Partial misalignment cancellation of the retroreflected beam.
Unfolded propagation diagram of a cat's eye retroreflector with a flat mirror.
Optical layout of the interferometer. A, C, D, E, E′, K, polarizing beam splitters; B, beam splitter; C′, compensation glass cube; F, F′, J, quarter-wave plates; H, H′, aspheric lenses; I, I′, convex mirrors; G, target mirror; PD 1, PD 2, PD 3, photodiodes.
This is the arm of the interferometer.
RMS wavefront error in waves with respect to the principal ray for both configurations.
Plot of the A and C coefficients versus the distance of the mirror from the sweet plane s. The results of a least squares analysis are also shown and described in the text.
Upper view of the interferometer. Only few of the components are shown.
The percentage error σ(Δθ) calculated with the simulation coincides with the error predicted by Eq. (19) .
Normalized amplitude of the signal as the mirror rotates, for the displacement of the mirror s ∈ [−10 mm, 10 mm].
A photograph of the interferometer on its holder. All components are labeled.
(a) Lissajous patterns produced by the interferometer in units of volts as given by the amplifiers. The amplitude of the circular pattern shown in blue has been normalized. (b) Calibration of the interferometer using the AC as reference.
Measurements of the amplitude of the Lissajous patterns at different orientations of the mirror, when this was located at the sweet plane (blue continuous line) or displaced from this plane (dashed lines). Data are normalized by the largest measured amplitude.
Values of the linear coefficient c 1 from the quadratic fit (28) for three types of linearity measurements. In (a) the parameter c 1 was measured several times at the sweet plane, in (b) as function of the position s of the mirror, and in (c) as function of the angle θ0. The dashed lines show ±1σ confidence level. Error bars on the measured fit coefficients are derived from uncertainties in the measurement mainly limited by noise in the AC and by mechanical vibration in the setup.
The sensitivity of the interferometer is shown in blue and its mean value is depicted in black. The plot also shows an estimate of the joint laser and readout noise in green. The readout includes the photodiodes, the amplifiers, and the ADC. Finally, the noise produced by the amplifiers and the ADC is shown in orange.
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