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	Primary mirror -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-07)
		A primary mirror is a form of distributed data management on the (A computer network consisting of a worldwide network of computer networks that use the TCP/IP network protocols to facilitate data transmission and exchange) Internet.
		A primary mirror (or primary) is the principal ((physics) electromagnetic radiation that can produce a visual sensation) light-gathering surface of a reflective (A magnifier of images of distant objects) telescope.
		For most of astronomy's history, primary mirrors used to be monolithic blocks of glass or other material, curved to exact shapes and coated with a reflective layer.
	www.absoluteastronomy.com /encyclopedia/p/pr/primary_mirror.htm (278 words)

	Primary Mirror (Site not responding. Last check: 2007-11-07)
		It is supported in the primary mirror cell by a clamping structure as shown in Figures 2-2 and 2-3.
		The mirror clamp is then attached to the mirror cell by three linear actuators (called the focus mechanisms) that can be used to focus and align the HUT optics.
		The HUT primary mirror shown with its clamping structure attached to the mirror cell assembly by the focus mechanism.
	archive.stsci.edu /hut/handbook/node6.html (528 words)

	The VLT primary mirrors
		The 8.2-m Zerodur primary mirrors (figure 1) of the ESO Very Large Telescope are 175 mm thick and their shape is actively controlled (active optics) by means of 150 axial force actuators, the necessary active corrections being obtained from wavefront sensors located off-axis on the image surface.
		For the VLT primary mirrors, active optics is achieved by modal corrections i.e., the measured deformation is fitted with the mirror's eigenmodes (up to 16) and the necessary correction forces are deduced linearly from the eigenmodes coefficients.
		The final map of the first mirror was obtained from a total of 1200 phase maps at three different orientation (mirror rotation with respect to the test set-up); the second one was mapped from 3200 phase maps taken at four different orientations.
	www.eso.org /projects/vlt/unit-tel/m1unit.html (3496 words)

	The Primary Mirror
		The function of the primary mirror is to bring the light that is received into an exact focus.
		In this formula the distance is calculated between the mirror surface and an imaginary plane that is tangent with the sphere at the optical axis.
		This is the cause for a permanent adjustment of the mirror's temperature, and thus for a permanent deformation.
	www.xs4all.nl /~lugt/tnp/newtonian/the_primary_mirror/the_primary_mirror.htm (1207 words)

	Rob's Astronomy Guide - Amateur Telescope Making
		The primary mirror is held in place by an adjustable frame attached to the telescope tube called the primary cell.
		Position the secondary mirror in the center of the focuser and adjust the mirror so the hole at the end of the tube is centered in the secondary mirror and focuser.
		Subtract this distance from your primary mirrors focal length to determine the distance from the primary mirror to the secondary.
	geologynet.com /astronomy/atm.htm (1276 words)

	Head up display projection system having a double reflecting primary mirror - Patent 5734506
		The secondary correcting mirror reflects the image back onto the primary mirror, and this image is reflected out of the projection unit to the combiner, which reflects the image that is displayed to a viewer.
		The light impinges upon the primary mirror 12 at such angle that it is reflected out of the projection unit 20 to the combiner 14, where it is reflected into the eyes of the viewer 15.
		Optical aberrations that are introduced by reflections from the primary mirror 12 are negated by the secondary correcting mirror 13 such that the image viewed by the viewer 15 is clear and legible.
	www.freepatentsonline.com /5734506.html (1967 words)

	Telescope Mirror Images (Site not responding. Last check: 2007-11-07)
		This primary mirror will be the main light gathering surface of the 16 inch Cassegrain telescope MDOA plans for the proposed observatory.
		The main mirror is called a primary, and the secondary is the smaller mirror that redirects light to an eyepiece.
		Light from the primary is reflected a second time by this mirror, and due to the convex surface of the mirror (it's curved outward) it redirects all light toward the central hole in the primary.
	www.mdia.org /Mirrors.htm (442 words)

	- Southern African Large Telescope - THE TELESCOPE (Site not responding. Last check: 2007-11-07)
		Each mirror mount spreads the mirror segment load from 9 contact points at the bottom of the segment surface through a lever to three actuators within the support frame.
		The main structural element of the Primary Mirror System is a space frame structure called the mirror truss, constructed out of nodes and struts.
		Mirror mounts are bolted to the top truss nodes and provide 9-point support to the mirror segments, as well as motion control in tip/tilt and piston.
	www.salt.ac.za /content/telescope/mirror2.htm (511 words)

	BorCon 2003: 3128, High Performance Disaster Recovery
		A primary mirror write transaction is not allowed to commit until its log records have been made durable on all read-only mirrors that have an "immediate" synchronization setting.
		Fail-over mirrors automatically detect that the primary, is not responding and switch one of the fail-over mirrors into the primary mirror.
		In this way the primary mirror, which must service all write requests, can be configured so that it is synchronizing a smaller number of mirrors.
	community.borland.com /article/borcon/files/3128/paper/3128.html (1195 words)

	Optical Telescope Element (OTE)
		Two primary mirror "wings" and a tripod structure supporting the secondary mirror are deployed during orbit insertion.
		The primary mirror consists of 36 hexagonal segments (1m flat-to-flat side), in three rings around the center, resulting in a 7m flat-to-flat diameter.
		Wave Front Sensing to keep the mirror in shape is currently studied at the Jet Propulsion Laboratories.
	www.stsci.edu /jwst/overview/mirrors.html (285 words)

	CloudyNight's forums: Yet another collimation question
		Because the rays from the primary mirror away from the focuser reach the secondary mirror a few inches before the rays from the edge of the primary closest to the focuser, the light beam is larger in diameter at that point, so it contacts the secondary mirror farther from the centerpoint of the secondary.
		Another way to look at it is: because the secondary mirror is tipped at a 45 degree angle, the light cone from the primary actually hits the secondary mirror in an oval(viewed perpendicular to the optical surface of the secondary mirror), with the long axis along the long axis of the secondary.
		Then, adjust rotation until the center dot on the primary is on the long axis of the secondary, and adjust the tilt of the secondary until your pupil (in the collimating eyepiece) coincides with the center dot on the primary.
	www.cloudynights.com /ubbthreads/showflat.php/Cat/0/Number/158229/Main/157843 (1629 words)

	An Alternative Primary Baffle Mounting for Cassegrain Telescopes (Site not responding. Last check: 2007-11-07)
		This tube is then clamped directly to the primary mirror by means of three nylon screws spaced equally around the circumference of the tube whose heads bear directly against the optical surface of the mirror.
		The mirror cell is held centered in the telescope tube by a thick rubber O-ring set into the inner bore of the cell, which allows the cell to slide along the protruding cylindrical portion of the backplate with sufficient travel for back-focus adjustment by the collimating screws.
		The mirror retainer ring is held to the front of the cell by three sets of push-pull screws, and is fitted with three small rubber pads that are adjusted to within a few thousandths of an inch of the surface of the mirror.
	www.atmsite.org /contrib/Sapp/Baffle (1772 words)

	Infrared catadioptric zoom relay telescope with an asperic primary mirror - Patent 5089910
		The secondary Mangin mirror 21 comprises a lens component whose back surface (i.e., the surface facing away from the primary mirror 20) is silvered to form a convex mirror.
		The lens component of the Mangin mirror 21 and the four lens elements 23, 24, 25 and 28 are all made from the same type of optical material, which is selected primarily on the basis of cost and availability.
		The surface of the primary mirror 20 functions as the entrance aperture of the telescope.
	www.freepatentsonline.com /5089910.html (4579 words)

	HubbleSite - Hubble's Amazing Optics
		If Hubble's primary mirror were scaled up to the diameter of the Earth, the biggest bump would be only six inches tall.
		Shortly after Hubble's deployment in 1990, scientists found that the curve to which the primary mirror was ground was incorrect, causing "spherical aberration." Fortunately, corrective optics were able to solve this problem.
		Hubble's mirrors are made of ultra-low expansion glass and kept at a nearly constant room temperature (about 70 degrees Fahrenheit) to avoid warping.
	hubblesite.org /sci.d.tech/nuts_.and._bolts/optics (322 words)

	Discovery Channel Telescope Primary Mirror Blank \| Technology News Daily (Site not responding. Last check: 2007-11-07)
		The advantage of such mirrors is their comparatively light weight and their ability to maintain a temperature close to that of the surrounding air as the temperature drops during the night.
		However, these mirrors are relatively flexible, and accordingly are supported by an active system that maintains optimum mirror shape regardless of the orientation of the telescope.
		A mirror of the correct shape in temperature equilibrium is crucial to producing ultra sharp images of celestial objects.
	www.technologynewsdaily.com /node/1589 (341 words)

	Measuring PT Primary Mirror Depth (Site not responding. Last check: 2007-11-07)
		Use the depth micrometer to measure the distance to the edge of the primary mirror.
		The mirror should be flat (level) in the cell before reinstallation on the telescope.
		Adjustment is with the three screws under the whiffles on the bottom of the primary cell.
	www.jhu.edu /~sdss/PT/Maintenance/PTMirrorLevel.html (58 words)

	WHT - Mirror Support Systems
		The optical performance of a telescope depends on controlling the deformation of the mirror surface when the mirror is contained in a mirror cell.
		The valves are controlled by the output of the associated load cell in such a way that the force exerted by the mirror on the defining point is maintained at 0±5 kg during tracking at all angles of the telescope tube from the zenith down to the horizon.
		The mirror is supported in a transverse direction by mechanical weighted levers coupled by link arms to brackets connected to the edge of the mirror ('axial definers') in much the same way as a conventional push-pull radial support system.
	www.ing.iac.es /PR/wht_info/whtsupport.html (512 words)

	phot-34-99.html
		That is, the mirror is forced upwards by 18 µm at two opposite points at the edge and 18 µm downwards at two points 90° removed from the first ones, i.e.
		Thus, when the primary mirror is saddle-shaped, the stellar image can be in focus in either of the perpendicular directions, depending on the actual distance between the mirrors.
		Then, maintaining the position of the secondary mirror, the deformation of the primary mirror is "rotated" by changing the support forces so that the "high" and "low" points shift along the mirror periphery in steps of approximately 20°.
	www.eso.org /outreach/press-rel/pr-1999/phot-34-99.html (2538 words)

	M1 cell and M3 tower
		The telescope tube is closed at the bottom by the primary mirror cell, while at its top it supports the secondary mirror unit.
		In the lateral plane the mirror is restrained by 64 hydraulic passive supports which, similarly to the passive axial supports, produce a reaction force to the portion of the mirror weight imposed on them.
		The total weight of the mirror is distributed between the axial and the lateral system depending on the zenithal angle (angular distance of the telescope tube from zenith).
	www.astropa.unipa.it /aol/vlt/systeng/m1cell/m1cellm3.htm (786 words)

	NASM Space Artifacts: Stratoscope I Primary Mirror
		Princeton University donated the mirror to NASM in June 1982; it was on display in the Stars Gallery from then until October 1987.
		A small secondary mirror, which rotated to minimize heating effects, reflected the image onto an enlarging lens which focused a portion of the resulting two-foot solar image onto the film plane of a 35-mm movie camera operating continuously at 1 frame per second.
		The telescope was oriented to stay fixed on the center of the sun by a mechanism which used a series of photoelectric cells and servomechanisms constructed by the Research Service Laboratories at the University of Colorado, a group well-known for its expertise at creating robotic stabilized platforms for balloons and sounding rockets.
	www.nasm.si.edu /research/dsh/artifacts/SS-Strato1mirror.htm (626 words)

	NASA - Mirror Production Begins on Webb Telescope
		The mirrors were a major technical challenge for the JWST telescope because of the need for large lightweight mirrors that can operate at cryogenic temperatures.
		The choice of beryllium for the mirrors was made after a six-month evaluation period that took advantage of insights from a panel of experts representing the contractor team, NASA and the science community.
		The mirrors will be incorporated into optical assemblies, mounted on the telescope structure, and subjected to a series of tests at cryogenic temperatures both individually and as an integrated system.
	www.nasa.gov /vision/universe/watchtheskies/jwst_mirror.html (821 words)

	ESA Science & Technology: Herschel Primary Mirror Fabrication
		The mirror blank is the biggest silicon carbide structure in the world and, when completed, the mirror will be the largest single-component telescope reflector ever made for use in space.
		All the major telescope components - the primary and secondary mirrors and the hexapod that supports the secondary mirror - are made from silicon carbide, allowing the telescope mass to be reduced to 300 kg rather than the 1.5 tonnes that would have resulted from using conventional materials.
		The mirror blank will now be machined by Boostec to remove the internal stiffeners, used to provide mechanical stability during manufacture, and reduce the shell thickness to 2.5 mm.
	sci.esa.int /science-e/www/object/index.cfm?fobjectid=34705 (386 words)

	The Primary Mirror Cell (Site not responding. Last check: 2007-11-07)
		There seems to be a pretty standard design recommended for the mirror cell in simple dobsonians: cut a disk of particle-board the same diameter as the mirror; hold it off of a backing board with three bolts and springs; add wingnuts for adjustment.
		The mirror is glued to the disk with 3 silicone blobs, 120 degrees apart and at ~70% of the mirror radius.
		The slab of wood which holds my mirror is actually almost the same height as the inside of the tube--so it is prevented from swaying too far in any direction by the tube itself.
	www.glpbooks.com /oyb/roscope/pri_cell.html (529 words)

	Diffraction Effects (Site not responding. Last check: 2007-11-07)
		When the primary mirror is moved to adjust focus, it moves both along the telescope axis, as intended, and side to side.
		This is why alternative focusers, covered near the end of this chapter, are often used on scopes with moving primary mirrors.
		When you flip the telescope across the meridian (that is the line directly over head running from north to south), the mirror may shift by a larger amount because the weighting has changed by 180 degrees.
	www.newastro.com /newastro/book/C2/moving_primary.htm (492 words)

	Primary mirror
		A primary mirror is also a form of distributed data management[?] on the Internet.
		A primary mirror is the principal light-gathering surface of a reflective telescope.
		The text of this article is licensed under the GFDL.
	www.ebroadcast.com.au /lookup/encyclopedia/pr/Primary_mirror.html (233 words)

	Aluminising the primary mirror (Site not responding. Last check: 2007-11-07)
		The mirror was cleaned using windowlean to remove the worst of any contaminates and then was thoroughly cleaned with swabs of alcohol to finally clean.
		The mirror was placed in a jig face down into the chamber.
		We had been speculating all day if we would still have one mirror at the end of the day or many and the concern if the surface was good enough.
	members.aol.com /DATSCOPE/30inchTRO12.html (589 words)

	Re-Aluminization of the 200-inch primary mirror of the Hale Telescope at the Palomar Observatory>
		The mirror cell is lowered and then cart with the mirror cell and its mirror is then pushed away from the telescope (right) and over to a position where it can be worked on (below, left).
		After a wash with soap and water the mirror is ready to have its old coating of aluminum stripped away.
		The mirror's ribbed backing creates hollow spaces that reduce the mirror's weight and provide locations for the mirror to be supported from underneath.
	www.astro.caltech.edu /observatories/palomar/alum_mirror/aluminization.htm (502 words)

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