I'm using a disc with a hole in it to stop by use of a stepper motor and IR sensor at the location of the hole. So I was trying to figure out what size hole I need to accurately stop the disc. I noticed that IR sensor vendors list "Aperture Sizes" for the LED and Sensors located within the casing (http://media.digikey.com/pdf/Data%20...B%20Series.pdf). Are the aperture sizes for the LED and/or Sensors the same size that I want to drill a hole in the disc to accurately stop the disc where I want with this sensor? Thank you.