Available Photonics Experiments:

P5827 Reflexion and Transmission Download this page Download page

  • Reflection law
  • Fresnel's law
  • Brewster's angle
  • Polarisation by reflection
  • Dielectric coating
  • Examples of investigations and measurements
OX-07-01 Reflection, Fresnel law and Brewster's angle
For this series of experiments a laser (12) emitting a wavelength of 532 nm is used. The individual probe (6, 7, 8) is placed into its holder of the swivel unit (16). By means of a scale the angle with respect to the optical axis can be set and read. A polarisation analyser (1), a focussing lens (4) and the photodetector (3) are mounted onto the swivel arm of the unit (16). The swivel arm can be rotated continuously around the probe and data series recorded for different angles of the probe. The reading of the light intensity is done by a digital meter which is switched into the µA mode to obtain a linear relation of the light intensity and photo current.
The measurements can be carried out with defined polarisation of the light source which are set by the two polariser (15). The polarisation sate of the reflected or transmitted light is measured by means of the polarisation analyser mounted to the swivel arm (1). Using this setup the full Fresnel equations are verified yielding the Brewster's angle and also verifying the law of reflection.
OX-07_01 Dielectric coating
A dielectric or optical coating consists of one or more thin layers of material which is deposited on the surface of an optical component. Such a coating alters the way in which the optic reflects and transmits light. In general the properties of these coatings depends on the angle of incidence which is investigated in this series of measurements. To demonstrate the spectral behaviour of the coating a white light source and a grating is used.
Within the measurements an antireflection coating and one dichroic thin-film optical filter or mirror is used. The antireflection coating (common abbreviation: AR) reduces the normal Fresnel reflection of about 4 % per surface down to around 0.1 %.
The dichroic mirror transmits light of one wavelength and reflects another one. The wavelength for which reflection or transmission occurs depends on the design of the coating
White light source
For the spectral characterization of coated optics a white light source (11) consisting of a high brightness LED is used. The spectrum of the lamp is shown in the figure on the right. Beside a peak at 440 nm a broad range from 500 to 700 nm is available.
The light source is connected to the adaptive power supply (10) which allows the variation of the injection current and that way the intensity of the emitted light.
The divergent radiation is collimated by means of a lens (5) having a focal length of 40 mm.
  • P5827 Reflexion and Transmission (OX-0700) consisting of:
12B-03601Polarisation analyzer 40 mm
22B-03701Collimation optics in mounting plate 40
32B-05401Photodetector for pivot arm
42B-11301Crossed hair target
54B-00501 Plano convex lens f=40 mm, C25 mount
64B-07801Glas plate on rotary disc
74B-07841Dichroic mirror on rotary disc
84B-07901Font face mirror on rotary disc
94K-T6001T - grating 600 l/mm
10ED-00101Adaptive power supply APS-05
11LS-00101LED white C25
12LS-01101DIMO diode laser module, 532 nm
13MC-02501Profile Rail MG-65, 300 mm
14TP-00301Digital multimeter 3 1/2 digits
15XM-01242Polariser / Analyser with rotator
16XM-02101Triple swivel unit
17XM-10901Mounting plate C25 with carrier 20 mm
18XM-11101Adjustment holder, 4 axes, carrier 20 mm