A black metal bracket supports a thick concave mirror made of glass.
The mirror is affixed to a round backing by three brackets arranged at intervals around its outer edge. On the back of the bracket there is a fastener securing it to the fame. At the back of the frame are adjusting screws used to fine-tune the mirror’s orientation. Pieces of masking tape are attached to the steel bracket.
Accession Number: 2017.ph.741
Alternative Name:
Primary Materials: Glass, Iron Aloy.
Markings:
Height=26, Width = 14, length=22. (Mirror diameter = 20)
Such concave mirrors—precisely formed glass surfaces coated with a reflective film of metal—are used in spectroscopic instruments to gather light from a sample onto a diffraction grating that then splits the light into its spectral components for analysis. The angle of this mirror can be adjusted using three screws at the back of its sturdy steel mounting bracket. The masking tape adhering to the bracket may once have been used to attach a protective cover when the mirror was not in use.
The mirror has a small chip on its edge at about the 3 o’clock position.
Associated Instruments:
(Probably) Jarrell-Ash Co., Franklin, Mass, USA
Date of Manufacture: c. 1961
This item was donated by Professor Henry van Driel on June 3, 2017, during the celebration of the 50th anniversary of the McLennan building.
Additional Information and References:
According to U of T physicist Henry van Driel, this concave mirror may have belonged to a Jarrell-Ash spectrometer that was purchased in 1961. This was a large and expensive instrument that remained a workhorse of the Department of Physics over the 1960s and 1970s. Among other investigations, it was used to study the properties of oxygen molecules by observing their spectra as they collided under pressure.
This mirror may later have been removed from the spectrometer for further experiments in Raman and infrared spectroscopy.