Function and Applications

When using the device as grating spectroscope the diffraction on gratings with different grating constants can be explores and wavelength can be measured with an accuracy of 0.1 nm.

If set up as a prism spectroscope, the device is suitable for examination of the laws of refraction. Refractive indexes and dispersion can be determined of different glass prisms and with a hollow prism refractive index and dispersion of liquids can be determined. The prism spectroscope also allows the observation of faint spectral lines and a wavelength measurement with an accuracy of 2 nm.

Measuring spectral line wavelengths is essential for the comprehension of atomic physics, which is part of physics curriculum. Adjusting a spectrometer-goniometer conveys basic skills in applied optics.

Light from an adjustable entrance slit of 6 mm length and 0...1.5 mm width is parallelised by the ocular telescope. The parallelised beam passes a grating or a prism on a rotating table, which can be adjusted in height and levelled with three spring fitted adjustment screws. The ocular telescope with reticule is fitted on a rotating mechanism. Angle scales allow for angle reading with half an arc minute (0° 0' 30") accuracy of both the angle between collimator and ocular telescopes and ocular telescope - which is fixed with the device - and rotating table. The angle scales are two per scale and opposite offset by 180°. The zero point of the scale for the rotating table is arbitrarily selectable and fixable. The telescope entrance lenses have a diameter of 32 mm and the ocular (15 x) has a pupil of 6 mm width. Both rotating table and ocular telescope have a backlash free fine adjustment mechanism that allows reproducible rotation to half arc minute accuracy.

Equipment and Technical Data

• Height beam path over table: 180 mm
• Focal lenght: 178 mm (collimator- and ocular telescope)
• magnification ocular: 15x
• free beam path: 32 mm
• width entrance slit: 0...1,5 mm
• prism table diameter: 85,5 mm
• scale diameter: 176 mm
• reading accuracy: 0°0'30"
• compact device with two angular verniers
• focussing fine drives for slit and ocular the collimator with adjustable slit is fixed in position with respect to the device
• grating with holder and prism with holder included

Grating:

• Size (mm): 38 x 50
• Lines / mm: 600

Prism:

• Size (mm): 38 x 38 x 38
• Material: Flintglas (n = 1.65)