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R. M. Morgan (OSC), J. M. Burge (OSC)
Schemes for detecting planets around other stars using interferometery have been developed which rely on a half wave phase delay to shift the central constructive fringe of an interferometer to a deep, destructive null fringe. To achieve the sensitivity and spectroscopy desired for exo-planets observations, such a null must be achromatic over a broad spectral region. One method for creating such a half wave phase delay achromatically involves the use of pairs of dielectric, plane parallel plates, analogous to the use of two types of glass in an achromatic lens. An analysis of the technique is presented with solutions using single plates to achieve null fringes to a cancellation of 10 exp -4 in the visible, near infrared, and mid infrared for null. Solutions using two matched materials show that nulls to a depth of 10 exp -6 are achievable in 2 um bands in the 7-17 um regime, or to a depth of 10 exp -5 over the entire 7-17 um band. Experimental results using a single plate of BK7 in the visible spectrum verify the technique.
The author(s) of this abstract have provided an email address for comments about the abstract: rhonda@as.arizona.edu