light guide for infra red emitter 1

[andym]

Hi,

I have posted this on the optical engineering and electrical/electronics forums. Please forgive me, but this is possibly a diverse question and people may have the answer for me in all or one of the forums.

I am designing a hand held infra red transmitter, I need to produce a light guide to get the infra red out of the case into the environment, so that the infra red receiver can pick up the signal. I am fairly happy about the coupling of the infra red led's into the light guide and I intend to have highly polished surfaces on the inside of the light guide in the case in order to enable me to transmit as much light through the light guide. The thought I am having is the exit surface, I obviously want to exit as much light as I possibly can and therefore I assume I need to minimise the internal reflection as much as possible on the exit surface. Does this mean this surface should be diffused? or alternatively should it be a highly polished surface, because I am not interested in even light distribution, just simply getting my light signal out?

Any help or thought would be appreciated.

Andy

 

[mrglynn]

This sounds to me like a basic light pipe design issue. The smoother (high polished) the surface, the more light will transmit through the light pipe. Difussion will alter the light path and thereby reduce the amount of light emitted.
Mike Glynn
763-428-6180