405nm vs 445nm comparison

I’ve been a bit disappointed by the 445 nm diode so far. It’s not really burning as well as the 405nm diode. So I decided to put down some estimates to see what is happening.

I was unable to focus the 445nm to a pinpoint as small as the 405nm. If I had to estimate it would be 0.4 – 0.6mm ‘dot’ for the 445nm vs a 0.1 – 0.2mm pin for the 405nm. Let’s run with that:

  • 405nm dot has a surface area of about 0.13mm^2 (using 0.2mm diameter)
  • 445nm dot has a surface area of about 0.79mm^2 (using 0.5mm diameter)
  • Assume the 405nm (200mA) puts out at 225mW
  • Assume the 445nm (700mA) puts out 500mW
  • 405nm delivers 225mW/0.13mm^2 = 1730mW / mm^2
  • 445nm delivers 500mW/0.79mm^2 = 633mW / mm^2

So unless I can get the dot size down with the better lens the 445nm will have a hard time competing with the 405nm. This is consistent with my observations on the CNC so far.

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