This conversation got off on a tangent here, but while we are there let me mention this. When my laser is in perfect focus I can see a faint, sharp image of the diode face. Focus the image of a light bulb on a piece of paper with a standard magnifying lens and you will see what I am talking about. On some LED flashlights the bright spot they project is an image of the diode face, even the lead connections are visible. I am going to go out on a limb here and make a guess that no two diodes are exactly the same. and that the shape of the beam, at focus is the shape of the emitting portion of the diode itself.
