Designing a holographic modal wavefront sensor for the detection of static ocular aberrations.
The extent to which holographic modal wavefront sensing can be applied to the detection of ocular aberrations was investigated. First, the idea of extending the dynamic range of the sensor by increasing the mask bias and the collection area of the pinhole detectors used in the sensor is reviewed. Errors in the detection of single-mode aberrations owing to reduced coherence from retinal scattering, photon, readout, and quantization noise are evaluated. A sensitivity-to-noise metric is introduced to evaluate sensor designs and is found to be maximized by using a pinhole detector radius of 8.6(flambda/NDelta) for every wave of mask bias (where f=transform lens focal length, lambda=wavelength, and N and Delta are the number and size of the hologram pixels, respectively). The problem of detecting ocular aberrations composed of multiple modes required a generalization of the sensitivity measure to include all incident aberration modes. A "detect and correct" ocular aberration detection scheme was implemented that reduced the effects of cross talk and showed a maximum sensitivity-to-noise ratio of 40, which varied inversely with the size of the ocular aberration being detected.
Corbett
Alexander D
AD
Department of Engineering, Cambridge University, UK. a.d.corbett.98@cantab.net
Wilkinson
Timothy D
TD
Zhong
Jiang J
JJ
Diaz-Santana
Luis
L
D019781:Corneal Topography / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006696:Holography / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D012030:Refractive Errors / Q000175:diagnosis*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers