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We performed an experimental verification of a coronagraph. As a result, we confirmed that, at the focal region where the planetary point spread function exists, the coronagraph system mitigates the raw contrast of a star-planet system by at least $1\times10^{-5}$ even for the 1-$\lambda/D$ star-planet separation. In addition, the verified coronagr...
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... for direct imaging of light from exoplanets contain stellar coronagraphs (Kenknight 1977), many of which consist of two main elements: focal-plane mask and pupil-plane aperture referred to as Lyot stop (Figure 1). Focalplane masks selectively modulate (i.e., absorb, reflect, or scatter) the on-axis focused light amplitudes. ...
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... real instruments may need to have larger pupil diameters (e.g., 10mm) and focal-plane masks with a finer scale compared to this configuration. Figure 1 indicates schematics for the experimental setup. The output of the single-mode fiber (Thorlabs, P1-630A-FC-2) with a mode field diameters of 3.6-5.3µm ...
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... resultant coupling efficiency η exceeds 75% when the source separation angles are larger than 8 × 10 −1 λ/D and exceeds 50% when the source separation angles are larger than 3-4×10 −1 λ/D. We can evaluate the off-axis throughput (with respect to no focal plane masks) by multiplying the following three factors: (1) the constant factor (a 2 = 0.486) of the mask function, (2) the peak values of the point spread functions (in Figure 8) normalized by the one in the case with 1 λ/D, and (3) the coupling efficiency η. Figure 10 shows the result of the evaluation. In this experiment, we implemented the focal plane mask in a particular way that requires perfectly linear-polarized incidence. ...
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... this experiment, we implemented the focal plane mask in a particular way that requires perfectly linear-polarized incidence. Hence, the values in Figure 10 also assumes perfectly linear-polarized incidence. When we use other implementation methods, we do not always need the assumption of a perfect linear polarization incidence. ...
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... constant factor (a 2 = 0.486) of the mask function comes from the conservative assumption on the mask function: |M (⃗ x)| ≤ 1. The phase-induced amplitude apodization may provide the focal-plane-mask function with values greater than one or less than minus one, leading to higher throughput than the values in Figure 10. ...
