Images(2)

small quartz spectrograph Littrow model

Date1940-1950

Inventory Number1997-1-0361

ClassificationSpectrograph

Subject

Maker Bausch & Lomb Optical Company 1853-present

User Bowdoin College, Department of Physics founded after 1794

Cultural Region

Place of Origin

Place of Use

Dimensions44.5 × 56.8 × 28.5 cm (17 1/2 × 22 3/8 × 11 1/4 in.)

Material

Accessoriesinstruction manual (in file)

Bibliography

Catalog D-111: Scientific Instruments

DescriptionThe optical system of this spectrograph is completely encased and requires no adjustments. It consists of a prism, lens and plate-back carefully adjusted for best performances. The front of the instrument consists of a brass frame with a scale divided in millimeters, the front opening where the light from the substance enters the instrument, a scale button and eccentric clamp on the side. A photographic plate and its holder would have slid between gibs. (These appear to have been replaced in this example by another type of photographic holder.)

The back of the instrument consists chiefly of the mechanism to adjust the quartz slit and the flashlight bulb socket. The instrument is supported by a tripod base on which is found a leveling screw and a contact switch.

Signedon top: BAUSCH & LOMB OPTICAL COMPANY

FunctionA spectrograph is an instrument used to obtain and record a light spectrum. The spectrograph splits the light from an object into its component wavelengths so that it can be analysed. In the present case, the spectral lines of a chemical element, for instance, is produced and photographed by the spectrograph. When the photographic plate is developed, the spectral lines are precisely measured to determine the composition of the said chemical element.

According to the B&L catalogue description: "This small quartz spectrograph provides a much needed instrument for industry and education, where moderately high dispersion, but no great resolving power, is necessary. It is of simple design, sturdily built, light and easily portable. It is offered at an unusually low price which has been made possible by a unique design, but without sacrificing the quality and precise construction which characterize larger Bausch & Lomb spectrographs.

With its wave-length rande of 2100A to 7000A, dispersed over a length of six inches, it affords a longer and more easily read spectrum than can ordinarily be obtained with any other small spectrograph now manufactured. Because of this greater spectrum length, measurements can also be made with greater precision. It is not, however, intended to replace the medium or large spectrographs for work, on complex spectra, where the lines are very close together and require high resolving power and dispersion for satisfactory separation."

ProvenanceFrom the Department of Physics, Bowdoin College.