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Method and apparatus to determine spatial distribution of magnitude and phase of electro-magnetic fields especially optical fields

  • US 3,950,103 A
  • Filed: 06/21/1974
  • Issued: 04/13/1976
  • Est. Priority Date: 10/27/1972
  • Status: Expired due to Term
First Claim
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1. A method of numerically determining the distribution of magnitude and phase of a time harmonic electromagnetic, particularly an optical, wave field comprising:

  • a. engendering a reference wave field such that its spatial distribution is similar to the field to be measured whereby fringes are obtained the position of which varies slowly with the recording coordinates;

    b. using the reference wave as reference surface;

    c. recording under far field conditions point by point by means of photodetector three interference fringe patterns which belong to the unknown field and variations of the said reference field distribution, the relationship of said variations as to magnitude and phase being such as to uniquely determine, for any recording point, the amplitude and phase distribution of the unknown electromagnetic wave field;

    d. recording data in numeral form obtained from the photodetector;

    e. placing an optical element in the said reference wave optical path such that the reference wave front is shifted in relation to the unknown wave front by a small known amount;

    f. repeating the measurements as in (c) and (d); and

    g. processing said data to obtain numeral values of magnitude and phase of the electromagnetic wave field being measured, such as to provide information in terms of a smooth spherical wavefront.

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