It is common practice in adaptive optics to use CCD detectors with global shutter readout for wavefront sensing. sCMOS detectors with rolling shutter readout are often not considered due to image distortion when the object is moving at high speed. However, sCMOS detectors have the potential to achieve lower readout noise, larger format, and lower cost. Therefore, we investigate the effect of rolling shutter readout in the context of the laser guide star wavefront sensors of ULTIMATE-Subaru, a Ground Layer Adaptive Optics project at the Subaru telescope. In the case of a laser guide star wavefront sensor, the wavefront tip-tilt component is filtered out in the measurement due to the tip-tilt indetermination effect. With the rolling shutter readout, the tip-tilt component can alias onto the higher-order wavefront components, it becomes a problem for the wavefront measurement. Firstly, we identify the particular modes that are aliased onto, as well as the frequency response of this aliasing. As a result, it is confirmed that when the oscillation frequency of tip-tilt is faster than about 10% of the sampling frequency of the detector, it is partially measured as higher-order components such as coma and trefoil. We also conduct a wavefront measurement experiment using the ORCA-Flash4.0 v2 sCMOS detector manufactured by Hamamatsu Photonics. The experiment with the optical system shows consistent results as the simulation. Finally, we estimate the effect of aliasing from the tip-tilt components of the atmospheric turbulence, telescope vibration, and laser guide star jitter using a end-to-end adaptive optics simulation.
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