This instrument has very good optic and mechanical features which allow the exact measurement of the optical ray deviation angles; therefore it can determine the refractive index of solids and liquids and the wavelength of monochromatic sources.
Base: made of fire-varnished cast-iron.
Goniometer: Ø 17.5 cm and divided in 360° with a precision of 1°.
It is equipped with a vernier, which allows to measure with an accuracy of 1/10 of degree.
Telescope: it has an achromatic objectives with an 178 mm focal length and a 15x eyepiece. Focusing allows fine regulation.
Collimator: endowed with an achromatic objective with 178 mm focal length and with a steady adjustable slit up to 6 mm.
Plane of the prism: it can be adjusted both vertically and horizontally and it is supplied with boss-heads for the fixing of the diffraction grating. Diameter: 80 mm.
Equipment: 1 Crown glass equilateral prism 32×32 mm; 1 diffraction grating 500 lines/mm; 1 magnifying lens.
Dimensions: 48x33x33h cm. Weight: 1.2 Kg.
The 80 lines/mm and 1000 lines/mm diffraction gratings are suggested to verify the variation of the spectral resolution.