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P5826 Polarisation of light PDF Download page

  • Polarisation of light
  • Malus Law
  • Optical activity, chirality
  • Double refraction
  • Phase retarder
  • Jones matrices
  • Examples of investigations and measurements

Polarization of light sources
In a first experiment the polarization state of the provided DPSS laser (9) is recorded. For this purpose one polarisation analyser (12) is placed in front of the laser. The light passing the polariser is measured by means of the photodetector (6) which is connected to digital meter (11).
In a next experiment the laser is exchanged against one of the provided LED which are connected in the same way to the controller as the laser before. The microprocessor operated unit detects what is connected and provides the proper voltage and current. To collimate the emitted light of the LED a collimating lens (1) is provided. The measured results are plotted against the angle of the polariser which can be set in steps of 5 degrees.

OX-06.03 Malus Law (1775 - 1812)
The transmission of light passing two polarisers for different angle orientation to each other was firstly derived by the French scientist Etienne-Louis Malus (1775 -1812). To verify this law a set-up with two polariser (12) is used.
As light source we again use one of the provided LED. Either the light source (7 or 8) or the first polariser (12) is rotated in such a way that maximum intensity will be observed. The second polariser is turned in steps of 5 degrees and the resulting intensity is measured by the photodetector (6). Beside the law of Malus the results are modified by the quality of the polariser. That means that the polariser absorbs already a certain amount of the radiation and the intensity will not drop completely to zero at the 90 degree crossing. To characterise the quality of a polariser the extinction ratio is introduced and discussed.
It will be shown that the here used film polariser a very useful for common application, however for high precision measurements still crystal polariser are required.
OX-04.04 Optical activity
The set-up is modified in such a way that the between of two crossed polariser (90°) an optically active quartz sample (2) is placed. By readjusting the analyser for maximum extinction the phase retardation of the used material is determined. It will be experimentally verified that the retardation depends on the rotational orientation of the sample.
Half- and quarter-wave plates
A speciality in light polarisation are the quarter and halve wave plates. The property of both kind are investigated by recording the respective transmission diagrams.
  • P5826 Polarisation of light consisting of:
14B-00401Plano-convex lens f=40 mm, mounted in click 30 mm
24B-06601Optical quartz plate, click 25
34B-08701Quarter wave plate, click 25
44B-08801Half wave plate, click 25
5ED-00101Adaptive power supply APS-05
6ED-02101PIN Photodetector, BPX61 with connection leads
7LS-00101LED white
8LS-00201LED Red
9LS-01101DIMO 532 nm
10MC-00052Profile rail MG-65, 500 mm
11TP-00301Digital multimeter 3 1/2 digits
12XM-01242Polariser / analyser with rotator
13XM-10902Mounting Plate, including carrier 20 mm, C 25
14XM-11101Adjustment holder, 4 axes, carrier 20 mm