Data can be exported in tabular form allowing further analysis with a spreadsheet.
The advantage of describing a spectrum in terms of energy or wavelength allows
different educational proposals: light could be seen as a wave or as a stream of
photons with specific energies.
22.4 Examples of Significant Measures
In principle, every light source could be coupled with SPETTROGRAFO system:
discrete spectra from gas-discharge or fluorescent lamps, continuous spectra from
incandescent lamps, or band spectra from LEDs and absorption spectra could be
detected and analyzed. To perform a measure, it is enough to point the webcam lens
towards the source (Fig. 22.5, left). One advantage is that no optical bench is needed:
operatively it is enough to assure the alignment between source, grating, and sensor
in a way that the spectrum is horizontal with respect to the array of pixels. Preliminary tests showed that the distance between the grating and the source does not
affect the precision of the measures.
22.4.1 Analysis of Discrete Emissions from Gas-Discharge
Lamps in “Static-Mode”
Using a thin gas-discharge tube, or a thin slit placed in front of an extended lamp in
order to make the shape of the source as thin as possible, the spectrum is created
reproducing the shape or the source in different positions on the CCD sensor in
different colors. Once digitalized, it is possible to observe and measure the position
(in wavelength or energy), width, and relative intensity of the various discrete
emissions (Fig. 22.6). Lines peculiar features such as intensity and width could be
discussed as consequences of quantum mechanical principles. Moreover, changing
the grating’s pitch, it is made clear how the resolving power of the measuring
Fig. 22.6 Spectra of a cadmium (left) and helium (right) gas-discharge lamp taken with the
SPETTROGRAFO system
278
D. Buongiorno et al.
The advantage of describing a spectrum in terms of energy or wavelength allows
different educational proposals: light could be seen as a wave or as a stream of
photons with specific energies.
22.4 Examples of Significant Measures
In principle, every light source could be coupled with SPETTROGRAFO system:
discrete spectra from gas-discharge or fluorescent lamps, continuous spectra from
incandescent lamps, or band spectra from LEDs and absorption spectra could be
detected and analyzed. To perform a measure, it is enough to point the webcam lens
towards the source (Fig. 22.5, left). One advantage is that no optical bench is needed:
operatively it is enough to assure the alignment between source, grating, and sensor
in a way that the spectrum is horizontal with respect to the array of pixels. Preliminary tests showed that the distance between the grating and the source does not
affect the precision of the measures.
22.4.1 Analysis of Discrete Emissions from Gas-Discharge
Lamps in “Static-Mode”
Using a thin gas-discharge tube, or a thin slit placed in front of an extended lamp in
order to make the shape of the source as thin as possible, the spectrum is created
reproducing the shape or the source in different positions on the CCD sensor in
different colors. Once digitalized, it is possible to observe and measure the position
(in wavelength or energy), width, and relative intensity of the various discrete
emissions (Fig. 22.6). Lines peculiar features such as intensity and width could be
discussed as consequences of quantum mechanical principles. Moreover, changing
the grating’s pitch, it is made clear how the resolving power of the measuring
Fig. 22.6 Spectra of a cadmium (left) and helium (right) gas-discharge lamp taken with the
SPETTROGRAFO system
278
D. Buongiorno et al.