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Topic: Concave lens

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	Focal length - Wikipedia, the free encyclopedia
		The focal length of a lens is the distance along the optical axis from the lens to the focus (or focal point).
		For a converging lens (e.g., a convex lens), the focal length is positive, and is the distance from the lens at which a beam of collimated light will be focused to a single spot.
		For a diverging lens (e.g., a concave lens), the focal length is negative, and is the distance from the lens to the point at which a collimated beam appears to be emerging from after passing through the lens.
	en.wikipedia.org /wiki/Focal_length (414 words)

	lens, in optics. The Columbia Encyclopedia, Sixth Edition. 2001-05 (Site not responding. Last check: 2007-10-08)
		The lens of the eye is known as a crystalline lens.
		The distance from the principal focus to the optical center of the lens is the focal length of the lens.
		As the object is brought toward the lens, the size of the image grows, becoming as large as the object when the object is at the center of curvature and larger than the object as the object is brought closer.
	www.bartleby.com /65/le/lens.html (756 words)

	Lab 5.1.3
		A convex lens is called a converging lens because rays parallel to the principal axis converge at the focal point.
		The distance, OF, is known as the focal length of the concave lens.
		In the case of the diverging lens the parallel rays of light appear to diverge from F and it is known as a virtual focus.
	www.usd.edu /phys/labs/Optics/5_1_3/5_1_3c.html (994 words)

	Concave lens - Wikipedia, the free encyclopedia
		A concave lens is a lens with inward-curving (concave) surfaces: the ends are wide, the middle is thin.
		Concave lenses can be used in telescopes, microscopes, and eyeglasses.
		Nicholas of Cusa is believed to have been the first to discover the benefits of concave lens for the treatment of myopia in 1451.
	en.wikipedia.org /wiki/Concave_lens (96 words)

	Making a Galilean Telescope
		The concave lens serves as the ocular lens, or the eyepiece, while the convex lens serves as the objective.
		The lens are situated on either side of a tube such that the focal point of the ocular lens is the same as the focal point for the objective lens.
		The concave convex is used as the "objective lens" that is aligned with the eyepiece and with the convex side facing the sky.
	galileo.rice.edu /lib/student_work/astronomy96/mtelescope.html (1944 words)

	Encyclopedia: Concave lens
		Concave lens Taken by fir0002 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version.
		In geometry, concavity is a property of certain geometric figures, and in calculus, a property of certain graphs of functions.
		Convex lens converging light rays A convex lens is a lens that is curved outward (convex): the ends are narrow and the middle is wide.
	www.nationmaster.com /encyclopedia/Concave-lens (424 words)

	Concave lens -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-08)
		A concave lens is a (A transparent optical device used to converge or diverge transmitted light and to form images) lens with inward-curving ((additional info and facts about concave) concave) surfaces: the ends are wide, the middle is small.
		Concave lenses can be used in (A magnifier of images of distant objects) telescopes, (Magnifier of the image of small objects) microscopes, and (Optical instrument consisting of a pair of lenses for correcting defective vision) eyeglasses.
		Compare: (Lens such that a beam of light passing through it is brought to a point or focus) convex lens
	www.absoluteastronomy.com /encyclopedia/c/co/concave_lens.htm (135 words)

	Illumination unit for endoscope - Patent 4266534 (Site not responding. Last check: 2007-10-08)
		The spread angle of rays b1 entering concave lens portion 21 and leaving the cover glass in the central region of concave lens surface 20 is larger than the spread angle of rays b.sub.0 leaving the exit surface in the central region of the cover glass 6 of FIG.
		This increased spread angle is due to the light refraction at concave central lens surface 21 along the entry surface of the cover glass and the light refraction at concave lens surface 20 along the exit surface 6 of the cover glass 30.
		The centers of radii of curvature of the individual concave lens portions on either the same side or on opposite sides of the cover glass need not be in complete alignment, but may be offset from each other depending on the area of the field of sight of the endoscope.
	www.freepatentsonline.com /4266534.html (2145 words)

	The Physics Classroom
		The fact that a double concave lens is thinner across its middle is an indicator that it will diverge rays of light which travel parallel to its principal axis.
		A double concave lens is a diverging lens.
		If a symmetrical lens is thought of as being a slice of a sphere, then there would be a line passing through the center of the sphere and attaching to the mirror in the exact center of the lens.
	www.physicsclassroom.com /Class/refrn/U14L5a.html (760 words)

	Olympus Microscopy Resource Center: Physics of Light and Color - Image Formation with Diverging Lenses: Interactive ...
		In a similar manner, as the object is moved away from the lens, the virtual image moves away from the lens and grows smaller.
		Negative lens elements are the bi-concave (Figure 1(a)), plano-concave (Figure 1(b); with a single planar surface), and concave-meniscus (also termed a negative meniscus lens; Figure 1(c)), which also has concave and convex surfaces, but with the center of the lens being thinner than the edges.
		The line passing through the center of the lens curved surfaces in Figure 1(a) is known as the optical axis of the lens.
	www.olympusmicro.com /primer/java/lenses/diverginglenses (1249 words)

	INSTRUMENTS - Online Information article about INSTRUMENTS
		These, falling in turn on the lens of the human eye, are converged by it and form an image on the retina.
		Kepler's, the latter Lippershey's or the Galilean telescope.
		The front lens is made of baryta light flint glass (o.543 of Schott's catalogue) and the back lens of a crown glass, styled 0.374 in Schott's older lists.
	encyclopedia.jrank.org /I27_INV/INSTRUMENTS.html (6915 words)

	Simulated Optics Experiments: Single Lens - Succeed in Physical Science
		A concave lens has the center "caved in" and is wider at the edges.
		A concave lens is wider at the edges than at the middle.
		Concave mirrors can be used to focus light to a point as in a solar heater and send out parallel beam of light as in a flashlight.
	www.school-for-champions.com /science/experiments/simopticslens.htm (1294 words)

	Contact lens suction cup - Patent 5456508
		The lens applicator 12 also includes a second diametrically reduced remote end portion 18 and a longitudinal duct 20 extends through the lens applicator 12 with one end of the duct 20 opening centrally through the surface 16 and the other end opening outwardly through the end surface 22 opposite the end surface 16.
		In operation, the lens handling device has the squeeze bulb 24 thereof gripped between the thumb and forefinger of the user's hand 44, in somewhat the manner in which a pencil or pen is held, and the device 10 is held in a vertical position with its end surface 16 disposed lowermost.
		When the device 10 is engaged with the contact lens 46, the end surface 16 is engaged with and generally conforms to the contour of the convex outer surface 47 of the lens 46.
	www.freepatentsonline.com /5456508.html (1168 words)

	Reading on Refraction, part 2
		Lens C in your Kit is called a double concave lens and has a negative focal length.
		A positive focal length means that the focal point of the lens is on the other side of the lens from where the object is placed.
		When light hits the surface of a concave mirror, an individual light ray is reflected at an acute angle and all the light converges at a point on the object side of the mirror.
	acept.la.asu.edu /PiN/rdg/lenses/lenses2.shtml (663 words)

	Images in Concave Lenses (Site not responding. Last check: 2007-10-08)
		The focal point of a concave lens is the point where light rays parallel to the axis seem to diverge from after passing through the lens.
		The lens does not need the same curvature on both sides for this to be true, and it doesn't depend on the direction the light takes entering the lens.
		The image formed by a concave lens for an object 40 cm away is reduced to one fourth its size.
	www.gunn.palo-alto.ca.us /~cbakken/p1A/optics/obookshelf/ccimages.html (1383 words)

	lens
		The distance between the focus and the lens is called the focal length.
		A concave (or diverging lens) causes light rays to refract outwards.
		The image formed by a single lens suffers from several defects or aberrations, notably spherical aberration in which an image becomes blurred, and chromatic aberration in which an image in white light tends to have coloured edges.
	www.streamsequence-tiscali.org.uk /reference/encyclopaedia/hutchinson/m0001983.html (266 words)

	NEWPORT GLASS WORKS, LTD. & NEWPORT INDUSTRIAL GLASS, A FULL SERVICE FABRICATOR AND DISTRIBUTOR OF TELESCOPE KITS, ...
		Two other tools are essential in making a cemented doublet lens whose rear radius is flat: A flat test plate at least 1/2 the diameter of the doublet, and an aluminized flat-full size or larger-to test the cemented lens in its cell.
		Do not use this procedure on the acute edge of the concave lens, instead grind it first on a flat surface with #400 until a flat border one sixteenth of an inch wide is produced.
		Instead, press the lens, off center, around the edge to depress the pitch there so that when the lens is slid around over the top of the pitch, no air will be entrapped and there will be a better chance to obtain a uniform fit all over.
	www.newportglass.com /share.htm (2784 words)

	Convex/Concave Lenses Science Lesson Plan, Thematic Unit, Activity, Worksheet, or Biology or Chemistry Teaching Idea
		2) Concave- A lens which is thinner in the middle than on the ends.
		Way to remember the difference: A concave lens looks like the opening to a cave, therefore you can remember that it curves inward.
		4) The thicker the middle of the lens the shorter the focal length.
	www.lessonplanspage.com /ScienceConvexConcaveLenses69.htm (753 words)

	Olympus Microscopy Resource Center: Light and Color - Bi-Concave Lenses: Interactive Java Tutorial
		where f is the focal length of the lens, p is the distance of the object with respect to the optical center of the lens, and q is the distance of the image to the optical center of the lens.
		The negatively curved surface of a bi-concave negative lens faces the object being imaged, and this results in a negative value for the focal length.
		In this instance, the lens equation yields a negative image distance resulting in the image being formed on the object side of the lens.
	www.olympusmicro.com /primer/java/lens/bi-concave.html (303 words)

	Lens, lens system and optical aberrations
		The amount of astigmatism in a lens depends on lens shape only when there is an aperture in the system that is not in contact with the lens itself.
		It should be apparent that a lens or lens system has opposite types of distortion depending on whether it is used forward or backward.
		It is important to remember that the spot size, caused by diffraction, of a circular lens is d = 2.44 L* f/# where d is the diameter of the focused spot produced from plane wave illumination and L is the wavelength of light being focused.
	cartage.org.lb /en/themes/Sciences/Physics/Optics/Optical/Lens/Lens.htm (1564 words)

	The Open Door Web Site : IB Physics : Practical Work : Lenses
		In this diagram, d is the diameter of the lens and x is half the thickness of the lens.
		The method proposed here involves first obtaining a real image of an object using a convex lens (diagram 1) and then observing the change in the image distance when the concave lens put is put in place (diagram 2).
		With the object and convex lens in the same positions, place the concave lens as shown and move the screen and/or the concave lens to obtain a clear image.
	www.saburchill.com /physics/practicals/030.html (449 words)

	Exercise, Image Formation by a Diverging Lens (Site not responding. Last check: 2007-10-08)
		The image appeares on the left of the lens as a gray arrow.
		Ray 1 is the ray which travels parallel to the axis and after going through the lens it passes through the focal point.
		is the distance from the object to the lens, and f is the focal distance of the lens.
	www.phys.hawaii.edu /~teb/optics/java/dlens (333 words)

	Convex (Site not responding. Last check: 2007-10-08)
		where f is the focal distance of the lens or reflecting surface, a is the distance between the object and the plane of the lens or reflecting surface and b is the distance between the image and the plane of the lens or reflecting surface.
		The focal length is a function of the refractive index of the lens material and the radius of the spherical or circular surface.
		When the object is between the lens plane and the focal plane, the result is a virtual image is seen below, with the above equations still applicable and consequently, b is negative, corresponding to the fact that the virtual image is formed on the same side as the object.
	trueforce.com /Optics/Convex.htm (626 words)

	PIRA Bibliography - (Site not responding. Last check: 2007-10-08)
		Blackboard optics are used with convex and concave thin lens elements.
		Various lens elements are used with the optical disc.
		A long plastic slab with a concave surface at one end and a convex surface at the other is used in the optical disc.
	physicslearning.colorado.edu /PIRA/PiraSubTOC.asp?STopic=6A60 (382 words)

	#1 Site To Learn About Light (Site not responding. Last check: 2007-10-08)
		To find out how images are formed with the concave lenses, we have to consider certain rules as regards to rays of light coming from different directions on the surface of the lens and how they get refracted.
		and strikes a concave lens, the refracted ray is parallel to the principal axis XY.
		The use of concave lenses is most widely seen in the use of spectacles for correcting short sightedness.
	home.att.net /~w.bed/light-XII.htm (344 words)

	Lithographic fabrication of large diffractive optical elements on a concave lens surface
		We demonstrate experimentally the lithography technique to fabricate a large computer-generated diffractive optical element (DOE) pattern on a concave lens surface with precise alignment by using a laser direct writer.
		We obtained photoresist film with uniform thickness on the large concave substrate by selecting proper spin-coating parameters, which mainly involve spin rate, spin acceleration, and viscosity of the photoresist.
		We have designed and fabricated a grating on the concave lens surface using the laser direct writing lithography technique.
	www.opticsexpress.org /abstract.cfm?URI=OPEX-10-20-1043. (385 words)

	[No title] (Site not responding. Last check: 2007-10-08)
		The elements discussed on this page are the double convex (converging) thin lens, the double concave (diverging) thin lens and the concave mirror and convex mirror.
		Blue Ray - this ray is drawn parallel to the optical axis (x-axis) until it reaches the plane of the lens (the y-axis).
		Now consider the same lens with the object located inside the focal point ofthe lens, that is an object distance less than the absolute value of the focal length.
	physics.angelo.edu /~dbixler/tutorial/raydiag.htm (1261 words)

	Diverging Lenses - Ray Diagrams
		The method of drawing ray diagrams for a double concave lens is described below.
		Using a straight edge, accurately draw one ray so that it travels towards the focal point on the opposite side of the lens; this ray will strike the lens before reaching the focal point; stop the ray at the point of incidence with the lens.
		Once these incident rays strike the lens, refract them according to the three rules of refraction for double concave lenses.
	www.glenbrook.k12.il.us /gbssci/phys/Class/refrn/u14l5ea.html (1015 words)

	Lenses
		Any ray aimed at a focal point will be bent parallel to the principal axis.
		F on the right of the lens is the only one shown.
		A 6.0 cm object is placed 30.0 cm from a lens.
	sol.sci.uop.edu /~jfalward/lenses/lenses.html (158 words)

	THIN LENS FORMULA - CONCAVE LENS
		placed in front of a concave lens of focal length " f " on the principle axis of the lens.
		Concave lens forms a virtual and erect image
		For a concave lens: f = negative, q = negative, i.e.
	www.citycollegiate.com /geometricaloptics4.htm (83 words)

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