Development of Wavefront Sensor using Shack-Hartmann Principle

Over the past years, wavefront technology is used in astronomy because it has better telescopic resolution for examining the universe. Since earth turbulence causes atmospheric aberrations, this technology is the solution compensating it. Human eye also has aberrations, which is divided into two, higher and lower order aberration. In this study, human eye is examined using the wavefront technology. Developing vision correction is the key technique to understand the condition and quality of a human eye. The wavefront sensor is composed of photodetector, visual stimulus, collimating lens and microlens array, which is based on the Shack Hartmann Principle. As the light from the visual stimulus enters the human eye, it is reflected by the retina. The light rays bounce back and will pass through the collimating lens that would make the reflected light parallel to configure illumination. Then, it will enter the microlens array that will divide it into discrete sections, one section for each lenslet. Therefore, each lenslet will focus its part of the incoming wavefront to a spot. It will be captured by the photodetector, which is controlled by a microcontroller. It would take only 5 seconds to capture the wavefront. This sensor creates a raw image showing how the light traveled in the eye and its imperfections. Numerous processing methods can be applied depending on the desired output. This raw image from the wavefront sensor contains information and parameters that can be helpful in detecting the aberrations.