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Topic: Airy disc

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	Spider diffraction and apodization
		While the spikes caused by spider vanes can be visually distracting, the amount of energy lost from the disc is usually negligible for general observing (3-vane spider spikes are usually shorter, due to the vanes being generally thicker, as it is needed for mechanical stability in that spider configuration).
		Relative intensity of the central peak to that of the Airy disc is proportional to the ratio of the vane area to the area of the clear aperture.
		The encircled energy (within the Airy disc) increase due to the apodizing mask is 20% for unobstructed apertures, with the gain steadily decreasing as the central obstruction grows larger: it is ~10% at 0.2D obstruction, and ~7% at 0.3D obstruction.
	www.telescope-optics.net /spider.htm (1528 words)

	Airy disc - Wikipedia, the free encyclopedia
		The diameter of this disc is related to the wavelength of the illuminating light and the size (f-number) of the circular aperture.
		The Rayleigh criterion for barely resolving two objects is that the centre of the Airy disc for the first object occurs at the first minima of the Airy disc of the second.
		The Airy disc is used in astronomy as one of several methods used to determine the quality and alignment of the optical components of a telescope.
	en.wikipedia.org /wiki/Airy_disc (273 words)

	Angular resolution - Wikipedia, the free encyclopedia
		The lens' aperture is a "hole" that is analogous to a two-dimensional version of the single-slit experiment; light passing through it interferes with itself, creating a ring-shaped diffraction pattern, known as the Airy pattern, that blurs the image.
		The factor 1.22 is derived from a calculation of the position of the first dark ring surrounding the central Airy disc of the diffraction pattern.
		This factor is used to approximate the ability of the human eye to distinguish two separate point sources depending on the overlap of their Airy discs.
	en.wikipedia.org /wiki/Angular_resolution (754 words)

	Philosophical Reflections in Physics and Math (Site not responding. Last check: 2007-10-31)
		However, whatever the precise source of the interference may be, the end result is to cause out-of-phase variations, either within the internal dialectic of the electron or between the interacting fields of the electrons from the gun and the molecules making up the material with the hole through which the former electrons are shot.
		In view of the foregoing, although one is able to derive a number of patterns in different experimental situations suggesting that interference phenomena are somehow involved, this constitutes a misinterpretation of the meaning of the patterns which emerge in the different contexts.
		In both cases, however, the structural character of the pattern on the screen is consistent with the presence of oscillatory which is generated by the shifts in the arrangement of ratios and phase relationship patterns in the electron's spectrum of constraints and degrees of freedom during its journey from the gun to the screen.
	amanesis.org /Physics/quantume.htm (4342 words)

	Untitled Document (Site not responding. Last check: 2007-10-31)
		When some larger 'discs' move from one side of the frame to the other, this notch changes position from top of the 'disc' to the bottom of the 'disc'.
		This is caused by the convex shape of the lens in the zoom, not rotation of the 'disc'.
		Airy Discs are semi-transparent due to the out-of-focus effect, and some of the tether is seen, but is reduced in clarity when seen through the Airy Disc passing INFRONT.
	home.manyrivers.aunz.com /sting1946/critter.htm (1541 words)

	Airy disc -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-31)
		Due to the ((physics) a movement up and down or back and forth) wave nature of ((physics) electromagnetic radiation that can produce a visual sensation) light, light passing through (A natural opening in something) apertures is (Click link for more info and facts about diffracted) diffracted, and the diffraction increases with decreasing aperture size.
		The diameter of this disc is related to the wavelength of the illuminating light and the (Click link for more info and facts about f-number) f-number of the circular aperture.
		The (Click link for more info and facts about Rayleigh criterion) Rayleigh criterion for barely resolving two objects is that the center of the Airy disc for the first object occurs at the first minima of the Airy disc of the second.
	www.absoluteastronomy.com /encyclopedia/a/ai/airy_disc.htm (235 words)

	Effects of wavefront aberrations
		Diameter of the first minima (approximately the middle of the first dark ring) of diffraction pattern determines the "Airy disc", in honor of the British astronomer Sir George B. Airy, who was the first to mathematically describe diffraction phenomenon back in 1834.
		Airy disc of the perfect diffraction pattern has linear radius of 1.22λF, angular radius of 1.22λ/D (in radians), and contains 83.8% of the total energy.
		While the size of the central diffraction disc determines limit to resolution of relatively bright point-objects, it is the amount of energy spread around the disc what critically influences the limit to resolution of details on low-contrast extended objects.
	www.telescope-optics.net /effects1.htm (1016 words)

	Lenox Laser - Laser drilling, aperture, orifice and microhole leader.
		For a l0 micron hole diameter, the Airy disc diameter is several degrees as subtended between element and image plane.
		Aperture substrate discs with a highly reflective surface facing the laser provide the advantage of reflecting away most of the energy so that the disc is not damaged by heat.
		A substrate disc thickness to hole diameter ratio of 2:1 or 3:1 is acceptable.
	www.lenoxlaser.com /opticalproducts/high_power_apertures.html (1915 words)

	Test Reports and Airy Discs (Site not responding. Last check: 2007-10-31)
		The in-focus Airy discs of the two lenses are virtually identical, and I doubt that anyone would be able to tell them apart from even the best lens in this run.
		While the lenses are nulled in the green, the inner and outer Fresnel patterns show the effect of sphero-chromatism at the ends of the spectrum (blue is overcorrected as shown in the inside pattern, red is undercorrected as shown in the outside pattern).
		However, this lens is made to be used in-focus, and the Airy pattern shows a nice central peak of ~ 84% of the energy (burned in unfortunately) and a first diffraction ring with approximately 7%.
	voltaire.csun.edu /roland/test.html (937 words)

	TBird Tech : Telescope Resolution
		The Airy disc size, however, is not the full determination of the resolution of a telescope.
		Since we have previously shown that the Airy disc size is not determined by the actual size of the telescope (but rather by the ratio of focal length to mirror diameter), this means that, for a given Airy disc size (i.e.
		The Airy disc size is determined by the angle at which the extreme marginal rays (from the primary mirror) approach the focal plane, relative to the optical centerline.
	thunderbirdtechnology.com /html/tbird_tech___telescope_resolution.html (1467 words)

	Glossary of Astronomical Terms
		It commonly refers to a simple device which consists of a pair of concentric discs, one of which has part of the celestial sphere projected onto it, the other of which has a window representing the horizon.
		Scales about the perimeters of the discs allow it to be set to show the sky at specific times and dates, enabling its use as a simple and convenient aid to location of objects.
		Transit (i) The passage of Mercury or Venus across the disc of the Sun (ii) The passage of a planet's moon across the disc of the parent planet (iii) The passage of a planetary feature (such as Jupiter's Great Red Spot) across the central meridian of the planet.
	www.astunit.com /tutorials/glossary.htm (4622 words)

	The Airy Discs VS. The Elohim Energy, what is and isn't ice crystals. - Forums powered by UBBThreads™ (Site not responding. Last check: 2007-10-31)
		She felt that what what were seeing on the tape, in the tether, were just airy discs.
		Airy discs are when you have a star or a pinpoint light source, and camera lens goes way out of focus.
		So what happens is the light becomes so diffused in the lens, because it's so out-of-focus, we get this phenonmenon called airy disc, and when many people would look at this they would say, "Wow, that looks like the ufos we've seen on the tape." I can understand how Claire Williams came to these conclusions.
	uplink.space.com /showflat.php?Cat=&Board=seti&Number=54498&page=14&view=collapsed&sb=5&o=0&fpart= (1240 words)

	Notes from Under Sky
		The width of the Airy disc is measured in angles, not in inches or mm.
		The angular width of the disc in my 5-inch scope is about one arcsecond--that is, 1/3,600 of a degree, and about 1/1,800 the width of the full moon.
		However, once you magnify that disc 250x--which is the 50x per inch "limit" on my telescope--that blows up to about 1/14 of a degree, and 1/7 the width of the full moon.
	astro.isi.edu /notes/magnify.html (1018 words)

	Digital Gallery Plus: Depth of Field 2 (Site not responding. Last check: 2007-10-31)
		A star, or point, object is thus focussed not to a point on a film or plate but to a disc called the Airy disc named after the astronomer George Airy who observed it when using a telescope to look at stars.
		The profile of an Airy disc is shown in figure 1 where its diameter d depends on the f-stop setting of the imaging lens.
		is the diameter of the disc of confusion for the eye at the viewing distance of 250mm, taking a value somewhere between 0.15mm and 0.25mm, and M is the magnification given by the ratio of the size of the print to the size of the film or CCD array.
	www.smls03494.pwp.blueyonder.co.uk /dof_2.htm (1838 words)

	Compact Disc Introduction: CD
		The compact disc is read by a laser which receives a series of digital pulses from a track of bumps (125 nanometer high) as it follows a spiral track from the middle of the disc outwards.
		Discs are written from the center to the outside (this increases manufacturing yield, and also allows for changes in disc size).
		Once the discs are molded, a metal layer is used to coat the discs.
	www.geocities.com /columbiaisa/cd_intro.htm (2999 words)

	Circular Aperture Diffraction
		When light from a point source passes through a small circular aperture, it does not produce a bright dot as an image, but rather a diffuse circular disc known as Airy's disc surrounded by much fainter concentric circular rings.
		This example of diffraction is of great importance because the eye and many optical instruments have circular apertures.
		The only retouching of the digital image was to paint in the washed out part of the central maximum (Airy's disc).
	hyperphysics.phy-astr.gsu.edu /hbase/phyopt/cirapp2.html (504 words)

	Test Reports and Airy Discs
		The in-focus Airy discs of the two lenses are virtually identical, and I doubt that anyone would be able to tell them apart from even the best lens in this run.
		While the lenses are nulled in the green, the inner and outer Fresnel patterns show the effect of sphero-chromatism at the ends of the spectrum (blue is overcorrected as shown in the inside pattern, red is undercorrected as shown in the outside pattern).
		However, this lens is made to be used in-focus, and the Airy pattern shows a nice central peak of ~ 84% of the energy (burned in unfortunately) and a first diffraction ring with approximately 7%.
	geogdata.csun.edu /~voltaire/roland/test.html (937 words)

	The Unofficial C5+ Home Page: Contrast
		The Airy pattern refers to the image of a point source (which a star is, for all intents and purposes) through perfect optics.
		The Airy disc is always present, although it's hard to see for the first time with powers under perhaps 125x or so (with the C5+).
		The diameter of the disc and the spread of the diffraction rings gets smaller as the aperture gets larger, so even though an 8-inch SCT has more of its light in its diffraction rings, those diffraction rings may lie almost entirely within the Airy disc of a smaller 4-inch refractor.
	astro.isi.edu /c5plus/contrast.html (1264 words)

	Scott McGill.com - Progressive Guitarist
		While the first disc offers a nice and often pleasing mix of songs and song sections with melodies and without melodies, with defined rhythms and without defined rhythms, the second disc is even more sparse and wide open.
		It's just that there are simply less of these moods on the airy disc two, and what makes disc two so attractive is the contrast between the moods and the little journeys between those moods.
		Of course, if you are nonplussed by disc two, it may, by contrast, enhance your enjoyment of disc one -- which, after all, is a fine, free-standing piece of exploratory, compelling and emotional progressive fusion.
	www.scottmcgill.com /reviews.cfm?id=26 (564 words)

	Cellscience - Technical Support (Site not responding. Last check: 2007-10-31)
		The image of a single point in the specimen has a characteristic pattern at the level of the aperture: a bright central spot with bright rings around it.
		The central part of this pattern is called the Airy disk.
		The size of the Airy disk is determined by the wavelength of the light, the numerical aperture of the objective lens and the magnification of the image at the level of the aperture.
	microscopy.bio-rad.com /help.htm (211 words)

	Digital Gallery Plus: Depth of Field 2
		A star, or point, object is thus focussed not to a point on a film or plate but to a disc called the Airy disc named after the astronomer George Airy who observed it when using a telescope to look at stars.
		The profile of an Airy disc is shown in figure 1 where its diameter d depends on the f-stop setting of the imaging lens.
		is the diameter of the disc of confusion for the eye at the viewing distance of 250mm, taking a value somewhere between 0.15mm and 0.25mm, and M is the magnification given by the ratio of the size of the print to the size of the film or CCD array.
	www.digitalgalleryplus.com /dof_2.htm (1838 words)

	Introduction to chromatic abberation in refractors
		The diameter of the Airy disc of a diffraction-limited f/10 objective is only about 13 microns, over 50 times smaller, so our simple-lens refractor won't work very well.
		A well-made four-inch f/10 doublet achromat using ED glass can have the purple blur the same size as the Airy disc, and a fluorite doublet of the same size can have the blur smaller than the Airy disc.
		Well, things scale as follows: The linear diameter of the Airy disc depends only on the f number of the telescope, and on the wavelength.
	www.maa.mhn.de /Scholar/chromatic_aberration.html (1878 words)

	Meade's 178 ED 7" refractor
		Here is what I saw: When you defocus a star, you expect the disc of light to expand evenly around the central airy disc.
		However, the airy disc is still a little fan-shaped, and seems to shift just a bit when you de-focus.
		Airy discs refused to remain points at high power.
	www.scopereviews.com /178ed.html (2937 words)

	What Does It Take To See Width In The Cassini Division? - Article
		The Airy disk radius is measured from the midpoint of the central diffraction disk to the minimum of the first diffraction interspace.
		Although Airy disk size is not dependant on magnitude, the extent of the bright central disk is dependant on magnitude.
		Airy disk radii for telescopes of diameter D inches: 4” = 1.36arcseconds, 5” = 1.09arc”, 6” = 0.91arc”, 7” = 0.78arc”, 8” = 0.69arc”, 9” = 0.61arc”, 10” = 0.55arc”.
	www.cloudynights.com /item.php?item_id=1132 (9304 words)

	startest
		Visibility of the rings is dependent on the collimation of the optics, warm air currents in the tube and the steadiness of the atmosphere (seeing).
		It is extremely prominent at the outer edges of the diffraction pattern.
		For OF, the light is concentrated at the centre of the image, and the central disc is nearly as small and bright as at the focused position.
	www.lincolnastrosoc.freeserve.co.uk /startest.html (1059 words)

	NOTE: THIS FOLLOWS A PIECE ABOUT THE THEORY OF CONFOCAL, IN WHICH THE AIRY DISC ETC IS DISCUSSED.
		The size of an Airy disc in the specimen plane depends on wavelength and the numerical aperture of the objective lens.
		The image of the Airy disc at the pinhole (image plane) is larger than the disc itself due to the magnification of the objective lens plus any subsequent optics.
		Airy disc size can be expressed in optical units.
	confocal.med.unc.edu /wwwleica/LeicaTCS-NT/PinHole.html (453 words)

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