyrian crystal lenses. Article Though the Visby lenses tentatively suggest that the technology was k...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Telescope Mountings
A simple telescope mount is an altitude-azimuth or altazimuth mount. It is similar to that of a surveying transit. A fork rotates in azim...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Telescope Mountings
A simple telescope mount is an altitude-azimuth or altazimuth mount. It is similar to that of a surveying transit. A fork rotates in azim...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Research Telescopes
Most large research telescopes can operate as either a Cassegrain telescope (longer focal length, and a narrower field with higher magnif...   » Read the article

Encyclopedia - Telescope: Encyclopedia Ii - Telescope - Research Telescopes
Most large research telescopes can operate as either a cassegrain telescope (longer focal length, and a narrower field with higher magnif...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Discovery And History Of Observations
The first Herbig-Haro object was observed in the late 19th century by Burnham, when he looked at the star T Tauri with the 36-inch refrac...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Technical Considerations
A curved primary mirror is the reflector telescope's basic optical element and creates an image at the focal plane. The distance from the...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Technical Considerations
The primary mirror is the reflector telescope's basic optical element and creates an image at the focal plane. The distance from the mirr...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Reflecting Telescope Designs
Reflecting telescope - Schmidt camera. The Schmidt camera, invented by Bernhard Schmidt, is not technically a telescope since the light...   » Read the article

Encyclopedia - Reflecting Telescope: Encyclopedia Ii - Reflecting Telescope - Reflecting Telescope Designs
Reflecting telescope - Newtonian focus. The Newtonian usually has a paraboloid primary mirror but for small apertures, say 12cm or less...   » Read the article

Encyclopedia - Optical Telescope: Encyclopedia Ii - Optical Telescope - How It Works
For detailed information on specific designs of reflecting and refracting telescopes, see the main articles on Reflecting telescopes and ...   » Read the article

Encyclopedia - Schmidt-cassegrain Telescope: Encyclopedia Ii - Schmidt-cassegrain Telescope - Variations
While there are countless variations, (both mirrors spherical, both mirrors aspherical, or one of each) they can be divided into two prin...   » Read the article

Encyclopedia - Angular Resolution: Encyclopedia Ii - Angular Resolution - Microscope Case
The resolution D depends on the angular aperture α: . Here α is the collecting angle of the lens, which depends on the width of objec...   » Read the article

Encyclopedia - Optician: Encyclopedia Ii - Optician - Eyecare Opticians
An optician is an eye care professional who provides lenses for the correction of vision defects. The lenses may be contact lenses, or he...   » Read the article

Encyclopedia - Binoculars: Encyclopedia Ii - Binoculars - Optical Construction
When light strikes an interface between two materials of different refractive index (e.g., at an air-glass interface), some of the light ...   » Read the article

Encyclopedia - Eyepiece: Encyclopedia Ii - Eyepiece - Eyepiece Properties
Several properties of an eyepiece are likely to be of interest to a user of an optical instrument, when comparing eyepieces and deciding ...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Speed Of Light
Although some people speak of the "velocity of light", the word velocity should be reserved for vector quantities, that is, those with bo...   » Read the article

Encyclopedia - Optical Telescope: Encyclopedia Ii - Optical Telescope - Angular Resolution
Ignoring blurring of the image by turbulence in the atmosphere (atmospheric seeing) and optical imperfections of the telescope, the angul...   » Read the article

Encyclopedia - Optical Telescope: Encyclopedia Ii - Optical Telescope - Research Telescopes
Nearly all large research-grade astronomical telescopes are reflectors. Some reasons are: In a lens the entire volume of material has to...   » Read the article

Encyclopedia - Angular Resolution: Encyclopedia Ii - Angular Resolution - Telescope Case
Point-like sources separated by an angle smaller than the angular resolution cannot be resolved. A single optical telescope has an angula...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Refraction
All light propagates at a finite speed. Even moving observers always measure the same value of c, the speed of light in vacuum, as c = 29...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Uses Of Lenses
One important use of lenses is as a prosthetic for the correction of visual impairments such as myopia, hyperopia, presbyopia, and astigm...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Uses Of Lenses
One important use of lenses is as a prosthetic for the correction of visual impairments such as myopia, hyperopia, presbyopia, and astigm...   » Read the article

Encyclopedia - Binoculars: Encyclopedia Ii - Binoculars - Design Details
Binoculars to be used to view objects which are not at a fixed distance must have a focussing arrangement. In some cases the two telescop...   » Read the article

Encyclopedia - Optician: Encyclopedia Ii - Optician - Scientific Equipment Opticians
An optician is also an individual who makes and adjusts other optical aids, including telescope optics and microscope lenses. Optician -...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Multiple Lenses
Lenses may be combined to form more complex optical systems. The simplest case is when lenses are placed in contact: if the lenses of foc...   » Read the article

Encyclopedia - Astronomical Seeing: Encyclopedia Ii - Astronomical Seeing - Measures Of Astronomical Seeing
There are three common descriptions of the astronomical seeing conditions at an observatory: The FWHM of the seeing disc r0 and t0 The C...   » Read the article

Encyclopedia - Aether Drag Hypothesis: Encyclopedia Ii - Aether Drag Hypothesis - Historical Importance
The aether drag hypothesis is historically important because it was one of the reasons why Newton's corpuscular theory of light was repla...   » Read the article

Encyclopedia - Fused Quartz: Encyclopedia Ii - Fused Quartz - Applications
Specially prepared fused silica is also the key starting material used to make optical fiber for telecommunications. Because of its stren...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Proper Motions And Variability
Spectroscopic observations of HH objects show that they are moving away from the source stars at speeds of 100 to 1000 km/s. In rece...   » Read the article

Encyclopedia - Glass: Encyclopedia Ii - Glass - Glass As A Liquid
One common misconception is that glass is a super-cooled liquid of practically infinite viscosity when at room temperature. Supporting ev...   » Read the article

Encyclopedia - Red Dot Sight: Encyclopedia Ii - Red Dot Sight - Types Of Red Dot Sights
Some of the first red dot sights to appear were "occluded" sights; the image of the target was not visible through the sight. Looking int...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Visible Electromagnetic Radiation
Visible light is the portion of the electromagnetic spectrum between the frequencies of 380 THz (3.8×1014 hertz) and 750 ...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Measurement Of Light
The following quantities and units are used to measure the quantity or "brightness" of light. edit edit Sometimes confusingly called "in...   » Read the article

Encyclopedia - Isaac Newton's Early Life And Achievements: Encyclopedia Ii - Isaac Newton's Early Life And Achievements - The Composition Of White Light
On December 21, 1671 he was proposed as a candidate for admission into the Royal Society by Dr Seth Ward, bishop of Salisbury, and on Jan...   » Read the article

Encyclopedia - Aberration In Optical Systems: Encyclopedia Ii - Aberration In Optical Systems - Analytic Treatment Of Aberrations
The preceding review of the several errors of reproduction belongs to the Abbe theory of aberrations, in which definite aberrations are d...   » Read the article

Encyclopedia - Ray Tracing: Encyclopedia Ii - Ray Tracing - Genesis And Description Of Ray Tracing
Ray tracing describes a realistic method for rendering images (or frames) constructed in 3D computer graphics environments. It works by t...   » Read the article

Encyclopedia - Ray Tracing: Encyclopedia Ii - Ray Tracing - Genesis And Description Of Ray Tracing
Ray tracing describes a realistic method for rendering images (or frames) constructed in 3D computer graphics environments. It works by t...   » Read the article

Encyclopedia - Wavefront: Encyclopedia Ii - Wavefront - Wavefront Aberrations
Methods utilizing wavefront measurements or predictions can be considered an advanced approach to lens optics, where a single focal dista...   » Read the article

Encyclopedia - James Lick: Encyclopedia Ii - James Lick - California Years
Lick arrived in San Francisco, California, in January 1848, bringing with him his tools, work bench, $30,000 in gold, and 600 pounds (300...   » Read the article

Encyclopedia - Spectrometer: Encyclopedia Ii - Spectrometer - Spectroscopes
Spectrometers known as spectroscopes are used in spectroscopic analysis to identify materials. Spectroscopes are used often in astronomy ...   » Read the article

Encyclopedia - Microscope: Encyclopedia Ii - Microscope - Optical Resolution
A lens magnifies by bending light (see refraction). Optical microscopes are restricted in their ability to resolve features by a phenomen...   » Read the article

Encyclopedia - Microscope: Encyclopedia Ii - Microscope - Optical Resolution
A lens magnifies by bending light (see refraction). Optical microscopes are restricted in their ability to resolve features by a phenomen...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Numbers And Distribution
Over 400 individual HH objects or groups are now known. They are ubiquitous in star-forming H II regions, and are often found in large gr...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Lens Construction
The most common type of lenses are spherical lenses, which are formed from surfaces that have spherical curvature, that is, the front and...   » Read the article

Encyclopedia - Aberration In Optical Systems: Encyclopedia Ii - Aberration In Optical Systems - Chromatic Or Colour Aberration
In optical systems composed of lenses, the position, magnitude and errors of the image depend upon the refractive indices of the glass em...   » Read the article

Encyclopedia - Binoculars: Encyclopedia Ii - Binoculars - Maintenance
If the binoculars are not collimated properly, i.e., if the images from the two tubes are not properly aligned, then they will give poor ...   » Read the article

Encyclopedia - Red Dot Sight: Encyclopedia Ii - Red Dot Sight - Reticles
The most common reticle is a small dot, covering 5 minutes of arc, illuminated by a red LED, hence the common term "red dot sight". Sight...   » Read the article

Encyclopedia - Binoculars: Encyclopedia Ii - Binoculars - Optical Parameters
The diameter of the objective lenses determines the light-gathering power and the ultimate resolving power of the binoculars. The ratio o...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Imaging Properties
As mentioned above, a positive or converging lens will focus a collimated beam travelling along the lens axis to a spot (known as the foc...   » Read the article

Encyclopedia - Angular Resolution: Encyclopedia Ii - Angular Resolution - Explanation
The resolving power of a lens is ultimately limited by diffraction effects. The lens' aperture is a "hole" that is analogous to a two-dim...   » Read the article

Encyclopedia - Lens Optics: Encyclopedia Ii - Lens Optics - Aberrations
Lenses do not form perfect images, and there is always some degree of distortion or aberration introduced by the lens which causes the im...   » Read the article

Encyclopedia - Eyepiece: Encyclopedia Ii - Eyepiece - Eyepiece Designs
Technology has developed over time and there are a variety of eyepiece designs for use with optical telescopes. They vary in their intern...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Color And Wavelengths
The different wavelengths are detected by the human eye and then interpreted by the brain as colors, ranging from red at the longest wave...   » Read the article

Encyclopedia - Light: Encyclopedia Ii - Light - Light Sources
There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum...   » Read the article

Encyclopedia - Galileo Galilei: Encyclopedia Ii - Galileo Galilei - Technology
Galileo made a few contributions to what we now call technology as distinct from pure physics, and suggested others. This is not the same...   » Read the article

Encyclopedia - Léon Foucault: Encyclopedia Ii - Léon Foucault - Middle Years
In the 1840s, he contributed to the Comptes Rendus a description of an electromagnetic regulator for the electric arc lamp, and, in conju...   » Read the article

Encyclopedia - Isaac Newton's Early Life And Achievements: Encyclopedia Ii - Isaac Newton's Early Life And Achievements - Newton's Poverty
On March 8, 1673 Newton wrote to Oldenburg, the secretary of the Royal Society: "Sir, I desire that you will procure that I may be put ou...   » Read the article

Encyclopedia - Light Pollution: Encyclopedia Ii - Light Pollution - Types Of Light Pollution
"Light pollution" is a broad term that refers to multiple problems, all of which are caused by inefficient, annoying or arguably unnecess...   » Read the article

Encyclopedia - Herbig-haro Object: Encyclopedia Ii - Herbig-haro Object - Physical Characteristics
Emission from HH objects is caused by shock waves when they collide with the interstellar medium, but their motions are complicated. Spec...   » Read the article

Encyclopedia - James Lick: Encyclopedia Ii - James Lick - South American Years
Lick found his time in Buenos Aires to be difficult, due to his ignorance of Spanish and the turbulent political situation in the country...   » Read the article

Encyclopedia - Tycho Brahe: Encyclopedia Ii - Tycho Brahe - Tycho And Astronomy
Tycho was the preeminent observational astronomer of the pre-telescopic period, and his observations of stellar and planetary positions a...   » Read the article

Encyclopedia - Glass: Encyclopedia Ii - Glass - Properties And Uses
One of the most obvious characteristics of ordinary glass is that it is transparent to visible light (not all glassy materials are). The ...   » Read the article

Encyclopedia - American Lobster: Encyclopedia Ii - American Lobster - Anatomical Features
American lobster - Antennae. The long antennae are used to feel the area around a lobster, and appear to be more useful than the eyes. ...   » Read the article

Encyclopedia - Laser Applications: Encyclopedia Ii - Laser Applications - Scientific
Laser applications - Spectroscopy. Most types of laser are an inherently pure source of light; they emit near-monochromatic light with ...   » Read the article

Encyclopedia - Aperture: Encyclopedia Ii - Aperture - Application
The aperture stop is an extremely important element in most optical designs. Its most obvious function is to reduce the amount of light t...   » Read the article

Encyclopedia - Fused Quartz: Encyclopedia Ii - Fused Quartz - Physical Properties
The extremely low coefficient of thermal expansion accounts for its remarkable ability to undergo large, rapid temperature changes withou...   » Read the article

Encyclopedia - Ray Tracing: Encyclopedia Ii - Ray Tracing - Example
As a demonstration of the principles involved in raytracing, let us consider how one would find the intersection between a ray and a sphe...   » Read the article

Encyclopedia - Aberration In Optical Systems: Encyclopedia Ii - Aberration In Optical Systems - Practical Elimination Of Aberrations
As Maxwell already claimed in 1858, there is no optical system, which reproduces absolutely a finite plane on another with pencils of fin...   » Read the article

Encyclopedia - Amateur Telescope Making: Encyclopedia Ii - Amateur Telescope Making - Mirror Making
The mirror is usually ground and polished to a shallow spherical section, and then carefully "figured" to a paraboloid using a special po...   » Read the article

Article - Popular Pages Sitemap Iv - Q
This is a sitemap for Popular Pages IV - Q . Click on a link and you will find multiple definitions and articles related to the word. ...   » Read the article