Multiwavelength Shack-Hartmann Aberrometer

Abstract

Measurement of higher order optical aberrations in the human eye has become important and common place now days, particularly in the advent of custom Lasik surgery and adaptive optics. The most widely used instrument in the industry and clinics is the Shack- Hartmann Aberrometer that utilizes the Shack-Hartmann sensor to measure the aberrations of the eye. The standard SH aberrometer is made of a chin rest and requires the subject to look at the target with one eye and measures the aberrations at an infrared wavelength which is generally 780 nm. This research work adds two improvements to the standard instrument. These two new SH aberrometers have been built and tested on Human subjects. The first modification is to make the aberrometer portable and unobtrusive so that it can be hand held and the subject is allowed to look at the target with both eyes. This instrument is called the Unobtrusive SH Aberrometer (USHA). The second modification is to measure the aberrations at three visible wavelengths spanning the visible spectrum so as to not only measure the aberrations over the visible spectrum but also measure the chromatic aberration. This instrument is called the Multiwavelength SH Aberrometer (MSHA). This instrument is probably a first of its kind, capable measuring the in vivo chromatic aberration in a single image.