Reply to "IR or Optical Sensors"

Thank you both for the input. And Stan by the way I have used the PWM output to dim LEDs and it's a great suggestion. One more question. If I did not use an Arduino, I would need a circuit to generate a LOW when the beam is detected (for the dead-man-sw approach). The 2 circuits I have produce a H or L when the beam is broken. I found that when using the circuit that triggers with a HIGH and connected to the relay that triggers with a LOW it does not trigger when the beam is detected. So I would need a circuit that toggles H and L.