Feasability of using interferometry for wavefront sensing in the eye

Alfredo Dubra, Carl Paterson, Pablo Artal, Brian Barry and Chris Dainty

(This page in under construction and will be updated shortly June/2004)

We are currently exploring the feasibility of using interferometric techniques for wavefront sensing in the human eye by qualitatively comparing a lateral shear interferometer and a Shack-Hartmann wavefront sensor under similar experimental conditions. We have recorded data that is currently being analysed.

Figure 1: In this figure we can see some lateral shear interferograms (left and central columns) and the associated Shack-Hartmann spot patterns. The wavelength used was 632.8 nm and no pupil dilation or accommodation paralisation drugs were applied. All pictures correspond to an off-axis entrance pupil of diameter 1mm to reduce double pass effects. We can see that speckle seems to have a stronger influence on the interferograms than in the Shack-Hartmann patterns. Actually, the interferograms were produced using wedges that should introduce around 50-80 vertical fringes across the pupil, but none can be observed, not even for the longer exposures.

Figure 2: In this figure we can see some lateral shear interferograms (left and central columns) and the associated Shack-Hartmann spot patterns, this time with an illumination source emitting at 780nm. Again, no pupil dilation or accommodation paralisation drugs were applied, and all pictures correspond to an off-axis entrance pupil of diameter 1.2mm to reduce double pass effects. We can see again that speckle seems to have a stronger influence on the interferograms than in the Shack-Hartmann patterns, although in this case, for the smaller shear interferograms we can see the vertical fringes produced by the tilt introduced by the wedges.