We propose a new derivation for two-plane wavefronts incident in a rotational shearing interferometer. We introduce a displacement in the optical path of the Rational Shearing Interferometer and therefore modify the spatial frequency. We obtain an approximate formulation for the total incidence for two independent signals. We use a 4f optical processor and interferometric cancellation to recover the weakest signal. We also use a cancellation signal’s advantage to improve the interest signal’s signal-to-noise ratio (SNR). The proposed method works efficiently for computer simulation, the next step uses the same procedure to eliminate frequencies for a laboratory interferogram. We simulate a Star-Planet system, and this process will help in exoplanet detection.
The signal-to-noise ratio compares the power of a signal with information of interest against an undesired signal considered noise. In a lab experiment, we measured the signal-to-noise ratio of two intensity patterns in a Rotational Shearing Interferometer based on a Mach-Zehnder configuration with a dove prism in one arm of the interferometer. One signal represents the faint radiation of a planet, and another means the high radiation from a star. The proper rotation of the dove prism eliminates the intensity pattern produced by the star, but the intensity pattern due to the planet prevails. The rotation of the dove prism improves the extremely small SNR of these signals. This improvement helps the planet detection near a star by interferometric methods.
More than 4000 planets beyond our solar system have been confirmed since 1995. Transit, radial velocity, microlensing, imaging, orbital brightness, timing variation, and optical detection are most common for exoplanet detection. Optical detection implies several challenges in selecting the proper wavelength range, the small angular resolution star-planet, and the extremely low SNR of the planet near the star. We propose lab proof-of-concept using a rotationally shearing interferometer. This approach includes enhancing the star-planet SNR by hybrid optical and electronic techniques with simulated planet-star signals. The planet's signal is modulated and then detected by a lock-in amplifier, and the rotational shearing interferometer performance cancels the star's signal.
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