Renseignements généraux

Nº de série

S/O

Nº de partie

3

Nombre total de parties

3

Ou

S/O

Brevets

S/O

Description générale

wood

Dimensions

Remarque : Cette information reflète la taille générale pour l’entreposage et ne représente pas nécessairement les véritables dimensions de l’objet.

Longueur

11,8 cm

Largeur

11,1 cm

Hauteur

1,8 cm

Épaisseur

S/O

Poids

S/O

Diamètre

S/O

Volume

S/O

Lexique

Groupe

Astronomie

Catégorie

Recherche

Sous-catégorie

S/O

Fabricant

Ou

Observatory CA

Pays

Canada

État/province

British Columbia

Ville

Victoria

Contexte

Pays

Canada

État/province

Colombie-Britannique

Période

Presumably used c. 1967-1980.

Canada

Lid for storage box for image slicer. Developed in 1966 by Dr. Harvey Richardson, his design for this device became the standard and remains so. He was assisted by the engineering and technical staff at the Dominion Astrophysical Observatory (DAO), including: George Brealey, ME (responsible for the jig used to position the mirror segments); Roy Dancey, who did the bonding of the segments and, with J. Miller made the optics (these were later made under contract by Applied Plastics Specialties Ltd. of Don Mills, Ont.); and J.R. White (who was involved in the design of the mechanical parts). This image slicer was used in the f/1.4 camera on the spectrograph that was mounted on the 1.8 m (72 inch) reflecting telescope at DAO. Richardson, through National Research Council (NRC) originally held the patent for the image slicers: these were later acquired by Scott Plastics in Sydney, BC. They produced them for observatories around the world. (Ref. 1) Among his varied activities, Dr. Richardson was a one-time federal New Democratic Party Candidate (c. 1970s). He operated EHR Associates in Victoria after his retirement, and it was still functioning c. 2002. He also participated in the ODIN project which used a spacecraft to study the Earth's atmosphere.

Fonction

To cover and protect contents of box from dust, dirt, etc.

Technique

The first image slicer was developed in 1935 by Ira Bowen at the Mount Wilson Observatory. Originally designed for use in stellar spectroscopy, design limitations in the Bowen-type image slicer limited it's use to solar spectroscopy. In 1966 Harvey Richardson, an astronomer & instrument designer at Dominion Astrophysical Observatory (DAO) developed a new version which replaced the stacked flat mirror plates with 2 concave mirrors which are cut in half, segmented and slightly separated (ie. separation adjustable). The first prototype, completed in 1967, was a failure., but the problems of the alignment of the mirror segments was overcome. The image of a star from the telescope is focussed on the cylindrical lens, the orientation of which is aligned with the grooves on the grating in the spectrograph. The light passes through a series of slits and is reflected off a series of mirrors. After passing through the final slit, a field lens focuses the light onto the grooved surface of the grating which reflects the spectrum into the spectrograph camera. By reflecting the light off the mirror segments and using the mirrors to create the spectrograph slit, very little light is lost by reflection of the usual polished slit jaws. This arrangement permitted a smaller grating to be used, and therefore further efficiency is achieved. The success of the design means the Richardson image slicer is still used in most spectrographs used on large telescopes. In addition to those made for the 1.8 and 1.2 m telescope spectroscopes at DAO, early examples were made for and tested on the 5 m (200 inch) Mt. Palomar Hale telescope, the 1.8 m (74 inch) telescope of the David Dunlop Observatory(Toronto); the 2.2 m Leoncito Observatory telescope (Argentina) and the 6 m reflector in the USSR. (Ref. 1)

Notes sur la région

Inconnu

Détails

Marques

"For F/1.4 camera/ not used anymore" handwritten in pencil on lid. "LIS" and 2.2 R" printed on black dymotape labels fixed to lid.

Manque

None.

Fini

Solid wood lid for box has been stained medium brown colour on all but top surfaces; top painted beige.

Décoration

S/O