From: "Dwight K. Elvey" 
To: atm{at}shore.net
Reply-To: "Dwight K. Elvey" 


>From: "Bob May" 
>
>You want to use a very short FL lens to concetrate the light from the LED.
>You may also need to work on the output end of the fiber also to get the
>light going where it needs to go rather than everywhere.  The problem there
>is that the addition of a lens at that point will affect the quality of the
>test.
>I'll note that most tests are done in the dark to eliminate the need for a
>very bright light that needs to overcome the room lighting.
>Lastly, you also need to have the sphere aluminized or the light level will
>be very low.
>
>
>

Hi
 Glass beads are often used as short focal length lenses.
Another thing you might try is to carefully grind down the LED until you
are right at the light emitting surface. You could then glue the fiber as
close as possible. Dwight

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