Link: LED at 50

Another day, another great History of Science BBC audio slideshow. This one's on the LED, the Light Emitting Diode, invented in 1962 by Nick Holonyak. He invented the lower energy red LED 50 years ago and it's taken much of that half-century to work our way up into the other (higher energy) colours so we can have white light. Holonyak says each higher energy colour required learning from the previous colour how to do it-- a very methodical, incremental way of cracking a problem.

Are blue LEDs out of focus for you? For me they are diffuse splodges compared to the red ones. 

Nick Holonyak and his Red LED