IR Photointeruppter Aperture

[gladiator98]

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 (https://www.electro-tech-online.com/custompdfs/2010/05/QVB20Series.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.

 

[MikeMl]

I'm thinking that the hole in your disc should be much larger than the aperture on the data sheet. Since you are moving the disc with a stepper motor, how are you going to align the stopping place of the disc (due to the motor steps) such that the hole is aligned with the optical axis of the photointerupter? If you make the hole too small, that will be very difficult. The motor likely has 200 steps per revolution. Figure the arc length between motor steps at the radius where the hole is to be drilled, and make the hole diameter be about 3/4 of one step...