TERMIUM Plus^®

Record 1,  Textual support,  English

Record number: 1, Textual support number: 1 DEF

... the principal light-gathering surface of a reflective telescope.  2, record 1, English, - primary%20mirror

Record number: 1, Textual support number: 1 CONT

The primary mirror is located at the lower end of the telescope tube in a reflector and has its front surface coated with an extremely thin film of metal, such as aluminum. The back of the mirror is usually made of glass, although other materials have been used from time to time. Pyrex(trademark) was the principal glass of choice for many of the older large telescopes, but new technology has led to the development and widespread use of a number of glasses with very low coefficients of expansion.  3, record 1, English, - primary%20mirror

Record 1,  Textual support,  French

Record number: 1, Textual support number: 1 CONT

On peut citer quelques formules optiques : le télescope de type Newton, qui utilise un miroir primaire concave sphérique ou parabolique et un miroir secondaire plan, c'est le montage le plus simple et le plus ancien, utilisé actuellement dans beaucoup de constructions d'amateurs. Il a été mis au point par Isaac Newton, le miroir plan est incliné à 45° et permet de renvoyer l'image focale à 90° de l'axe optique près de l'ouverture du tube.  2, record 1, French, - miroir%20primaire

Record 1,  Textual support,  Spanish

Record 2,  Textual support,  English

Record number: 2, Textual support number: 1 DEF

A construction method for a large mirror in which the back is hollowed-out to leave a ribbed structure that resembles a honeycomb.  2, record 2, English, - honeycomb%20mirror

Record number: 2, Textual support number: 1 CONT

We report on the casting of the first 8. 4 meter diameter borosilicate honeycomb mirror at the Steward Observatory Mirror Laboratory. This blank will become the world's largest monolithic glass telescope mirror, and is the first of two mirrors for the Large Binocular Telescope Project. The honeycomb 8. 4 meter mirror was cast from 21 tons of E6 borosilicate glass manufactured by Ohara. This glass is melted into a mold constructed of aluminosilicate fiber to produce a honeycomb structure with roughly 20% of solid density. The 1662 hexagonal voids that form the honeycomb structure are produced by ceramic fiber boxes bolted to the bottom of the mold with SiC bolts. The furnace rotates at 6. 8 rpm during the casting process to produce the F/1. 14 paraboloid on the front surface. This shaping minimizes the amount of glass which must be removed during the grinding process. The front faceplate of the mirror will be 28 mm thick after generating and the back faceplate will be 25 mm. The overall thickness of the finished honeycomb blank is 89 cm at the outer edge and 44 cm at the central hole.  3, record 2, English, - honeycomb%20mirror

Record 2,  Textual support,  French

Record number: 2, Textual support number: 1 CONT

Le miroir alvéolé [permet] de conserver le bon rapport épaisseur/diamètre pour assurer la rigidité, mais de diminuer la masse en laissant des alvéoles vides dans l'épaisseur du verre: on parle aussi de «miroir en nid d'abeilles». [Une technique novatrice] mise au point par Roger Angel (Université Steward, Arizona) [consistait à] mettre en place les alvéoles dès le coulage du verre, évitant ainsi le travail d'évidement ultérieur. [...] un four tournant, [permettait] de donner au miroir une forme parabolique pendant son refroidissement [..]  2, record 2, French, - miroir%20alv%C3%A9ol%C3%A9

Record number: 2, Textual support number: 1 OBS

Cette méthode de fabrication a été mise au point sur des miroirs de plus en plus grands, en commençant par un miroir de 3,50m pour le télescope WYNN à Kitt Peak (Arizona). Les premiers «grands» miroirs ont été coulés pour le MMT (ex Multi Mirror Telescope), puis pour les deux télescopes Magellan de 6.50m, et en ce moment, pour le premier des deux miroirs de 8,4m du LBT (Large Binocular Telescope).  2, record 2, French, - miroir%20alv%C3%A9ol%C3%A9

Record 2,  Textual support,  Spanish

Record 3,  Textual support,  English

Record number: 3, Textual support number: 1 CONT

In a conventional back-surface mirror, the reflective coating is protected with a heavy paint-like substance; reflections are seen through the glass.  2, record 3, English, - back%20surface%20mirror

Record 3,  Textual support,  French

Record number: 3, Textual support number: 1 DEF

Miroir qui réfléchit depuis la face arrière d'une couche réfractante, généralement du verre.  1, record 3, French, - miroir%20%C3%A0%20argenture%20post%C3%A9rieure

Record number: 3, Textual support number: 1 OBS

Source MVISI-F : Le nouveau dictionnaire de la vision par Michel Millodot, Médiacom Vision Éditeur, 1997.  2, record 3, French, - miroir%20%C3%A0%20argenture%20post%C3%A9rieure

Record 3,  Textual support,  Spanish