Heterodyne common path interferometers for surface profilometry and characterization

Michael Geoffrey Somekh, M. J. Offside, R. K. Appel, C. W. See

Research output: Journal article publicationJournal articleAcademic researchpeer-review

5 Citations (Scopus)


This paper describes two common path heterodyne interferometer systems. In each case the two arms of the interferometer traverse a very similar path so that the deleterious effects of microphonics cancel out. The first system is differential in that the relative phase between two displaced spots of similar dimensions are compared. The novel feature of this system is that in addition to obtaining the phase difference between the spots the differential of the intensity reflection coefficient can also be obtained by modulating the power in each of the spots. The second system is an absolute interferometer where the phase between two spots of very dissimilar sizes is obtained. The large spot thus measures the average sample phase whilst the tightly focused beam measures the local phase variation. By using an additional reference beam one can ensure that the two beams of dissimilar profiles interfere effectively. Results from each of the systems are presented.
Original languageEnglish
Pages (from-to)121-125
Number of pages5
JournalMaterials Science and Engineering A
Issue number1
Publication statusPublished - 10 Dec 1989
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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