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Interferometric measurement with .lambda./4 resolution

  • US 4,221,486 A
  • Filed: 10/06/1978
  • Issued: 09/09/1980
  • Est. Priority Date: 12/27/1977
  • Status: Expired due to Term
First Claim
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1. An inteferometric method with λ

  • /4 resolution for distance, thickness, and/or flatness measuring, characterized in that a collimated, convergent or divergent radiation (So) is directed at a first angle of incidence (θ

    1), or at a first range of angles of incidence onto an object (1) to be measured, that the components (S1, S2) of the radiation (So) reflected from different surfaces or different parts of the object to be measured are superimposed to a new radiation (S'"'"'), with this new radiation redirected onto the object to be measured at a second angle of incidence (θ

    2) differing from the first angle of incidence, or at a second range of angles of incidence differing from the first range, that the components (S3, S4) of this radiation reflected from different surfaces or parts of the object to be measured are brought into interference, and that the resulting interference fringe pattern is imaged for evaluation.

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