Accession No
3800
Brief Description
diffraction grating, by Bausch and Lomb Optical Company, U.S.A., c. 1876-1916
Origin
U.S.A.; Rochester; New York
Maker
Bausch and Lomb Optical Company
Class
optical
Earliest Date
1876
Latest Date
1916
Inscription Date
Material
glass; metal (speculum metal); hide (leather); cloth (velvet)
Dimensions
length 72mm; breadth 24mm case length 89mm; breadth 39mm; thickness 19mm
Special Collection
Provenance
Transferred from Dept of Metallurgy, University of Cambridge, Cambridge, England, 1991. ex Cavendish Laboratory, date unknown.
Inscription
‘BAUSCH
& LOMB
OPT. CO.
ROCHESTER
N.Y. U.S.A.’ (inside of case)
‘0.1mm
0.01mm’ (inside of case)
Description Notes
Grating embedded in a glass slide in a fitted black leather case, lined with blue velvet.
Condition good; complete.
References
Events
Description
Diffraction grating
Grimaldi (an Italian physicist) saw that the edges of shadows are not completely sharp, but have fringes. Only later, in 1785, when multiple edges were placed next to one another to form a grating, was the full importance of this observation elucidated.
A diffraction grating consists of very closely spaced lines on a reflecting surface (the line ruling process must be very precise). The lines disperse light into component wavelengths (much like a prism does) and this is useful for precise determination of the magnitude of wavelengths.
18/10/2002
Created by: Saffron Clackson on 18/10/2002
FM:43649
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