Physics Teaching
The following applications showcase the use of high-resolution spectroscopy in university physics teaching labs.
Clients: University of Newcastle (NSW, Australia), University of Sydney, Macquarie University
Challenge: Efficiently facilitate student understanding of concepts in physics through laboratory experiments and teaching demonstrations.
Application: The flexibility of our Redback Systems spectrometers allow a single device to rapidly redeploy between a diverse range of teaching labs and demonstrations. A number of application examples are listed on this page.
Methodology: Our RS10k spectrometer is particularly well suited to teaching situations due to its compact portability. Many of these demonstrations involve light sources which are bright enough to bypass any need to optically focus light into the single-mode optical fibre. Positioning the fibre tip near the experiment is typically enough to collect strong signals.
Zeeman Splitting
Experiment: Observe Zeeman splitting of Cadmium atomic emission.
Summary: Atomic orbitals can be labelled by a quantum number Mj indicating the total angular momentum. In a vapour lamp the excited atoms emit resonant light as they relax from a higher state to a lower state, and the optical transitions are only allowed if the spin number Mj differs by 1 or less. Transitions where Mj changes by -1 lead to sigma(-) circular polarised light, and transitions where Mj changes by +1 lead to sigma(+) circular polarised light. The Zeeman splitting of spin levels in an external magnetic field can be measured spectrally, and is made easier by using polarisation to independently isolate the sigma(-) and sigma(+) transitions. The Zeeman splittings of 4 different atomic transitions of Cadmium were recorded simultaneously, and are shown to have different spin-orbit couplings.
Laser Modes
Experiment: Laser mode hopping and lasing threshold.
Summary: Diode lasers typically emit a beam that has a small range of wavelengths, known as an optical bandwidth. This is caused by the fact that multiple different modes of oscillation are happening simultaneously within the resonator of the laser diode. These can include both longitudinal and transverse modes, leading to a multimode laser diode. The plot below shows a spectrum of an inexpensive fibre fault detector with 650±20 nm central peak wavelength.
Solar Spectroscopy
Experiment: Fibre pointed at Sun
Summary: The solar spectrum is rich and complex, combining a continuum spectrum with numerous absorption lines. The analysis of these features provides valuable information about the Sun's composition, temperature, and activity, contributing to our understanding of solar and stellar physics. The plot below shows a 350 nm wide section of the solar spectrum with regions of interest of prominent features (e.g. sodium doublet and H-alpha).
