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Unambigous measuring of great retardations with a modified Senarmont method

: Kaufmann, S.; Zeitner, U.


Optik 113 (2002), Nr.11, S.476-480
ISSN: 0030-4026
Fraunhofer IOF ()

Tiltable compensators are often used for measuring of great retardations of media with birefringence. In case false colours do appear a destruction-free measuring would not be possible with this method. That is why we present a multi-colour or multi-Senarmont-method basing on a simultaneous or sucsessive measuring of the Senarmont-angle with two or more wavelengths and a subsequent minimization calculation. Two principal advantages will result:

1. Retardations Gamma > lambda will be measured unambigously. 2. Samples with false colours will be also measured without any destruction and unambigously. Important condition: The difference of the measuring-wavelengths can amount to at most 10 nm. Further advantages of the multicolour-Senarmont-method (opportunities for automatic contactless and short-period measuring [minimal integration time]) will be published later.