1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

LED light diffraction, scattering

  1. Jan 28, 2008 #1
    I am constructing a 'white line detector' to use on the underside of a robot. The crucial components are an ultrabright red LED and a light-to-voltage converter. My initial idea is to leave the LED as it is, i.e. unshielded. I have to light-to-voltage converter, which is a phototransistor with a lens (TSL-257), connected nearby and it is shielded using heat-shrink tubing to block out ambient light. it is being used to detect a change in color from black to white.

    My question is, do I need to worry about "shielding" the LED to guard against scattering. If I just shield the TSL257, I get a voltage reading of 125mV, and when it crosses over to white, it is about 2V. This is perfectly fine, but the other members of my team want to put a heat-shrink tube over the LED as well because they think it will concentrate the light into more of a "beam". My concern is, the black heat-shrink tube will absorb the LED light and the intensity that is emitted to the floor will be weaker than if it just left alone.

    Which is more justified? placing a tube over the LED or just letting it shine?

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted