Point spread function engineering with a double helix (DH) phase mask has been recently used in a joint computationaloptical
approach for the determination of depth and intensity information from fluorescence images. In this study,
theoretically determined DH-PSFs computed from a model that incorporates different amounts of depth-induced
spherical aberration (SA) due to refractive-index mismatch in the three-dimensional imaging layers, are evaluated
through a comparison to empirically determined DH-PSFs measured from quantum dots. The theoretically-determined
DH-PSFs show a trend that captures the main effects observed in the empirically-determined DH-PSFs. Calibration
curves computed from these DH-PSFs show that SA slows down the rate of rotation observed in a DH-PSF which results
in: 1) an extended range of rotation; and 2) asymmetric rotation ranges as the focus is moved in opposite directions.
Thus, for accurate particle localization different calibration curves need to be known for different amounts of SA.
Results also show that the DH-PSF is less sensitive to SA than the conventional PSF. Based on this result, it is expected
that fewer depth-variant (DV) DH-PSFs will be required for 3D computational microscopy imaging in the presence of
SA compared to the required number of conventional DV PSFs.