Which way does the light go?

American Journal of Physics

Volumn 70, Issue 6, 2002, Pages 599-606

  Wünscher, Thilo ^a   Hauptmann, Holger ^a   Herrmann, Friedrich ^a  

^a UNIVERSITY OF KARLSRUHE   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33646653299     PISSN: 00029505     EISSN: None     Source Type: Journal    
DOI: 10.1119/1.1450570     Document Type: Article

References (16)

1. W. T. Welford and R. Winston, High Collection Nonimaging Optics (Academic, New York, 1989).
2. P. Würfel, Physik der Solarzellen (Spektrum, Akademischer Verlag, Heidelberg, 2000), p. 34.
3. H. Hinlerberger and R. Winston, "Efficient light coupler for threshold Cerenkov counters," Rev. Sci. Instrum. 37, 1094-1095 (1966).
4. D. Didascalou, T. M. Schäfer, F. Weinmann, and W. Wiesbeck, "Raydensity normalization for ray-optical wave propagation modeling in arbitrarily shaped tunnels," IEEE Trans. Antennas Propag. 48, 1316-1325 (2000).
5. A. S. Glassner, An Introduction to Ray Tracing (Academic, New York, 1989).
6. To most of the "radiometric" quantities (energy, energy flow, energy flow density, etc.), a corresponding "photometric" quantity can be defined (quantity of light, luminous flux, illuminance, etc.). The photometric quantities are obtained by multiplying the spectral energetic quantities by a wavelength dependent weighting factor. Thus, all of our energy flow diagrams can also be interpreted as the flow lines of the (photometric) "quantity of light."
7. Max Planck, Vorlesttngen über die Theorie der Wärmestrahlung (Verlag Johann Ambrosius Barth, Leipzig, 1913), pp. 22-23.
8. A cosine appears in Eq. (1) when written with the magnitudes of the vector quantities j and dΩ. See for example, Max Born and Emil Wolf, Principles of Optics (Pergamon, Oxford, 1964), 2nd ed., p. 182, Eq. (5).
9. z.) equivalent to the spherical bookkeeping (k, δ, and φ), where k is the magnitude of the momentum.
10. Note that the angular resolution cannot be increased arbitrarily, because for d'/f;ltλ/d, the resolution is diffraction limited. (λ is the wavelength of the radiation.)
11. The radiance meter will indicate the correct value of L only as long as it "sees" the light source under an angle that is greater than its angular resolving power. Thus, if the source is too small and/or too far away, as for example a star other than the sun, the meter will no longer measure correctly.
12. The energy (low of Eq. (1) can be interpreted as the time average of the Poynting vector. Note, however, that this remark is not of much use. For the kind of fields that we are considering, the distributions of the electric and magnetic field strength are so complicated that there is no possibility to know them and no interest in knowing them. Knowing the electric and magnetic fields of, say, thermal radiation would be a task similar to knowing the positions and momenta of all of the molecules of a material gas in thermodynamic equilibrium.
13. A free download of LIGIITLAB 2.0 is available at http://www. physikdidaktik.uni-karlsruhe.de.
14. A. Wolf, J. van Hook, and E. R. Weeks, "Electric field line diagrams don't work," Am. J. Phys. 64, 714-724 (1996).
15. F. Herrmann, H. Hauptmann, and M. Suleder, "Representations of electric and magnetic fields," Am. J. Phys. 68, 171-174 (2000).
16. F. Herrmann, "Is an energy current energy in motion?," Eur. J. Phys. 7, 198 -204 (1986).