The principle of Hartmann wavefront sensor is that the centroid angle deviation of spot equals to the mean slope of the phase on the subaperture, but its precision is up to one of two assumptions: the beam is divided into plan wave and the beam intensity distribution is uniform on each subaperture. When none of these two assumptions is satisfied in the wavefront detection, the centroid angle deviation of far field spot is not exactly equals to the mean slope of the phase on each subaperture, and finally the wavefront detecting error is produced. A similar case occurs when calibrating the Hartmann wavefront sensor. The translation error of microlens arrays and the focal length differences of microlens arrays would introduce defocuses on all subapertures, the centroid of the far-field spot is not the same as the mean slope of the phase of calibrating beam when the calibrating beam has nonuniform intensity distribution, as a result, the calibration error of Hartmann wavefront sensor comes out. Two formulas, which evaluate the calibration error associated with the nonumiform intensity distribution and the defocus of microlens arrays are obtained in this paper, these formulas provide theoretical supports to design and calibrate a Hartman Sensor required millesimal wavelength precision. Also a new parameter is derived to characterize the nonuniformity of the intensity distribution.

Date Published: 12 October 2010
PDF: 6 pages
Proc. SPIE 7656, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 765675 (12 October 2010); doi: 10.1117/12.866666

Published in SPIE Proceedings Vol. 7656:
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; Jose M. Sasian; Libin Xiang; Sandy To, Editor(s)