Antiques of Science and Technology

SPECTROSCOPE, College Model, B & L, a sturdy instrument of the Bunsen-Kirchhoff type
Jim & Rhoda Morris             781 245 2897          email

Click on above Spectrum see  spectroscopes in our  basement laboratory studying Plasmas

The Prism and Prism Table

Inv.#1959.  SPECTROSCOPE, College Model, B & L, a sturdy instrument of the Bunsen-Kirchhoff type producing a brilliant spectrum of about 12 mm length with very satisfactory definition The resolving power is sufficient to effect separation of the two sodium D lines with little difficulty. These features, together with the low cost, exceptionally sturdy construction, and the fact that it is completely adjustable throughout, make this instrument especially suitable for student studies in charting the line and absorption spectra of various elements.
The telescope and collimator are equipped with achromatic objectives 22 mm in diameter and 125 mm focal length. The telescope is fitted with a Ramsden eyepiece of 18 mm focal length, which magnifies about 14 diameters. It is focused by a simple draw-tube adjustment The telescope may be adjusted horizontally and its carriage locked in position by means of a conveniently located thumb screw. The slit is made of nickel-silver, carefully machined and fitted, with a delicate unilateral adjustment for width.
The scale tube is provided with a collimating lens and carries at the outer end a numbered scale and a ground glass diffusing screen. The scale, 15 mm in length, divided into tenths, provides an accurate arbitrary reference which is easily focusable adjacent to the spectrum. Since the relation between the scale and spectrum is fixed, the user may calibrate the scale in wavelengths by plotting the wavelengths of known spectral lines against scale readings.
The prism is securely clamped on the prism table by means of a strong spring clip and may be easily moved to the position of minimum deviation. The prism table can be adjusted precisely by means of three screws allowing the teacher to demonstrate the effect of moving the prism on the vertical plane. The prism, with 60' angles between each pair of polished faces, has a refractive index of approximately 1.65. The faces are 32x18 mm. The prism table is covered by a housing with removable top which encloses the prism and objective lenses, protecting these parts from dust and excluding stray light
The pillar base is a heavy casting of instrument metal nicely finished in black crackled lacquer and forms a strong and steady support. Height to optical axis, 345 mm. Complete with prism and  in excellent condition.

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Copyright Jim & Rhoda Morris 6/6/2005