| dc.description.abstract | Shack-Hartmann（SH）wavefront sensor is a powerful and robust tool in wavefront sensing and has a good performance even compare with phase- shifting interferometer or shearing interferometer. It also can do absolute measurement in very high accuracy and has applied to many other fields like position sensing and ocular optics. However, in a common configuration of a SH wavefront sensor, there is always a relay optics placed before the sensor to relay the test beam. The relay optics is not perfect, thus additional aberrations and measurement uncertainties will be introduced into the system.
To reduce the system uncertainties and additional aberrations, a system without relay optics is constructed. A convergent beam, instead of a collimated beam, is incident into the wavefront sensor. Without using the relay optics, the system aberrations and uncertainties could be reduced.
However, since the lens arrays are not perfect, off-axis aberrations occurs when a convergent beam is incident on it. These aberrations incur shifts in the focal spot positions. Therefore, calibration on the lens array at different angle of incidence is needed. Besides, the shifts will larger than lens array’s lens pitch, which means that the shift spot will out of its relative lens region and this cannot be satisfied with the conventional algorithm. Thus, a proper spot assignment algorithm should be adopted. Furthermore, since the system becomes simpler and clearer, it is possible to remove the alignment error through analytical methods. Through remove the alignment error, the requirement for alignment could be looser.
In this thesis, we demonstrate a SH wavefront sensor that is free of relay optics and investigate the feasibility of remove the alignment error. Measured the lenses with different f-number then compare the results with Fizeau interferometer and analyze the system’s performance. | en_US |