capture data off retina screen - mobile expirement

Need to do a preliminary test on both iPad & iPhone devices that involves capturing handwriting data - x & y coordinates - off retina screen every 2.5 milliseconds and generating output in excel file. Should be a relatively straightforward job for those that are familiar with the intricacies of mobile development. Will follow up in PM with serious developers. This is just a test. If it goes well, will have you develop the full application needed.