Complete Zeeman Effect Apparatus

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Complete Zeeman Effect Apparatus
Integrated Equipment Set For The Study of Light Emission In a Magnetic Field

Integrated Equipment Set For The Study of Light Emission In a Magnetic Field

The Zeeman Effect, the splitting of spectral emission lines under the influence of a magnetic field, is a fundamental phenomenon of the physics of the atomic shell, and its study offers insight into the behavior of light emitting atoms and the quantum nature of spectral interactions. The observation of the Zeeman effect requires a powerful magnetic field and a high-resolution spectrometer. Traditional versions of the setup have been notoriously difficult to adjust and use, and this has discouraged the widespread use of this important experiment in university and college physics teaching laboratories. The new integrated design of this apparatus and the use of a video camera and evaluation software have now made the experiment much easier to use, more reliable, and more accessible.

The Equipment
The equipment set consists of a large electromagnet with a built in power supply to generate the 1.3Tesla magnetic field needed, a slim low pressure mercury lamp that fits between the pole pieces of the magnet, an optical bench with an array of optical elements, a video camera with a video capture card, and PC software for observation, measurement, and analysis. The optical arrangement includes an imaging lens for collimating the mercury light, a polarization filter, an interference filter, and a high resolution Fabry-Perot etalon as the analyzing spectrometer. The interference filter has a central wavelength of 546.1nm and a transmission bandwidth of less than10nm to select the mercury green line for analysis. The Fabry-Perot etalon has quartz plates with an aperture of 40mm and a spacing of 2mm. It has a central wavelength of 589.3nm, a resolution (λ/dλ) greater than 2 x 105, and a high reflection bandwidth of 100nm. A quarter wave plate is also provided for investigating the circularly polarized light emitted in the axial direction.

The Experiment
The mercury green line at 546.1nm spits into nine possible components in a magnetic field, three p-polarized and six s-polarized. When observed transverse to the field, all nine components appear, but overlap makes them difficult to distinguish. The polarizing filter allows the three p lines to be isolated and the radius shift of the Fabry-Perot interference fringes to be measured for each of these at various magnetic field values. The magnet can then be rotated 90° to observe and measure the two circularly polarized s lines emitted parallel to the field.

The Software
The custom software presents a live video image of the Fabry-Perot interference pattern, which is much easier to see than by direct visual observation. The pattern can be captured for measurement and evaluation. Ring diameters are precisely measured on the video image by placing three reference points on the ring. An optimal algorithm determines the ring radius and center and calculates the wavelength shift. To reduce noise and improve accuracy, multi-pass gray scale processing of the image can be optionally used. Apparatus connects to your computer via USB cable. The software requires 64Mb of memory and up to 1Gb of hard disk storage (to accommodate the images) and operates on Windows ME, 2000, and XP.